////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 1993-2022 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/>.
//
////////////////////////////////////////////////////////////////////////

#if ! defined (octave_parse_h)
#define octave_parse_h 1

#include "octave-config.h"

#include <cstdio>

#include <deque>
#include <map>
#include <memory>
#include <set>
#include <string>

#include "input.h"
#include "lex.h"
#include "pt-misc.h"
#include "symscope.h"
#include "token.h"

class octave_function;
class octave_user_code;
class octave_user_function;

namespace octave
{
  class comment_list;
  class parse_exception;
  class tree;
  class tree_anon_fcn_handle;
  class tree_arg_size_spec;
  class tree_arg_validation;
  class tree_arg_validation_fcns;
  class tree_args_block_attribute_list;
  class tree_args_block_validation_list;
  class tree_argument_list;
  class tree_arguments_block;
  class tree_array_list;
  class tree_cell;
  class tree_classdef;
  class tree_classdef_attribute_list;
  class tree_classdef_body;
  class tree_classdef_enum_block;
  class tree_classdef_enum_list;
  class tree_classdef_events_block;
  class tree_classdef_events_list;
  class tree_classdef_methods_block;
  class tree_classdef_methods_list;
  class tree_classdef_properties_block;
  class tree_classdef_property_list;
  class tree_classdef_superclass_list;
  class tree_colon_expression;
  class tree_command;
  class tree_constant;
  class tree_decl_command;
  class tree_decl_init_list;
  class tree_expression;
  class tree_fcn_handle;
  class tree_function_def;
  class tree_identifier;
  class tree_if_clause;
  class tree_if_command;
  class tree_if_command_list;
  class tree_index_expression;
  class tree_matrix;
  class tree_matrix;
  class tree_parameter_list;
  class tree_spmd_command;
  class tree_statement;
  class tree_statement_list;
  class tree_statement_listtree_statement;
  class tree_switch_case;
  class tree_switch_case_list;
  class tree_switch_command;
}

#include "ovl.h"

// Nonzero means print parser debugging info (-d).
extern int octave_debug;

namespace octave
{
  class base_parser
  {
  private:

    class parent_scope_info
    {
    public:

      typedef std::pair<symbol_scope, std::string> value_type;

      typedef std::deque<value_type>::iterator iterator;
      typedef std::deque<value_type>::const_iterator const_iterator;

      typedef std::deque<value_type>::reverse_iterator reverse_iterator;
      typedef std::deque<value_type>::const_reverse_iterator const_reverse_iterator;

      parent_scope_info (void) = delete;

      parent_scope_info (base_parser& parser)
        : m_parser (parser), m_info (), m_all_names ()
      { }

      // No copying!

      parent_scope_info (const parent_scope_info&) = delete;

      parent_scope_info& operator = (const parent_scope_info&) = delete;

      ~parent_scope_info (void) = default;

      OCTINTERP_API std::size_t size (void) const;

      OCTINTERP_API void push (const value_type& elt);

      OCTINTERP_API void push (const symbol_scope& id);

      OCTINTERP_API void pop (void);

      OCTINTERP_API bool name_ok (const std::string& name);

      OCTINTERP_API bool name_current_scope (const std::string& name);

      OCTINTERP_API symbol_scope parent_scope (void) const;

      OCTINTERP_API std::string parent_name (void) const;

      OCTINTERP_API void clear (void);

    private:

      base_parser& m_parser;
      std::deque<value_type> m_info;
      std::set<std::string> m_all_names;
    };

  public:

    OCTINTERP_API base_parser (base_lexer& lxr);

    // No copying!

    base_parser (const base_parser&) = delete;

    base_parser& operator = (const base_parser&) = delete;

    virtual ~base_parser (void);

    base_lexer& get_lexer (void) const { return m_lexer; }

    bool at_end_of_input (void) const { return m_lexer.m_end_of_input; }

    OCTINTERP_API void reset (void);

    void classdef_object (const std::shared_ptr<tree_classdef>& obj)
    {
      m_classdef_object = obj;
    }

    std::shared_ptr<tree_classdef> classdef_object (void) const
    {
      return m_classdef_object;
    }

