////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 1993-2024 The Octave Project Developers
//
// See the file COPYRIGHT.md in the top-level directory of this
// distribution or <https://octave.org/copyright/>.
//
// This file is part of Octave.
//
// Octave is free software: you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Octave is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Octave; see the file COPYING.  If not, see
// <https://www.gnu.org/licenses/>.
//
////////////////////////////////////////////////////////////////////////

// Parser for Octave.

// C decarations.

%{

#define YYDEBUG 1

#if defined (HAVE_CONFIG_H)
#  include "config.h"
#endif

#include <cstdio>
#include <cstdlib>

#include <iostream>
#include <map>
#include <sstream>

#include "Matrix.h"
#include "cmd-edit.h"
#include "cmd-hist.h"
#include "file-ops.h"
#include "file-stat.h"
#include "oct-env.h"
#include "oct-time.h"
#include "quit.h"

#include "Cell.h"
#include "anon-fcn-validator.h"
#include "builtin-defun-decls.h"
#include "defun.h"
#include "dynamic-ld.h"
#include "error.h"
#include "input.h"
#include "interpreter-private.h"
#include "interpreter.h"
#include "lex.h"
#include "load-path.h"
#include "lo-sysdep.h"
#include "oct-hist.h"
#include "oct-map.h"
#include "ov-classdef.h"
#include "ov-fcn-handle.h"
#include "ov-usr-fcn.h"
#include "ov-null-mat.h"
#include "pager.h"
#include "parse.h"
#include "pt-all.h"
#include "pt-eval.h"
#include "separator-list.h"
#include "symtab.h"
#include "token.h"
#include "unwind-prot.h"
#include "utils.h"
#include "variables.h"

// oct-parse.h must be included after pt-all.h
#include "oct-parse.h"

extern int octave_lex (YYSTYPE *, void *);

// Forward declarations for some functions defined at the bottom of
// the file.

static void yyerror (octave::base_parser& parser, const char *s);

#define lexer (parser.get_lexer ())
#define scanner lexer.m_scanner

// Previous versions of Octave used Bison's YYUSE macro to avoid
// warnings about unused values in rules.  But that Bison macro was
// apparently never intended to be public.  So define our own.  All we
// need to do is mention the symantic value somewhere in the rule.  It
// doesn't actually need to be used to avoid the Bison warning, so just
// define this macro to discard its parameter.
#define OCTAVE_YYUSE(...)

#if defined (HAVE_PRAGMA_GCC_DIAGNOSTIC)
   // Disable this warning for code that is generated by Bison,
   // including grammar rules.  Push the current state so we can
   // restore the warning state prior to functions we define at
   // the bottom of the file.
#  pragma GCC diagnostic push
#  pragma GCC diagnostic ignored "-Wold-style-cast"
#endif

%}

// Bison declarations.

// The grammar currently has 9 shift/reduce conflicts.  Ensure that
// we notice if that number changes.

%expect 9

// We are using the pure parser interface and the reentrant lexer
// interface but the Octave parser and lexer are NOT properly
// reentrant because both still use many global variables.  It should be
// safe to create a parser object and call it while another parser
// object is active (to parse a callback function while the main
// interactive parser is waiting for input, for example) if you take
// care to properly save and restore (typically with an unwind_protect
// object) relevant global values before and after the nested call.

%define api.pure
// No spaces inside the braces for the prefix and push-pull definitions!
%define api.prefix {octave_}
%define api.push-pull both
%parse-param { octave::base_parser& parser }
%lex-param { void *lexer.scanner }

%union
{
  int dummy_type;

  // The type of the basic tokens returned by the lexer.
  octave::token *tok;

  // Lists of separators with optional comment lists attached.
  octave::separator_list *sep_list_type;

  // Types for the nonterminals we generate.
  octave::tree *tree_type;
  octave::tree_matrix *tree_matrix_type;
  octave::tree_cell *tree_cell_type;
  octave::tree_expression *tree_expression_type;
  octave::tree_constant *tree_constant_type;
  octave::tree_fcn_handle *tree_fcn_handle_type;
  octave::tree_superclass_ref *tree_superclass_ref_type;
  octave::tree_metaclass_query *tree_metaclass_query_type;
  octave::tree_function_def *tree_function_def_type;
  octave::tree_anon_fcn_handle *tree_anon_fcn_handle_type;
  octave::tree_identifier *tree_identifier_type;
  octave::tree_index_expression *tree_index_expression_type;
  octave::tree_colon_expression *tree_colon_expression_type;
  octave::tree_argument_list *tree_argument_list_type;
  octave::tree_parameter_list *tree_parameter_list_type;
  octave::tree_command *tree_command_type;
  octave::tree_if_command *tree_if_command_type;
  octave::tree_if_clause *tree_if_clause_type;
  octave::tree_if_command_list *tree_if_command_list_type;
  octave::tree_switch_command *tree_switch_command_type;
  octave::tree_switch_case *tree_switch_case_type;
  octave::tree_switch_case_list *tree_switch_case_list_type;
  octave::tree_decl_elt *tree_decl_elt_type;
  octave::tree_decl_init_list *tree_decl_init_list_type;
  octave::tree_decl_command *tree_decl_command_type;
  octave::tree_statement *tree_statement_type;
  octave::tree_statement_list *tree_statement_list_type;
  octave::tree_arguments_block *tree_arguments_block_type;
  octave::tree_args_block_attribute_list *tree_args_block_attribute_list_type;
  octave::tree_args_block_validation_list *tree_args_block_validation_list_type;
  octave::tree_arg_size_spec *tree_arg_size_spec_type;
  octave::tree_arg_validation *tree_arg_validation_type;
  octave::tree_arg_validation_fcns *tree_arg_validation_fcns_type;
  octave_user_function *octave_user_function_type;

  octave::tree_classdef *tree_classdef_type;
  octave::tree_classdef_attribute* tree_classdef_attribute_type;
  octave::tree_classdef_attribute_list* tree_classdef_attribute_list_type;
  octave::tree_classdef_superclass* tree_classdef_superclass_type;
  octave::tree_classdef_superclass_list* tree_classdef_superclass_list_type;
  octave::tree_classdef_body* tree_classdef_body_type;
  octave::tree_classdef_property* tree_classdef_property_type;
  octave::tree_classdef_property_list* tree_classdef_property_list_type;
  octave::tree_classdef_properties_block* tree_classdef_properties_block_type;
  octave::tree_classdef_method_list* tree_classdef_method_list_type;
  octave::tree_classdef_methods_block* tree_classdef_methods_block_type;
  octave::tree_classdef_event* tree_classdef_event_type;
  octave::tree_classdef_event_list* tree_classdef_event_list_type;
  octave::tree_classdef_events_block* tree_classdef_events_block_type;
  octave::tree_classdef_enum* tree_classdef_enum_type;
  octave::tree_classdef_enum_list* tree_classdef_enum_list_type;
  octave::tree_classdef_enum_block* tree_classdef_enum_block_type;
}

// Tokens with position information.
%token <tok> '=' ':' '-' '+' '*' '/' '~' '!'
%token <tok> '(' ')' '[' ']' '{' '}' '.' '@'
%token <tok> ',' ';' '\n'
%token <tok> ADD_EQ SUB_EQ MUL_EQ DIV_EQ LEFTDIV_EQ POW_EQ
%token <tok> EMUL_EQ EDIV_EQ ELEFTDIV_EQ EPOW_EQ AND_EQ OR_EQ
%token <tok> EXPR_AND_AND EXPR_OR_OR
%token <tok> EXPR_AND EXPR_OR
%token <tok> EXPR_LT EXPR_LE EXPR_EQ EXPR_NE EXPR_GE EXPR_GT
%token <tok> LEFTDIV EMUL EDIV ELEFTDIV
%token <tok> HERMITIAN TRANSPOSE
%token <tok> PLUS_PLUS MINUS_MINUS POW EPOW
%token <tok> NUMBER
// The result of a constant folding operation.
%token <tok> CONSTANT
%token <tok> STRUCT_ELT
%token <tok> NAME
%token <tok> END
%token <tok> DQ_STRING SQ_STRING
%token <tok> FOR PARFOR WHILE DO UNTIL
%token <tok> SPMD
%token <tok> IF ELSEIF ELSE
%token <tok> SWITCH CASE OTHERWISE
%token <tok> BREAK CONTINUE RETURN
%token <tok> UNWIND CLEANUP
%token <tok> TRY CATCH
%token <tok> GLOBAL PERSISTENT
%token <tok> FCN_HANDLE
%token <tok> CLASSDEF
%token <tok> PROPERTIES METHODS EVENTS ENUMERATION
%token <tok> METAQUERY
%token <tok> SUPERCLASSREF
%token <tok> FQ_IDENT
%token <tok> GET SET
%token <tok> FUNCTION
%token <tok> ARGUMENTS
%token <tok> LEXICAL_ERROR
%token <tok> END_OF_INPUT

// Other tokens.
%token <dummy_type> INPUT_FILE
// %token VARARGIN VARARGOUT

// Nonterminals we construct.
%type <dummy_type> push_fcn_symtab push_script_symtab begin_file
%type <dummy_type> stmt_begin anon_fcn_begin
%type <dummy_type> parsing_local_fcns parse_error
%type <tok> param_list_beg param_list_end
%type <tok> function_beg classdef_beg arguments_beg indirect_ref_op
%type <tok> properties_beg methods_beg events_beg enumeration_beg
%type <sep_list_type> sep_no_nl opt_sep_no_nl sep opt_sep
%type <tree_type> input
%type <tree_constant_type> string constant magic_colon
%type <tree_anon_fcn_handle_type> anon_fcn_handle
%type <tree_fcn_handle_type> fcn_handle
%type <tree_matrix_type> matrix_rows
%type <tree_cell_type> cell_rows
%type <tree_expression_type> matrix cell
%type <tree_expression_type> primary_expr oper_expr power_expr
%type <tree_expression_type> simple_expr colon_expr assign_expr expression
%type <tree_expression_type> arg_name
%type <tree_identifier_type> identifier fcn_name magic_tilde
%type <tree_superclass_ref_type> superclass_identifier
%type <tree_metaclass_query_type> meta_identifier
%type <tree_index_expression_type> word_list_cmd
%type <tree_argument_list_type> arg_list word_list assign_lhs
%type <tree_argument_list_type> cell_or_matrix_row
%type <tree_parameter_list_type> opt_param_list param_list
%type <tree_parameter_list_type> param_list1 param_list2
%type <tree_parameter_list_type> return_list return_list1
%type <tree_command_type> command select_command loop_command
%type <tree_command_type> jump_command spmd_command except_command
%type <tree_function_def_type> function
%type <tree_classdef_type> classdef
%type <tree_command_type> file
%type <tree_if_command_type> if_command
%type <tree_if_command_list_type> if_clause_list
%type <tree_if_clause_type> if_clause elseif_clause else_clause
%type <tree_switch_command_type> switch_command
%type <tree_switch_case_type> switch_case default_case
%type <tree_switch_case_list_type> case_list1 case_list
%type <tree_decl_elt_type> decl_elt param_list_elt
%type <tree_decl_init_list_type> decl_init_list
%type <tree_decl_command_type> declaration
%type <tree_statement_type> statement function_end
%type <tree_statement_list_type> simple_list simple_list1 list list1
%type <tree_statement_list_type> statement_list opt_list
%type <tree_statement_list_type> arguments_block_list function_body
%type <tree_statement_list_type> opt_fcn_list fcn_list fcn_list1
%type <tree_classdef_attribute_type> attr
%type <tree_classdef_attribute_list_type> attr_list attr_list1
%type <tree_classdef_superclass_type> superclass
%type <tree_classdef_superclass_list_type> superclass_list superclass_list1
%type <tree_classdef_body_type> class_body class_body1
%type <tree_classdef_property_type> class_property
%type <tree_classdef_property_list_type> property_list property_list1
%type <tree_classdef_properties_block_type> properties_block
%type <tree_classdef_method_list_type> method_list method_list1
%type <tree_classdef_methods_block_type> methods_block
%type <tree_classdef_event_type> class_event
%type <tree_classdef_event_list_type> event_list event_list1
%type <tree_classdef_events_block_type> events_block
%type <tree_classdef_enum_type> class_enum
%type <tree_classdef_enum_list_type> enum_list enum_list1
%type <tree_classdef_enum_block_type> enum_block
%type <tree_function_def_type> method_decl method
%type <tree_arguments_block_type> arguments_block
%type <tree_args_block_attribute_list_type> args_attr_list
%type <tree_args_block_validation_list_type> args_validation_list
%type <tree_arg_validation_type> arg_validation
%type <tree_arg_size_spec_type> size_spec
%type <tree_identifier_type> class_name
%type <tree_arg_validation_fcns_type> validation_fcns
%type <octave_user_function_type> method_decl1

// Precedence and associativity.
%right '=' ADD_EQ SUB_EQ MUL_EQ DIV_EQ LEFTDIV_EQ POW_EQ EMUL_EQ EDIV_EQ ELEFTDIV_EQ EPOW_EQ OR_EQ AND_EQ
%left EXPR_OR_OR
%left EXPR_AND_AND
%left EXPR_OR
%left EXPR_AND
%left EXPR_LT EXPR_LE EXPR_EQ EXPR_NE EXPR_GE EXPR_GT
%left ':'
%left '-' '+'
%left '*' '/' LEFTDIV EMUL EDIV ELEFTDIV
%right UNARY '~' '!'
%left POW EPOW HERMITIAN TRANSPOSE
%right PLUS_PLUS MINUS_MINUS
%left '(' '.' '{'

// How to clean up if there is a parse error.  We handle deleting tokens
// and comments separately and separators are just characters.  The
// remaining items are dynamically allocated parse tree objects that
// must be deleted.  Use the wildcard case (<*>) to detect unhandled
// cases (for example, a new semantic type is added but not handled
// here).

%destructor { } <tok>
%destructor { } <>

%destructor { delete $$; } <tree_type>
%destructor { delete $$; } <tree_matrix_type>
%destructor { delete $$; } <tree_cell_type>
%destructor { delete $$; } <tree_expression_type>
%destructor { delete $$; } <tree_constant_type>
%destructor { delete $$; } <tree_fcn_handle_type>
%destructor { delete $$; } <tree_superclass_ref_type>
%destructor { delete $$; } <tree_metaclass_query_type>
%destructor { delete $$; } <tree_function_def_type>
%destructor { delete $$; } <tree_anon_fcn_handle_type>
%destructor { delete $$; } <tree_identifier_type>
%destructor { delete $$; } <tree_index_expression_type>
%destructor { delete $$; } <tree_argument_list_type>
%destructor { delete $$; } <tree_parameter_list_type>
%destructor { delete $$; } <tree_command_type>
%destructor { delete $$; } <tree_if_command_type>
%destructor { delete $$; } <tree_if_clause_type>
%destructor { delete $$; } <tree_if_command_list_type>
%destructor { delete $$; } <tree_switch_command_type>
%destructor { delete $$; } <tree_switch_case_type>
%destructor { delete $$; } <tree_switch_case_list_type>
%destructor { delete $$; } <tree_decl_elt_type>
%destructor { delete $$; } <tree_decl_init_list_type>
%destructor { delete $$; } <tree_decl_command_type>
%destructor { delete $$; } <tree_statement_type>
%destructor { delete $$; } <tree_statement_list_type>
%destructor { delete $$; } <tree_arguments_block_type>
%destructor { delete $$; } <tree_args_block_attribute_list_type>
%destructor { delete $$; } <tree_args_block_validation_list_type>
%destructor { delete $$; } <tree_arg_validation_type>
%destructor { delete $$; } <tree_arg_size_spec_type>
%destructor { delete $$; } <tree_arg_validation_fcns_type>
%destructor { delete $$; } <octave_user_function_type>

%destructor { delete $$; } <tree_classdef_type>
%destructor { delete $$; } <tree_classdef_attribute_type>
%destructor { delete $$; } <tree_classdef_attribute_list_type>
%destructor { delete $$; } <tree_classdef_superclass_type>
%destructor { delete $$; } <tree_classdef_superclass_list_type>
%destructor { delete $$; } <tree_classdef_body_type>
%destructor { delete $$; } <tree_classdef_property_type>
%destructor { delete $$; } <tree_classdef_property_list_type>
%destructor { delete $$; } <tree_classdef_properties_block_type>
%destructor { delete $$; } <tree_classdef_method_list_type>
%destructor { delete $$; } <tree_classdef_methods_block_type>
%destructor { delete $$; } <tree_classdef_event_type>
%destructor { delete $$; } <tree_classdef_event_list_type>
%destructor { delete $$; } <tree_classdef_events_block_type>
%destructor { delete $$; } <tree_classdef_enum_type>
%destructor { delete $$; } <tree_classdef_enum_list_type>
%destructor { delete $$; } <tree_classdef_enum_block_type>

// Defining a generic destructor generates a warning if destructors are
// already explicitly declared for all types.
//
// %destructor {
//    warning_with_id ("Octave:parser-destructor", "possible memory leak in cleanup following parse error");
// } <*>

// Where to start.
%start input

%%

// ==============================
// Statements and statement lists
// ==============================

input           : simple_list '\n'
                  {
                    OCTAVE_YYUSE ($2);

                    $$ = nullptr;

                    if (! parser.finish_input ($1))
                      YYABORT;
                    else
                      YYACCEPT;
                  }
                | simple_list END_OF_INPUT
                  {
                    OCTAVE_YYUSE ($2);

                    $$ = nullptr;

                    if (! parser.finish_input ($1, true))
                      YYABORT;
                    else
                      YYACCEPT;
                  }
                | file
                  {
                    lexer.m_end_of_input = true;

                    $$ = $1;
                    YYACCEPT;
                  }
                | parse_error
                  {
                    $$ = nullptr;
                    YYABORT;
                  }
                ;

simple_list     : opt_sep_no_nl
                  {
                    // FIXME: should we return an empty statement list
                    // with the separators attached?  For now, delete
                    // the unused list.
                    delete $1;

                    $$ = nullptr;
                  }
                | simple_list1 opt_sep_no_nl
                  { $$ = parser.set_stmt_print_flag ($1, $2, false); }
                ;

simple_list1    : statement
                  { $$ = parser.make_statement_list ($1); }
                | simple_list1 sep_no_nl statement
                  { $$ = parser.append_statement_list ($1, $2, $3, false); }
                ;

statement_list  : opt_sep opt_list
                  {
                    // FIXME: Need to capture separator list here.
                    // For now, delete the unused list.
                    delete $1;

                    $$ = $2;
                  }
                ;

opt_list        : // empty
                  { $$ = nullptr; }
                | list
                  { $$ = $1; }
                ;

list            : list1 opt_sep
                  {
                    $$ = parser.set_stmt_print_flag ($1, $2, true);

                    // FIXME: Need to capture separator list here.
                    // For now, delete the unused list.
                    delete $2;
                  }
                ;

list1           : statement
                  { $$ = parser.make_statement_list ($1); }
                | list1 sep statement
                  { $$ = parser.append_statement_list ($1, $2, $3, true); }
                ;

opt_fcn_list    : // empty
                  { $$ = nullptr; }
                | fcn_list
                  { $$ = $1; }
                ;

fcn_list        : fcn_list1 opt_sep
                  {
                    // FIXME: Need to capture separator list here.
                    // For now, delete the unused list.
                    delete $2;

                    $$ = $1;
                  }
                ;

fcn_list1       : function
                  { $$ = parser.make_function_def_list ($1); }
                | fcn_list1 opt_sep function
                  { $$ = parser.append_function_def_list ($1, $2, $3); }
                ;

statement       : expression
                  { $$ = parser.make_statement ($1); }
                | command
                  { $$ = parser.make_statement ($1); }
                | word_list_cmd
                  { $$ = parser.make_statement ($1); }
                ;

// =================
// Word-list command
// =================

// These are not really like expressions since they can't appear on
// the RHS of an assignment.  But they are also not like commands (IF,
// WHILE, etc.

word_list_cmd   : identifier word_list
                  {
                    if (! ($$ = parser.make_word_list_command ($1, $2)))
                      {
                        // make_index_expression deleted $1 and $2.
                        YYABORT;
                      }
                  }
                ;

word_list       : string
                  { $$ = parser.make_argument_list ($1); }
                | word_list string
                  { $$ = parser.append_argument_list ($1, nullptr, $2); }
                ;

// ===========
// Expressions
// ===========

identifier      : NAME
                  { $$ = parser.make_identifier ($1); }
                ;

superclass_identifier
                : SUPERCLASSREF
                  { $$ = parser.make_superclass_ref ($1); }
                ;

meta_identifier : METAQUERY
                  { $$ = parser.make_metaclass_query ($1); }
                ;

string          : DQ_STRING
                  { $$ = parser.make_constant ($1); }
                | SQ_STRING
                  { $$ = parser.make_constant ($1); }
                ;

constant        : NUMBER
                  { $$ = parser.make_constant ($1); }
                | string
                  { $$ = $1; }
                ;

matrix          : '[' matrix_rows ']'
                  { $$ = parser.finish_matrix ($1, $2, $3); }
                ;

matrix_rows     : cell_or_matrix_row
                  { $$ = parser.make_matrix ($1); }
                | matrix_rows ';' cell_or_matrix_row
                  { $$ = parser.append_matrix_row ($1, $2, $3); }
                ;

cell            : '{' cell_rows '}'
                  { $$ = parser.finish_cell ($1, $2, $3); }
                ;

cell_rows       : cell_or_matrix_row
                  { $$ = parser.make_cell ($1); }
                | cell_rows ';' cell_or_matrix_row
                  { $$ = parser.append_cell_row ($1, $2, $3); }
                ;

// tree_argument_list objects can't be empty or have leading or trailing
// commas, but those are all allowed in matrix and cell array rows.

