/*

Copyright (C) 1996 John W. Eaton

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 2, 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, write to the Free
Software Foundation, 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

*/

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <cfloat>
#include <cstdio>
#include <cstring>

#include <string>

#include <strstream.h>

#ifdef HAVE_UNISTD_H
#include <sys/types.h>
#include <unistd.h>
#endif

#include <readline/readline.h>

#include "file-ops.h"
#include "oct-glob.h"
#include "str-vec.h"

#include "defaults.h"
#include "defun.h"
#include "dirfns.h"
#include "dynamic-ld.h"
#include "error.h"
#include "help.h"
#include "input.h"
#include "lex.h"
#include "mappers.h"
#include "oct-hist.h"
#include "toplev.h"
#include "pager.h"
#include "parse.h"
#include "symtab.h"
#include "sysdep.h"
#include "pt-const.h"
#include "oct-obj.h"
#include "pt-exp.h"
#include "pt-fvc.h"
#include "syscalls.h"
#include "unwind-prot.h"
#include "user-prefs.h"
#include "utils.h"
#include "variables.h"
#include "version.h"

// Symbol table for symbols at the top level.
symbol_table *top_level_sym_tab = 0;

// Symbol table for the current scope.
symbol_table *curr_sym_tab = 0;

// Symbol table for global symbols.
symbol_table *global_sym_tab = 0;

// Initialization.

// Create the initial symbol tables and set the current scope at the
// top level.

void
initialize_symbol_tables (void)
{
  if (! global_sym_tab)
    global_sym_tab = new symbol_table ();

  if (! top_level_sym_tab)
    top_level_sym_tab = new symbol_table ();

  curr_sym_tab = top_level_sym_tab;
}

// Attributes of variables and functions.

// Is this variable a builtin?

bool
is_builtin_variable (const string& name)
{
  symbol_record *sr = global_sym_tab->lookup (name, 0, 0);
  return (sr && sr->is_builtin_variable ());
}

// Is this a text-style function?

bool
is_text_function_name (const string& s)
{
  symbol_record *sr = global_sym_tab->lookup (s);
  return (sr && sr->is_text_function ());
}

// Is this function globally in this scope?

bool
is_globally_visible (const string& name)
{
  symbol_record *sr = curr_sym_tab->lookup (name, 0, 0);
  return (sr && sr->is_linked_to_global ());
}

// Is this octave_value a valid function?

tree_fvc *
is_valid_function (const octave_value& arg, const string& warn_for, int warn)
{
  tree_fvc *ans = 0;

  string fcn_name;

  if (arg.is_string ())
    fcn_name = arg.string_value ();

  if (fcn_name.empty () || error_state)
    {
      if (warn)
	error ("%s: expecting function name as argument",
	       warn_for.c_str ());
      return ans;
    }

  symbol_record *sr = 0;

  if (! fcn_name.empty ())
    sr = lookup_by_name (fcn_name);

  if (sr)
    ans = sr->def ();

  if (! sr || ! ans || ! sr->is_function ())
    {
      if (warn)
	error ("%s: the symbol `%s' is not valid as a function",
	       warn_for.c_str (), fcn_name.c_str ());
      ans = 0;
    }

  return ans;
}

DEFUN (is_global, args, ,
  "is_global (X): return 1 if the string X names a global variable\n\
otherwise, return 0.")
{
  octave_value_list retval = 0.0;

  int nargin = args.length ();

  if (nargin != 1)
    {
      print_usage ("is_global");
      return retval;
    }

  string name = args(0).string_value ();

  if (error_state)
    {
      error ("is_global: expecting string argument");
      return retval;
    }

  symbol_record *sr = curr_sym_tab->lookup (name, 0, 0);

  retval = (double) (sr && sr->is_linked_to_global ());

  return retval;
}

DEFUN (exist, args, ,
  "exist (NAME): check if variable or file exists\n\
\n\
returns:\n\
\n\
   0 : NAME is undefined\n\
   1 : NAME is a variable\n\
   2 : NAME is a function\n\
   3 : NAME is a .oct file in the current LOADPATH\n\
   5 : NAME is a built-in function")
{
  octave_value_list retval;

  int nargin = args.length ();

  if (nargin != 1)
    {
      print_usage ("exist");
      return retval;
    }

  string name = args(0).string_value ();

  if (error_state)
    {
      error ("exist: expecting string argument");
      return retval;
    }

  string struct_elts;

  size_t pos = name.find ('.');

  if (pos != NPOS)
    {
      struct_elts = name.substr (pos+1);
      name = name.substr (0, pos);
    }

  symbol_record *sr = curr_sym_tab->lookup (name, 0, 0);
  if (! sr)
    sr = global_sym_tab->lookup (name, 0, 0);

  retval = 0.0;

  if (sr && sr->is_variable () && sr->is_defined ())
    {
      retval = 1.0;
      tree_fvc *def = sr->def ();

      if (! struct_elts.empty ())
	{
	  retval = 0.0;
	  if (def->is_constant ())
	    {
	      octave_value *tmp = (octave_value *) def;

	      octave_value ult	= tmp->lookup_map_element (struct_elts, 0, 1);

	      if (ult.is_defined ())
		retval = 1.0;
	    }
	}
    }
  else if (sr && sr->is_builtin_function ())
    {
      retval = 5.0;
    }
  else if (sr && sr->is_user_function ())
    {
      retval = 2.0;
    }
  else
    {
      string path = fcn_file_in_path (name);

      if (path.length () > 0)
	{
	  retval = 2.0;
	}
      else
	{
	  path = oct_file_in_path (name);

	  if (path.length () > 0)
	    {
	      retval = 3.0;
	    }
	  else
	    {
	      file_stat fs (name);

	      if (fs && fs.is_reg ())
		retval = 2.0;
	    }
	}
    }

  return retval;
}

// XXX FIXME XXX -- should these really be here?