    OCTINTERP_API void statement_list (std::shared_ptr<tree_statement_list>& lst);

    std::shared_ptr<tree_statement_list> statement_list (void) const
    {
      return m_stmt_list;
    }

    void parsing_subfunctions (bool flag)
    {
      m_parsing_subfunctions = flag;
    }

    bool parsing_subfunctions (void) const
    {
      return m_parsing_subfunctions;
    }

    void parsing_local_functions (bool flag)
    {
      m_parsing_local_functions = flag;
    }

    bool parsing_local_functions (void) const
    {
      return m_parsing_local_functions;
    }

    int curr_fcn_depth (void) const
    {
      return m_curr_fcn_depth;
    }

    void endfunction_found (bool flag)
    {
      m_endfunction_found = flag;
    }

    bool endfunction_found (void) const
    {
      return m_endfunction_found;
    }

    // Error messages for mismatched end tokens.
    OCTINTERP_API void
    end_token_error (token *tok, token::end_tok_type expected);

    // Check to see that end tokens are properly matched.
    OCTINTERP_API bool end_token_ok (token *tok, token::end_tok_type expected);

    // Handle pushing symbol table for new function scope.
    OCTINTERP_API bool push_fcn_symtab (void);

    // Build a constant.
    OCTINTERP_API tree_constant * make_constant (token *tok_val);

    OCTINTERP_API tree_black_hole * make_black_hole (void);

    OCTINTERP_API tree_matrix * make_matrix (tree_argument_list *row);

    OCTINTERP_API tree_matrix *
    append_matrix_row (tree_matrix *matrix, tree_argument_list *row);

    OCTINTERP_API tree_cell * make_cell (tree_argument_list *row);

    OCTINTERP_API tree_cell *
    append_cell_row (tree_cell *cell, tree_argument_list *row);

    // Build a function handle.
    OCTINTERP_API tree_fcn_handle * make_fcn_handle (token *tok_val);

    // Build an anonymous function handle.
    OCTINTERP_API tree_anon_fcn_handle *
    make_anon_fcn_handle (tree_parameter_list *param_list,
                          tree_expression *expr, const filepos& at_pos);

    // Build a colon expression.
    OCTINTERP_API tree_expression *
    make_colon_expression (tree_expression *base, tree_expression *limit,
                           tree_expression *incr = nullptr);

    // Build a binary expression.
    OCTINTERP_API tree_expression *
    make_binary_op (int op, tree_expression *op1, token *tok_val,
                    tree_expression *op2);

    // Maybe convert EXPR to a braindead_shortcircuit expression.
    OCTINTERP_API void
    maybe_convert_to_braindead_shortcircuit (tree_expression*& expr);

    // Build a boolean expression.
    OCTINTERP_API tree_expression *
    make_boolean_op (int op, tree_expression *op1, token *tok_val,
                     tree_expression *op2);

    // Build a prefix expression.
    OCTINTERP_API tree_expression *
    make_prefix_op (int op, tree_expression *op1, token *tok_val);

    // Build a postfix expression.
    OCTINTERP_API tree_expression *
    make_postfix_op (int op, tree_expression *op1, token *tok_val);

    // Build an unwind-protect command.
    OCTINTERP_API tree_command *
    make_unwind_command (token *unwind_tok, tree_statement_list *body,
                         tree_statement_list *cleanup, token *end_tok,
                         comment_list *lc, comment_list *mc);

    // Build a try-catch command.
    OCTINTERP_API tree_command *
    make_try_command (token *try_tok, tree_statement_list *body,
                      char catch_sep, tree_statement_list *cleanup,
                      token *end_tok, comment_list *lc,
                      comment_list *mc);

    // Build a while command.
    OCTINTERP_API tree_command *
    make_while_command (token *while_tok, tree_expression *expr,
                        tree_statement_list *body, token *end_tok,
                        comment_list *lc);

    // Build a do-until command.
    OCTINTERP_API tree_command *
    make_do_until_command (token *until_tok, tree_statement_list *body,
                           tree_expression *expr, comment_list *lc);

    // Build a for command.
    OCTINTERP_API tree_command *
    make_for_command (int tok_id, token *for_tok, tree_argument_list *lhs,
                      tree_expression *expr, tree_expression *maxproc,
                      tree_statement_list *body, token *end_tok,
                      comment_list *lc);

    // Build a break command.
    OCTINTERP_API tree_command * make_break_command (token *break_tok);

    // Build a continue command.
    OCTINTERP_API tree_command * make_continue_command (token *continue_tok);

    // Build a return command.
    OCTINTERP_API tree_command * make_return_command (token *return_tok);

    // Build an spmd command.