// FIXME: is tree_argument_list the best object for this purpose, or
// should we have a separate one intended specifically to represent the
// list of objects that make up elements in cell and matrix expressions?

cell_or_matrix_row
                : // empty
                  { $$ = nullptr; }
                | ','
                  {
                    // FIXME: Need to capture separator token info here.
                    OCTAVE_YYUSE ($1);

                    $$ = nullptr;
                  }
                | arg_list
                  { $$ = $1; }
                | arg_list ','
                  {
                    // FIXME: Need to capture separator token info here.
                    OCTAVE_YYUSE ($2);

                    $$ = $1;
                  }
                | ',' arg_list
                  {
                    // FIXME: Need to capture separator token info here.
                    OCTAVE_YYUSE ($1);

                    $$ = $2;
                  }
                | ',' arg_list ','
                  {
                    // FIXME: Need to capture separator token info here.
                    OCTAVE_YYUSE ($1, $3);

                    $$ = $2;
                  }
                ;

fcn_handle      : FCN_HANDLE
                  { $$ = parser.make_fcn_handle ($1); }
                ;

// Note that we are deliberately not setting the beginning of statement
// flag after recognizing the parameter list because we don't want to
// accept word list commands in anonymous function bodies.

anon_fcn_handle : '@' param_list anon_fcn_begin expression
                  {
                    if (! ($$ = parser.make_anon_fcn_handle ($1, $2, $4)))
                      {
                        // make_anon_fcn_handle deleted $2 and $4.
                        YYABORT;
                      }

                    lexer.m_parsing_anon_fcn_body = false;
                    lexer.m_nesting_level.remove ();
                  }
                | '@' param_list anon_fcn_begin error
                  {
                    OCTAVE_YYUSE ($1, $2);

                    lexer.m_parsing_anon_fcn_body = false;

                    $$ = nullptr;

                    parser.bison_error ("anonymous function bodies must be single expressions");
                    YYABORT;
                  }
                ;

primary_expr    : identifier
                  { $$ = $1; }
                | constant
                  { $$ = $1; }
                | fcn_handle
                  { $$ = $1; }
                | matrix
                  {
                    lexer.m_looking_at_matrix_or_assign_lhs = false;
                    $$ = $1;
                  }
                | cell
                  { $$ = $1; }
                | meta_identifier
                  { $$ = $1; }
                | superclass_identifier
                  { $$ = $1; }
                | '(' expression ')'
                  { $$ = $2->mark_in_delims (*($1), *($3)); }
                ;

magic_colon     : ':'
                  { $$ = parser.make_constant ($1); }
                ;

magic_tilde     : '~'
                  { $$ = parser.make_black_hole ($1); }
                ;

arg_list        : expression
                  { $$ = parser.make_argument_list ($1); }
                | magic_colon
                  { $$ = parser.make_argument_list ($1); }
                | magic_tilde
                  { $$ = parser.make_argument_list ($1); }
                | arg_list ',' magic_colon
                  { $$ = parser.append_argument_list ($1, $2, $3); }
                | arg_list ',' magic_tilde
                  { $$ = parser.append_argument_list ($1, $2, $3); }
                | arg_list ',' expression
                  { $$ = parser.append_argument_list ($1, $2, $3); }
                ;

indirect_ref_op : '.'
                  {
                    lexer.m_looking_at_indirect_ref = true;
                    $$ = $1;
                  }
                ;

oper_expr       : primary_expr
                  { $$ = $1; }
                | oper_expr PLUS_PLUS
                  { $$ = parser.make_postfix_op ($1, $2); }
                | oper_expr MINUS_MINUS
                  { $$ = parser.make_postfix_op ($1, $2); }
                | oper_expr '(' ')'
                  {
                    if (! ($$ = parser.make_index_expression ($1, $2, nullptr, $3, '(')))
                      {
                        // make_index_expression deleted $1.
                        YYABORT;
                      }
                  }
                | oper_expr '(' arg_list ')'
                  {
                    if (! ($$ = parser.make_index_expression ($1, $2, $3, $4, '(')))
                      {
                        // make_index_expression deleted $1 and $3.
                        YYABORT;
                      }
                  }
                | oper_expr '{' '}'
                  {
                    if (! ($$ = parser.make_index_expression ($1, $2, nullptr, $3, '{')))
                      {
                        // make_index_expression deleted $1.
                        YYABORT;
                      }
                  }
                | oper_expr '{' arg_list '}'
                  {
                    if (! ($$ = parser.make_index_expression ($1, $2, $3, $4, '{')))
                      {
                        // make_index_expression deleted $1 and $3.
                        YYABORT;
                      }
                  }
                | oper_expr HERMITIAN
                  { $$ = parser.make_postfix_op ($1, $2); }
                | oper_expr TRANSPOSE
                  { $$ = parser.make_postfix_op ($1, $2); }
                | oper_expr indirect_ref_op STRUCT_ELT
                  { $$ = parser.make_indirect_ref ($1, $2, $3); }
                | oper_expr indirect_ref_op '(' expression ')'
                  { $$ = parser.make_indirect_ref ($1, $2, $3, $4, $5); }
                | PLUS_PLUS oper_expr %prec UNARY
                  { $$ = parser.make_prefix_op ($1, $2); }
                | MINUS_MINUS oper_expr %prec UNARY
                  { $$ = parser.make_prefix_op ($1, $2); }
                | '~' oper_expr %prec UNARY
                  { $$ = parser.make_prefix_op ($1, $2); }
                | '!' oper_expr %prec UNARY
                  { $$ = parser.make_prefix_op ($1, $2); }
                | '+' oper_expr %prec UNARY
                  { $$ = parser.make_prefix_op ($1, $2); }
                | '-' oper_expr %prec UNARY
                  { $$ = parser.make_prefix_op ($1, $2); }
                | oper_expr POW power_expr
                  { $$ = parser.make_binary_op ($1, $2, $3); }
                | oper_expr EPOW power_expr
                  { $$ = parser.make_binary_op ($1, $2, $3); }
                | oper_expr '+' oper_expr
                  { $$ = parser.make_binary_op ($1, $2, $3); }
                | oper_expr '-' oper_expr
                  { $$ = parser.make_binary_op ($1, $2, $3); }
                | oper_expr '*' oper_expr
                  { $$ = parser.make_binary_op ($1, $2, $3); }
                | oper_expr '/' oper_expr
                  { $$ = parser.make_binary_op ($1, $2, $3); }
                | oper_expr EMUL oper_expr
                  { $$ = parser.make_binary_op ($1, $2, $3); }
                | oper_expr EDIV oper_expr
                  { $$ = parser.make_binary_op ($1, $2, $3); }
                | oper_expr LEFTDIV oper_expr
                  { $$ = parser.make_binary_op ($1, $2, $3); }
                | oper_expr ELEFTDIV oper_expr
                  { $$ = parser.make_binary_op ($1, $2, $3); }
                ;

power_expr      : primary_expr
                  { $$ = $1; }
                | power_expr PLUS_PLUS
                  { $$ = parser.make_postfix_op ($1, $2); }
                | power_expr MINUS_MINUS
                  { $$ = parser.make_postfix_op ($1, $2); }
                | power_expr '(' ')'
                  {
                    if (! ($$ = parser.make_index_expression ($1, $2, nullptr, $3, '(')))
                      {
                        // make_index_expression deleted $1.
                        YYABORT;
                      }
                  }
                | power_expr '(' arg_list ')'
                  {
                    if (! ($$ = parser.make_index_expression ($1, $2, $3, $4, '(')))
                      {
                        // make_index_expression deleted $1 and $3.
                        YYABORT;
                      }
                  }
                | power_expr '{' '}'
                  {
                    if (! ($$ = parser.make_index_expression ($1, $2, nullptr, $3, '{')))
                      {
                        // make_index_expression deleted $1.
                        YYABORT;
                      }
                  }
                | power_expr '{' arg_list '}'
                  {
                    if (! ($$ = parser.make_index_expression ($1, $2, $3, $4, '{')))
                      {
                        // make_index_expression deleted $1 and $3.
                        YYABORT;
                      }
                  }
                | power_expr indirect_ref_op STRUCT_ELT
                  { $$ = parser.make_indirect_ref ($1, $2, $3); }
                | power_expr indirect_ref_op '(' expression ')'
                  { $$ = parser.make_indirect_ref ($1, $2, $3, $4, $5); }
                | PLUS_PLUS power_expr %prec POW
                  { $$ = parser.make_prefix_op ($1, $2); }
                | MINUS_MINUS power_expr %prec POW
                  { $$ = parser.make_prefix_op ($1, $2); }
                | '~' power_expr %prec POW
                  { $$ = parser.make_prefix_op ($1, $2); }
                | '!' power_expr %prec POW
                  { $$ = parser.make_prefix_op ($1, $2); }
                | '+' power_expr %prec POW
                  { $$ = parser.make_prefix_op ($1, $2); }
                | '-' power_expr %prec POW
                  { $$ = parser.make_prefix_op ($1, $2); }
                ;

colon_expr      : oper_expr ':' oper_expr
                  {
                    if (! ($$ = parser.make_colon_expression ($1, $2, $3)))
                      {
                        // make_colon_expression deleted $1 and $3.
                        YYABORT;
                      }
                  }
                | oper_expr ':' oper_expr ':' oper_expr
                  {
                    if (! ($$ = parser.make_colon_expression ($1, $2, $3, $4, $5)))
                      {
                        // make_colon_expression deleted $1, $3, and $5.
                        YYABORT;
                      }
                  }
                ;

simple_expr     : oper_expr
                  { $$ = $1; }
                | colon_expr
                  { $$ = $1; }
                | simple_expr EXPR_LT simple_expr
                  { $$ = parser.make_binary_op ($1, $2, $3); }
                | simple_expr EXPR_LE simple_expr
                  { $$ = parser.make_binary_op ($1, $2, $3); }
                | simple_expr EXPR_EQ simple_expr
                  { $$ = parser.make_binary_op ($1, $2, $3); }
                | simple_expr EXPR_GE simple_expr
                  { $$ = parser.make_binary_op ($1, $2, $3); }
                | simple_expr EXPR_GT simple_expr
                  { $$ = parser.make_binary_op ($1, $2, $3); }
                | simple_expr EXPR_NE simple_expr
                  { $$ = parser.make_binary_op ($1, $2, $3); }
                | simple_expr EXPR_AND simple_expr
                  { $$ = parser.make_binary_op ($1, $2, $3); }
                | simple_expr EXPR_OR simple_expr
                  { $$ = parser.make_binary_op ($1, $2, $3); }
                | simple_expr EXPR_AND_AND simple_expr
                  { $$ = parser.make_boolean_op ($1, $2, $3); }
                | simple_expr EXPR_OR_OR simple_expr
                  { $$ = parser.make_boolean_op ($1, $2, $3); }
                ;

assign_lhs      : simple_expr
                  {
                    if (! ($$ = parser.validate_matrix_for_assignment ($1)))
                      {
                        // validate_matrix_for_assignment deleted $1.
                        YYABORT;
                      }

                    lexer.m_looking_at_matrix_or_assign_lhs = false;
                  }
                ;

assign_expr     : assign_lhs '=' expression
                  { $$ = parser.make_assign_op ($1, $2, $3); }
                | assign_lhs ADD_EQ expression
                  { $$ = parser.make_assign_op ($1, $2, $3); }
                | assign_lhs SUB_EQ expression
                  { $$ = parser.make_assign_op ($1, $2, $3); }
                | assign_lhs MUL_EQ expression
                  { $$ = parser.make_assign_op ($1, $2, $3); }
                | assign_lhs DIV_EQ expression
                  { $$ = parser.make_assign_op ($1, $2, $3); }
                | assign_lhs LEFTDIV_EQ expression
                  { $$ = parser.make_assign_op ($1, $2, $3); }
                | assign_lhs POW_EQ expression
                  { $$ = parser.make_assign_op ($1, $2, $3); }
                | assign_lhs EMUL_EQ expression
                  { $$ = parser.make_assign_op ($1, $2, $3); }
                | assign_lhs EDIV_EQ expression
                  { $$ = parser.make_assign_op ($1, $2, $3); }
                | assign_lhs ELEFTDIV_EQ expression
                  { $$ = parser.make_assign_op ($1, $2, $3); }
                | assign_lhs EPOW_EQ expression
                  { $$ = parser.make_assign_op ($1, $2, $3); }
                | assign_lhs AND_EQ expression
                  { $$ = parser.make_assign_op ($1, $2, $3); }
                | assign_lhs OR_EQ expression
                  { $$ = parser.make_assign_op ($1, $2, $3); }
                ;

expression      : simple_expr
                  {
                    if ($1 && ($1->is_matrix () || $1->iscell ()))
                      {
                        if (parser.validate_array_list ($1))
                          $$ = $1;
                        else
                          {
                            delete $1;
                            YYABORT;
                          }
                      }
                    else
                      $$ = $1;
                  }
                | assign_expr
                  {
                    if (! $1)
                      YYABORT;

                    $$ = $1;
                  }
                | anon_fcn_handle
                  { $$ = $1; }
                ;

// ================================================
// Commands, declarations, and function definitions
// ================================================

command         : declaration
                  { $$ = $1; }
                | select_command
                  { $$ = $1; }
                | loop_command
                  { $$ = $1; }
                | jump_command
                  { $$ = $1; }
                | spmd_command
                  { $$ = $1; }
                | except_command
                  { $$ = $1; }
                | function
                  { $$ = $1; }
                ;

// ======================
// Declaration statements
// ======================

declaration     : GLOBAL decl_init_list
                  {
                    $$ = parser.make_decl_command ($1, $2);
                    lexer.m_looking_at_decl_list = false;
                  }
                | PERSISTENT decl_init_list
                  {
                    $$ = parser.make_decl_command ($1, $2);
                    lexer.m_looking_at_decl_list = false;
                  }
                ;

decl_init_list   : decl_elt
                  { $$ = parser.make_decl_init_list ($1); }
                | decl_init_list decl_elt
                  { $$ = parser.append_decl_init_list ($1, $2); }
                ;

decl_elt        : identifier
                  { $$ = parser.make_decl_elt ($1); }
                | identifier '=' expression
                  { $$ = parser.make_decl_elt ($1, $2, $3); }
                ;

// ====================
// Selection statements
// ====================

select_command  : if_command
                  { $$ = $1; }
                | switch_command
                  { $$ = $1; }
                ;

// ============
// If statement
// ============

if_command      : if_clause_list else_clause END
                  {
                    if (! ($$ = parser.finish_if_command ($1, $2, $3)))
                      {
                        // finish_if_command deleted $1 and $2.
                        YYABORT;
                      }
                  }
                ;

if_clause_list  : if_clause
                  { $$ = parser.start_if_command ($1); }
                | if_clause_list elseif_clause
                  { $$ = parser.append_if_clause ($1, $2); }
                ;

if_clause       : IF opt_sep expression stmt_begin statement_list
                  { $$ = parser.make_if_clause ($1, $2, $3, $5); }
                ;

elseif_clause   : ELSEIF opt_sep expression stmt_begin statement_list
                  { $$ = parser.make_if_clause ($1, $2, $3, $5); }
                ;

else_clause     : // empty
                  { $$ = nullptr; }
                | ELSE statement_list
                  { $$ = parser.make_if_clause ($1, nullptr, nullptr, $2); }
                ;

// ================
// Switch statement
// ================

switch_command  : SWITCH expression opt_sep case_list END
                  {
                    // FIXME: Need to capture separator list here.
                    // For now, delete the unused list.
                    delete $3;

                    if (! ($$ = parser.finish_switch_command ($1, $2, $4, $5)))
                      {
                        // finish_switch_command deleted $2 and $4.
                        YYABORT;
                      }
                  }
                ;

case_list       : // empty
                  { $$ = nullptr; }
                | default_case
                  { $$ = parser.make_switch_case_list ($1); }
                | case_list1
                  { $$ = $1; }
                | case_list1 default_case
                  { $$ = parser.append_switch_case ($1, $2); }
                ;

case_list1      : switch_case
                  { $$ = parser.make_switch_case_list ($1); }
                | case_list1 switch_case
                  { $$ = parser.append_switch_case ($1, $2); }
                ;

switch_case     : CASE opt_sep expression stmt_begin statement_list
                  {
                    // FIXME: Need to capture separator list here.
                    // For now, delete the unused list.
                    delete $2;

                    $$ = parser.make_switch_case ($1, $3, $5);
                  }
                ;

default_case    : OTHERWISE statement_list
                  { $$ = parser.make_default_switch_case ($1, $2); }
                ;

// =======
// Looping
// =======

loop_command    : WHILE expression stmt_begin statement_list END
                  {
                    parser.maybe_convert_to_braindead_shortcircuit ($2);

                    if (! ($$ = parser.make_while_command ($1, $2, $4, $5)))
                      {
                        // make_while_command deleted $2 and $4.
                        YYABORT;
                      }
                  }
                | DO statement_list UNTIL expression
                  {
                    $$ = parser.make_do_until_command ($1, $2, $3, $4);
                  }
                | FOR assign_lhs '=' expression stmt_begin statement_list END
                  {
                    if (! ($$ = parser.make_for_command ($1, nullptr, $2, $3, $4, nullptr, nullptr, nullptr, $6, $7)))
                      {
                        // make_for_command deleted $2, $4, and $6.
                        YYABORT;
                      }
                  }
                | FOR '(' assign_lhs '=' expression ')' statement_list END
                  {
                    // FIXME: Need to capture token info here.
                    OCTAVE_YYUSE ($2, $4, $6);

                    if (! ($$ = parser.make_for_command ($1, $2, $3, $4, $5, nullptr, nullptr, $6, $7, $8)))
                      {
                        // make_for_command deleted $3, $5, and $7.
                        YYABORT;
                      }
                  }
                | PARFOR assign_lhs '=' expression stmt_begin statement_list END
                  {
                    // FIXME: Need to capture token info here.
                    OCTAVE_YYUSE ($3);

                    if (! ($$ = parser.make_for_command ($1, nullptr, $2, $3, $4, nullptr, nullptr, nullptr, $6, $7)))
                      {
                        // make_for_command deleted $2, $4, and $6.
                        YYABORT;
                      }
                  }
                | PARFOR '(' assign_lhs '=' expression ',' expression ')' statement_list END
                  {
                    // FIXME: Need to capture token info here.
                    OCTAVE_YYUSE ($2, $4, $6, $8);

                    if (! ($$ = parser.make_for_command ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10)))
                      {
                        // make_for_command deleted $3, $5, $7, and $9.
                        YYABORT;
                      }
                  }
                ;

// =======
// Jumping
// =======

jump_command    : BREAK
                  {
                    if (! ($$ = parser.make_break_command ($1)))
                      YYABORT;
                  }
                | CONTINUE
                  {
                    if (! ($$ = parser.make_continue_command ($1)))
                      YYABORT;
                  }
                | RETURN
                  { $$ = parser.make_return_command ($1); }
                ;

// =======================
// Parallel execution pool
// =======================

spmd_command    : SPMD statement_list END
                  {
                    if (! ($$ = parser.make_spmd_command ($1, $2, $3)))
                      {
                        // make_spmd_command deleted $2.
                        YYABORT;
                      }
                  }
                ;

// ==========
// Exceptions
// ==========

except_command  : UNWIND statement_list CLEANUP statement_list END
                  {
                    if (! ($$ = parser.make_unwind_command ($1, $2, $3, $4, $5)))
                      {
                        // make_unwind_command deleted $2 and $4.
                        YYABORT;
                      }
                  }
                | TRY statement_list CATCH opt_sep opt_list END
                  {
                    if (! ($$ = parser.make_try_command ($1, $2, $3, $4, $5, $6)))
                      {
                        // make_try_command deleted $2, $4, and $5.
                        YYABORT;
                      }
                  }
                | TRY statement_list END
                  {
                    if (! ($$ = parser.make_try_command ($1, $2, nullptr, nullptr, nullptr, $3)))
                      {
                        // make_try_command deleted $2.
                        YYABORT;
                      }
                  }
                ;

// ===========================================
// Some 'subroutines' for function definitions
// ===========================================

push_fcn_symtab : // empty
                  {
                    if (! parser.push_fcn_symtab ())
                      YYABORT;

                    $$ = 0;
                  }
                ;

// ===========================
// List of function parameters
// ===========================

param_list_beg  : '('
                  {
                    lexer.m_looking_at_parameter_list = true;
                    lexer.m_arguments_is_keyword = false;

                    if (lexer.m_looking_at_function_handle)
                      {
                        // Will get a real name later.
                        lexer.m_symtab_context.push (octave::symbol_scope ("parser:param_list_beg"));
                        lexer.m_looking_at_function_handle--;
                        lexer.m_looking_at_anon_fcn_args = true;
                      }

                    $$ = $1;
                  }
                ;

param_list_end  : ')'
                  {
                    lexer.m_looking_at_parameter_list = false;
                    lexer.m_arguments_is_keyword = true;
                    lexer.m_looking_for_object_index = false;
                    $$ = $1;
                  }
                ;

opt_param_list  : // empty
                  { $$ = nullptr; }
                | param_list
                  { $$ = $1; }
                ;

param_list      : param_list_beg param_list1 param_list_end
                  {
                    if ($2)
                      lexer.mark_as_variables ($2->variable_names ());

                    $$ = $2->mark_in_delims (*($1), *($3));
                  }
                | param_list_beg error
                  {
                    OCTAVE_YYUSE ($1);

                    $$ = nullptr;

                    parser.bison_error ("invalid parameter list");
                    YYABORT;
                  }
                ;

param_list1     : // empty
                  { $$ = parser.make_parameter_list (octave::tree_parameter_list::in); }
                | param_list2
                  {
                    $1->mark_as_formal_parameters ();

                    if (parser.validate_param_list ($1, octave::tree_parameter_list::in))
                      {
                        lexer.mark_as_variables ($1->variable_names ());
                        $$ = $1;
                      }
                    else
                      {
                        delete $1;
                        YYABORT;
                      }
                  }
                ;

param_list2     : param_list_elt
                  { $$ = parser.make_parameter_list (octave::tree_parameter_list::in, $1); }
                | param_list2 ',' param_list_elt
                  { $$ = parser.append_parameter_list ($1, $2, $3); }
                ;

param_list_elt  : decl_elt
                  { $$ = $1; }
                | magic_tilde
                  { $$ = parser.make_decl_elt ($1); }
                ;

// ===================================
// List of function return value names
// ===================================

return_list     : '[' ']'
                  {
                    lexer.m_looking_at_return_list = false;

                    octave::tree_parameter_list *tmp = parser.make_parameter_list (octave::tree_parameter_list::out);

                    $$ = tmp->mark_in_delims (*($1), *($2));
                  }
                | identifier
                  {
                    lexer.m_looking_at_return_list = false;

                    octave::tree_parameter_list *tmp = parser.make_parameter_list (octave::tree_parameter_list::out, $1);

                    // Even though this parameter list can contain only
                    // a single identifier, we still need to validate it
                    // to check for varargin or varargout.

                    if (parser.validate_param_list (tmp, octave::tree_parameter_list::out))
                      $$ = tmp;
                    else
                      {
                        delete tmp;
                        YYABORT;
                      }
                  }
                | '[' return_list1 ']'
                  {
                    lexer.m_looking_at_return_list = false;

                    // Check for duplicate parameter names, varargin,
                    // or varargout.

                    if (parser.validate_param_list ($2, octave::tree_parameter_list::out))
                      $$ = $2->mark_in_delims (*($1), *($3));
                    else
                      {
                        delete $2;
                        YYABORT;
                      }
                  }
                ;

return_list1    : identifier
                  { $$ = parser.make_parameter_list (octave::tree_parameter_list::out, $1); }
                | return_list1 ',' identifier
                  { $$ = parser.append_parameter_list ($1, $2, $3); }
                ;

// =======================
// Script or function file
// =======================

parsing_local_fcns
                : // empty
                  { parser.parsing_local_functions (true); }
                ;

push_script_symtab : // empty
                  {
                    $$ = 0;

                    // This scope may serve as the parent scope for local
                    // functions in classdef files..
                    lexer.m_symtab_context.push (octave::symbol_scope ("parser:push_script_symtab"));
                  }
                ;

begin_file      : push_script_symtab INPUT_FILE
                  { $$ = 0; }
                ;

file            : begin_file statement_list END_OF_INPUT
                  {
                    if (lexer.m_reading_fcn_file)
                      {
                        // Delete the dummy statement_list we created
                        // after parsing the function.  Any function
                        // definitions found in the file have already
                        // been stored in the symbol table or in
                        // base_parser::m_primary_fcn.