static string
octave_home (void)
{
  char *oh = getenv ("OCTAVE_HOME");

  return oh ? string (oh) : string (OCTAVE_PREFIX);
}

static string
subst_octave_home (const string& s)
{
  string retval;

  string home = octave_home ();
  string prefix = OCTAVE_PREFIX;

  retval = s;

  if (home != prefix)
    {
      int len = prefix.length ();
      size_t start = 0;
      while ((start = s.find (prefix)) != NPOS)
	{
	  retval.replace (start, len, home);
	  start++;
	}
    }

  return retval;
}

static string
octave_info_dir (void)
{
  return subst_octave_home (OCTAVE_INFODIR);
}

string
octave_arch_lib_dir (void)
{
  return subst_octave_home (OCTAVE_ARCHLIBDIR);
}

string
octave_fcn_file_dir (void)
{
  return subst_octave_home (OCTAVE_FCNFILEDIR);
}

string
octave_bin_dir (void)
{
  return subst_octave_home (OCTAVE_BINDIR);
}

string
default_pager (void)
{
  string pager_binary;

  char *pgr = getenv ("PAGER");

  if (pgr)
    pager_binary = string (pgr);
#ifdef DEFAULT_PAGER
  else
    pager_binary = string (DEFAULT_PAGER);
#endif

  return pager_binary;
}

string
maybe_add_default_load_path (const string& pathstring)
{
  string std_path = subst_octave_home (OCTAVE_FCNFILEPATH);

  string retval;

  if (! pathstring.empty ())
    {
      if (pathstring[0] == SEPCHAR)
	{
	  retval = std_path;
	  retval.append (pathstring);
	}
      else
	retval = pathstring;

      if (pathstring[pathstring.length () - 1] == SEPCHAR)
	retval.append (std_path);
    }

  return retval;
}

string
octave_lib_dir (void)
{
  return subst_octave_home (OCTAVE_LIBDIR);
}

string
default_exec_path (void)
{
  string exec_path_string;

  char *octave_exec_path = getenv ("OCTAVE_EXEC_PATH");

  if (octave_exec_path)
    exec_path_string = string (octave_exec_path);
  else
    {
      char *shell_path = getenv ("PATH");

      if (shell_path)
	{
	  exec_path_string = string (":");
	  exec_path_string.append (shell_path);
	}
    }

  return exec_path_string;
}

// Handle OCTAVE_PATH from the environment like TeX handles TEXINPUTS.
// If the path starts with `:', prepend the standard path.  If it ends
// with `:' append the standard path.  If it begins and ends with
// `:', do both (which is useless, but the luser asked for it...).

string
default_path (void)
{
  string std_path = subst_octave_home (OCTAVE_FCNFILEPATH);

  char *oct_path = getenv ("OCTAVE_PATH");

  return oct_path ? string (oct_path) : std_path;
}

string
default_info_file (void)
{
  string info_file_string;

  char *oct_info_file = getenv ("OCTAVE_INFO_FILE");

  if (oct_info_file)
    info_file_string = string (oct_info_file);
  else
    {
      string infodir = octave_info_dir ();
      info_file_string = infodir.append ("/octave.info");
    }

  return info_file_string;
}

string
default_info_prog (void)
{
  string info_prog_string;

  char *oct_info_prog = getenv ("OCTAVE_INFO_PROGRAM");

  if (oct_info_prog)
    info_prog_string = string (oct_info_prog);
  else
    {
      string archdir = octave_arch_lib_dir ();
      info_prog_string = archdir.append ("/info");
    }

  return info_prog_string;
}

string
default_editor (void)
{
  string editor_string = "vi";

  char *env_editor = getenv ("EDITOR");

  if (env_editor && *env_editor)
    editor_string = string (env_editor);

  return editor_string;
}

string
get_local_site_defaults (void)
{
  string startupdir = subst_octave_home (OCTAVE_LOCALSTARTUPFILEDIR);
  return startupdir.append ("/octaverc");
}

string
get_site_defaults (void)
{
  string startupdir = subst_octave_home (OCTAVE_STARTUPFILEDIR);
  return startupdir.append ("/octaverc");
}

// Functions for looking up variables and functions.

// Is there a corresponding function file that is newer than the
// symbol definition?

static int
symbol_out_of_date (symbol_record *sr)
{
  int ignore = user_pref.ignore_function_time_stamp;

  if (ignore == 2)
    return 0;

  if (sr)
    {
      tree_fvc *ans = sr->def ();
      if (ans)
	{
	  string ff = ans->fcn_file_name ();
	  if (! ff.empty () && ! (ignore && ans->is_system_fcn_file ()))
	    {
	      time_t tp = ans->time_parsed ();

	      string fname = fcn_file_in_path (ff);

	      int status = is_newer (fname, tp);

	      if (status > 0)
		return 1;
	    }
	}
    }
  return 0;
}

static int
looks_like_octave_copyright (const string& s)
{
  string t = s.substr (0, 15);

  if (t == " Copyright (C) ")
    {
      size_t pos = s.find ('\n');

      if (pos != NPOS)
	{
	  pos = s.find ('\n', pos + 1);

	  if (pos != NPOS)
	    {
	      pos++;

	      t = s.substr (pos, 29);

	      if (t == " This file is part of Octave."
		  || t == " This program is free softwar")
		return 1;
	    }
	}
    }
  return 0;
}