    OCTINTERP_API tree_spmd_command *
    make_spmd_command (token *spmd_tok, tree_statement_list *body,
                       token *end_tok, comment_list *lc, comment_list *tc);

    // Start an if command.
    OCTINTERP_API tree_if_command_list *
    start_if_command (tree_expression *expr, tree_statement_list *list);

    // Finish an if command.
    OCTINTERP_API tree_if_command *
    finish_if_command (token *if_tok, tree_if_command_list *list,
                       token *end_tok, comment_list *lc);

    // Build an elseif clause.
    OCTINTERP_API tree_if_clause *
    make_elseif_clause (token *elseif_tok, tree_expression *expr,
                        tree_statement_list *list, comment_list *lc);

    OCTINTERP_API tree_if_clause *
    make_else_clause (token *else_tok, comment_list *lc,
                      tree_statement_list *list);

    OCTINTERP_API tree_if_command_list *
    append_if_clause (tree_if_command_list *list, tree_if_clause *clause);

    // Finish a switch command.
    OCTINTERP_API tree_switch_command *
    finish_switch_command (token *switch_tok, tree_expression *expr,
                           tree_switch_case_list *list, token *end_tok,
                           comment_list *lc);

    OCTINTERP_API tree_switch_case_list *
    make_switch_case_list (tree_switch_case *switch_case);

    // Build a switch case.
    OCTINTERP_API tree_switch_case *
    make_switch_case (token *case_tok, tree_expression *expr,
                      tree_statement_list *list, comment_list *lc);

    OCTINTERP_API tree_switch_case *
    make_default_switch_case (token *default_tok, comment_list *lc,
                              tree_statement_list *list);

    OCTINTERP_API tree_switch_case_list *
    append_switch_case (tree_switch_case_list *list, tree_switch_case *elt);

    // Build an assignment to a variable.
    OCTINTERP_API tree_expression *
    make_assign_op (int op, tree_argument_list *lhs, token *eq_tok,
                    tree_expression *rhs);

    // Define a script.
    OCTINTERP_API void
    make_script (tree_statement_list *cmds, tree_statement *end_script);

    // Handle identifier that is recognized as a function name.
    OCTINTERP_API tree_identifier *
    make_fcn_name (tree_identifier *id);

    // Define a function.
    OCTINTERP_API tree_function_def *
    make_function (token *fcn_tok, tree_parameter_list *ret_list,
                   tree_identifier *id, tree_parameter_list *param_list,
                   tree_statement_list *body, tree_statement *end_fcn_stmt,
                   comment_list *lc);

    // Begin defining a function.
    OCTINTERP_API octave_user_function *
    start_function (tree_identifier *id, tree_parameter_list *param_list,
                    tree_statement_list *body, tree_statement *end_function);

    // Create a no-op statement for end_function.
    OCTINTERP_API tree_statement *
    make_end (const std::string& type, bool eof,
              const filepos& beg_pos, const filepos& end_pos);

    // Do most of the work for defining a function.
    OCTINTERP_API octave_user_function *
    frob_function (tree_identifier *id, octave_user_function *fcn);

    // Finish defining a function.
    OCTINTERP_API tree_function_def *
    finish_function (tree_parameter_list *ret_list,
                     octave_user_function *fcn, comment_list *lc,
                     int l, int c);

    OCTINTERP_API tree_statement_list *
    append_function_body (tree_statement_list *body, tree_statement_list *list);

    // Make an arguments validation block.
    OCTINTERP_API tree_arguments_block *
    make_arguments_block (token *arguments_tok,
                          tree_args_block_attribute_list *attr_list,
                          tree_args_block_validation_list *validation_list,
                          token *end_tok, comment_list *lc, comment_list *tc);

    OCTINTERP_API tree_args_block_attribute_list *
    make_args_attribute_list (tree_identifier *attribute_name);

    // Make an argument validation.
    OCTINTERP_API tree_arg_validation *
    make_arg_validation (tree_arg_size_spec *size_spec,
                         tree_identifier *class_name,
                         tree_arg_validation_fcns *validation_fcns,
                         tree_expression *default_value);