                        // Unused symbol table context.
                        lexer.m_symtab_context.pop ();

                        delete $2;
                      }
                    else
                      {
                        octave::tree_statement *end_of_script = parser.make_end ("endscript", true, $3);

                        parser.make_script ($2, end_of_script);
                      }

                    if (! parser.validate_primary_fcn ())
                      YYABORT;

                    $$ = nullptr;
                  }
                | begin_file opt_sep classdef parsing_local_fcns opt_sep opt_fcn_list END_OF_INPUT
                  {
                    // We need to skip whitespace before the classdef
                    // keyword.  The opt_sep rule is more liberal than
                    // we need to be because it accepts ';' and ',' in
                    // addition to '\n', but we need to use it to avoid
                    // creating a reduce/reduce conflict with the rule
                    // above.  Matching the extra ';' and ',' characters
                    // doesn't cause trouble because the lexer ensures
                    // that classdef is the first token in the file.

                    // FIXME: Need to capture separator lists here.
                    // For now, delete the unused lists.
                    delete $2;
                    delete $5;

                    // Unused symbol table context.
                    lexer.m_symtab_context.pop ();

                    if (! parser.finish_classdef_file ($3, $6, $7))
                      YYABORT;

                    $$ = nullptr;
                  }
                ;

// ===================
// Function definition
// ===================

function_beg    : push_fcn_symtab FUNCTION
                  {
                    if (lexer.m_reading_classdef_file || lexer.m_parsing_classdef)
                      lexer.m_maybe_classdef_get_set_method = true;

                    $$ = $2;
                  }
                ;

fcn_name        : identifier
                  {
                    if (! ($$ = parser.make_fcn_name ($1)))
                      {
                        // make_fcn_name deleted $1.
                        YYABORT;
                      }

                    lexer.m_arguments_is_keyword = true;
                  }
                | GET '.' identifier
                  {
                    $$ = $3->mark_get_set (*($1), *($2));

                    lexer.m_parsed_function_name.top () = true;
                    lexer.m_maybe_classdef_get_set_method = false;
                    lexer.m_parsing_classdef_get_method = true;
                    lexer.m_arguments_is_keyword = true;
                  }
                | SET '.' identifier
                  {
                    $$ = $3->mark_get_set (*($1), *($2));

                    lexer.m_parsed_function_name.top () = true;
                    lexer.m_maybe_classdef_get_set_method = false;
                    lexer.m_parsing_classdef_set_method = true;
                    lexer.m_arguments_is_keyword = true;
                  }
                ;

function_end    : END
                  {
                    parser.endfunction_found (true);

                    if (parser.end_token_ok ($1, octave::token::function_end))
                      $$ = parser.make_end ("endfunction", false, $1);
                    else
                      {
                        parser.end_token_error ($1, octave::token::function_end);
                        YYABORT;
                      }
                  }
                | END_OF_INPUT
                  {
// A lot of tests are based on the assumption that this is OK
//                  if (lexer.m_reading_script_file)
//                    {
//                      parser.bison_error ("function body open at end of script");
//                      YYABORT;
//                    }

                    if (parser.endfunction_found ())
                      {
                        parser.bison_error ("inconsistent function endings -- "
                                 "if one function is explicitly ended, "
                                 "so must all the others");
                        YYABORT;
                      }

                    if (! (lexer.m_reading_fcn_file || lexer.m_reading_script_file
                           || lexer.input_from_eval_string ()))
                      {
                        parser.bison_error ("function body open at end of input");
                        YYABORT;
                      }

                    if (lexer.m_reading_classdef_file)
                      {
                        parser.bison_error ("classdef body open at end of input");
                        YYABORT;
                      }

                    $$ = parser.make_end ("endfunction", true, $1);
                  }
                ;

function        : function_beg fcn_name opt_param_list function_body function_end
                  {
                    $$ = parser.make_function ($1, nullptr, nullptr, $2, $3, $4, $5);
                  }
                | function_beg return_list '=' fcn_name opt_param_list function_body function_end
                  {
                    $$ = parser.make_function ($1, $2, $3, $4, $5, $6, $7);
                  }
                ;

function_body   : statement_list
                  {
                    $$ = $1;
                  }
                | opt_sep arguments_block_list statement_list
                  {
                    $$ = parser.append_function_body ($2, $3);
                  }
                ;

arguments_block_list
                : arguments_block
                  {
                    octave::tree_statement *stmt = parser.make_statement ($1);

                    $$ = parser.make_statement_list (stmt);
                  }
                | arguments_block_list opt_sep arguments_block
                  {
                    octave::tree_statement *stmt = parser.make_statement ($3);

                    $$ = parser.append_statement_list ($1, $2, stmt, false);
                  }
                ;

arguments_block : arguments_beg opt_sep args_attr_list args_validation_list opt_sep END
                  {
                    // FIXME: Need to capture separator list here.
                    // For now, delete the unused lists.
                    delete $2;
                    delete $5;

                    if (! ($$ = parser.make_arguments_block ($1, $3, $4, $6)))
                      {
                        // make_arguments_block deleted $3, and $4.
                        YYABORT;
                      }

                    lexer.m_arguments_is_keyword = true;
                  }
                ;

arguments_beg   : ARGUMENTS
                  {
                    $$ = $1;

                    lexer.m_arguments_is_keyword = false;
                  }
                ;

args_attr_list  : // empty
                  { $$ = nullptr; }
                | '(' identifier ')'
                  {
                    $2->mark_in_delims (*($1), *($3));

                    // Error if $$ is nullptr.
                    if  (! ($$ = parser.make_args_attribute_list ($2)))
                      {
                        // make_args_attribute_list deleted $2.
                        YYABORT;
                      }
                  }
                ;

args_validation_list
                  : arg_name arg_validation
                    {
                      $2->arg_name ($1);
                      $$ = parser.make_args_validation_list ($2);
                    }
                  | args_validation_list sep arg_name arg_validation
                    {
                      // FIXME: Need to capture SEP here.
                      // For now, delete the unused list.
                      delete $2;

                      $4->arg_name ($3);
                      $$ = parser.append_args_validation_list ($1, $4);
                    }
                  ;

// FIXME: Change grammar to allow IDENTIFIER to be be either
// "NAME" or "NAME '.' NAME", possibly not entered in the symbol
// table for the current scope.  Also stash comments before identifier.

arg_name          : identifier
                    { $$ = $1; }
                  ;

arg_validation    : size_spec class_name validation_fcns
                    {
                      if (! ($$ = parser.make_arg_validation ($1, $2, $3)))
                        {
                          // make_arg_validation deleted ...
                          YYABORT;
                        }
                    }
                  | size_spec class_name validation_fcns '=' expression
                    {
                      if (! ($$ = parser.make_arg_validation ($1, $2, $3, $4, $5)))
                        {
                          // make_arg_validation deleted ...
                          YYABORT;
                        }
                    }
                ;

size_spec       : // empty
                  { $$ = nullptr; }
                | '(' arg_list ')'
                  {
                    $2->mark_in_delims (*($1), *($3));

                    if (! ($$ = parser.make_arg_size_spec ($2)))
                      {
                        // make_arg_size_spec deleted $2.
                        YYABORT;
                      }
                  }
                ;

class_name      : // empty
                  { $$ = nullptr; }
                | identifier
                  { $$ = $1; }
                ;

// Use argument list so we can accept anonymous functions.
validation_fcns : // empty
                  { $$ = nullptr; }
                | '{' arg_list '}'
                  {
                    $2->mark_in_delims (*($1), *($3));

                    if (! ($$ = parser.make_arg_validation_fcns ($2)))
                      {
                        // make_arg_validation_fcns deleted $2.
                        YYABORT;
                      }
                  }
                ;

// ========
// Classdef
// ========

classdef_beg    : CLASSDEF
                  {
                    if (! lexer.m_reading_classdef_file)
                      {
                        parser.bison_error ("classdef must appear inside a file containing only a class definition");
                        YYABORT;
                      }

                    // Create invalid parent scope.
                    lexer.m_symtab_context.push (octave::symbol_scope::anonymous ());
                    lexer.m_parsing_classdef = true;
                    lexer.m_parsing_classdef_decl = true;
                    lexer.m_classdef_element_names_are_keywords = true;

                    $$ = $1;
                  }
                ;

classdef        : classdef_beg attr_list identifier opt_sep superclass_list class_body END
                  {
                    // FIXME: Need to capture separator list here.
                    // For now, delete the unused list.
                    delete $4;

                    lexer.m_parsing_classdef = false;

                    if (! ($$ = parser.make_classdef ($1, $2, $3, $5, $6, $7)))
                      {
                        // make_classdef deleted $2, $3, $5, $6
                        YYABORT;
                      }
                  }
                ;

attr_list       : // empty
                  { $$ = nullptr; }
                | '(' attr_list1 ')' opt_sep
                  {
                    // FIXME: Need to capture separator list here.
                    // For now, delete the unused list.
                    delete $4;

                    $$ = $2->mark_in_delims (*($1), *($3));
                  }
                ;

attr_list1      : attr
                  { $$ = parser.make_classdef_attribute_list ($1); }
                | attr_list1 ',' attr
                  { $$ = parser.append_classdef_attribute ($1, $2, $3); }
                ;

attr            : identifier
                  { $$ = parser.make_classdef_attribute ($1); }
                | identifier '=' expression
                  { $$ = parser.make_classdef_attribute ($1, $2, $3); }
                | '~' identifier
                  { $$ = parser.make_not_classdef_attribute ($1, $2); }
                | '!' identifier
                  { $$ = parser.make_not_classdef_attribute ($1, $2); }
                ;

superclass_list : // empty
                  {
                    lexer.m_parsing_classdef_decl = false;
                    lexer.m_parsing_classdef_superclass = false;
                    $$ = nullptr;
                  }
                | superclass_list1 opt_sep
                  {
                    // FIXME: Need to capture separator list here.
                    // For now, delete the unused list.
                    delete $2;

                    lexer.m_parsing_classdef_decl = false;
                    lexer.m_parsing_classdef_superclass = false;
                    $$ = $1;
                  }
                ;

superclass_list1
                : EXPR_LT superclass
                  { $$ = parser.make_classdef_superclass_list ($1, $2); }
                | superclass_list1 EXPR_AND superclass
                  { $$ = parser.append_classdef_superclass ($1, $2, $3); }
                ;

superclass      : FQ_IDENT
                  { $$ = parser.make_classdef_superclass ($1); }
                ;

class_body      : // empty
                  {
                    lexer.m_classdef_element_names_are_keywords = false;
                    $$ = nullptr;
                  }
                | class_body1 opt_sep
                  {
                    // FIXME: Need to capture separator list here.
                    // For now, delete the unused list.
                    delete $2;

                    lexer.m_classdef_element_names_are_keywords = false;
                    $$ = $1;
                  }
                ;

class_body1     : properties_block
                  { $$ = parser.make_classdef_body ($1); }
                | methods_block
                  { $$ = parser.make_classdef_body ($1); }
                | events_block
                  { $$ = parser.make_classdef_body ($1); }
                | enum_block
                  { $$ = parser.make_classdef_body ($1); }
                | class_body1 opt_sep properties_block
                  {
                    // FIXME: Need to capture separator list here.
                    // For now, delete the unused list.
                    delete $2;

                    $$ = parser.append_classdef_properties_block ($1, $3);
                  }
                | class_body1 opt_sep methods_block
                  {
                    // FIXME: Need to capture separator list here.
                    // For now, delete the unused list.
                    delete $2;

                    $$ = parser.append_classdef_methods_block ($1, $3);
                  }
                | class_body1 opt_sep events_block
                  {
                    // FIXME: Need to capture separator list here.
                    // For now, delete the unused list.
                    delete $2;

                    $$ = parser.append_classdef_events_block ($1, $3);
                  }
                | class_body1 opt_sep enum_block
                  {
                    // FIXME: Need to capture separator list here.
                    // For now, delete the unused list.
                    delete $2;

                    $$ = parser.append_classdef_enum_block ($1, $3);
                  }
                ;

properties_block
                : properties_beg opt_sep attr_list property_list END
                  {
                    // FIXME: Need to capture separator list here.
                    // For now, delete the unused list.
                    delete $2;

                    if (! ($$ = parser.make_classdef_properties_block ($1, $3, $4, $5)))
                      {
                        // make_classdef_properties_block deleted $3 and $4.
                        YYABORT;
                      }
                  }
                ;

properties_beg  : PROPERTIES
                  {
                    lexer.m_classdef_element_names_are_keywords = false;
                    $$ = $1;
                  }
                ;

property_list   : // empty
                  {
                    lexer.m_classdef_element_names_are_keywords = true;
                    $$ = nullptr;
                  }
                | property_list1 opt_sep
                  {
                    // FIXME: Need to capture separator list here.
                    // For now, delete the unused list.
                    delete $2;

                    lexer.m_classdef_element_names_are_keywords = true;
                    $$ = $1;
                  }
                ;

property_list1
                : class_property
                  { $$ = parser.make_classdef_property_list ($1); }
                | property_list1 sep class_property
                  {
                    // FIXME: Need to capture SEP here.
                    // For now, delete the unused list.
                    delete $2;

                    // We don't look ahead to grab end-of-line comments.
                    // Instead, they are grabbed when we see the
                    // identifier that becomes the next element in the
                    // list.  If the element at the end of the list
                    // doesn't have a doc string, see whether the
                    // element we are adding is storing an end-of-line
                    // comment for us to use.

                    octave::tree_classdef_property *last_elt = $1->back ();

                    if (! last_elt->have_doc_string ())
                      {
                        octave::comment_list comments = $3->leading_comments ();

                        if (! comments.empty ())
                          {
                            octave::comment_elt elt = comments.front ();

                            if (elt.is_end_of_line ())
                              last_elt->doc_string (elt.text ());
                          }
                      }

                    $$ = parser.append_classdef_property ($1, $3);
                  }
                ;

class_property  : identifier arg_validation
                  { $$ = parser.make_classdef_property ($1, $2); }
                ;

methods_block   : methods_beg opt_sep attr_list method_list END
                  {
                    // FIXME: Need to capture separator list here.
                    // For now, delete the unused list.
                    delete $2;

                    if (! ($$ = parser.make_classdef_methods_block ($1, $3, $4, $5)))
                      {
                        // make_classdef_methods_block deleted $3 and $4.
                        YYABORT;
                      }
                  }
                ;

methods_beg     : METHODS
                  {
                    lexer.m_classdef_element_names_are_keywords = false;
                    $$ = $1;
                  }
                ;

method_decl1    : identifier
                  {
                    if (! ($$ = parser.start_classdef_external_method ($1)))
                      YYABORT;
                  }
                | identifier param_list
                  {
                    if (! ($$ = parser.start_classdef_external_method ($1, $2)))
                      YYABORT;
                  }
                ;

method_decl     : method_decl1
                  { $$ = parser.finish_classdef_external_method ($1); }
                | return_list '='
                  {
                    lexer.m_defining_fcn++;
                    lexer.m_parsed_function_name.push (false);
                  }
                  method_decl1
                  {
                    lexer.m_defining_fcn--;
                    lexer.m_parsed_function_name.pop ();

                    $$ = parser.finish_classdef_external_method ($4, $1, $2);
                  }
                ;

method          : method_decl
                  { $$ = $1; }
                | function
                  { $$ = $1; }
                ;

method_list     : // empty
                  {
                    lexer.m_classdef_element_names_are_keywords = true;
                    $$ = nullptr;
                  }
                | method_list1 opt_sep
                  {
                    // FIXME: Need to capture separator list here.
                    // For now, delete the unused list.
                    delete $2;

                    lexer.m_classdef_element_names_are_keywords = true;
                    $$ = $1;
                  }
                ;

method_list1    : method
                  { $$ = parser.make_classdef_method_list ($1); }
                | method_list1 opt_sep method
                  {
                    // FIXME: Need to capture separator list here.
                    // For now, delete the unused list.
                    delete $2;

                    $$ = parser.append_classdef_method ($1, $3);
                  }
                ;

events_block    : events_beg opt_sep attr_list event_list END
                  {
                    // FIXME: Need to capture separator list here.
                    // For now, delete the unused list.
                    delete $2;

                    if (! ($$ = parser.make_classdef_events_block ($1, $3, $4, $5)))
                      {
                        // make_classdef_events_block deleted $4 and $5.
                        YYABORT;
                      }
                  }
                ;

events_beg      : EVENTS
                  {
                    lexer.m_classdef_element_names_are_keywords = false;
                    $$ = $1;
                  }
                ;

event_list      : // empty
                  {
                    lexer.m_classdef_element_names_are_keywords = true;
                    $$ = nullptr;
                  }
                | event_list1 opt_sep
                  {
                    // FIXME: Need to capture separator list here.
                    // For now, delete the unused list.
                    delete $2;

                    lexer.m_classdef_element_names_are_keywords = true;
                    $$ = $1;
                  }
                ;

event_list1     : class_event
                  { $$ = parser.make_classdef_event_list ($1); }
                | event_list1 opt_sep class_event
                  {
                    // FIXME: Need to capture separator list here.
                    // For now, delete the unused list.
                    delete $2;

                    $$ = parser.append_classdef_event ($1, $3);
                  }
                ;

class_event     : identifier
                  { $$ = parser.make_classdef_event ($1); }
                ;

enum_block      : enumeration_beg opt_sep attr_list enum_list END
                  {
                    // FIXME: Need to capture separator list here.
                    // For now, delete the unused list.
                    delete $2;

                    if (! ($$ = parser.make_classdef_enum_block ($1, $3, $4, $5)))
                      {
                        // make_classdef_enum_block deleted $3 and $4.
                        YYABORT;
                      }
                  }
                ;

enumeration_beg : ENUMERATION
                  {
                    lexer.m_classdef_element_names_are_keywords = false;
                    $$ = $1;
                  }
                ;

enum_list       : // empty
                  {
                    lexer.m_classdef_element_names_are_keywords = true;
                    $$ = nullptr;
                  }
                | enum_list1 opt_sep
                  {
                    // FIXME: Need to capture separator list here.
                    // For now, delete the unused list.
                    delete $2;

                    lexer.m_classdef_element_names_are_keywords = true;
                    $$ = $1;
                  }
                ;

enum_list1      : class_enum
                  { $$ = parser.make_classdef_enum_list ($1); }
                | enum_list1 opt_sep class_enum
                  {
                    // FIXME: Need to capture separator list here.
                    // For now, delete the unused list.
                    delete $2;

                    $$ = parser.append_classdef_enum ($1, $3);
                  }
                ;

class_enum      : identifier '(' expression ')'
                  { $$ = parser.make_classdef_enum ($1, $2, $3, $4); }
                ;

// =============
// Miscellaneous
// =============

stmt_begin      : // empty
                  {
                    $$ = 0;
                    lexer.m_at_beginning_of_statement = true;
                  }
                ;

anon_fcn_begin  : // empty
                  {
                    $$ = 0;
                    lexer.m_at_beginning_of_statement = true;
                    lexer.m_parsing_anon_fcn_body = true;
                  }
                ;

parse_error     : LEXICAL_ERROR
                  {
                    $$ = 0;
                    std::string msg = $1->text ();
                    parser.bison_error (msg.c_str ());
                  }
                | error
                  { $$ = 0; }
                ;

sep_no_nl       : ','
                  { $$ = new octave::separator_list (*($1)); }
                | ';'
                  { $$ = new octave::separator_list (*($1)); }
                | sep_no_nl ','
                  { $$ = $1->append (*($2)); }
                | sep_no_nl ';'
                  { $$ = $1->append (*($2)); }
                ;

opt_sep_no_nl   : // empty
                  { $$ = nullptr; }
                | sep_no_nl
                  { $$ = $1; }
                ;

sep             : ','
                  { $$ = new octave::separator_list (*($1)); }
                | ';'
                  { $$ = new octave::separator_list (*($1)); }
                | '\n'
                  { $$ = new octave::separator_list (*($1)); }
                | sep ','
                  { $$ = $1->append (*($2)); }
                | sep ';'
                  { $$ = $1->append (*($2)); }
                | sep '\n'
                  { $$ = $1->append (*($2)); }
                ;

opt_sep         : // empty
                  { $$ = nullptr; }
                | sep
                  { $$ = $1; }
                ;

%%

#if defined (HAVE_PRAGMA_GCC_DIAGNOSTIC)
   // Restore prevailing warning state for remainder of the file.
#  pragma GCC diagnostic pop
#endif

// Generic error messages.