// Eat whitespace and comments from FFILE, returning the text of the
// comments read if it doesn't look like a copyright notice.  If
// IN_PARTS, consider each block of comments separately; otherwise,
// grab them all at once.

static string
gobble_leading_white_space (FILE *ffile, int in_parts)
{
  string help_txt;

  int first_comments_seen = 0;
  int have_help_text = 0;
  int in_comment = 0;
  int c;

  while ((c = getc (ffile)) != EOF)
    {
      current_input_column++;

      if (in_comment)
	{
	  if (! have_help_text)
	    {
	      first_comments_seen = 1;
	      help_txt += (char) c;
	    }

	  if (c == '\n')
	    {
	      input_line_number++;
	      current_input_column = 0;
	      in_comment = 0;

	      if (in_parts)
		{
		  if ((c = getc (ffile)) != EOF)
		    {
		      current_input_column--;
		      ungetc (c, ffile);
		      if (c == '\n')
			break;
		    }
		  else
		    break;
		}
	    }
	}
      else
	{
	  switch (c)
	    {
	    case ' ':
	    case '\t':
	      if (first_comments_seen)
		have_help_text = 1;
	      break;

	    case '\n':
	      if (first_comments_seen)
		have_help_text = 1;
	      input_line_number++;
	      current_input_column = 0;
	      continue;

	    case '%':
	    case '#':
	      in_comment = 1;
	      break;

	    default:
	      current_input_column--;
	      ungetc (c, ffile);
	      goto done;
	    }
	}
    }

 done:

  if (! help_txt.empty ())
    {
      if (looks_like_octave_copyright (help_txt)) 
	help_txt.resize (0);

      if (in_parts && help_txt.empty ())
	help_txt = gobble_leading_white_space (ffile, in_parts);
    }

  return help_txt;
}

static int
is_function_file (FILE *ffile)
{
  int status = 0;

  long pos = ftell (ffile);

  char buf [10];
  fgets (buf, 10, ffile);
  int len = strlen (buf);
  if (len > 8 && strncmp (buf, "function", 8) == 0
      && ! (isalnum (buf[8]) || buf[8] == '_'))
    status = 1;

  fseek (ffile, pos, SEEK_SET);

  return status;
}

static void
restore_command_history (void *)
{
  octave_command_history.ignore_entries (! user_pref.saving_history);
}

static int
parse_fcn_file (int exec_script, const string& ff)
{
  begin_unwind_frame ("parse_fcn_file");

  int script_file_executed = 0;

  // Open function file and parse.

  int old_reading_fcn_file_state = reading_fcn_file;

  unwind_protect_ptr (rl_instream);
  unwind_protect_ptr (ff_instream);

  unwind_protect_int (using_readline);
  unwind_protect_int (input_line_number);
  unwind_protect_int (current_input_column);
  unwind_protect_int (reading_fcn_file);

  using_readline = 0;
  reading_fcn_file = 1;
  input_line_number = 0;
  current_input_column = 1;

  FILE *ffile = get_input_from_file (ff, 0);

  if (ffile)
    {
      // Check to see if this file defines a function or is just a
      // list of commands.

      string tmp_help_txt = gobble_leading_white_space (ffile, 0);

      if (is_function_file (ffile))
	{
	  // XXX FIXME XXX -- we shouldn't need both the
	  // octave_command_history object and the
	  // user_pref.saving_history variable...
	  octave_command_history.ignore_entries ();

	  add_unwind_protect (restore_command_history, 0);

	  unwind_protect_int (user_pref.echo_executing_commands);
	  unwind_protect_int (user_pref.saving_history);
	  unwind_protect_int (reading_fcn_file);
	  unwind_protect_int (input_from_command_line_file);

	  user_pref.echo_executing_commands = ECHO_OFF;
	  user_pref.saving_history = 0;
	  reading_fcn_file = 1;
	  input_from_command_line_file = 0;

	  YY_BUFFER_STATE old_buf = current_buffer ();
	  YY_BUFFER_STATE new_buf = create_buffer (ffile);

	  add_unwind_protect (restore_input_buffer, (void *) old_buf);
	  add_unwind_protect (delete_input_buffer, (void *) new_buf);

	  switch_to_buffer (new_buf);

	  unwind_protect_ptr (curr_sym_tab);

	  reset_parser ();

	  help_buf = tmp_help_txt;

	  int status = yyparse ();

	  if (status != 0)
	    {
	      error ("parse error while reading function file %s",
		     ff.c_str ());
	      global_sym_tab->clear (curr_fcn_file_name);
	    }
	}
      else if (exec_script)
	{
	  // The value of `reading_fcn_file' will be restored to the
	  // proper value when we unwind from this frame.
	  reading_fcn_file = old_reading_fcn_file_state;

	  // XXX FIXME XXX -- we shouldn't need both the
	  // octave_command_history object and the
	  // user_pref.saving_history variable...
	  octave_command_history.ignore_entries ();

	  add_unwind_protect (restore_command_history, 0);

	  unwind_protect_int (user_pref.saving_history);
	  unwind_protect_int (reading_script_file);

	  user_pref.saving_history = 0;
	  reading_script_file = 1;

	  parse_and_execute (ffile, 1);

	  script_file_executed = 1;
	}
      fclose (ffile);
    }

  run_unwind_frame ("parse_fcn_file");

  return script_file_executed;
}

static bool
load_fcn_from_file (symbol_record *sym_rec, int exec_script)
{
  bool script_file_executed = false;

  string nm = sym_rec->name ();

  if (load_octave_oct_file (nm))
    {
      force_link_to_function (nm);
    }
  else
    {
      string ff = fcn_file_in_path (nm);