    // Make an argument validation list.
    OCTINTERP_API tree_args_block_validation_list *
    make_args_validation_list (tree_arg_validation *arg_validation);

    // Append an argument validation to an existing list.
    OCTINTERP_API tree_args_block_validation_list *
    append_args_validation_list (tree_args_block_validation_list *list,
                                 tree_arg_validation *arg_validation);

    // Make an argument size specification object.
    OCTINTERP_API tree_arg_size_spec *
    make_arg_size_spec (tree_argument_list *size_args);

    // Make a list of argument validation functions.
    OCTINTERP_API tree_arg_validation_fcns *
    make_arg_validation_fcns (tree_argument_list *fcn_args);

    // Reset state after parsing function.
    OCTINTERP_API void
    recover_from_parsing_function (void);

    OCTINTERP_API tree_classdef *
    make_classdef (token *tok_val, tree_classdef_attribute_list *a,
                   tree_identifier *id, tree_classdef_superclass_list *sc,
                   tree_classdef_body *body, token *end_tok,
                   comment_list *lc, comment_list *tc);

    OCTINTERP_API tree_classdef_properties_block *
    make_classdef_properties_block (token *tok_val,
                                    tree_classdef_attribute_list *a,
                                    tree_classdef_property_list *plist,
                                    token *end_tok, comment_list *lc,
                                    comment_list *tc);

    OCTINTERP_API tree_classdef_property_list *
    make_classdef_property_list (tree_classdef_property *prop);

    OCTINTERP_API tree_classdef_property *
    make_classdef_property (comment_list *lc, tree_identifier *id,
                            tree_arg_validation *av);

    OCTINTERP_API tree_classdef_property_list *
    append_classdef_property (tree_classdef_property_list *list,
                              tree_classdef_property *elt);

    OCTINTERP_API tree_classdef_methods_block *
    make_classdef_methods_block (token *tok_val,
                                 tree_classdef_attribute_list *a,
                                 tree_classdef_methods_list *mlist,
                                 token *end_tok, comment_list *lc,
                                 comment_list *tc);

    OCTINTERP_API tree_classdef_events_block *
    make_classdef_events_block (token *tok_val,
                                tree_classdef_attribute_list *a,
                                tree_classdef_events_list *elist,
                                token *end_tok, comment_list *lc,
                                comment_list *tc);

    OCTINTERP_API tree_classdef_events_list *
    make_classdef_events_list (tree_classdef_event *e);

    OCTINTERP_API tree_classdef_event *
    make_classdef_event (comment_list *lc, tree_identifier *id);

    OCTINTERP_API tree_classdef_events_list *
    append_classdef_event (tree_classdef_events_list *list,
                           tree_classdef_event *elt);

    OCTINTERP_API tree_classdef_enum_block *
    make_classdef_enum_block (token *tok_val,
                              tree_classdef_attribute_list *a,
                              tree_classdef_enum_list *elist,
                              token *end_tok, comment_list *lc,
                              comment_list *tc);

    OCTINTERP_API tree_classdef_enum_list *
    make_classdef_enum_list (tree_classdef_enum *e);

    OCTINTERP_API tree_classdef_enum *
    make_classdef_enum (tree_identifier *id, tree_expression *expr,
                        comment_list *lc);

    OCTINTERP_API tree_classdef_enum_list *
    append_classdef_enum (tree_classdef_enum_list *list,
                          tree_classdef_enum *elt);

    OCTINTERP_API tree_classdef_superclass_list *
    make_classdef_superclass_list (tree_classdef_superclass *sc);

    OCTINTERP_API tree_classdef_superclass *
    make_classdef_superclass (token *fqident);

    OCTINTERP_API tree_classdef_superclass_list *
    append_classdef_superclass (tree_classdef_superclass_list *list,
                                tree_classdef_superclass *elt);

    OCTINTERP_API tree_classdef_attribute_list *
    make_classdef_attribute_list (tree_classdef_attribute *attr);

    OCTINTERP_API tree_classdef_attribute *
    make_classdef_attribute (tree_identifier *id,
                             tree_expression *expr = nullptr);

    OCTINTERP_API tree_classdef_attribute *
    make_not_classdef_attribute (tree_identifier *id);