#undef lexer
#undef scanner

static void
yyerror (octave::base_parser& parser, const char *s)
{
  parser.bison_error (s);
}

OCTAVE_BEGIN_NAMESPACE(octave)

class parse_exception : public std::runtime_error
{
public:

  parse_exception () = delete;

  parse_exception (const std::string& message, const std::string& fcn_name = "", const std::string& file_name = "", const filepos& pos = filepos ())
    : runtime_error (message), m_message (message), m_fcn_name (fcn_name), m_file_name (file_name), m_pos (pos)
  { }

  OCTAVE_DEFAULT_COPY_MOVE_DELETE (parse_exception)

  std::string message () const { return m_message; }

  // Provided for std::exception interface.
  const char * what () const noexcept { return m_message.c_str (); }

  std::string fcn_name () const { return m_fcn_name; }
  std::string file_name () const { return m_file_name; }

  filepos pos () const { return m_pos; }

  // virtual void display (std::ostream& os) const;

private:

  std::string m_message;

  std::string m_fcn_name;
  std::string m_file_name;
  filepos m_pos;
};

class parse_tree_validator : public tree_walker
{
public:

  parse_tree_validator ()
    : m_scope (symbol_scope::anonymous ()), m_error_list ()
  { }

  OCTAVE_DISABLE_COPY_MOVE (parse_tree_validator)

  ~parse_tree_validator () = default;

  symbol_scope get_scope () const { return m_scope; }

  bool ok () const { return m_error_list.empty (); }

  std::list<parse_exception> error_list () const
  {
    return m_error_list;
  }

  void visit_octave_user_script (octave_user_script& script)
  {
    unwind_protect_var<symbol_scope> restore_var (m_scope, script.scope ());

    tree_statement_list *stmt_list = script.body ();

    if (stmt_list)
      stmt_list->accept (*this);
  }

  void visit_octave_user_function (octave_user_function& fcn)
  {
    unwind_protect_var<symbol_scope> restore_var (m_scope, fcn.scope ());

    tree_statement_list *stmt_list = fcn.body ();

    if (stmt_list)
      stmt_list->accept (*this);

    std::map<std::string, octave_value> subfcns = fcn.subfunctions ();

    if (! subfcns.empty ())
      {
        for (auto& nm_val : subfcns)
          {
            octave_user_function *subfcn = nm_val.second.user_function_value ();

            if (subfcn)
              subfcn->accept (*this);
          }
      }
  }

  void visit_index_expression (tree_index_expression& idx_expr)
  {
    if (idx_expr.is_word_list_cmd ())
      {
        std::string sym_nm = idx_expr.name ();

        if (m_scope.is_variable (sym_nm))
          {
            std::string message = sym_nm + ": invalid use of symbol as both variable and command";
            parse_exception pe (message, m_scope.fcn_name (), m_scope.fcn_file_name (), idx_expr.beg_pos ());

            m_error_list.push_back (pe);
          }
      }
  }

private:

  symbol_scope m_scope;

  std::list<parse_exception> m_error_list;
};

template <typename LIST_T, typename ELT_T>
static LIST_T *
list_append (LIST_T *list, ELT_T elt)
{
  list->push_back (elt);
  return list;
}

template <typename LIST_T, typename ELT_T>
static LIST_T *
list_append (LIST_T *list, const token& /*sep_tok*/, ELT_T elt)
{
  // FIXME: Need to capture SEP_TOK here
  list->push_back (elt);
  return list;
}

std::size_t
base_parser::parent_scope_info::size () const
{
  return m_info.size ();
}

void
base_parser::parent_scope_info::push (const value_type& elt)
{
  m_info.push_back (elt);
}

void
base_parser::parent_scope_info::push (const symbol_scope& scope)
{
  push (value_type (scope, ""));
}

void
base_parser::parent_scope_info::pop ()
{
  m_info.pop_back ();
}

bool
base_parser::parent_scope_info::name_ok (const std::string& name)
{
  // Name can't be the same as any parent function or any other
  // function we've already seen.  We could maintain a complex
  // tree structure of names, or we can just store the set of
  // full names of all the functions, which must be unique.

  std::string full_name;

  for (std::size_t i = 0; i < size()-1; i++)
    {
      const value_type& elt = m_info[i];

      if (name == elt.second)
        return false;

      full_name += elt.second + ">";
    }

  full_name += name;

  if (m_all_names.find (full_name) != m_all_names.end ())
    {
      // Return false (failure) if we are parsing a subfunction, local
      // function, or nested function.  Otherwise, it is OK to have a
      // duplicate name.

      return ! (m_parser.parsing_subfunctions () || m_parser.parsing_local_functions () || m_parser.curr_fcn_depth () > 0);
    }

  m_all_names.insert (full_name);

  return true;
}

bool
base_parser::parent_scope_info::name_current_scope (const std::string& name)
{
  if (! name_ok (name))
    return false;

  if (size () > 0)
    m_info.back().second = name;

  return true;
}

symbol_scope
base_parser::parent_scope_info::parent_scope () const
{
  return size () > 1 ? m_info[size()-2].first : symbol_scope::invalid ();
}

std::string
base_parser::parent_scope_info::parent_name () const
{
  return m_info[size()-2].second;
}

void base_parser::parent_scope_info::clear ()
{
  m_info.clear ();
  m_all_names.clear ();
}

base_parser::base_parser (base_lexer& lxr)
  : m_endfunction_found (false), m_autoloading (false),
    m_fcn_file_from_relative_lookup (false),
    m_parsing_subfunctions (false), m_parsing_local_functions (false),
    m_max_fcn_depth (-1), m_curr_fcn_depth (-1),
    m_primary_fcn_scope (symbol_scope::invalid ()),
    m_curr_class_name (), m_curr_package_name (), m_function_scopes (*this),
    m_primary_fcn (), m_subfunction_names (), m_classdef_object (),
    m_stmt_list (), m_lexer (lxr), m_parser_state (yypstate_new ())
{ }

base_parser::~base_parser ()
{
  delete &m_lexer;

  // FIXME: Deleting the internal Bison parser state structure does
  // not clean up any partial parse trees in the event of an interrupt or
  // error.  It's not clear how to safely do that with the C language
  // parser that Bison generates.  The C++ language parser that Bison
  // generates would do it for us automatically whenever an exception
  // is thrown while parsing input, but there is currently no C++
  // interface for a push parser.

  yypstate_delete (static_cast<yypstate *> (m_parser_state));
}

void
base_parser::reset ()
{
  m_endfunction_found = false;
  m_autoloading = false;
  m_fcn_file_from_relative_lookup = false;
  m_parsing_subfunctions = false;
  m_parsing_local_functions = false;
  m_max_fcn_depth = -1;
  m_curr_fcn_depth = -1;
  m_primary_fcn_scope = symbol_scope::invalid ();
  m_curr_class_name = "";
  m_curr_package_name = "";
  m_function_scopes.clear ();
  m_primary_fcn = octave_value ();
  m_subfunction_names.clear ();
  m_classdef_object.reset ();
  m_stmt_list.reset ();

  m_lexer.reset ();

  yypstate_delete (static_cast<yypstate *> (m_parser_state));
  m_parser_state = yypstate_new ();
}

OCTAVE_NORETURN static void
unexpected_token (int tok_id, const char *where)
{
  error ("unexpected token (= %d) in %s - please report this bug", tok_id, where);
}

// Error messages for mismatched end tokens.

static std::string
end_token_as_string (token::end_tok_type ettype)
{
  std::string retval = "<unknown>";

  switch (ettype)
    {
    case token::simple_end:
      retval = "end";
      break;

    case token::arguments_end:
      retval = "endarguments";
      break;

    case token::classdef_end:
      retval = "endclassdef";
      break;

    case token::enumeration_end:
      retval = "endenumeration";
      break;

    case token::events_end:
      retval = "endevents";
      break;

    case token::for_end:
      retval = "endfor";
      break;

    case token::function_end:
      retval = "endfunction";
      break;

    case token::if_end:
      retval = "endif";
      break;

    case token::methods_end:
      retval = "endmethods";
      break;

    case token::parfor_end:
      retval = "endparfor";
      break;

    case token::properties_end:
      retval = "endproperties";
      break;

    case token::spmd_end:
      retval = "endspmd";
      break;

    case token::switch_end:
      retval = "endswitch";
      break;

    case token::try_catch_end:
      retval = "end_try_catch";
      break;

    case token::unwind_protect_end:
      retval = "end_unwind_protect";
      break;

    case token::while_end:
      retval = "endwhile";
      break;

      // We should have handled all possible enum values above.  Rely on
      // compiler diagnostics to warn if we haven't.  For example, GCC's
      // -Wswitch option, enabled by -Wall, will provide a warning.
    }

  return retval;
}

void
base_parser::statement_list (std::shared_ptr<tree_statement_list>& lst)
{
  if (! lst)
    return;

  if (m_stmt_list)
    {
      // Append additional code to existing statement list.

      while (! lst->empty ())
        {
          m_stmt_list->push_back (lst->front ());
          lst->pop_front ();
        }
    }
  else
    m_stmt_list = lst;
}

void
base_parser::end_token_error (token *tok, token::end_tok_type expected)
{
  std::string msg = ("'" + end_token_as_string (expected) + "' command matched by '" + end_token_as_string (tok->ettype ()) + "'");

  bison_error (msg, tok->beg_pos ());
}

// Check to see that end tokens are properly matched.

bool
base_parser::end_token_ok (token *tok, token::end_tok_type expected)
{
  token::end_tok_type ettype = tok->ettype ();

  return ettype == expected || ettype == token::simple_end;
}

bool
base_parser::push_fcn_symtab ()
{
  m_curr_fcn_depth++;

  if (m_max_fcn_depth < m_curr_fcn_depth)
    m_max_fcn_depth = m_curr_fcn_depth;

  // Will get a real name later.
  m_lexer.m_symtab_context.push (symbol_scope ("parser:push_fcn_symtab"));
  m_function_scopes.push (m_lexer.m_symtab_context.curr_scope ());

  if (! m_lexer.m_reading_script_file && m_curr_fcn_depth == 0 && ! m_parsing_subfunctions)
    {
      m_primary_fcn_scope = m_lexer.m_symtab_context.curr_scope ();
      m_primary_fcn_scope.mark_primary_fcn_scope ();
    }

  if (m_lexer.m_reading_script_file && m_curr_fcn_depth > 0)
    {
      bison_error ("nested functions not implemented in this context");

      return false;
    }

  return true;
}

// Make a constant.

tree_constant *
base_parser::make_constant (token *tok)
{
  int tok_id = tok->token_id ();

  tree_constant *retval = nullptr;

  switch (tok_id)
    {
    case ':':
      retval = new tree_constant (octave_value (octave_value::magic_colon_t), *tok);
      break;

    case NUMBER:
      retval = new tree_constant (tok->number (), tok->text_rep (), *tok);
      break;

    case DQ_STRING:
    case SQ_STRING:
      {
        std::string txt = tok->text ();

        char delim = tok_id == DQ_STRING ? '"' : '\'';
        octave_value tmp (txt, delim);

        if (txt.empty ())
          {
            if (tok_id == DQ_STRING)
              tmp = octave_null_str::instance;
            else
              tmp = octave_null_sq_str::instance;
          }

        if (tok_id == DQ_STRING)
          txt = undo_string_escapes (txt);

        // FIXME: maybe the addition of delims should be handled by
        // tok->text_rep () for character strings?

        retval = new tree_constant (tmp, delim + txt + delim, *tok);
      }
      break;

    default:
      unexpected_token (tok_id, "base_parser::make_constant");
      break;
    }

  return retval;
}

tree_black_hole *
base_parser::make_black_hole (token *tilde)
{
  return new tree_black_hole (*tilde);
}

// Make a function handle.

tree_fcn_handle *
base_parser::make_fcn_handle (token *tok)
{
  tree_fcn_handle *retval = new tree_fcn_handle (*tok);

  return retval;
}

// Make an anonymous function handle.

tree_anon_fcn_handle *
base_parser::make_anon_fcn_handle (token *at_tok, tree_parameter_list *param_list, tree_expression *expr)
{
  // FIXME: We need to examine EXPR and issue an error if any
  // sub-expression contains an assignment, compound assignment,
  // increment, or decrement operator.

  anon_fcn_validator validator (param_list, expr);

  if (! validator.ok ())
    {
      delete param_list;
      delete expr;

      bison_error (validator.message (), validator.beg_pos ());

      return nullptr;
    }

  symbol_scope fcn_scope = m_lexer.m_symtab_context.curr_scope ();
  symbol_scope parent_scope = m_lexer.m_symtab_context.parent_scope ();

  m_lexer.m_symtab_context.pop ();

  expr->set_print_flag (false);

  fcn_scope.mark_static ();

  tree_anon_fcn_handle *retval = new tree_anon_fcn_handle (*at_tok, param_list, expr, fcn_scope, parent_scope);

  std::ostringstream buf;

  tree_print_code tpc (buf);

  retval->accept (tpc);

  std::string file = m_lexer.m_fcn_file_full_name;
  if (! file.empty ())
    buf << ": file: " << file;
  else if (m_lexer.input_from_terminal ())
    buf << ": *terminal input*";
  else if (m_lexer.input_from_eval_string ())
    buf << ": *eval string*";

  filepos at_pos = at_tok->beg_pos ();
  buf << ": line: " << at_pos.line () << " column: " << at_pos.column ();

  std::string scope_name = buf.str ();

  fcn_scope.cache_name (scope_name);

  // FIXME: Stash the filename.  This does not work and produces
  // errors when executed.
  //retval->stash_file_name (m_lexer.m_fcn_file_name);

  return retval;
}

// Build a colon expression.

tree_expression *
base_parser::make_colon_expression (tree_expression *base, token *colon_tok, tree_expression *limit)
{
  return make_colon_expression (base, colon_tok, nullptr, nullptr, limit);
}

tree_expression *
base_parser::make_colon_expression (tree_expression *base, token *colon_1_tok, tree_expression *incr, token *colon_2_tok, tree_expression *limit)
{
  tree_expression *retval = nullptr;

  if (! base || ! limit)
    {
      delete base;
      delete limit;
      delete incr;

      return retval;
    }

  token tmp_colon_2_tok = colon_2_tok ? *colon_2_tok : token ();

  tree_colon_expression *expr = new tree_colon_expression (base, *colon_1_tok, incr, tmp_colon_2_tok, limit);

  retval = expr;

  if (base->is_constant () && limit->is_constant () && (! incr || incr->is_constant ()))
    {
      interpreter& interp = m_lexer.m_interpreter;

      try
        {
          // If the evaluation generates a warning message, restore
          // the previous value of last_warning_message and skip the
          // conversion to a constant value.

          error_system& es = interp.get_error_system ();

          unwind_action restore_last_warning_message (&error_system::set_last_warning_message, &es, es.last_warning_message (""));

          unwind_action restore_discard_warning_messages (&error_system::set_discard_warning_messages, &es, es.discard_warning_messages (true));

          tree_evaluator& tw = interp.get_evaluator ();

          octave_value tmp = expr->evaluate (tw);

          std::string msg = es.last_warning_message ();

          if (msg.empty ())
            {
              std::ostringstream buf;

              tree_print_code tpc (buf);

              expr->accept (tpc);

              std::string orig_text = buf.str ();

              token tok (CONSTANT, tmp, orig_text, expr->beg_pos (), expr->end_pos ());

              tree_constant *tc_retval = new tree_constant (tmp, orig_text, tok);

              delete expr;

              retval = tc_retval;
            }
        }
      catch (const execution_exception&)
        {
          interp.recover_from_exception ();
        }
    }

  return retval;
}

// Build a binary expression.

tree_expression *
base_parser::make_binary_op (tree_expression *op1, token *op_tok, tree_expression *op2)
{
  octave_value::binary_op t = octave_value::unknown_binary_op;

  int tok_id = op_tok->token_id ();

  switch (tok_id)
    {
    case POW:
      t = octave_value::op_pow;
      break;

    case EPOW:
      t = octave_value::op_el_pow;
      break;

    case '+':
      t = octave_value::op_add;
      break;

    case '-':
      t = octave_value::op_sub;
      break;

    case '*':
      t = octave_value::op_mul;
      break;

    case '/':
      t = octave_value::op_div;
      break;

    case EMUL:
      t = octave_value::op_el_mul;
      break;

    case EDIV:
      t = octave_value::op_el_div;
      break;

    case LEFTDIV:
      t = octave_value::op_ldiv;
      break;

    case ELEFTDIV:
      t = octave_value::op_el_ldiv;
      break;

    case EXPR_LT:
      t = octave_value::op_lt;
      break;

    case EXPR_LE:
      t = octave_value::op_le;
      break;

    case EXPR_EQ:
      t = octave_value::op_eq;
      break;

    case EXPR_GE:
      t = octave_value::op_ge;
      break;

    case EXPR_GT:
      t = octave_value::op_gt;
      break;

    case EXPR_NE:
      t = octave_value::op_ne;
      break;

    case EXPR_AND:
      t = octave_value::op_el_and;
      break;

    case EXPR_OR:
      t = octave_value::op_el_or;
      break;

    default:
      unexpected_token (tok_id, "base_parser::make_binary_op");
      break;
    }

  return maybe_compound_binary_expression (op1, *op_tok, op2, t);
}

void
base_parser::maybe_convert_to_braindead_shortcircuit (tree_expression*& expr)
{
  if (expr->is_binary_expression ())
    {
      tree_binary_expression *binexp = dynamic_cast<tree_binary_expression *> (expr);

      token op_tok = binexp->operator_token ();

      tree_expression *lhs = binexp->lhs ();
      tree_expression *rhs = binexp->rhs ();

      maybe_convert_to_braindead_shortcircuit (lhs);
      maybe_convert_to_braindead_shortcircuit (rhs);

      // Operands may have changed.
      binexp->lhs (lhs);
      binexp->rhs (rhs);

      octave_value::binary_op op_type = binexp->op_type ();
      if (op_type == octave_value::op_el_and || op_type == octave_value::op_el_or)
        {
          binexp->preserve_operands ();

          delete expr;

          expr = new tree_braindead_shortcircuit_binary_expression (lhs, op_tok, rhs, op_type);
        }
    }
}

// Build a boolean expression.

tree_expression *
base_parser::make_boolean_op (tree_expression *op1, token *op_tok, tree_expression *op2)
{
  tree_boolean_expression::type t;

  int tok_id = op_tok->token_id ();

  switch (tok_id)
    {
    case EXPR_AND_AND:
      t = tree_boolean_expression::bool_and;
      break;

    case EXPR_OR_OR:
      t = tree_boolean_expression::bool_or;
      break;

    default:
      unexpected_token (tok_id, "base_parser::make_boolean_op");
      break;
    }

  return new tree_boolean_expression (op1, *op_tok, op2, t);
}

// Build a prefix expression.

tree_expression *
base_parser::make_prefix_op (token *op_tok, tree_expression *op1)
{
  octave_value::unary_op t = octave_value::unknown_unary_op;

  int tok_id = op_tok->token_id ();

  switch (tok_id)
    {
    case '~':
    case '!':
      t = octave_value::op_not;
      break;

    case '+':
      t = octave_value::op_uplus;
      break;

    case '-':
      t = octave_value::op_uminus;
      break;

    case PLUS_PLUS:
      t = octave_value::op_incr;
      break;

    case MINUS_MINUS:
      t = octave_value::op_decr;
      break;

    default:
      unexpected_token (tok_id, "base_parser::make_prefix_op");
      break;
    }

  return new tree_prefix_expression (*op_tok, op1, t);
}

// Build a postfix expression.

tree_expression *
base_parser::make_postfix_op (tree_expression *op1, token *op_tok)
{
  octave_value::unary_op t = octave_value::unknown_unary_op;

  int tok_id = op_tok->token_id ();

  switch (tok_id)
    {
    case HERMITIAN:
      t = octave_value::op_hermitian;
      break;

    case TRANSPOSE:
      t = octave_value::op_transpose;
      break;

    case PLUS_PLUS:
      t = octave_value::op_incr;
      break;

    case MINUS_MINUS:
      t = octave_value::op_decr;
      break;

    default:
      unexpected_token (tok_id, "base_parser::make_postfix_op");
      break;
    }

  return new tree_postfix_expression (op1, *op_tok, t);
}

// Build an unwind-protect command.