      // These are needed by yyparse.

      begin_unwind_frame ("load_fcn_from_file");

      unwind_protect_str (curr_fcn_file_name);
      unwind_protect_str (curr_fcn_file_full_name);

      curr_fcn_file_name = nm;
      curr_fcn_file_full_name = ff;

      if (ff.length () > 0)
	script_file_executed = parse_fcn_file (exec_script, ff);

      if (! (error_state || script_file_executed))
	force_link_to_function (nm);

      run_unwind_frame ("load_fcn_from_file");
    }

  return script_file_executed;
}

bool
lookup (symbol_record *sym_rec, int exec_script)
{
  bool script_executed = false;

  if (! sym_rec->is_linked_to_global ())
    {
      if (sym_rec->is_defined ())
	{
	  if (sym_rec->is_function () && symbol_out_of_date (sym_rec))
	    script_executed = load_fcn_from_file (sym_rec, exec_script);
	}
      else if (! sym_rec->is_formal_parameter ())
	{
	  link_to_builtin_or_function (sym_rec);

	  if (! sym_rec->is_defined ())
	    script_executed = load_fcn_from_file (sym_rec, exec_script);
	  else if (sym_rec->is_function () && symbol_out_of_date (sym_rec))
	    script_executed = load_fcn_from_file (sym_rec, exec_script);
	}
    }

  return script_executed;
}

// Get the symbol record for the given name that is visible in the
// current scope.  Reread any function definitions that appear to be
// out of date.  If a function is available in a file but is not
// currently loaded, this will load it and insert the name in the
// current symbol table.

symbol_record *
lookup_by_name (const string& nm, int exec_script)
{
  symbol_record *sym_rec = curr_sym_tab->lookup (nm, 1, 0);

  lookup (sym_rec, exec_script);

  return sym_rec;
}

string
get_help_from_file (const string& path)
{
  string retval;

  if (! path.empty ())
    {
      FILE *fptr = fopen (path.c_str (), "r");

      if (fptr)
	{
	  retval = gobble_leading_white_space (fptr, 1);
	  fclose (fptr);
	}
    }

  return retval;
}

// Variable values.

// Look for the given name in the global symbol table.  If it refers
// to a string, return a new copy.  If not, return 0;

string
builtin_string_variable (const string& name)
{
  symbol_record *sr = global_sym_tab->lookup (name, 0, 0);

  // It is a prorgramming error to look for builtins that aren't.

  assert (sr);

  string retval;

  tree_fvc *defn = sr->def ();

  if (defn)
    {
      octave_value val = defn->eval (0);

      if (! error_state && val.is_string ())
	retval = val.string_value ();
    }

  return retval;
}

// Look for the given name in the global symbol table.  If it refers
// to a real scalar, place the value in d and return 1.  Otherwise,
// return 0.

int
builtin_real_scalar_variable (const string& name, double& d)
{
  int status = 0;
  symbol_record *sr = global_sym_tab->lookup (name, 0, 0);

  // It is a prorgramming error to look for builtins that aren't.

  assert (sr);

  tree_fvc *defn = sr->def ();

  if (defn)
    {
      octave_value val = defn->eval (0);

      if (! error_state && val.is_scalar_type ())
	{
	  d = val.double_value ();
	  status = 1;
	}
    }

  return status;
}

// Look for the given name in the global symbol table.

octave_value
builtin_any_variable (const string& name)
{
  octave_value retval;

  symbol_record *sr = global_sym_tab->lookup (name, 0, 0);

  // It is a prorgramming error to look for builtins that aren't.

  assert (sr);

  tree_fvc *defn = sr->def ();

  if (defn)
    retval = defn->eval (0);

  return retval;
}

// Global stuff and links to builtin variables and functions.

// Make the definition of the symbol record sr be the same as the
// definition of the global variable of the same name, creating it if
// it doesn't already exist.

void
link_to_global_variable (symbol_record *sr)
{
  if (sr->is_linked_to_global ())
    return;

  string nm = sr->name ();

  symbol_record *gsr = global_sym_tab->lookup (nm, 1, 0);

  if (sr->is_formal_parameter ())
    {
      error ("can't make function parameter `%s' global", nm.c_str ());
      return;
    }

  // There must be a better way to do this.   XXX FIXME XXX

  if (sr->is_variable ())
    {
      // Would be nice not to have this cast.  XXX FIXME XXX

      octave_value *tmp = (octave_value *) sr->def ();
      if (tmp)
	tmp = new octave_value (*tmp);
      else
	tmp = new octave_value ();
      gsr->define (tmp);
    }
  else
    sr->clear ();

  // If the global symbol is currently defined as a function, we need
  // to hide it with a variable.

  if (gsr->is_function ())
    gsr->define ((octave_value *) 0);

  sr->alias (gsr, 1);
  sr->mark_as_linked_to_global ();
}

// Make the definition of the symbol record sr be the same as the
// definition of the builtin variable of the same name.

void
link_to_builtin_variable (symbol_record *sr)
{
  symbol_record *tmp_sym = global_sym_tab->lookup (sr->name (), 0, 0);

  if (tmp_sym && tmp_sym->is_builtin_variable ())
    sr->alias (tmp_sym);
}

// Make the definition of the symbol record sr be the same as the
// definition of the builtin variable or function, or user function of
// the same name, provided that the name has not been used as a formal
// parameter.