    OCTINTERP_API tree_classdef_attribute_list *
    append_classdef_attribute (tree_classdef_attribute_list *list,
                               tree_classdef_attribute *elt);

    OCTINTERP_API tree_classdef_body *
    make_classdef_body (tree_classdef_properties_block *pb);

    OCTINTERP_API tree_classdef_body *
    make_classdef_body (tree_classdef_methods_block *mb);

    OCTINTERP_API tree_classdef_body *
    make_classdef_body (tree_classdef_events_block *evb);

    OCTINTERP_API tree_classdef_body *
    make_classdef_body  (tree_classdef_enum_block *enb);

    OCTINTERP_API tree_classdef_body *
    append_classdef_properties_block (tree_classdef_body *body,
                                      tree_classdef_properties_block *block);

    OCTINTERP_API tree_classdef_body *
    append_classdef_methods_block (tree_classdef_body *body,
                                   tree_classdef_methods_block *block);

    OCTINTERP_API tree_classdef_body *
    append_classdef_events_block (tree_classdef_body *body,
                                  tree_classdef_events_block *block);

    OCTINTERP_API tree_classdef_body *
    append_classdef_enum_block (tree_classdef_body *body,
                                tree_classdef_enum_block *block);

    OCTINTERP_API octave_user_function *
    start_classdef_external_method (tree_identifier *id,
                                    tree_parameter_list *pl);

    OCTINTERP_API tree_function_def *
    finish_classdef_external_method (octave_user_function *fcn,
                                     tree_parameter_list *ret_list,
                                     comment_list *cl);

    OCTINTERP_API tree_classdef_methods_list *
    make_classdef_methods_list (tree_function_def *fcn_def);

    OCTINTERP_API tree_classdef_methods_list *
    append_classdef_method (tree_classdef_methods_list *list,
                            tree_function_def *fcn_def);

    OCTINTERP_API bool
    finish_classdef_file (tree_classdef *cls,
                          tree_statement_list *local_fcns);

    // Make an index expression.
    OCTINTERP_API tree_index_expression *
    make_index_expression (tree_expression *expr,
                           tree_argument_list *args, char type);

    // Make an indirect reference expression.
    OCTINTERP_API tree_index_expression *
    make_indirect_ref (tree_expression *expr, const std::string&);

    // Make an indirect reference expression with dynamic field name.
    OCTINTERP_API tree_index_expression *
    make_indirect_ref (tree_expression *expr, tree_expression *field);

    // Make a declaration command.
    OCTINTERP_API tree_decl_command *
    make_decl_command (int tok, token *tok_val, tree_decl_init_list *lst);

    OCTINTERP_API tree_decl_init_list *
    make_decl_init_list (tree_decl_elt *elt);

    OCTINTERP_API tree_decl_elt *
    make_decl_elt (tree_identifier *id, token *eq_op = nullptr,
                   tree_expression *expr = nullptr);

    OCTINTERP_API tree_decl_init_list *
    append_decl_init_list (tree_decl_init_list *list, tree_decl_elt *elt);

    // Validate an function parameter list.
    OCTINTERP_API bool
    validate_param_list (tree_parameter_list *lst,
                         tree_parameter_list::in_or_out type);
    // Validate matrix or cell
    OCTINTERP_API bool validate_array_list (tree_expression *e);

    // Validate matrix object used in "[lhs] = ..." assignments.
    OCTINTERP_API tree_argument_list *
    validate_matrix_for_assignment (tree_expression *e);

    // Finish building an array_list (common action for finish_matrix
    // and finish_cell).
    OCTINTERP_API tree_expression *
    finish_array_list (tree_array_list *a, token *open_delim,
                       token *close_delim);

    // Finish building a matrix list.
    OCTINTERP_API tree_expression *
    finish_matrix (tree_matrix *m, token *open_delim, token *close_delim);

    // Finish building a cell list.
    OCTINTERP_API tree_expression *
    finish_cell (tree_cell *c, token *open_delim, token *close_delim);

    OCTINTERP_API tree_identifier *
    make_identifier (token *ident);

    OCTINTERP_API tree_superclass_ref *
    make_superclass_ref (token *superclassref);

    OCTINTERP_API tree_metaclass_query *
    make_metaclass_query (token *metaquery);