tree_command *
base_parser::make_unwind_command (token *unwind_tok, tree_statement_list *body, token *cleanup_tok, tree_statement_list *cleanup_stmts, token *end_tok)
{
  tree_command *retval = nullptr;

  if (end_token_ok (end_tok, token::unwind_protect_end))
    {
      retval = new tree_unwind_protect_command (*unwind_tok, body, *cleanup_tok, cleanup_stmts, *end_tok);
    }
  else
    {
      delete body;
      delete cleanup_stmts;

      end_token_error (end_tok, token::unwind_protect_end);
    }

  return retval;
}

// Build a try-catch command.

tree_command *
base_parser::make_try_command (token *try_tok, tree_statement_list *body, token *catch_tok, separator_list *catch_sep_list, tree_statement_list *cleanup_stmts, token *end_tok)
{
  tree_command *retval = nullptr;

  if (end_token_ok (end_tok, token::try_catch_end))
    {
      tree_identifier *id = nullptr;

      // Look for exception ID.  Note that adding a separate rule to
      // match
      //
      //   try
      //     try-body
      //   catch IDENTIFIER
      //     catch-body
      //   end
      //
      // in the grammar leads to yet another shift-reduce conflict, so
      // instead we only match
      //
      //   try
      //     try-body
      //   catch
      //     catch-body
      //   end
      //
      // and then recognize the first form above by checking that the
      // first element of CATCH-BODY is an identifier and that there is
      // is no separator (comma, semicolon, or newline) between the
      // CATCH token and the identifier.

      if (! catch_sep_list && cleanup_stmts && ! cleanup_stmts->empty ())
        {
          tree_statement *stmt = cleanup_stmts->front ();

          if (stmt)
            {
              tree_expression *expr = stmt->expression ();

              if (expr && expr->is_identifier ())
                {
                  id = dynamic_cast<tree_identifier *> (expr);

                  cleanup_stmts->pop_front ();

                  stmt->set_expression (nullptr);
                  delete stmt;
                }
            }
        }

      token tmp_catch_tok = catch_tok ? *catch_tok : token ();

      // FIXME: Need to capture separator list here.
      // For now, delete the unused list.
      delete catch_sep_list;

      retval = new tree_try_catch_command (*try_tok, body, tmp_catch_tok, id, cleanup_stmts, *end_tok);
    }
  else
    {
      delete body;
      delete catch_sep_list;
      delete cleanup_stmts;

      end_token_error (end_tok, token::try_catch_end);
    }

  return retval;
}

// Build a while command.

tree_command *
base_parser::make_while_command (token *while_tok, tree_expression *expr, tree_statement_list *body, token *end_tok)
{
  tree_command *retval = nullptr;

  maybe_warn_assign_as_truth_value (expr);

  if (end_token_ok (end_tok, token::while_end))
    {
      m_lexer.m_looping--;

      retval = new tree_while_command (*while_tok, expr, body, *end_tok);
    }
  else
    {
      delete expr;
      delete body;

      end_token_error (end_tok, token::while_end);
    }

  return retval;
}

// Build a do-until command.

tree_command *
base_parser::make_do_until_command (token *do_tok, tree_statement_list *body, token *until_tok, tree_expression *expr)
{
  maybe_warn_assign_as_truth_value (expr);

  m_lexer.m_looping--;

  return new tree_do_until_command (*do_tok, body, *until_tok, expr);
}

// Build a for command.

tree_command *
base_parser::make_for_command (token *for_tok, token *open_paren, tree_argument_list *lhs, token *eq_tok, tree_expression *expr, token *sep_tok, tree_expression *maxproc, token *close_paren, tree_statement_list *body, token *end_tok)
{
  tree_command *retval = nullptr;

  bool parfor = for_tok->token_id () == PARFOR;

  token tmp_open_paren = open_paren ? *open_paren : token ();
  token tmp_close_paren = close_paren ? *close_paren : token ();
  token tmp_sep_tok = sep_tok ? *sep_tok : token ();

  if (end_token_ok (end_tok, parfor ? token::parfor_end : token::for_end))
    {
      expr->mark_as_for_cmd_expr ();

      m_lexer.m_looping--;

      if (lhs->size () == 1)
        {
          tree_expression *tmp = lhs->remove_front ();

          m_lexer.mark_as_variable (tmp->name ());

          retval = new tree_simple_for_command (parfor, *for_tok, tmp_open_paren, tmp, *eq_tok, expr, tmp_sep_tok, maxproc, tmp_close_paren, body, *end_tok);

          delete lhs;
        }
      else if (parfor)
        {
          delete lhs;
          delete expr;
          delete maxproc;
          delete body;

          bison_error ("invalid syntax for parfor statement");
        }
      else
        {
          m_lexer.mark_as_variables (lhs->variable_names ());

          retval = new tree_complex_for_command (*for_tok, lhs, *eq_tok, expr, body, *end_tok);
        }
    }
  else
    {
      delete lhs;
      delete expr;
      delete maxproc;
      delete body;

      end_token_error (end_tok, parfor ? token::parfor_end : token::for_end);
    }

  return retval;
}

// Build a break command.

tree_command *
base_parser::make_break_command (token *break_tok)
{
  if (! m_lexer.m_looping)
    {
      bison_error ("break must appear within a loop");
      return nullptr;
    }
  else
    return new tree_break_command (*break_tok);
}

// Build a continue command.

tree_command *
base_parser::make_continue_command (token *continue_tok)
{
  if (! m_lexer.m_looping)
    {
      bison_error ("continue must appear within a loop");
      return nullptr;
    }
  else
    return new tree_continue_command (*continue_tok);
}

// Build a return command.

tree_command *
base_parser::make_return_command (token *return_tok)
{
  return new tree_return_command (*return_tok);
}

// Build an spmd command.

tree_spmd_command *
base_parser::make_spmd_command (token *spmd_tok, tree_statement_list *body, token *end_tok)
{
  tree_spmd_command *retval = nullptr;

  if (end_token_ok (end_tok, token::spmd_end))
    retval = new tree_spmd_command (*spmd_tok, body, *end_tok);
  else
    {
      delete body;

      end_token_error (end_tok, token::spmd_end);
    }

  return retval;
}

// Start an if command.

tree_if_command_list *
base_parser::start_if_command (tree_if_clause *clause)
{
  return new tree_if_command_list (clause);
}

// Finish an if command.

tree_if_command *
base_parser::finish_if_command (tree_if_command_list *list, tree_if_clause *else_clause, token *end_tok)
{
  tree_if_command *retval = nullptr;

  if (end_token_ok (end_tok, token::if_end))
    {
      if (else_clause)
        list_append (list, else_clause);

      token if_tok = list->if_token ();

      retval = new tree_if_command (if_tok, list, *end_tok);
    }
  else
    {
      delete list;
      delete else_clause;

      end_token_error (end_tok, token::if_end);
    }

  return retval;
}

// Build an if, elseif, or else clause.

tree_if_clause *
base_parser::make_if_clause (token *if_tok, separator_list *if_sep_list, tree_expression *expr, tree_statement_list *list)
{
  if (expr)
    {
      maybe_warn_assign_as_truth_value (expr);

      maybe_convert_to_braindead_shortcircuit (expr);
    }

  // FIXME: Need to capture separator list here.
  // For now, delete the unused list.
  delete if_sep_list;

  return new tree_if_clause (*if_tok, expr, list);
}

tree_if_command_list *
base_parser::append_if_clause (tree_if_command_list *list, tree_if_clause *clause)
{
  return list_append (list, clause);
}

// Finish a switch command.

tree_switch_command *
base_parser::finish_switch_command (token *switch_tok, tree_expression *expr, tree_switch_case_list *list, token *end_tok)
{
  tree_switch_command *retval = nullptr;

  if (end_token_ok (end_tok, token::switch_end))
    retval = new tree_switch_command (*switch_tok, expr, list, *end_tok);
  else
    {
      delete expr;
      delete list;

      end_token_error (end_tok, token::switch_end);
    }

  return retval;
}

tree_switch_case_list *
base_parser::make_switch_case_list (tree_switch_case *switch_case)
{
  return new tree_switch_case_list (switch_case);
}

// Build a switch case.

tree_switch_case *
base_parser::make_switch_case (token *case_tok, tree_expression *expr, tree_statement_list *list)
{
  maybe_warn_variable_switch_label (expr);

  return new tree_switch_case (*case_tok, expr, list);
}

tree_switch_case *
base_parser::make_default_switch_case (token *default_tok, tree_statement_list *list)
{
  return new tree_switch_case (*default_tok, list);
}

tree_switch_case_list *
base_parser::append_switch_case (tree_switch_case_list *list, tree_switch_case *elt)
{
  return list_append (list, elt);
}

// Build an assignment to a variable.

tree_expression *
base_parser::make_assign_op (tree_argument_list *lhs, token *eq_tok, tree_expression *rhs)
{
  octave_value::assign_op t = octave_value::unknown_assign_op;

  int tok_id = eq_tok->token_id ();

  switch (tok_id)
    {
    case '=':
      t = octave_value::op_asn_eq;
      break;

    case ADD_EQ:
      t = octave_value::op_add_eq;
      break;

    case SUB_EQ:
      t = octave_value::op_sub_eq;
      break;

    case MUL_EQ:
      t = octave_value::op_mul_eq;
      break;

    case DIV_EQ:
      t = octave_value::op_div_eq;
      break;

    case LEFTDIV_EQ:
      t = octave_value::op_ldiv_eq;
      break;

    case POW_EQ:
      t = octave_value::op_pow_eq;
      break;

    case EMUL_EQ:
      t = octave_value::op_el_mul_eq;
      break;

    case EDIV_EQ:
      t = octave_value::op_el_div_eq;
      break;

    case ELEFTDIV_EQ:
      t = octave_value::op_el_ldiv_eq;
      break;

    case EPOW_EQ:
      t = octave_value::op_el_pow_eq;
      break;

    case AND_EQ:
      t = octave_value::op_el_and_eq;
      break;

    case OR_EQ:
      t = octave_value::op_el_or_eq;
      break;

    default:
      unexpected_token (tok_id, "base_parser::make_assign_op");
      break;
    }

  if (! lhs->is_simple_assign_lhs () && t != octave_value::op_asn_eq)
    {
      // Multiple assignments like [x,y] OP= rhs are only valid for
      // '=', not '+=', etc.

      delete lhs;
      delete rhs;

      bison_error ("computed multiple assignment not allowed", eq_tok->beg_pos ());

      return nullptr;
    }

  if (lhs->is_simple_assign_lhs ())
    {
      // We are looking at a simple assignment statement like x = rhs;

      tree_expression *tmp = lhs->remove_front ();

      if ((tmp->is_identifier () || tmp->is_index_expression ()) && iskeyword (tmp->name ()))
        {
          std::string kw = tmp->name ();

          delete tmp;
          delete lhs;
          delete rhs;

          bison_error ("invalid assignment to keyword \"" + kw + "\"", eq_tok->beg_pos ());

          return nullptr;
        }

      delete lhs;

      m_lexer.mark_as_variable (tmp->name ());

      return new tree_simple_assignment (tmp, rhs, false, t);
    }
  else
    {
      std::list<std::string> names = lhs->variable_names ();

      for (const auto& kw : names)
        {
          if (iskeyword (kw))
            {
              delete lhs;
              delete rhs;

              bison_error ("invalid assignment to keyword \"" + kw + "\"", eq_tok->beg_pos ());

              return nullptr;
            }
        }

      m_lexer.mark_as_variables (names);

      return new tree_multi_assignment (lhs, rhs, false);
    }
}

void
base_parser::make_script (tree_statement_list *cmds, tree_statement *end_script)
{
  // Any comments at the beginning of a script file should be
  // attached to the first statement in the file or the END_SCRIPT
  // statement created by the parser.

  if (! cmds)
    cmds = new tree_statement_list ();

  cmds->push_back (end_script);

  symbol_scope script_scope = m_lexer.m_symtab_context.curr_scope ();

  script_scope.cache_name (m_lexer.m_fcn_file_full_name);
  script_scope.cache_fcn_file_name (m_lexer.m_fcn_file_full_name);
  script_scope.cache_dir_name (m_lexer.m_dir_name);

  // First non-copyright comment in classdef body, before first
  // properties, methods, etc. block.

  comment_list leading_comments = cmds->leading_comments ();

  std::string doc_string = leading_comments.find_doc_string ();

  octave_user_script *script = new octave_user_script (m_lexer.m_fcn_file_full_name, m_lexer.m_fcn_file_name, script_scope, cmds, doc_string);

  m_lexer.m_symtab_context.pop ();

  sys::time now;

  script->stash_fcn_file_time (now);
  script->stash_dir_name (m_lexer.m_dir_name);

  m_primary_fcn = octave_value (script);
}

tree_identifier *
base_parser::make_fcn_name (tree_identifier *id)
{
  std::string id_name = id->name ();

  // Make classdef local functions unique from classdef methods.

  if (m_parsing_local_functions && m_curr_fcn_depth == 0)
    id_name = m_lexer.m_fcn_file_name + ">" + id_name;

  if (! m_function_scopes.name_current_scope (id_name))
    {
      // FIXME: is this correct?  Before using position, the column
      // was incremented.  Hmm.

      filepos id_pos = id->beg_pos ();
      id_pos.increment_column ();

      bison_error ("duplicate subfunction or nested function name", id_pos);

      delete id;
      return nullptr;
    }

  symbol_scope curr_scope = m_lexer.m_symtab_context.curr_scope ();
  curr_scope.cache_name (id_name);

  m_lexer.m_parsed_function_name.top () = true;
  m_lexer.m_maybe_classdef_get_set_method = false;

  return id;
}

// Define a function.

// FIXME: combining start_function, finish_function, and
// recover_from_parsing_function should be possible, but it makes
// for a large mess.  Maybe this could be a bit better organized?

tree_function_def *
base_parser::make_function (token *fcn_tok, tree_parameter_list *ret_list, token *eq_tok, tree_identifier *id, tree_parameter_list *param_list, tree_statement_list *body, tree_statement *end_fcn_stmt)
{
  // First non-copyright comments found above and below function keyword.
  comment_elt leading_doc_comment;
  comment_elt body_doc_comment;

  comment_list lc = fcn_tok->leading_comments ();

  if (! lc.empty ())
    leading_doc_comment = lc.find_doc_comment ();

  if (body)
    {
      comment_list bc = body->leading_comments ();

      if (! bc.empty ())
        body_doc_comment = bc.find_doc_comment ();
    }
  else if (end_fcn_stmt)
    {
      comment_list ec = end_fcn_stmt->leading_comments ();

      if (! ec.empty ())
        body_doc_comment = ec.find_doc_comment ();
    }

  // Choose which comment to use for doc string.

  // For ordinary functions, use the first comment that isn't empty.

  // If we are looking at a classdef method and there is a comment
  // prior to the function keyword and another after, then
  //
  //   * Choose the one outside the function definition if either of
  //     the comments use hash '#' characters.  This is the preferred
  //     Octave style.
  //
  //   * Choose the one inside the function definition if both
  //     comments use percent '%' characters.  This is
  //     Matlab-compatible behavior.

  // FIXME: maybe choose which comment to used by checking whether
  // any language extensions are noticed in the entire source file,
  // not just in the comments that are candidates to become the
  // function doc string.

  std::string doc_string;

  if (leading_doc_comment.empty ()
      || (m_lexer.m_parsing_classdef && ! body_doc_comment.empty ()
          && (! (leading_doc_comment.uses_hash_char () || body_doc_comment.uses_hash_char ()))))
    doc_string = body_doc_comment.text ();
  else
    doc_string = leading_doc_comment.text ();

  octave_user_function *tmp_fcn = start_function (id, param_list, body, end_fcn_stmt, doc_string);

  tree_function_def *retval = finish_function (fcn_tok, ret_list, eq_tok, tmp_fcn);

  recover_from_parsing_function ();

  return retval;
}

// Begin defining a function.

octave_user_function *
base_parser::start_function (tree_identifier *id, tree_parameter_list *param_list, tree_statement_list *body, tree_statement *end_fcn_stmt, const std::string& doc_string)
{
  // We'll fill in the return list later.

  std::string id_name = id->name ();

  if (m_lexer.m_parsing_classdef_get_method)
    id_name.insert (0, "get.");
  else if (m_lexer.m_parsing_classdef_set_method)
    id_name.insert (0, "set.");

  m_lexer.m_parsing_classdef_get_method = false;
  m_lexer.m_parsing_classdef_set_method = false;

  if (! body)
    body = new tree_statement_list ();

  body->push_back (end_fcn_stmt);

  octave_user_function *fcn = new octave_user_function (m_lexer.m_symtab_context.curr_scope (), id, param_list, nullptr, body);

  // If input is coming from a file, issue a warning if the name of
  // the file does not match the name of the function stated in the
  // file.  Matlab doesn't provide a diagnostic (it ignores the stated
  // name).
  if (! m_autoloading && m_lexer.m_reading_fcn_file && m_curr_fcn_depth == 0 && ! m_parsing_subfunctions)
    {
      // FIXME: should m_lexer.m_fcn_file_name already be
      // preprocessed when we get here?  It seems to only be a
      // problem with relative filenames.

      std::string nm = m_lexer.m_fcn_file_name;

      std::size_t pos = nm.find_last_of (sys::file_ops::dir_sep_chars ());

      if (pos != std::string::npos)
        nm = m_lexer.m_fcn_file_name.substr (pos+1);

      if (nm != id_name)
        {
          warning_with_id ("Octave:function-name-clash", "function name '%s' does not agree with function filename '%s'", id_name.c_str (), m_lexer.m_fcn_file_full_name.c_str ());

          id_name = nm;
        }
    }

  sys::time now;

  fcn->stash_fcn_file_name (m_lexer.m_fcn_file_full_name);
  fcn->stash_fcn_file_time (now);
  fcn->stash_dir_name (m_lexer.m_dir_name);
  fcn->stash_package_name (m_lexer.m_package_name);
  fcn->mark_as_system_fcn_file ();
  fcn->stash_function_name (id_name);

  if (m_lexer.m_reading_fcn_file || m_lexer.m_reading_classdef_file || m_autoloading)
    {
      if (m_fcn_file_from_relative_lookup)
        fcn->mark_relative ();

      if (m_lexer.m_parsing_class_method)
        {
          if (m_lexer.m_parsing_classdef)
            {
              if (m_curr_class_name == id_name)
                fcn->mark_as_classdef_constructor ();
              else
                fcn->mark_as_classdef_method ();
            }
          else
            {
              if (m_curr_class_name == id_name)
                fcn->mark_as_legacy_constructor ();
              else
                fcn->mark_as_legacy_method ();
            }

          fcn->stash_dispatch_class (m_curr_class_name);
        }

      std::string nm = fcn->fcn_file_name ();

      sys::file_stat fs (nm);

      if (fs && fs.is_newer (now))
        warning_with_id ("Octave:future-time-stamp", "time stamp for '%s' is in the future", nm.c_str ());
    }
  else if (! m_lexer.input_from_tmp_history_file () && ! m_lexer.m_force_script && m_lexer.m_reading_script_file && m_lexer.m_fcn_file_name == id_name)
    warning ("function '%s' defined within script file '%s'", id_name.c_str (), m_lexer.m_fcn_file_full_name.c_str ());

  // Record doc string for functions other than nested functions.
  // We cannot currently record help for nested functions (bug #46008)
  // because the doc_string of the outermost function is read first,
  // whereas this function is called for the innermost function first.
  // We could have a stack of doc_string objects in lexer.
  if (! doc_string.empty () && m_curr_fcn_depth == 0)
    fcn->document (doc_string);


  if (m_lexer.m_reading_fcn_file && m_curr_fcn_depth == 0 && ! m_parsing_subfunctions)
    m_primary_fcn = octave_value (fcn);

  return fcn;
}

tree_statement *
base_parser::make_end (const std::string& type, bool eof, token *end_tok)
{
  return make_statement (new tree_no_op_command (type, eof, *end_tok));
}

tree_function_def *
base_parser::finish_function (token *fcn_tok, tree_parameter_list *ret_list, token *eq_tok, octave_user_function *fcn)
{
  tree_function_def *retval = nullptr;

  if (! ret_list)
    ret_list = new tree_parameter_list (tree_parameter_list::out);

  ret_list->mark_as_formal_parameters ();

  if (fcn)
    {
      fcn->set_fcn_tok (*fcn_tok);

      if (eq_tok)
        fcn->set_eq_tok (*eq_tok);

      std::string fcn_nm = fcn->name ();
      std::string file = fcn->fcn_file_name ();

      std::string tmp = fcn_nm;
      if (! file.empty ())
        tmp += ": " + file;

      symbol_scope fcn_scope = fcn->scope ();
      fcn_scope.cache_name (tmp);
      fcn_scope.cache_fcn_name (fcn_nm);
      fcn_scope.cache_fcn_file_name (file);
      fcn_scope.cache_dir_name (m_lexer.m_dir_name);

      fcn->define_ret_list (ret_list);

      if (m_curr_fcn_depth > 0 || m_parsing_subfunctions)
        {
          octave_value ov_fcn (fcn);

          if (m_endfunction_found && m_function_scopes.size () > 1)
            {
              fcn->mark_as_nested_function ();
              fcn_scope.set_nesting_depth (m_curr_fcn_depth);

              symbol_scope pscope = m_function_scopes.parent_scope ();
              fcn_scope.set_parent (pscope);
              fcn_scope.set_primary_parent (m_primary_fcn_scope);

              pscope.install_nestfunction (fcn_nm, ov_fcn, fcn_scope);