void
link_to_builtin_or_function (symbol_record *sr)
{
  symbol_record *tmp_sym = global_sym_tab->lookup (sr->name (), 0, 0);

  if (tmp_sym
      && (tmp_sym->is_builtin_variable () || tmp_sym->is_function ())
      && ! tmp_sym->is_formal_parameter ())
    sr->alias (tmp_sym);
}

// Force a link to a function in the current symbol table.  This is
// used just after defining a function to avoid different behavior
// depending on whether or not the function has been evaluated after
// being defined.
//
// Return without doing anything if there isn't a function with the
// given name defined in the global symbol table.

void
force_link_to_function (const string& id_name)
{
  symbol_record *gsr = global_sym_tab->lookup (id_name, 1, 0);
  if (gsr->is_function ())
    {
      curr_sym_tab->clear (id_name);
      symbol_record *csr = curr_sym_tab->lookup (id_name, 1, 0);
      csr->alias (gsr);
    }
}

// Help stuff.  Shouldn't this go in help.cc?

// It's not likely that this does the right thing now.  XXX FIXME XXX

string_vector
make_name_list (void)
{
  int key_len = 0;
  int glb_len = 0;
  int top_len = 0;
  int lcl_len = 0;

  string_vector key;
  string_vector glb;
  string_vector top;
  string_vector lcl;
  string_vector ffl;

  // Each of these functions returns a new vector of pointers to new
  // strings.

  key = names (keyword_help (), key_len);

  glb = global_sym_tab->list (glb_len);

  top = top_level_sym_tab->list (top_len);

  if (top_level_sym_tab != curr_sym_tab)
    lcl = curr_sym_tab->list (lcl_len);

  ffl = get_fcn_file_names (1);
  int ffl_len = ffl.length ();

  int total_len = key_len + glb_len + top_len + lcl_len + ffl_len;

  string_vector list (total_len);

  // Put all the symbols in one big list.  Only copy pointers, not the
  // strings they point to, then only delete the original array of
  // pointers, and not the strings they point to.

  int j = 0;
  int i = 0;
  for (i = 0; i < key_len; i++)
    list[j++] = key[i];

  for (i = 0; i < glb_len; i++)
    list[j++] = glb[i];

  for (i = 0; i < top_len; i++)
    list[j++] = top[i];

  for (i = 0; i < lcl_len; i++)
    list[j++] = lcl[i];

  for (i = 0; i < ffl_len; i++)
    list[j++] = ffl[i];

  return list;
}

// List variable names.

static void
print_symbol_info_line (ostrstream& output_buf, const symbol_record_info& s)
{
  output_buf << (s.is_read_only () ? " -" : " w");
  output_buf << (s.is_eternal () ? "- " : "d ");
#if 0
  output_buf << (s.hides_fcn () ? "f" : (s.hides_builtin () ? "F" : "-"));
#endif
  output_buf.form ("  %-16s", s.type_as_string ().c_str ());
  if (s.is_function ())
    output_buf << "      -      -";
  else
    {
      output_buf.form ("%7d", s.rows ());
      output_buf.form ("%7d", s.columns ());
    }
  output_buf << "  " << s.name () << "\n";
}

static void
print_long_listing (ostrstream& output_buf, symbol_record_info *s)
{
  if (! s)
    return;

  symbol_record_info *ptr = s;
  while (ptr->is_defined ())
    {
      print_symbol_info_line (output_buf, *ptr);
      ptr++;
    }
}

static int
maybe_list (const char *header, const string_vector& argv, int argc,
	    ostrstream& output_buf, int show_verbose, symbol_table
	    *sym_tab, unsigned type, unsigned scope)
{
  int count;
  int status = 0;
  if (show_verbose)
    {
      symbol_record_info *symbols;
      symbols = sym_tab->long_list (count, argv, argc, 1, type, scope);
      if (symbols && count > 0)
	{
	  output_buf << "\n" << header << "\n\n"
		     << "prot  type               rows   cols  name\n"
		     << "====  ====               ====   ====  ====\n";

	  print_long_listing (output_buf, symbols);
	  status = 1;
	}
      delete [] symbols;
    }
  else
    {
      string_vector symbols = sym_tab->list (count, argv, argc, 1,
					     type, scope);
      if (symbols.length () > 0 && count > 0)
	{
	  output_buf << "\n" << header << "\n\n";
	  symbols.list_in_columns (output_buf);
	  status = 1;
	}
    }
  return status;
}

DEFUN_TEXT (document, args, ,
  "document symbol string ...\n\
\n\
Associate a cryptic message with a variable name.")
{
  octave_value_list retval;

  int argc = args.length () + 1;

  string_vector argv = args.make_argv ("document");

  if (error_state)
    return retval;

  if (argc == 3)
    {
      string name = argv[1];
      string help = argv[2];

      if (is_builtin_variable (name))
	error ("sorry, can't redefine help for builtin variables");
      else
	{
	  symbol_record *sym_rec = curr_sym_tab->lookup (name, 0);

	  if (sym_rec)
	    sym_rec->document (help);
	  else
	    error ("document: no such symbol `%s'", name.c_str ());
	}
    }
  else
    print_usage ("document");

  return retval;
}

// XXX FIXME XXX -- this should take a list of regular expressions
// naming the variables to look for.