    // Set the print flag for a statement based on the separator type.
    OCTINTERP_API tree_statement_list *
    set_stmt_print_flag (tree_statement_list *, char, bool);

    // Finish building a statement.
    template <typename T>
    OCTINTERP_API tree_statement * make_statement (T *arg);

    // Create a statement list.
    OCTINTERP_API tree_statement_list *
    make_statement_list (tree_statement *stmt);

    // Append a statement to an existing statement list.
    OCTINTERP_API tree_statement_list *
    append_statement_list (tree_statement_list *list, char sep,
                           tree_statement *stmt, bool warn_missing_semi);

    OCTINTERP_API tree_argument_list *
    make_argument_list (tree_expression *expr);

    OCTINTERP_API tree_argument_list *
    append_argument_list (tree_argument_list *list, tree_expression *expr);

    OCTINTERP_API tree_parameter_list *
    make_parameter_list (tree_parameter_list::in_or_out io);

    OCTINTERP_API tree_parameter_list *
    make_parameter_list (tree_parameter_list::in_or_out io, tree_decl_elt *t);

    OCTINTERP_API tree_parameter_list *
    make_parameter_list (tree_parameter_list::in_or_out io,
                         tree_identifier *id);

    OCTINTERP_API tree_parameter_list *
    append_parameter_list (tree_parameter_list *list, tree_decl_elt *t);

    OCTINTERP_API tree_parameter_list *
    append_parameter_list (tree_parameter_list *list, tree_identifier *id);

    // Don't allow parsing command syntax.  If the parser/lexer is
    // reset, this setting is also reset to the default (allow command
    // syntax).
    OCTINTERP_API void disallow_command_syntax (void);

    // Generic error messages.
    OCTINTERP_API void bison_error (const std::string& s);
    OCTINTERP_API void bison_error (const std::string& s, const filepos& pos);
    OCTINTERP_API void bison_error (const std::string& s, int line, int column);
    OCTINTERP_API void bison_error (const std::list<parse_exception>& pe);
    OCTINTERP_API void bison_error (const parse_exception& pe);

    friend OCTINTERP_API 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);

    // Thih interface allows push or pull parsers to be used
    // equivalently, provided that the push parser also owns its input
    // method (see below).  Alternatively, the push parser interface may
    // use a separate run method and completely separate input from
    // lexical analysis and parsing.

    virtual int run (void) = 0;

    // Check primary script or function generated by the parser for
    // semantic errors.
    OCTINTERP_API bool validate_primary_fcn (void);

    OCTINTERP_API bool finish_input (tree_statement_list *lst,
                                     bool at_eof = false);

  protected:

    // Contains error message if Bison-generated parser returns non-zero
    // status.
    std::string m_parse_error_msg;

    // Have we found an explicit end to a function?
    bool m_endfunction_found;

    // TRUE means we are in the process of autoloading a function.
    bool m_autoloading;

    // TRUE means the current function file was found in a relative path
    // element.
    bool m_fcn_file_from_relative_lookup;

    // FALSE if we are still at the primary function.  Subfunctions can
    // only be declared inside function files.
    bool m_parsing_subfunctions;

    // TRUE if we are parsing local functions defined at after a
    // classdef block.  Local functions can only be declared inside
    // classdef files.
    bool m_parsing_local_functions;

    // Maximum function depth detected.  Used to determine whether
    // we have nested functions or just implicitly ended subfunctions.
    int m_max_fcn_depth;

    // = 0 currently outside any function.
    // = 1 inside the primary function or a subfunction.
    // > 1 means we are looking at a function definition that seems to be
    //     inside a function.  Note that the function still might not be a
    //     nested function.
    int m_curr_fcn_depth;

    // Scope where we install all subfunctions and nested functions.  Only
    // used while reading function files.
    symbol_scope m_primary_fcn_scope;

    // Name of the current class when we are parsing class methods or
    // constructors.
    std::string m_curr_class_name;

    // Name of the current package when we are parsing an element contained
    // in a package directory (+-directory).
    std::string m_curr_package_name;

    // Nested function scopes and names currently being parsed.
    parent_scope_info m_function_scopes;

    // Pointer to the primary user function or user script function.
    octave_value m_primary_fcn;