              // For nested functions, the list of parent functions is
              // set in symbol_scope::update_nest.
            }
          else
            {
              fcn->mark_as_subfunction ();
              m_subfunction_names.push_back (fcn_nm);

              fcn_scope.set_parent (m_primary_fcn_scope);
              if (m_parsing_subfunctions)
                fcn_scope.set_primary_parent (m_primary_fcn_scope);

              m_primary_fcn_scope.install_subfunction (fcn_nm, ov_fcn);
            }
        }

      if (m_curr_fcn_depth == 0)
        fcn_scope.update_nest ();

      if (! m_lexer.m_reading_fcn_file && m_curr_fcn_depth == 0)
        {
          // We are either reading a script file or defining a function
          // at the command line, so this definition creates a
          // tree_function object that is placed in the parse tree.
          // Otherwise, it is just inserted in the symbol table,
          // either as a subfunction or nested function (see above),
          // or as the primary function for the file, via
          // m_primary_fcn (see also load_fcn_from_file,,
          // parse_fcn_file, and
          // fcn_info::fcn_info_rep::find_user_function).

          if (m_lexer.m_buffer_function_text)
            {
              fcn->cache_function_text (m_lexer.m_function_text, fcn->time_parsed ());
              m_lexer.m_buffer_function_text = false;
            }

          retval = new tree_function_def (fcn);
        }
    }

  return retval;
}

tree_statement_list *
base_parser::append_function_body (tree_statement_list *body, tree_statement_list *list)
{
  if (list)
    {
      for (const auto& elt : *list)
        list_append (body, elt);

      list->clear ();
      delete (list);
    }

  return body;
}

tree_arguments_block *
base_parser::make_arguments_block (token *arguments_tok, tree_args_block_attribute_list *attr_list, tree_args_block_validation_list *validation_list, token *end_tok)
{
  tree_arguments_block *retval = nullptr;

  if (end_token_ok (end_tok, token::arguments_end))
    retval = new tree_arguments_block (*arguments_tok, attr_list, validation_list, *end_tok);
  else
    {
      delete attr_list;
      delete validation_list;
    }

  return retval;
}

tree_arg_validation *
base_parser::make_arg_validation (tree_arg_size_spec *size_spec, tree_identifier *class_name, tree_arg_validation_fcns *validation_fcns, token *eq_tok, tree_expression *default_value)
{
  // FIXME: Validate arguments and convert to more specific types
  // (std::string for arg_name and class_name, etc).

  token tmp_eq_tok = eq_tok ? *eq_tok : token ();

  return new tree_arg_validation (size_spec, class_name, validation_fcns, tmp_eq_tok, default_value);
}

tree_args_block_attribute_list *
base_parser::make_args_attribute_list (tree_identifier *attribute_name)
{
  // FIXME: Validate argument and convert to more specific type
  // (std::string for attribute_name).

  return new tree_args_block_attribute_list (attribute_name);
}

tree_args_block_validation_list *
base_parser::make_args_validation_list (tree_arg_validation *arg_validation)
{
  return new tree_args_block_validation_list (arg_validation);
}

tree_args_block_validation_list *
base_parser::append_args_validation_list (tree_args_block_validation_list *list, tree_arg_validation *arg_validation)
{
  return list_append (list, arg_validation);
}

tree_arg_size_spec *
base_parser::make_arg_size_spec (tree_argument_list *size_args)
{
  // FIXME: Validate argument.

  return new tree_arg_size_spec (size_args);
}

tree_arg_validation_fcns *
base_parser::make_arg_validation_fcns (tree_argument_list *fcn_args)
{
  // FIXME: Validate argument.

  return new tree_arg_validation_fcns (fcn_args);
}

void
base_parser::recover_from_parsing_function ()
{
  m_lexer.m_symtab_context.pop ();

  if (m_lexer.m_reading_fcn_file && m_curr_fcn_depth == 0 && ! m_parsing_subfunctions)
    m_parsing_subfunctions = true;

  m_curr_fcn_depth--;
  m_function_scopes.pop ();

  m_lexer.m_defining_fcn--;
  m_lexer.m_parsed_function_name.pop ();
  m_lexer.m_looking_at_return_list = false;
  m_lexer.m_looking_at_parameter_list = false;
}

// A CLASSDEF block defines a class that has a constructor and other
// methods, but it is not an executable command.  Parsing the block
// makes some changes in the symbol table (inserting the constructor
// and methods, and adding to the list of known objects) and creates
// a parse tree containing meta information about the class.

tree_classdef *
base_parser::make_classdef (token *cdef_tok, tree_classdef_attribute_list *a, tree_identifier *id, tree_classdef_superclass_list *sc, tree_classdef_body *body, token *end_tok)
{
  tree_classdef *retval = nullptr;

  m_lexer.m_symtab_context.pop ();

  std::string cls_name = id->name ();

  std::string full_name = m_lexer.m_fcn_file_full_name;
  std::string short_name = m_lexer.m_fcn_file_name;

  std::size_t pos = short_name.find_last_of (sys::file_ops::dir_sep_chars ());

  if (pos != std::string::npos)
    short_name = short_name.substr (pos+1);

  if (short_name != cls_name)
    {
      filepos f_pos = id->beg_pos ();

      delete a;
      delete id;
      delete sc;
      delete body;

      bison_error ("invalid classdef definition, the class name must match the filename", f_pos);

    }
  else
    {
      if (end_token_ok (end_tok, token::classdef_end))
        {
          if (! body)
            body = new tree_classdef_body ();

          retval = new tree_classdef (m_lexer.m_symtab_context.curr_scope (), *cdef_tok, a, id, sc, body, *end_tok, m_curr_package_name, full_name);
        }
      else
        {
          delete a;
          delete id;
          delete sc;
          delete body;

          end_token_error (end_tok, token::switch_end);
        }
    }

  return retval;
}

tree_classdef_properties_block *
base_parser::make_classdef_properties_block (token *tok, tree_classdef_attribute_list *a, tree_classdef_property_list *plist, token *end_tok)
{
  tree_classdef_properties_block *retval = nullptr;

  if (end_token_ok (end_tok, token::properties_end))
    {
      if (plist)
        {
          // If the element at the end of the list doesn't have a doc
          // string, see whether the first element of the comments
          // attached to the end token is an end-of-line comment for
          // us to use.

          tree_classdef_property *last_elt = plist->back ();

          if (last_elt && ! last_elt->have_doc_string ())
            {
              comment_list comments = end_tok->leading_comments ();

              if (! comments.empty ())
                {
                  comment_elt elt = comments.front ();

                  if (elt.is_end_of_line ())
                    last_elt->doc_string (elt.text ());
                }
            }
        }
      else
        plist = new tree_classdef_property_list ();

      retval = new tree_classdef_properties_block (*tok, a, plist, *end_tok);
    }
  else
    {
      delete a;
      delete plist;

      end_token_error (end_tok, token::properties_end);
    }

  return retval;
}

tree_classdef_property_list *
base_parser::make_classdef_property_list (tree_classdef_property *prop)
{
  return new tree_classdef_property_list (prop);
}

tree_classdef_property *
base_parser::make_classdef_property (tree_identifier *id, tree_arg_validation *av)
{
  av->arg_name (id);

  if (av->size_spec () || av->class_name () || av->validation_fcns ())
    warning ("size, class, and validation function specifications are not yet supported for classdef properties; INCORRECT RESULTS ARE POSSIBLE!");

  return new tree_classdef_property (av);
}

tree_classdef_methods_block *
base_parser::make_classdef_methods_block (token *tok, tree_classdef_attribute_list *a, tree_classdef_method_list *mlist, token *end_tok)
{
  tree_classdef_methods_block *retval = nullptr;

  if (end_token_ok (end_tok, token::methods_end))
    {
      if (! mlist)
        mlist = new tree_classdef_method_list ();

      retval = new tree_classdef_methods_block (*tok, a, mlist, *end_tok);
    }
  else
    {
      delete a;
      delete mlist;

      end_token_error (end_tok, token::methods_end);
    }

  return retval;
}

tree_classdef_events_block *
base_parser::make_classdef_events_block (token *tok, tree_classdef_attribute_list *a, tree_classdef_event_list *elist, token *end_tok)
{
  tree_classdef_events_block *retval = nullptr;

  if (end_token_ok (end_tok, token::events_end))
    {
      if (! elist)
        elist = new tree_classdef_event_list ();

      retval = new tree_classdef_events_block (*tok, a, elist, *end_tok);
    }
  else
    {
      delete a;
      delete elist;

      end_token_error (end_tok, token::events_end);
    }

  return retval;
}

tree_classdef_event_list *
base_parser::make_classdef_event_list (tree_classdef_event *e)
{
  return new tree_classdef_event_list (e);
}

tree_classdef_event *
base_parser::make_classdef_event (tree_identifier *id)
{
  return new tree_classdef_event (id);
}

tree_classdef_enum_block *
base_parser::make_classdef_enum_block (token *tok, tree_classdef_attribute_list *a, tree_classdef_enum_list *elist, token *end_tok)
{
  tree_classdef_enum_block *retval = nullptr;

  if (end_token_ok (end_tok, token::enumeration_end))
    {
      if (! elist)
        elist = new tree_classdef_enum_list ();

      retval = new tree_classdef_enum_block (*tok, a, elist, *end_tok);
    }
  else
    {
      delete a;
      delete elist;

      end_token_error (end_tok, token::enumeration_end);
    }

  return retval;
}

tree_classdef_enum_list *
base_parser::make_classdef_enum_list (tree_classdef_enum *e)
{
  return new tree_classdef_enum_list (e);
}

tree_classdef_enum *
base_parser::make_classdef_enum (tree_identifier *id, token *open_paren, tree_expression *expr, token *close_paren)
{
  return new tree_classdef_enum (id, *open_paren, expr, *close_paren);
}

tree_classdef_property_list *
base_parser::append_classdef_property (tree_classdef_property_list *list, tree_classdef_property *elt)
{
  return list_append (list, elt);
}

tree_classdef_event_list *
base_parser::append_classdef_event (tree_classdef_event_list *list, tree_classdef_event *elt)
{
  return list_append (list, elt);
}

tree_classdef_enum_list *
base_parser::append_classdef_enum (tree_classdef_enum_list *list, tree_classdef_enum *elt)
{
  return list_append (list, elt);
}

tree_classdef_superclass_list *
base_parser::make_classdef_superclass_list (token *lt_tok, tree_classdef_superclass *sc)
{
  sc->set_separator (*lt_tok);

  return new tree_classdef_superclass_list (sc);
}

tree_classdef_superclass *
base_parser::make_classdef_superclass (token *fqident)
{
  return new tree_classdef_superclass (*fqident);
}

tree_classdef_superclass_list *
base_parser::append_classdef_superclass (tree_classdef_superclass_list *list, token *and_tok, tree_classdef_superclass *elt)
{
  elt->set_separator (*and_tok);

  return list_append (list, elt);
}

tree_classdef_attribute_list *
base_parser::make_classdef_attribute_list (tree_classdef_attribute *attr)
{
  return new tree_classdef_attribute_list (attr);
}

tree_classdef_attribute *
base_parser::make_classdef_attribute (tree_identifier *id)
{
  return make_classdef_attribute (id, nullptr, nullptr);
}

tree_classdef_attribute *
base_parser::make_classdef_attribute (tree_identifier *id, token *eq_tok, tree_expression *expr)
{
  return (expr ? new tree_classdef_attribute (id, *eq_tok, expr) : new tree_classdef_attribute (id));
}

tree_classdef_attribute *
base_parser::make_not_classdef_attribute (token *not_tok, tree_identifier *id)
{
  return new tree_classdef_attribute (*not_tok, id, false);
}

tree_classdef_attribute_list *
base_parser::append_classdef_attribute (tree_classdef_attribute_list *list, token *sep_tok, tree_classdef_attribute *elt)
{
  return list_append (list, *sep_tok, elt);
}

tree_classdef_body *
base_parser::make_classdef_body (tree_classdef_properties_block *pb)
{
  return new tree_classdef_body (pb);
}

tree_classdef_body *
base_parser::make_classdef_body (tree_classdef_methods_block *mb)
{
  return new tree_classdef_body (mb);
}

tree_classdef_body *
base_parser::make_classdef_body (tree_classdef_events_block *evb)
{
  return new tree_classdef_body (evb);
}

tree_classdef_body *
base_parser::make_classdef_body  (tree_classdef_enum_block *enb)
{
  return new tree_classdef_body (enb);
}

tree_classdef_body *
base_parser::append_classdef_properties_block (tree_classdef_body *body, tree_classdef_properties_block *block)
{
  return body->append (block);
}

tree_classdef_body *
base_parser::append_classdef_methods_block (tree_classdef_body *body, tree_classdef_methods_block *block)
{
  return body->append (block);
}

tree_classdef_body *
base_parser::append_classdef_events_block (tree_classdef_body *body, tree_classdef_events_block *block)
{
  return body->append (block);
}

tree_classdef_body *
base_parser::append_classdef_enum_block (tree_classdef_body *body, tree_classdef_enum_block *block)
{
  return body->append (block);
}

octave_user_function*
base_parser::start_classdef_external_method (tree_identifier *id, tree_parameter_list *pl)
{
  octave_user_function* retval = nullptr;

  // External methods are only allowed within @-folders. In this case,
  // m_curr_class_name will be non-empty.

  if (! m_curr_class_name.empty ())
    {
      std::string mname = id->name ();

      // Methods that cannot be declared outside the classdef file:
      // - methods with '.' character (e.g. property accessors)
      // - class constructor
      // - 'delete'

      if (mname.find_first_of (".") == std::string::npos && mname != "delete" && mname != m_curr_class_name)
        {
          // Create a dummy function that is used until the real method
          // is loaded.

          retval = new octave_user_function (symbol_scope::anonymous (), id, pl);

          retval->stash_function_name (mname);
        }
      else
        bison_error ("invalid external method declaration, an external method cannot be the class constructor, 'delete' or have a dot (.) character in its name");
    }
  else
    bison_error ("external methods are only allowed in @-folders");

  return retval;
}

tree_function_def *
base_parser::finish_classdef_external_method (octave_user_function *fcn, tree_parameter_list *ret_list, token *eq_tok)
{
  if (! ret_list)
    ret_list = new tree_parameter_list (tree_parameter_list::out);

  fcn->define_ret_list (ret_list);

  if (eq_tok)
    fcn->set_eq_tok (*eq_tok);

  return new tree_function_def (fcn);
}

tree_classdef_method_list *
base_parser::make_classdef_method_list (tree_function_def *fcn_def)
{
  octave_value fcn;

  if (fcn_def)
    fcn = fcn_def->function ();

  delete fcn_def;

  return new tree_classdef_method_list (fcn);
}

tree_classdef_method_list *
base_parser::append_classdef_method (tree_classdef_method_list *list, tree_function_def *fcn_def)
{
  octave_value fcn;

  if (fcn_def)
    {
      fcn = fcn_def->function ();

      delete fcn_def;
    }

  return list_append (list, fcn);
}

bool
base_parser::finish_classdef_file (tree_classdef *cls, tree_statement_list *local_fcns, token *eof_tok)
{
  parse_tree_validator validator;

  cls->accept (validator);

  if (local_fcns)
    {
      for (tree_statement *elt : *local_fcns)
        {
          tree_command *cmd = elt->command ();

          tree_function_def *fcn_def = dynamic_cast<tree_function_def *> (cmd);

          fcn_def->accept (validator);
        }
    }

  if (! validator.ok ())
    {
      delete cls;
      delete local_fcns;

      bison_error (validator.error_list ());

      return false;
    }

  // Require all validations to succeed before installing any local
  // functions or defining the classdef object for later use.

  if (local_fcns)
    {
      interpreter& interp = m_lexer.m_interpreter;

      symbol_table& symtab = interp.get_symbol_table ();

      for (tree_statement *elt : *local_fcns)
        {
          tree_command *cmd = elt->command ();

          tree_function_def *fcn_def = dynamic_cast<tree_function_def *> (cmd);

          octave_value ov_fcn = fcn_def->function ();
          octave_user_function *fcn = ov_fcn.user_function_value ();

          std::string nm = fcn->name ();
          std::string file = fcn->fcn_file_name ();

          fcn->attach_trailing_comments (eof_tok->leading_comments ());

          symtab.install_local_function (nm, ov_fcn, file);
        }

      delete local_fcns;
    }

  // FIXME: Is it possible for the following condition to be false?
  if (m_lexer.m_reading_classdef_file)
    m_classdef_object = std::shared_ptr<tree_classdef> (cls);

  return true;
}

// Make a word list command.
tree_index_expression *
base_parser::make_word_list_command (tree_expression *expr, tree_argument_list *args)
{
  tree_index_expression *retval = make_index_expression (expr, nullptr, args, nullptr, '(');

  if (retval)
    retval->mark_word_list_cmd ();

  return retval;
}

// Make an index expression.

tree_index_expression *
base_parser::make_index_expression (tree_expression *expr, token *open_delim, tree_argument_list *args, token *close_delim, char type)
{
  tree_index_expression *retval = nullptr;

  if (! args)
    args = new tree_argument_list ();

  if (args->has_magic_tilde ())
    {
      delete expr;
      delete args;

      bison_error ("invalid use of empty argument (~) in index expression");
    }
  else
    {
      if (! expr->is_postfix_indexed ())
        expr->set_postfix_index (type);

      token tmp_open_delim = open_delim ? *open_delim : token ();
      token tmp_close_delim = close_delim ? *close_delim : token ();

      if (expr->is_index_expression ())
        {
          retval = dynamic_cast<tree_index_expression *> (expr);

          retval->append (tmp_open_delim, args, tmp_close_delim, type);
        }
      else
        retval = new tree_index_expression (expr, tmp_open_delim, args, tmp_close_delim, type);
    }

  return retval;
}

// Make an indirect reference expression.

tree_index_expression *
base_parser::make_indirect_ref (tree_expression *expr, token *dot_tok, token *struct_elt_tok)
{
  tree_index_expression *retval = nullptr;

  if (! expr->is_postfix_indexed ())
    expr->set_postfix_index ('.');

  if (expr->is_index_expression ())
    {
      retval = dynamic_cast<tree_index_expression *> (expr);

      retval->append (*dot_tok, *struct_elt_tok);
    }
  else
    retval = new tree_index_expression (expr, *dot_tok, *struct_elt_tok);

  m_lexer.m_looking_at_indirect_ref = false;

  return retval;
}

// Make an indirect reference expression with dynamic field name.

tree_index_expression *
base_parser::make_indirect_ref (tree_expression *expr, token *dot_tok, token *open_paren, tree_expression *elt, token *close_paren)
{
  tree_index_expression *retval = nullptr;

  if (! expr->is_postfix_indexed ())
    expr->set_postfix_index ('.');

  if (expr->is_index_expression ())
    {
      retval = dynamic_cast<tree_index_expression *> (expr);

      retval->append (*dot_tok, *open_paren, elt, *close_paren);
    }
  else
    retval = new tree_index_expression (expr, *dot_tok, *open_paren, elt, *close_paren);

  m_lexer.m_looking_at_indirect_ref = false;

  return retval;
}

// Make a declaration command.

tree_decl_command *
base_parser::make_decl_command (token *tok, tree_decl_init_list *lst)
{
  tree_decl_command *retval = nullptr;

  if (lst)
    m_lexer.mark_as_variables (lst->variable_names ());

  int tok_id = tok->token_id ();

  switch (tok->token_id ())
    {
    case GLOBAL:
      {
        retval = new tree_decl_command ("global", *tok, lst);
        retval->mark_global ();
      }
      break;

    case PERSISTENT:
      if (m_curr_fcn_depth >= 0)
        {
          retval = new tree_decl_command ("persistent", *tok, lst);
          retval->mark_persistent ();
        }
      else
        {
          filepos pos = tok->beg_pos ();
          int line = pos.line ();

          if (m_lexer.m_reading_script_file)
            warning ("ignoring persistent declaration near line %d of file '%s'", line, m_lexer.m_fcn_file_full_name.c_str ());
          else
            warning ("ignoring persistent declaration near line %d", line);
        }
      break;

    default:
      unexpected_token (tok_id, "base_parser::make_decl_command");
      break;
    }

  return retval;
}

tree_decl_init_list *
base_parser::make_decl_init_list (tree_decl_elt *elt)
{
  return new tree_decl_init_list (elt);
}

tree_decl_init_list *
base_parser::append_decl_init_list (tree_decl_init_list *list, tree_decl_elt *elt)
{
  return list_append (list, elt);
}

tree_decl_elt *
base_parser::make_decl_elt (tree_identifier *id, token */*eq_op*/, tree_expression *expr)
{
  // FIXME: Need to capture EQ_OP here.
  return expr ? new tree_decl_elt (id, expr) : new tree_decl_elt (id);
}

bool
base_parser::validate_param_list (tree_parameter_list *lst, tree_parameter_list::in_or_out type)
{
  std::set<std::string> dict;

  for (tree_decl_elt *elt : *lst)
    {
      tree_identifier *id = elt->ident ();

      if (id)
        {
          std::string name = id->name ();

          if (id->is_black_hole ())
            {
              if (type != tree_parameter_list::in)
                {
                  bison_error ("invalid use of ~ in output list");
                  return false;
                }
            }
          else if (iskeyword (name))
            {
              bison_error ("invalid use of keyword '" + name + "' in parameter list");
              return false;
            }
          else if (dict.find (name) != dict.end ())
            {
              bison_error ("'" + name + "' appears more than once in parameter list");
              return false;
            }
          else
            dict.insert (name);
        }
    }

  std::string va_type = (type == tree_parameter_list::in ? "varargin" : "varargout");

  std::size_t len = lst->size ();

  if (len > 0)
    {
      tree_decl_elt *elt = lst->back ();

      tree_identifier *id = elt->ident ();

      if (id && id->name () == va_type)
        {
          if (len == 1)
            lst->mark_varargs_only ();
          else
            lst->mark_varargs ();

          tree_parameter_list::iterator p = lst->end ();
          --p;
          delete *p;
          lst->erase (p);
        }
    }

  return true;
}

bool
base_parser::validate_array_list (tree_expression *e)
{
  bool retval = true;

  tree_array_list *al = dynamic_cast<tree_array_list *> (e);

  for (tree_argument_list* row : *al)
    {
      if (row && row->has_magic_tilde ())
        {
          retval = false;

          if (e->is_matrix ())
            bison_error ("invalid use of tilde (~) in matrix expression");
          else
            bison_error ("invalid use of tilde (~) in cell expression");

          break;
        }
    }

  return retval;
}

tree_argument_list *
base_parser::validate_matrix_for_assignment (tree_expression *e)
{
  tree_argument_list *retval = nullptr;

  if (e->is_constant ())
    {
      interpreter& interp = m_lexer.m_interpreter;

      tree_evaluator& tw = interp.get_evaluator ();

      octave_value ov = e->evaluate (tw);

      delete e;

      if (ov.isempty ())
        bison_error ("invalid empty left hand side of assignment");
      else
        bison_error ("invalid constant left hand side of assignment");
    }
  else
    {
      bool is_simple_assign = true;

      tree_argument_list *tmp = nullptr;

      if (e->is_matrix ())
        {
          tree_matrix *mat = dynamic_cast<tree_matrix *> (e);

          if (mat && mat->size () == 1)
            {
              tmp = mat->front ();
              mat->pop_front ();
              delete e;
              is_simple_assign = false;
            }
        }
      else
        tmp = new tree_argument_list (e);

      if (tmp && tmp->is_valid_lvalue_list ())
        {
          m_lexer.mark_as_variables (tmp->variable_names ());
          retval = tmp;
        }
      else
        {
          delete tmp;

          bison_error ("invalid left hand side of assignment");
        }

      if (retval && is_simple_assign)
        retval->mark_as_simple_assign_lhs ();
    }

  return retval;
}

// Finish building an array_list.