static octave_value_list
do_who (int argc, const string_vector& argv)
{
  octave_value_list retval;

  int show_builtins = 0;
  int show_functions = (curr_sym_tab == top_level_sym_tab);
  int show_variables = 1;
  int show_verbose = 0;

  string my_name = argv[0];

  if (argc > 1)
    {
      show_functions = 0;
      show_variables = 0;
    }

  int i;
  for (i = 1; i < argc; i++)
    {
      if (argv[i] == "-all" || argv[i] == "-a")
	{
	  show_builtins++;
	  show_functions++;
	  show_variables++;
	}
      else if (argv[i] == "-builtins" || argv[i] == "-b")
	show_builtins++;
      else if (argv[i] == "-functions" || argv[i] == "-f")
	show_functions++;
      else if (argv[i] == "-long" || argv[i] == "-l")
	show_verbose++;
      else if (argv[i] == "-variables" || argv[i] == "-v")
	show_variables++;
      else if (argv[i][0] == '-')
	warning ("%s: unrecognized option `%s'", my_name.c_str (),
		 argv[i].c_str ());
      else
	break;
    }

  int npats = argc - i;
  string_vector pats (npats);
  for (int j = 0; j < npats; j++)
    pats[j] = argv[i+j];

  // If the user specified -l and nothing else, show variables.  If
  // evaluating this at the top level, also show functions.

  if (show_verbose && ! (show_builtins || show_functions || show_variables))
    {
      show_functions = (curr_sym_tab == top_level_sym_tab);
      show_variables = 1;
    }

  ostrstream output_buf;
  int pad_after = 0;

  if (show_builtins)
    {
      pad_after += maybe_list ("*** built-in variables:", pats, npats,
			       output_buf, show_verbose, global_sym_tab,
			       symbol_def::BUILTIN_VARIABLE,
			       SYMTAB_ALL_SCOPES);

      pad_after += maybe_list ("*** built-in functions:", pats, npats,
			       output_buf, show_verbose, global_sym_tab,
			       symbol_def::BUILTIN_FUNCTION,
			       SYMTAB_ALL_SCOPES);
    }

  if (show_functions)
    {
      pad_after += maybe_list ("*** currently compiled functions:",
			       pats, npats, output_buf, show_verbose,
			       global_sym_tab, symbol_def::USER_FUNCTION,
			       SYMTAB_ALL_SCOPES);
    }

  if (show_variables)
    {
      pad_after += maybe_list ("*** local user variables:", pats, npats,
			       output_buf, show_verbose, curr_sym_tab,
			       symbol_def::USER_VARIABLE,
			       SYMTAB_LOCAL_SCOPE);

      pad_after += maybe_list ("*** globally visible user variables:",
			       pats, npats, output_buf, show_verbose,
			       curr_sym_tab, symbol_def::USER_VARIABLE,
			       SYMTAB_GLOBAL_SCOPE);
    }

  if (pad_after)
    output_buf << "\n";

  output_buf << ends;
  maybe_page_output (output_buf);

  return retval;
}

DEFUN_TEXT (who, args, ,
  "who [-all] [-builtins] [-functions] [-long] [-variables]\n\
\n\
List currently defined symbol(s).  Options may be shortened to one\n\
character, but may not be combined.")
{
  octave_value_list retval;

  int argc = args.length () + 1;

  string_vector argv = args.make_argv ("who");

  if (error_state)
    return retval;

  retval = do_who (argc, argv);

  return retval;
}

DEFUN_TEXT (whos, args, ,
  "whos [-all] [-builtins] [-functions] [-long] [-variables]\n\
\n\
List currently defined symbol(s).  Options may be shortened to one\n\
character, but may not be combined.")
{
  octave_value_list retval;

  int nargin = args.length ();

  octave_value_list tmp_args;
  for (int i = nargin; i > 0; i--)
    tmp_args(i) = args(i-1);
  tmp_args(0) = "-long";

  int argc = tmp_args.length () + 1;

  string_vector argv = tmp_args.make_argv ("whos");

  if (error_state)
    return retval;

  retval = do_who (argc, argv);

  return retval;
}

// Install variables and functions in the symbol tables.

void
install_builtin_mapper (const builtin_mapper_function& mf)
{
  symbol_record *sym_rec = global_sym_tab->lookup (mf.name, 1);
  sym_rec->unprotect ();

  tree_builtin *def = new tree_builtin (mf, mf.name);

  sym_rec->define (def);

  sym_rec->document (mf.help_string);
  sym_rec->make_eternal ();
  sym_rec->protect ();
}

void
install_builtin_function (const builtin_function& f)
{
  symbol_record *sym_rec = global_sym_tab->lookup (f.name, 1);
  sym_rec->unprotect ();

  tree_builtin *def = new tree_builtin (f.fcn, f.name);

  sym_rec->define (def, f.is_text_fcn);

  sym_rec->document (f.help_string);
  sym_rec->make_eternal ();
  sym_rec->protect ();
}

void
install_builtin_variable (const builtin_variable& v)
{
  if (v.install_as_function)
    install_builtin_variable_as_function (v.name, v.value, v.protect,
					  v.eternal, v.help_string);
  else
    bind_builtin_variable (v.name, v.value, v.protect, v.eternal,
			   v.sv_function, v.help_string);
}

void
install_builtin_variable_as_function (const string& name, octave_value *val,
				      int protect, int eternal,
				      const string& help)
{
  symbol_record *sym_rec = global_sym_tab->lookup (name, 1);
  sym_rec->unprotect ();

  string tmp_help = help.empty () ? sym_rec->help () : help;

  sym_rec->define_as_fcn (val);

  sym_rec->document (tmp_help);

  if (protect)
    sym_rec->protect ();

  if (eternal)
    sym_rec->make_eternal ();
}

void
alias_builtin (const string& alias, const string& name)
{
  symbol_record *sr_name = global_sym_tab->lookup (name, 0, 0);

  if (! sr_name)
    panic ("can't alias to undefined name!");

  symbol_record *sr_alias = global_sym_tab->lookup (alias, 1, 0);

  if (sr_alias)
    sr_alias->alias (sr_name);
  else
    panic ("can't find symbol record for builtin function `%s'",
	   alias.c_str ());
}

// Defining variables.