    // List of subfunction names, initially in the order they are
    // installed in the symbol table, then ordered as they appear in the
    // file.  Eventually stashed in the primary function object.
    std::list<std::string> m_subfunction_names;

    // Pointer to the classdef object we just parsed, if any.
    std::shared_ptr<tree_classdef> m_classdef_object;

    // Result of parsing input.
    std::shared_ptr <tree_statement_list> m_stmt_list;

    // State of the lexer.
    base_lexer& m_lexer;

    // Internal state of the Bison parser.
    void *m_parser_state;

  private:

    // Maybe print a warning if an assignment expression is used as the
    // test in a logical expression.
    OCTINTERP_API void maybe_warn_assign_as_truth_value (tree_expression *expr);

    // Maybe print a warning about switch labels that aren't constants.
    OCTINTERP_API void maybe_warn_variable_switch_label (tree_expression *expr);

    // Maybe print a warning.
    OCTINTERP_API void maybe_warn_missing_semi (tree_statement_list *);
  };

  // Publish externally used friend functions.

  extern OCTINTERP_API 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);

  class parser : public base_parser
  {
  public:

    parser (interpreter& interp)
      : base_parser (*(new lexer (interp)))
    { }

    parser (FILE *file, interpreter& interp)
      : base_parser (*(new lexer (file, interp)))
    { }

    parser (FILE *file, interpreter& interp, std::string encoding)
      : base_parser (*(new lexer (file, interp, encoding)))
    { }

    parser (const std::string& eval_string, interpreter& interp)
      : base_parser (*(new lexer (eval_string, interp)))
    { }

    // The lexer must be allocated with new.  The parser object
    // takes ownership of and deletes the lexer object in its
    // destructor.

    parser (lexer *lxr)
      : base_parser (*lxr)
    { }

    // No copying!

    parser (const parser&) = delete;

    parser& operator = (const parser&) = delete;

    ~parser (void) = default;

    OCTINTERP_API int run (void);
  };

  class push_parser : public base_parser
  {
  public:

    push_parser (interpreter& interp)
      : base_parser (*(new push_lexer (interp))),
        m_interpreter (interp), m_reader ()
    { }

    // The parser assumes ownership of READER, which must be created
    // with new.

    push_parser (interpreter& interp, input_reader *reader)
      : base_parser (*(new push_lexer (interp))),
        m_interpreter (interp), m_reader (reader)
    { }

    // No copying!

    push_parser (const push_parser&) = delete;

    push_parser& operator = (const push_parser&) = delete;

    ~push_parser (void) = default;

    // Use the push parser in the same way as the pull parser.  The
    // parser arranges for input through the M_READER object.  See, for
    // example, interpreter::main_loop.

    OCTINTERP_API int run (void);

    // Parse INPUT.  M_READER is not used.  The user is responsible for
    // collecting input.

    OCTINTERP_API int run (const std::string& input, bool eof);

  private:

    interpreter& m_interpreter;

    std::shared_ptr<input_reader> m_reader;
  };

  extern OCTINTERP_API std::string
  get_help_from_file (const std::string& nm, bool& symbol_found,
                      std::string& file);

  extern OCTINTERP_API std::string
  get_help_from_file (const std::string& nm, bool& symbol_found);

  extern OCTINTERP_API 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 = false);

  extern OCTINTERP_API void
  source_file (const std::string& file_name,
               const std::string& context = "",
               bool verbose = false, bool require_file = true);

  extern OCTINTERP_API octave_value_list
  feval (const char *name,
         const octave_value_list& args = octave_value_list (),
         int nargout = 0);

  extern OCTINTERP_API octave_value_list
  feval (const std::string& name,
         const octave_value_list& args = octave_value_list (),
         int nargout = 0);

  extern OCTINTERP_API octave_value_list
  feval (octave_function *fcn,
         const octave_value_list& args = octave_value_list (),
         int nargout = 0);

  extern OCTINTERP_API octave_value_list
  feval (const octave_value& val,
         const octave_value_list& args = octave_value_list (),
         int nargout = 0);

  extern OCTINTERP_API octave_value_list
  feval (const octave_value_list& args, int nargout = 0);

  extern OCTINTERP_API void
  cleanup_statement_list (tree_statement_list **lst);
}

#endif