tree_expression *
base_parser::finish_array_list (token *open_delim, tree_array_list *array_list, token *close_delim)
{
  tree_expression *retval = array_list;

  array_list->mark_in_delims (*open_delim, *close_delim);

  if (array_list->all_elements_are_constant ())
    {
      interpreter& interp = m_lexer.m_interpreter;

      try
        {
          // If the evaluation generates a warning message, restore
          // the previous value of last_warning_message and skip the
          // conversion to a constant value.

          error_system& es = interp.get_error_system ();

          unwind_action restore_last_warning_message (&error_system::set_last_warning_message, &es, es.last_warning_message (""));

          unwind_action restore_discard_warning_messages (&error_system::set_discard_warning_messages, &es, es.discard_warning_messages (true));

          tree_evaluator& tw = interp.get_evaluator ();

          octave_value tmp = array_list->evaluate (tw);

          std::string msg = es.last_warning_message ();

          if (msg.empty ())
            {
              std::ostringstream buf;

              tree_print_code tpc (buf);

              array_list->accept (tpc);

              std::string orig_text = buf.str ();

              token tok (CONSTANT, tmp, orig_text, open_delim->beg_pos (), close_delim->end_pos ());

              tree_constant *tc_retval = new tree_constant (tmp, orig_text, tok);

              delete array_list;

              retval = tc_retval;
            }
        }
      catch (const execution_exception&)
        {
          interp.recover_from_exception ();
        }
    }

  return retval;
}

// Finish building a matrix list.

tree_expression *
base_parser::finish_matrix (token *open_delim, tree_matrix *m, token *close_delim)
{
  if (m)
    return finish_array_list (open_delim, m, close_delim);

  octave_value tmp {octave_null_matrix::instance};
  std::string orig_text {"{}"};

  token tok (CONSTANT, tmp, orig_text, open_delim->beg_pos (), close_delim->end_pos ());

  return new tree_constant (tmp, orig_text, tok);
}

tree_matrix *
base_parser::make_matrix (tree_argument_list *row)
{
  return row ? new tree_matrix (row) : nullptr;
}

tree_matrix *
base_parser::append_matrix_row (tree_matrix *matrix, token *sep_tok, tree_argument_list *row)
{
  if (! matrix)
    return make_matrix (row);

  return row ? list_append (matrix, *sep_tok, row) : matrix;
}

// Finish building a cell list.

tree_expression *
base_parser::finish_cell (token *open_delim, tree_cell *c, token *close_delim)
{
  if (c)
    return finish_array_list (open_delim, c, close_delim);

  octave_value tmp {Cell ()};
  std::string orig_text {"{}"};

  token tok (CONSTANT, tmp, orig_text, open_delim->beg_pos (), close_delim->end_pos ());

  return new tree_constant (tmp, orig_text, tok);
}

tree_cell *
base_parser::make_cell (tree_argument_list *row)
{
  return row ? new tree_cell (row) : nullptr;
}

tree_cell *
base_parser::append_cell_row (tree_cell *cell, token *sep_tok, tree_argument_list *row)
{
  if (! cell)
    return make_cell (row);

  return row ? list_append (cell, *sep_tok, row) : cell;
}

tree_identifier *
base_parser::make_identifier (token *ident)
{
  symbol_scope scope = m_lexer.m_symtab_context.curr_scope ();

  return new tree_identifier (scope, *ident);
}

tree_superclass_ref *
base_parser::make_superclass_ref (token *superclassref)
{
  std::string meth = superclassref->superclass_method_name ();
  std::string cls = superclassref->superclass_class_name ();

  return new tree_superclass_ref (meth, cls, *superclassref);
}

tree_metaclass_query *
base_parser::make_metaclass_query (token *metaquery)
{
  std::string cls = metaquery->text ();

  return new tree_metaclass_query (cls, *metaquery);
}

tree_statement_list *
base_parser::set_stmt_print_flag (tree_statement_list *list, int sep_char, bool warn_missing_semi)
{
  tree_statement *tmp = list->back ();

  switch (sep_char)
    {
    case ';':
      tmp->set_print_flag (false);
      break;

    case '\0':
    case ',':
    case '\n':
      tmp->set_print_flag (true);
      if (warn_missing_semi)
        maybe_warn_missing_semi (list);
      break;

    default:
      warning ("unrecognized separator type!");
      break;
    }

  // Even if a statement is null, we add it to the list then remove it
  // here so that the print flag is applied to the correct statement.

  if (tmp->is_null_statement ())
    {
      list->pop_back ();
      delete tmp;
    }

  return list;
}

tree_statement_list *
base_parser::set_stmt_print_flag (tree_statement_list *list, const token& sep_tok, bool warn_missing_semi)
{
  return set_stmt_print_flag (list, sep_tok.token_id (), warn_missing_semi);
}

tree_statement_list *
base_parser::set_stmt_print_flag (tree_statement_list *list, separator_list *sep_list, bool warn_missing_semi)
{
  return (sep_list
          ? set_stmt_print_flag (list, sep_list->front (), warn_missing_semi)
          : set_stmt_print_flag (list, '\0', warn_missing_semi));
}

// Finish building a statement.
template <typename T>
tree_statement *
base_parser::make_statement (T *arg)
{
  return new tree_statement (arg);
}

tree_statement_list *
base_parser::make_statement_list (tree_statement *stmt)
{
  return new tree_statement_list (stmt);
}

tree_statement_list *
base_parser::append_statement_list (tree_statement_list *list, int sep_char, tree_statement *stmt, bool warn_missing_semi)
{
  set_stmt_print_flag (list, sep_char, warn_missing_semi);

  // FIXME: need to capture SEP_CHAR here.
  return list_append (list, stmt);
}

tree_statement_list *
base_parser::append_statement_list (tree_statement_list *list, token *sep_tok, tree_statement *stmt, bool warn_missing_semi)
{
  if (sep_tok)
    set_stmt_print_flag (list, *sep_tok, warn_missing_semi);
  else
    set_stmt_print_flag (list, '\0', warn_missing_semi);

  // FIXME: need to capture SEP_TOK here.
  return list_append (list, stmt);
}

tree_statement_list *
base_parser::append_statement_list (tree_statement_list *list, separator_list *sep_list, tree_statement *stmt, bool warn_missing_semi)
{
  set_stmt_print_flag (list, sep_list, warn_missing_semi);

  // FIXME: need to capture separator list here.
  // For now, delete the unused list.
  delete sep_list;

  return list_append (list, stmt);
}

tree_statement_list *
base_parser::make_function_def_list (tree_function_def *fcn_def)
{
  tree_statement *stmt = make_statement (fcn_def);

  return new tree_statement_list (stmt);
}

tree_statement_list *
base_parser::append_function_def_list (tree_statement_list *list, separator_list *sep_list, tree_function_def *fcn_def)
{
  tree_statement *stmt = make_statement (fcn_def);

  // FIXME: Need to capture separator list here.
  // For now, delete the unused list.
  delete sep_list;

  return list_append (list, stmt);
}

tree_argument_list *
base_parser::make_argument_list (tree_expression *expr)
{
  return new tree_argument_list (expr);
}

tree_argument_list *
base_parser::append_argument_list (tree_argument_list *list, token *sep_tok, tree_expression *expr)
{
  return list_append (list, *sep_tok, expr);
}

tree_parameter_list *
base_parser::make_parameter_list (tree_parameter_list::in_or_out io)
{
  return new tree_parameter_list (io);
}

tree_parameter_list *
base_parser::make_parameter_list (tree_parameter_list::in_or_out io, tree_decl_elt *t)
{
  return new tree_parameter_list (io, t);
}

tree_parameter_list *
base_parser::make_parameter_list (tree_parameter_list::in_or_out io, tree_identifier *id)
{
  return new tree_parameter_list (io, id);
}

tree_parameter_list *
base_parser::append_parameter_list (tree_parameter_list *list, token *sep_tok, tree_decl_elt *t)
{
  return list_append (list, *sep_tok, t);
}

tree_parameter_list *
base_parser::append_parameter_list (tree_parameter_list *list, token *sep_tok, tree_identifier *id)
{
  return list_append (list, *sep_tok, new tree_decl_elt (id));
}

void
base_parser::disallow_command_syntax ()
{
  m_lexer.m_allow_command_syntax = false;
}

void
base_parser::bison_error (const std::string& str)
{
  bison_error (str, m_lexer.m_filepos);
}

void
base_parser::bison_error (const std::string& str, const filepos& pos)
{
  std::ostringstream output_buf;

  int err_line = pos.line ();
  int err_col = pos.column ();

  bool in_file = (m_lexer.m_reading_fcn_file || m_lexer.m_reading_script_file || m_lexer.m_reading_classdef_file);

  // Adjust the error column for display because it is 1-based in the
  // lexer for easier reporting.
  err_col--;

  if (in_file)
    output_buf << str << " near line " << err_line << ", column " << err_col << " in file " << m_lexer.m_fcn_file_full_name << "\n";
  else
    {
      // On command line, point directly to error
      output_buf << str << "\n\n";
      std::string curr_line = m_lexer.m_current_input_line;

      if (! curr_line.empty ())
        {
          // FIXME: we could do better if we just cached lines from the
          // input file in a list.  See also functions for managing input
          // buffers in lex.ll.
          std::size_t len = curr_line.length ();

          if (curr_line[len-1] == '\n')
            curr_line.resize (len-1);

          // Print the line, maybe with a pointer near the error token.
          output_buf << ">>> " << curr_line << "\n";

          if (err_col == 0)
            err_col = len;

          for (int i = 0; i < err_col + 3; i++)
            output_buf << " ";

          output_buf << "^" << "\n";
        }

    }

  m_parse_error_msg = output_buf.str ();
}

void
base_parser::bison_error (const parse_exception& pe)
{
  bison_error (pe.message (), pe.pos ());
}

void
base_parser::bison_error (const std::list<parse_exception>& pe_list)
{
  // For now, we just report the first error found.  Reporting all
  // errors will require a bit more refactoring.

  parse_exception pe = pe_list.front ();

  bison_error (pe.message (), pe.pos ());
}

int
parser::run ()
{
  int status = -1;

  yypstate *pstate = static_cast<yypstate *> (m_parser_state);

  try
    {
      status = octave_pull_parse (pstate, *this);
    }
  catch (const execution_exception&)
    {
      // FIXME: In previous versions, we emitted a parse error here
      // but that is not always correct because the error could have
      // happened inside a GUI callback functions executing in the
      // readline event_hook loop.  Maybe we need a separate exception
      // class for parse errors?

      throw;
    }
  catch (const exit_exception&)
    {
      throw;
    }
  catch (const interrupt_exception&)
    {
      throw;
    }
  catch (...)
    {
      std::string file = m_lexer.m_fcn_file_full_name;

      if (file.empty ())
        error ("unexpected exception while parsing input");
      else
        error ("unexpected exception while parsing %s", file.c_str ());
    }

  if (status != 0)
    parse_error_with_id ("Octave:parse-error", "%s", m_parse_error_msg.c_str ());

  return status;
}

// Parse input from INPUT.  Pass TRUE for EOF if the end of INPUT should
// finish the parse.

int
push_parser::run (const std::string& input, bool eof)
{
  int status = -1;

  dynamic_cast<push_lexer&> (m_lexer).append_input (input, eof);

  do
    {
      YYSTYPE lval;

      int tok_id = octave_lex (&lval, m_lexer.m_scanner);

      if (tok_id < 0)
        {
          // TOKEN == -2 means that the lexer recognized a comment
          // and we should be at the end of the buffer but not the
          // end of the file so we should return 0 to indicate
          // "complete input" instead of -1 to request more input.

          status = (tok_id == -2 ? 0 : -1);

          if (! eof && m_lexer.at_end_of_buffer ())
            return status;

          break;
        }

      yypstate *pstate = static_cast<yypstate *> (m_parser_state);

      try
        {
          status = octave_push_parse (pstate, tok_id, &lval, *this);
        }
      catch (execution_exception& e)
        {
          std::string file = m_lexer.m_fcn_file_full_name;

          if (file.empty ())
            error (e, "parse error");
          else
            error (e, "parse error in %s", file.c_str ());
        }
      catch (const exit_exception&)
        {
          throw;
        }
      catch (interrupt_exception &)
        {
          throw;
        }
      catch (...)
        {
          std::string file = m_lexer.m_fcn_file_full_name;

          if (file.empty ())
            error ("unexpected exception while parsing input");
          else
            error ("unexpected exception while parsing %s", file.c_str ());
        }
    }
  while (status == YYPUSH_MORE || ! m_lexer.at_end_of_buffer ());

  if (status != 0)
    parse_error_with_id ("Octave:parse-error", "%s", m_parse_error_msg.c_str ());

  return status;
}

int
push_parser::run ()
{
  if (! m_reader)
    error ("push_parser::run requires valid input_reader");

  int exit_status = 0;

  std::string prompt = command_editor::decode_prompt_string (m_interpreter.PS1 ());

  do
    {
      // Reset status each time through the read loop so that
      // it won't be set to -1 and cause us to exit the outer
      // loop early if there is an exception while reading
      // input or parsing.

      exit_status = 0;

      bool eof = false;
      std::string input_line = m_reader->get_input (prompt, eof);

      if (eof)
        {
          exit_status = EOF;
          break;
        }

      exit_status = run (input_line, false);

      prompt = command_editor::decode_prompt_string (m_interpreter.PS2 ());
    }
  while (exit_status < 0);

  return exit_status;
}

octave_value
parse_fcn_file (interpreter& interp, const std::string& full_file, const std::string& file, const std::string& dir_name, const std::string& dispatch_type, const std::string& package_name, bool require_file, bool force_script, bool autoload, bool relative_lookup)
{
  octave_value retval;

  FILE *ffile = nullptr;

  if (! full_file.empty ())
    {
      // Check that m-file is not overly large which can segfault interpreter.
      const int max_file_size = 512 * 1024 * 1024;  // 512 MB
      sys::file_stat fs (full_file);

      if (fs && fs.size () > max_file_size)
        {
          error ("file '%s' is too large, > 512 MB", full_file.c_str ());

          return octave_value ();
        }

      ffile = sys::fopen (full_file, "rb");
    }

  if (! ffile)
    {
      if (require_file)
        error ("no such file, '%s'", full_file.c_str ());

      return octave_value ();
    }

  unwind_action act ([ffile] () { ::fclose (ffile); });

  // get the encoding for this folder
  input_system& input_sys = interp.get_input_system ();
  parser parser (ffile, interp, input_sys.dir_encoding (dir_name));

  parser.m_curr_class_name = dispatch_type;
  parser.m_curr_package_name = package_name;
  parser.m_autoloading = autoload;
  parser.m_fcn_file_from_relative_lookup = relative_lookup;

  parser.m_lexer.m_force_script = force_script;
  parser.m_lexer.prep_for_file ();
  parser.m_lexer.m_parsing_class_method = ! dispatch_type.empty ();

  parser.m_lexer.m_fcn_file_name = file;
  parser.m_lexer.m_fcn_file_full_name = full_file;
  parser.m_lexer.m_dir_name = dir_name;
  parser.m_lexer.m_package_name = package_name;

  int err = parser.run ();

  if (err)
    error ("parse error while reading file %s", full_file.c_str ());

  octave_value ov_fcn = parser.m_primary_fcn;

  if (parser.m_lexer.m_reading_classdef_file && parser.classdef_object ())
    {
      // Convert parse tree for classdef object to
      // meta.class info (and stash it in the symbol
      // table?).  Return pointer to constructor?

      if (ov_fcn.is_defined ())
        error ("unexpected: defining classdef object but primary_fcn is already defined - please report this bug");

      bool is_at_folder = ! dispatch_type.empty ();

      std::shared_ptr<tree_classdef> cdef_obj = parser.classdef_object();

      return cdef_obj->make_meta_class (interp, is_at_folder);
    }
  else if (ov_fcn.is_defined ())
    {
      octave_function *fcn = ov_fcn.function_value ();

      fcn->maybe_relocate_end ();

      if (parser.m_parsing_subfunctions)
        {
          if (! parser.m_endfunction_found)
            parser.m_subfunction_names.reverse ();

          fcn->stash_subfunction_names (parser.m_subfunction_names);
        }

      return ov_fcn;
    }

  return octave_value ();
}

bool
base_parser::finish_input (tree_statement_list *lst, bool at_eof)
{
  m_lexer.m_end_of_input = at_eof;

  if (lst)
    {
      parse_tree_validator validator;

      lst->accept (validator);

      if (! validator.ok ())
        {
          delete lst;

          bison_error (validator.error_list ());

          return false;
        }
    }

  std::shared_ptr<tree_statement_list> tmp_lst (lst);

  statement_list (tmp_lst);

  return true;
}

// Check script or function for semantic errors.
bool
base_parser::validate_primary_fcn ()
{
  octave_user_code *code = m_primary_fcn.user_code_value ();

  if (code)
    {
      parse_tree_validator validator;

      code->accept (validator);

      if (! validator.ok ())
        {
          bison_error (validator.error_list ());

          return false;
        }
    }

  return true;
}

// Maybe print a warning if an assignment expression is used as the
// test in a logical expression.

void
base_parser::maybe_warn_assign_as_truth_value (tree_expression *expr)
{
  if (expr->is_assignment_expression () && expr->delim_count () < 2)
    {
      if (m_lexer.m_fcn_file_full_name.empty ())
        warning_with_id ("Octave:assign-as-truth-value", "suggest parenthesis around assignment used as truth value");
      else
        warning_with_id ("Octave:assign-as-truth-value", "suggest parenthesis around assignment used as truth value near line %d, column %d in file '%s'", expr->line (), expr->column (), m_lexer.m_fcn_file_full_name.c_str ());
    }
}

// Maybe print a warning about switch labels that aren't constants.