#if 0
void
bind_nargin_and_nargout (symbol_table *sym_tab, int nargin, int nargout)
{
  octave_value *tmp;
  symbol_record *sr;

  sr = sym_tab->lookup ("nargin", 1, 0);
  sr->unprotect ();
  tmp = new octave_value (nargin);
  sr->define (tmp);

  sr = sym_tab->lookup ("nargout", 1, 0);
  sr->unprotect ();
  tmp = new octave_value (nargout);
  sr->define (tmp);
}
#endif

void
bind_ans (const octave_value& val, int print)
{
  static symbol_record *sr = global_sym_tab->lookup ("ans", 1, 0);

  tree_identifier *ans_id = new tree_identifier (sr);
  octave_value *tmp = new octave_value (val);

  // XXX FIXME XXX -- making ans_id static, passing its address to
  // tree_simple_assignment_expression along with a flag to not delete
  // it seems to create a memory leak.  Hmm.

  tree_simple_assignment_expression tmp_ass (ans_id, tmp, false, true);

  tmp_ass.eval (print);
}

void
bind_global_error_variable (void)
{
  *error_message_buffer << ends;

  char *error_text = error_message_buffer->str ();

  bind_builtin_variable ("__error_text__", error_text, 1);

  delete [] error_text;

  delete error_message_buffer;

  error_message_buffer = 0;
}

void
clear_global_error_variable (void *)
{
  delete error_message_buffer;
  error_message_buffer = 0;

  bind_builtin_variable ("__error_text__", "", 1);
}

// Give a global variable a definition.  This will insert the symbol
// in the global table if necessary.

// How is this different than install_builtin_variable?  Are both
// functions needed?

void
bind_builtin_variable (const string& varname, octave_value *val,
		       int protect, int eternal, sv_Function sv_fcn,
		       const string& help)
{
  symbol_record *sr = global_sym_tab->lookup (varname, 1, 0);

  // It is a programming error for a builtin symbol to be missing.
  // Besides, we just inserted it, so it must be there.

  assert (sr);

  sr->unprotect ();

  // Must do this before define, since define will call the special
  // variable function only if it knows about it, and it needs to, so
  // that user prefs can be properly initialized.

  if (sv_fcn)
    sr->set_sv_function (sv_fcn);

  sr->define_builtin_var (val);

  if (protect)
    sr->protect ();

  if (eternal)
    sr->make_eternal ();

  sr->document (help);
}

void
bind_builtin_variable (const string& varname, const octave_value& val,
		       int protect, int eternal, sv_Function sv_fcn,
		       const string& help)
{
  octave_value *tc = new octave_value (val);
  bind_builtin_variable (varname, tc, protect, eternal, sv_fcn, help);
}

// XXX FIXME XX -- these should probably be moved to where they
// logically belong instead of being all grouped here.

// This is split up to try to make compiling with gcc consume less
// memory and go a little faster.

static void
install_builtin_variables_1 (void)
{
  DEFVAR (EDITOR, editor, 0, sv_editor,
    "name of the editor to be invoked by the edit_history command");

  DEFVAR (EXEC_PATH, exec_path, 0, sv_exec_path,
    "colon separated list of directories to search for programs to run");

  DEFCONST (I, Complex (0.0, 1.0), 0, 0,
    "sqrt (-1)");

  DEFCONST (Inf, octave_Inf, 0, 0,
    "infinity");

  DEFVAR (INFO_FILE, info_file, 0, sv_info_file,
    "name of the Octave info file");

  DEFVAR (INFO_PROGRAM, info_prog, 0, sv_info_prog,
    "name of the Octave info reader");

  DEFCONST (J, Complex (0.0, 1.0), 0, 0,
    "sqrt (-1)");

  DEFCONST (NaN, octave_NaN, 0, 0,
    "not a number");

  DEFVAR (LOADPATH, load_path, 0, sv_loadpath,
    "colon separated list of directories to search for scripts");

  DEFVAR (IMAGEPATH, OCTAVE_IMAGEPATH, 0,
	  sv_imagepath,
    "colon separated list of directories to search for image files");
}

static void
install_builtin_variables_2 (void)
{
  DEFCONSTX ("OCTAVE_VERSION", SBV_OCTAVE_VERSION, OCTAVE_VERSION, 0, 0,
    "Octave version");

  DEFVAR (PAGER, default_pager (), 0, sv_pager_binary,
    "path to pager binary");

  DEFVAR (PS1, "\\s:\\#> ", 0, sv_ps1,
    "primary prompt string");

  DEFVAR (PS2, "> ", 0, sv_ps2,
    "secondary prompt string");

  DEFVAR (PS4, "+ ", 0, sv_ps4,
    "string printed before echoed input (enabled by --echo-input)");

  DEFCONST (PWD, get_working_directory ("initialize_globals"), 0, sv_pwd,
    "current working directory");

  DEFCONST (SEEK_SET, 0.0, 0, 0,
    "used with fseek to position file relative to the beginning");

  DEFCONST (SEEK_CUR, 1.0, 0, 0,
    "used with fseek to position file relative to the current position");

  DEFCONST (SEEK_END, 2.0, 0, 0,
    "used with fseek to position file relative to the end");

  DEFVAR (ans, , 0, 0,
    "");
}

static void
install_builtin_variables_3 (void)
{
  DEFCONST (argv, , 0, 0,
    "the command line arguments this program was invoked with");