void
base_parser::maybe_warn_variable_switch_label (tree_expression *expr)
{
  if (! expr->is_constant ())
    {
      if (m_lexer.m_fcn_file_full_name.empty ())
        warning_with_id ("Octave:variable-switch-label", "variable switch label");
      else
        warning_with_id ("Octave:variable-switch-label", "variable switch label near line %d, column %d in file '%s'", expr->line (), expr->column (), m_lexer.m_fcn_file_full_name.c_str ());
    }
}

void
base_parser::maybe_warn_missing_semi (tree_statement_list *t)
{
  if (m_curr_fcn_depth >= 0)
    {
      tree_statement *tmp = t->back ();

      if (tmp->is_expression ())
        warning_with_id ("Octave:missing-semicolon", "missing semicolon near line %d, column %d in file '%s'", tmp->line (), tmp->column (), m_lexer.m_fcn_file_full_name.c_str ());
    }
}

std::string
get_help_from_file (const std::string& nm, bool& symbol_found, std::string& full_file)
{
  std::string retval;

  full_file = fcn_file_in_path (nm);

  std::string file = full_file;

  std::size_t file_len = file.length ();

  if ((file_len > 4 && file.substr (file_len-4) == ".oct")
      || (file_len > 4 && file.substr (file_len-4) == ".mex")
      || (file_len > 2 && file.substr (file_len-2) == ".m"))
    {
      file = sys::env::base_pathname (file);
      file = file.substr (0, file.find_last_of ('.'));

      std::size_t pos = file.find_last_of (sys::file_ops::dir_sep_str ());
      if (pos != std::string::npos)
        file = file.substr (pos+1);
    }

  if (! file.empty ())
    {
      interpreter& interp = __get_interpreter__ ();

      symbol_found = true;

      octave_value ov_fcn = parse_fcn_file (interp, full_file, file, "", "", "", true, false, false, false);

      if (ov_fcn.is_defined ())
        {
          octave_function *fcn = ov_fcn.function_value ();

          if (fcn)
            retval = fcn->doc_string ();
        }
    }

  return retval;
}

std::string
get_help_from_file (const std::string& nm, bool& symbol_found)
{
  std::string file;
  return get_help_from_file (nm, symbol_found, file);
}

octave_value
load_fcn_from_file (const std::string& file_name, const std::string& dir_name, const std::string& dispatch_type, const std::string& package_name, const std::string& fcn_name, bool autoload)
{
  octave_value retval;

  unwind_protect frame;

  std::string nm = file_name;

  std::size_t nm_len = nm.length ();

  std::string file;

  bool relative_lookup = false;

  file = nm;

  if ((nm_len > 4 && nm.substr (nm_len-4) == ".oct")
      || (nm_len > 4 && nm.substr (nm_len-4) == ".mex")
      || (nm_len > 2 && nm.substr (nm_len-2) == ".m"))
    {
      nm = sys::env::base_pathname (file);
      nm = nm.substr (0, nm.find_last_of ('.'));

      std::size_t pos = nm.find_last_of (sys::file_ops::dir_sep_str ());
      if (pos != std::string::npos)
        nm = nm.substr (pos+1);
    }

  relative_lookup = ! sys::env::absolute_pathname (file);

  file = sys::env::make_absolute (file);

  int len = file.length ();

  interpreter& interp = __get_interpreter__ ();

  dynamic_loader& dyn_loader = interp.get_dynamic_loader ();

  if (len > 4 && file.substr (len-4, len-1) == ".oct")
    {
      if (autoload && ! fcn_name.empty ())
        nm = fcn_name;

      octave_function *tmpfcn = dyn_loader.load_oct (nm, file, relative_lookup);

      if (tmpfcn)
        {
          tmpfcn->stash_package_name (package_name);
          retval = octave_value (tmpfcn);
        }
    }
  else if (len > 4 && file.substr (len-4, len-1) == ".mex")
    {
      // Temporarily load m-file version of mex-file, if it exists,
      // to get the help-string to use.

      std::string doc_string;

      octave_value ov_fcn = parse_fcn_file (interp, file.substr (0, len - 2), nm, dir_name, dispatch_type, package_name, false, autoload, autoload, relative_lookup);

      if (ov_fcn.is_defined ())
        {
          octave_function *tmpfcn = ov_fcn.function_value ();

          if (tmpfcn)
            doc_string = tmpfcn->doc_string ();
        }

      octave_function *tmpfcn = dyn_loader.load_mex (nm, file, relative_lookup);

      if (tmpfcn)
        {
          tmpfcn->document (doc_string);
          tmpfcn->stash_package_name (package_name);

          retval = octave_value (tmpfcn);
        }
    }
  else if (len > 2)
    retval = parse_fcn_file (interp, file, nm, dir_name, dispatch_type, package_name, true, autoload, autoload, relative_lookup);

  return retval;
}

DEFMETHOD (autoload, interp, args, ,
           doc: /* -*- texinfo -*-
@deftypefn  {} {@var{autoload_map} =} autoload ()
@deftypefnx {} {} autoload (@var{function}, @var{file})
@deftypefnx {} {} autoload (@dots{}, "remove")
Define @var{function} to autoload from @var{file}.

The second argument, @var{file}, should be an absolute filename or a file
name in the same directory as the function or script from which the autoload
command was run.  @var{file} @emph{should not} depend on the Octave load
path.

Normally, calls to @code{autoload} appear in PKG_ADD script files that are
evaluated when a directory is added to Octave's load path.  To avoid having
to hardcode directory names in @var{file}, if @var{file} is in the same
directory as the PKG_ADD script then

@example
autoload ("foo", "bar.oct");
@end example

@noindent
will load the function @code{foo} from the file @code{bar.oct}.  The above
usage when @code{bar.oct} is not in the same directory, or usages such as

@example
autoload ("foo", file_in_loadpath ("bar.oct"))
@end example

@noindent
are strongly discouraged, as their behavior may be unpredictable.

With no arguments, return a structure containing the current autoload map.

If a third argument @qcode{"remove"} is given, the function is cleared and
not loaded anymore during the current Octave session.

@seealso{PKG_ADD}
@end deftypefn */)
{
  int nargin = args.length ();

  if (nargin == 1 || nargin > 3)
    print_usage ();

  tree_evaluator& tw = interp.get_evaluator ();

  if (nargin == 0)
    return octave_value (tw.get_autoload_map ());
  else
    {
      string_vector argv = args.make_argv ("autoload");

      if (nargin == 2)
        tw.add_autoload (argv[1], argv[2]);
      else if (nargin == 3)
        {
          if (argv[3] != "remove")
            error_with_id ("Octave:invalid-input-arg", "autoload: third argument can only be 'remove'");

          tw.remove_autoload (argv[1], argv[2]);
        }
    }

  return octave_value_list ();
}

DEFMETHOD (mfilename, interp, args, ,
           doc: /* -*- texinfo -*-
@deftypefn  {} {} mfilename ()
@deftypefnx {} {} mfilename ("fullpath")
@deftypefnx {} {} mfilename ("fullpathext")
Return the name of the currently executing file.

The base name of the currently executing script or function is returned without
any extension.  If called from outside an m-file, such as the command line,
return the empty string.

Given the argument @qcode{"fullpath"}, include the directory part of the
filename, but not the extension.

Given the argument @qcode{"fullpathext"}, include the directory part of
the filename and the extension.
@seealso{inputname, dbstack}
@end deftypefn */)
{
  int nargin = args.length ();

  if (nargin > 1)
    print_usage ();

  std::string opt;

  if (nargin == 1)
    opt = args(0).xstring_value ("mfilename: option argument must be a string");

  return octave_value (interp.mfilename (opt));
}

  // Execute the contents of a script file.  For compatibility with
  // Matlab, also execute a function file by calling the function it
  // defines with no arguments and nargout = 0.

  void
  source_file (const std::string& file_name, const std::string& context,
               bool verbose, bool require_file)
  {
    interpreter& interp = __get_interpreter__ ();

    interp.source_file (file_name, context, verbose, require_file);
  }

DEFMETHOD (source, interp, args, ,
           doc: /* -*- texinfo -*-
@deftypefn  {} {} source (@var{file})
@deftypefnx {} {} source (@var{file}, @var{context})
Parse and execute the contents of @var{file}.

Without specifying @var{context}, this is equivalent to executing commands
from a script file, but without requiring the file to be named
@file{@var{file}.m} or to be on the execution path.

Instead of the current context, the script may be executed in either the
context of the function that called the present function
(@qcode{"caller"}), or the top-level context (@qcode{"base"}).
@seealso{run}
@end deftypefn */)
{
  int nargin = args.length ();

  if (nargin < 1 || nargin > 2)
    print_usage ();

  std::string file_name = args(0).xstring_value ("source: FILE must be a string");

  std::string context;
  if (nargin == 2)
    context = args(1).xstring_value ("source: CONTEXT must be a string");

  interp.source_file (file_name, context);

  return octave_value_list ();
}

  //! Evaluate an Octave function (built-in or interpreted) and return
  //! the list of result values.
  //!
  //! @param name The name of the function to call.
  //! @param args The arguments to the function.
  //! @param nargout The number of output arguments expected.
  //! @return A list of output values.  The length of the list is not
  //!         necessarily the same as @c nargout.

  octave_value_list
  feval (const char *name, const octave_value_list& args, int nargout)
  {
    interpreter& interp = __get_interpreter__ ();

    return interp.feval (name, args, nargout);
  }

  octave_value_list
  feval (const std::string& name, const octave_value_list& args, int nargout)
  {
    interpreter& interp = __get_interpreter__ ();

    return interp.feval (name, args, nargout);
  }

  octave_value_list
  feval (octave_function *fcn, const octave_value_list& args, int nargout)
  {
    interpreter& interp = __get_interpreter__ ();

    return interp.feval (fcn, args, nargout);
  }

  octave_value_list
  feval (const octave_value& val, const octave_value_list& args, int nargout)
  {
    interpreter& interp = __get_interpreter__ ();

    return interp.feval (val, args, nargout);
  }

  octave_value_list
  feval (const octave_value_list& args, int nargout)
  {
    interpreter& interp = __get_interpreter__ ();

    return interp.feval (args, nargout);
  }

DEFMETHOD (feval, interp, args, nargout,
           doc: /* -*- texinfo -*-
@deftypefn {} {@var{retval} =} feval (@var{name}, @dots{})
Evaluate the function named @var{name}.

Any arguments after the first are passed as inputs to the named function.
For example,

@example
@group
feval ("acos", -1)
     @result{} 3.1416
@end group
@end example

@noindent
calls the function @code{acos} with the argument @samp{-1}.

The function @code{feval} can also be used with function handles of any sort
(@pxref{Function Handles}).  Historically, @code{feval} was the only way to
call user-supplied functions in strings, but function handles are now
preferred due to the cleaner syntax they offer.  For example,

@example
@group
@var{f} = @@exp;
feval (@var{f}, 1)
    @result{} 2.7183
@var{f} (1)
    @result{} 2.7183
@end group
@end example

@noindent
are equivalent ways to call the function referred to by @var{f}.  If it
cannot be predicted beforehand whether @var{f} is a function handle,
function name in a string, or inline function then @code{feval} can be used
instead.
@end deftypefn */)
{
  if (args.length () == 0)
    print_usage ();

  return interp.feval (args, nargout);
}

DEFMETHOD (builtin, interp, args, nargout,
           doc: /* -*- texinfo -*-
@deftypefn {} {[@dots{}] =} builtin (@var{f}, @dots{})
Call the base function @var{f} even if @var{f} is overloaded to another
function for the given type signature.

This is normally useful when doing object-oriented programming and there is
a requirement to call one of Octave's base functions rather than the
overloaded one of a new class.

A trivial example which redefines the @code{sin} function to be the
@code{cos} function shows how @code{builtin} works.

@example
@group
sin (0)
  @result{} 0
function y = sin (x), y = cos (x); endfunction
sin (0)
  @result{} 1
builtin ("sin", 0)
  @result{} 0
@end group
@end example
@end deftypefn */)
{
  octave_value_list retval;

  if (args.length () == 0)
    print_usage ();

  const std::string name (args(0).xstring_value ("builtin: function name (F) must be a string"));

  symbol_table& symtab = interp.get_symbol_table ();

  octave_value fcn = symtab.builtin_find (name);

  if (fcn.is_defined ())
    retval = interp.feval (fcn.function_value (), args.splice (0, 1), nargout);
  else
    error ("builtin: lookup for symbol '%s' failed", name.c_str ());

  return retval;
}

DEFMETHOD (eval, interp, args, nargout,
           doc: /* -*- texinfo -*-
@deftypefn  {} {} eval (@var{try})
@deftypefnx {} {} eval (@var{try}, @var{catch})
Parse the string @var{try} and evaluate it as if it were an Octave
program.

If execution fails, evaluate the optional string @var{catch}.

The string @var{try} is evaluated in the current context, so any results
remain available after @code{eval} returns.

The following example creates the variable @var{A} with the approximate
value of 3.1416 in the current workspace.

@example
eval ("A = acos(-1);");
@end example

If an error occurs during the evaluation of @var{try} then the @var{catch}
string is evaluated, as the following example shows:

@example
@group
eval ('error ("This is a bad example");',
      'printf ("This error occurred:\n%s\n", lasterr ());');
     @print{} This error occurred:
        This is a bad example
@end group
@end example

Programming Note: if you are only using @code{eval} as an error-capturing
mechanism, rather than for the execution of arbitrary code strings,
Consider using try/catch blocks or unwind_protect/unwind_protect_cleanup
blocks instead.  These techniques have higher performance and don't
introduce the security considerations that the evaluation of arbitrary code
does.
@seealso{evalin, evalc, assignin, feval}
@end deftypefn */)
{
  int nargin = args.length ();

  if (nargin < 1 || nargin > 2)
    print_usage ();

  if (! args(0).is_string () || args(0).rows () > 1 || args(0).ndims () != 2)
    error ("eval: TRY must be a string");

  std::string try_code = args(0).string_value ();

  if (nargin == 1)
    return interp.eval (try_code, nargout);
  else
    {
      if (! args(1).is_string () || args(1).rows () > 1 || args(1).ndims () != 2)
        error ("eval: CATCH must be a string");

      std::string catch_code = args(1).string_value ();

      return interp.eval (try_code, catch_code, nargout);
    }
}

/*

%!shared x
%! x = 1;

%!assert (eval ("x"), 1)
%!assert (eval ("x;"))
%!assert (eval ("x;"), 1)

%!test
%! y = eval ("x");
%! assert (y, 1);

%!test
%! y = eval ("x;");
%! assert (y, 1);

%!test
%! eval ("x = 1;");
%! assert (x,1);

%!test
%! eval ("flipud = 2;");
%! assert (flipud, 2);

%!function y = __f ()
%!  eval ("flipud = 2;");
%!  y = flipud;
%!endfunction
%!assert (__f(), 2)

%!test <*35645>
%! [a,] = gcd (1,2);
%! [a,b,] = gcd (1, 2);

## Can't assign to a keyword
%!error eval ("switch = 13;")

%!shared str
%! str = "disp ('hello');";
%! str(:,:,2) = str(:,:,1);

%!error <TRY must be a string> eval (1)
%!error <TRY must be a string> eval (['a';'b'])
%!error <TRY must be a string> eval (str)

%!error <CATCH must be a string> eval (str(:,:,1), 1)
%!error <CATCH must be a string> eval (str(:,:,1), ['a';'b'])
%!error <CATCH must be a string> eval (str(:,:,1), str)

*/

DEFMETHOD (assignin, interp, args, ,
           doc: /* -*- texinfo -*-
@deftypefn {} {} assignin (@var{context}, @var{varname}, @var{value})
Assign @var{value} to @var{varname} in context @var{context}, which
may be either @qcode{"base"} or @qcode{"caller"}.
@seealso{evalin}
@end deftypefn */)
{
  if (args.length () != 3)
    print_usage ();

  std::string context = args(0).xstring_value ("assignin: CONTEXT must be a string");

  std::string varname = args(1).xstring_value ("assignin: VARNAME must be a string");

  interp.assignin (context, varname, args(2));

  return octave_value_list ();
}

/*

%!error assignin ("base", "switch", "13")

*/

DEFMETHOD (evalin, interp, args, nargout,
           doc: /* -*- texinfo -*-
@deftypefn  {} {} evalin (@var{context}, @var{try})
@deftypefnx {} {} evalin (@var{context}, @var{try}, @var{catch})
Like @code{eval}, except that the expressions are evaluated in the context
@var{context}, which may be either @qcode{"caller"} or @qcode{"base"}.
@seealso{eval, assignin}
@end deftypefn */)
{
  int nargin = args.length ();

  if (nargin < 2 || nargin > 3)
    print_usage ();

  std::string context = args(0).xstring_value ("evalin: CONTEXT must be a string");

  std::string try_code = args(1).xstring_value ("evalin: TRY must be a string");

  if (nargin == 3)
    {
      std::string catch_code = args(2).xstring_value ("evalin: CATCH must be a string");

      return interp.evalin (context, try_code, catch_code, nargout);
    }

  return interp.evalin (context, try_code, nargout);
}

DEFMETHOD (evalc, interp, args, nargout,
           doc: /* -*- texinfo -*-
@deftypefn  {} {@var{s} =} evalc (@var{try})
@deftypefnx {} {@var{s} =} evalc (@var{try}, @var{catch})
Parse and evaluate the string @var{try} as if it were an Octave program,
while capturing the output into the return variable @var{s}.

If execution fails, evaluate the optional string @var{catch}.

This function behaves like @code{eval}, but any output or warning messages
which would normally be written to the console are captured and returned in
the string @var{s}.

The @code{diary} is disabled during the execution of this function.  When
@code{system} is used, any output produced by external programs is
@emph{not} captured, unless their output is captured by the @code{system}
function itself.

@example
@group
s = evalc ("t = 42"), t
  @result{} s = t =  42

  @result{} t =  42
@end group
@end example
@seealso{eval, diary}
@end deftypefn */)
{
  int nargin = args.length ();

  if (nargin == 0 || nargin > 2)
    print_usage ();

  // Flush pending output and redirect stdout/stderr to capturing
  // buffer.

  octave_stdout.flush ();
  std::cerr.flush ();

  std::stringbuf buffer;

  std::streambuf *old_out_buf = octave_stdout.rdbuf (&buffer);
  std::streambuf *old_err_buf = std::cerr.rdbuf (&buffer);

  // Restore previous output buffers no matter how control exits this
  // function.  There's no need to flush here.  That has already
  // happened for the normal execution path.  If an error happens during
  // the eval, then the message is stored in the exception object and we
  // will display it later, after the buffers have been restored.

  unwind_action act ([old_out_buf, old_err_buf] ()
                             {
                               octave_stdout.rdbuf (old_out_buf);
                               std::cerr.rdbuf (old_err_buf);
                             });

  // Call standard eval function.

  int eval_nargout = std::max (0, nargout - 1);

  octave_value_list retval = Feval (interp, args, eval_nargout);

  // Make sure we capture all pending output.

  octave_stdout.flush ();
  std::cerr.flush ();

  retval.prepend (buffer.str ());

  return retval;
}

/*

%!test
%! [old_fmt, old_spacing] = format ();
%! unwind_protect
%!   format short;
%!   str = evalc ("1");
%!   assert (str, "ans = 1\n");
%! unwind_protect_cleanup
%!   format (old_fmt);
%!   format (old_spacing);
%! end_unwind_protect

%!assert (evalc ("1;"), "")

%!test
%! [s, y] = evalc ("1");
%! assert (s, "");
%! assert (y, 1);

%!test
%! [s, y] = evalc ("1;");
%! assert (s, "");
%! assert (y, 1);

%!test
%! [old_fmt, old_spacing] = format ();
%! unwind_protect
%!   format short;
%!   str = evalc ("y = 2");
%!   assert (str, "y = 2\n");
%!   assert (y, 2);
%! unwind_protect_cleanup
%!   format (old_fmt);
%!   format (old_spacing);
%! end_unwind_protect

%!test
%! assert (evalc ("y = 3;"), "");
%! assert (y, 3);

%!test
%! [s, a, b] = evalc ("deal (1, 2)");
%! assert (s, "");
%! assert (a, 1);
%! assert (b, 2);

%!function [a, b] = __f_evalc ()
%!  printf ("foo");
%!  fprintf (stdout, "bar ");
%!  disp (pi);
%!  a = 1;
%!  b = 2;
%!endfunction
%!test
%! [old_fmt, old_spacing] = format ();
%! unwind_protect
%!   format short;
%!   [s, a, b] = evalc ("__f_evalc ()");
%!   assert (s, "foobar 3.1416\n");
%!   assert (a, 1);
%!   assert (b, 2);
%! unwind_protect_cleanup
%!   format (old_fmt);
%!   format (old_spacing);
%! end_unwind_protect

%!error <foo> (evalc ("error ('foo')"))
%!error <bar> (evalc ("error ('foo')", "error ('bar')"))

%!test
%! warning ("off", "quiet", "local");
%! str = evalc ("warning ('foo')");
%! assert (str(1:13), "warning: foo\n");

%!test
%! warning ("off", "quiet", "local");
%! str = evalc ("error ('foo')", "warning ('bar')");
%! assert (str(1:13), "warning: bar\n");

%!error evalc ("switch = 13;")

*/

DEFUN (__parser_debug_flag__, args, nargout,
       doc: /* -*- texinfo -*-
@deftypefn  {} {@var{val} =} __parser_debug_flag__ ()
@deftypefnx {} {@var{old_val} =} __parser_debug_flag__ (@var{new_val})
Query or set the internal flag that determines whether Octave's parser
prints debug information as it processes an expression.
@seealso{__lexer_debug_flag__}
@end deftypefn */)
{
  octave_value retval;

  bool debug_flag = octave_debug;

  retval = set_internal_variable (debug_flag, args, nargout,
                                  "__parser_debug_flag__");

  octave_debug = debug_flag;

  return retval;
}

DEFMETHOD (__parse_file__, interp, args, ,
           doc: /* -*- texinfo -*-
@deftypefn {} {} __parse_file__ (@var{file}, @var{verbose})
Undocumented internal function.
@end deftypefn */)
{
  octave_value retval;

  int nargin = args.length ();

  if (nargin < 1 || nargin > 2)
    print_usage ();

  std::string file = args(0).xstring_value ("__parse_file__: expecting filename as argument");

  std::string full_file = sys::file_ops::tilde_expand (file);

  full_file = sys::env::make_absolute (full_file);

  std::string dir_name;

  std::size_t file_len = file.length ();

  if ((file_len > 4 && file.substr (file_len-4) == ".oct")
      || (file_len > 4 && file.substr (file_len-4) == ".mex")
      || (file_len > 2 && file.substr (file_len-2) == ".m"))
    {
      file = sys::env::base_pathname (file);
      file = file.substr (0, file.find_last_of ('.'));

      std::size_t pos = file.find_last_of (sys::file_ops::dir_sep_str ());
      if (pos != std::string::npos)
        {
          dir_name = file.substr (0, pos);
          file = file.substr (pos+1);
        }
    }

  if (nargin == 2)
    octave_stdout << "parsing " << full_file << std::endl;

  octave_value ov_fcn = parse_fcn_file (interp, full_file, file, dir_name, "", "", true, false, false, false);

  return retval;
}

OCTAVE_END_NAMESPACE(octave)