  DEFVAR (automatic_replot, 0.0, 0, automatic_replot,
    "if true, auto-insert a replot command when a plot changes");

  DEFVAR (beep_on_error, 0.0, 0, beep_on_error,
    "if true, beep before printing error messages");

  DEFVAR (completion_append_char, " ", 0, sv_completion_append_char,
    "the string to append after successful command-line completion\n\
attempts");

  DEFCONST (error_text, "", 0, 0,
    "the text of error messages that would have been printed in the
body of the most recent unwind_protect statement or the TRY part of\n\
the most recent eval() command.  Outside of unwind_protect and\n\
eval(), or if no error has ocurred within them, the value of\n\
__error_text__ is guaranteed to be the empty string.");

  DEFVAR (default_return_value, Matrix (), 0, 0,
    "the default for value for unitialized variables returned from\n\
functions.  Only used if the variable initialize_return_values is\n\
set to \"true\".");

  DEFVAR (default_save_format, "ascii", 0, sv_default_save_format,
    "default format for files created with save, may be one of\n\
\"binary\", \"text\", or \"mat-binary\"");

  DEFVAR (define_all_return_values, 0.0, 0, define_all_return_values,
    "control whether values returned from functions should have a\n\
value even if one has not been explicitly assigned.  See also\n\
default_return_value");

  DEFVAR (do_fortran_indexing, 0.0, 0, do_fortran_indexing,
    "allow single indices for matrices");

  DEFVAR (echo_executing_commands, 0.0, 0, echo_executing_commands,
    "echo commands as they are executed");
}

static void
install_builtin_variables_4 (void)
{
  DEFCONST (e, exp (1.0), 0, 0,
    "exp (1)");

  DEFVAR (empty_list_elements_ok, "warn", 0, empty_list_elements_ok,
    "ignore the empty element in expressions like `a = [[], 1]'");

  DEFCONST (eps, DBL_EPSILON, 0, 0,
    "machine precision");

  DEFVAR (gnuplot_binary, "gnuplot", 0, sv_gnuplot_binary,
    "path to gnuplot binary");

#ifdef GNUPLOT_HAS_MULTIPLOT
  double with_multiplot = 1.0;
#else
  double with_multiplot = 0.0;
#endif

  DEFVAR (gnuplot_has_multiplot, with_multiplot, 0, gnuplot_has_multiplot,
    "true if gnuplot supports multiplot, false otherwise");

  DEFVAR (history_file, default_history_file (), 0, sv_history_file,
    "name of command history file");

  DEFVAR (history_size, default_history_size (), 0, history_size,
    "number of commands to save in the history list");

  DEFCONST (i, Complex (0.0, 1.0), 1, 0,
    "sqrt (-1)");

  DEFVAR (ignore_function_time_stamp, "system", 0, ignore_function_time_stamp,
    "don't check to see if function files have changed since they were\n\
  last compiled.  Possible values are \"system\" and \"all\"");

  DEFVAR (implicit_str_to_num_ok, 0.0, 0, implicit_str_to_num_ok,
    "allow implicit string to number conversion");
}

static void
install_builtin_variables_5 (void)
{
  DEFCONST (inf, octave_Inf, 0, 0,
    "infinity");

  DEFCONST (j, Complex (0.0, 1.0), 1, 0,
    "sqrt (-1)");

  DEFCONST (nan, octave_NaN, 0, 0,
    "not a number");

  DEFVAR (ok_to_lose_imaginary_part, "warn", 0, ok_to_lose_imaginary_part,
    "silently convert from complex to real by dropping imaginary part");

  DEFVAR (output_max_field_width, 10.0, 0, set_output_max_field_width,
    "maximum width of an output field for numeric output");

  DEFVAR (output_precision, 5.0, 0, set_output_precision,
    "number of significant figures to display for numeric output");

  DEFVAR (page_screen_output, 1.0, 0, page_screen_output,
    "if possible, send output intended for the screen through the pager");

  DEFCONST (pi, 4.0 * atan (1.0), 0, 0,
    "ratio of the circumference of a circle to its diameter");

  DEFVAR (prefer_column_vectors, 1.0, 0, prefer_column_vectors,
    "prefer column/row vectors");

  DEFVAR (prefer_zero_one_indexing, 0.0, 0, prefer_zero_one_indexing,
    "when there is a conflict, prefer zero-one style indexing");
}

static void
install_builtin_variables_6 (void)
{
  DEFVAR (print_answer_id_name, 1.0, 0, print_answer_id_name,
    "set output style to print `var_name = ...'");

  DEFVAR (print_empty_dimensions, 1.0, 0, print_empty_dimensions,
    "also print dimensions of empty matrices");

  DEFCONST (program_invocation_name, raw_prog_name, 0, 0,
    "the full name of the current program or script, including the\n\
directory specification");

  DEFCONST (program_name, prog_name, 0, 0,
    "the name of the current program or script");

  DEFVAR (propagate_empty_matrices, 1.0, 0, propagate_empty_matrices,
    "operations on empty matrices return an empty matrix, not an error");

#if 0
  DEFVAR (read_only_constants, 1.0, 0, read_only_constants,
    "allow built-in constants to be modified");
#endif

  DEFCONST (realmax, DBL_MAX, 0, 0,
    "realmax (): return largest representable floating point number");

  DEFCONST (realmin, DBL_MIN, 0, 0,
    "realmin (): return smallest representable floating point number");

  DEFVAR (resize_on_range_error, 1.0, 0, resize_on_range_error,
    "enlarge matrices on assignment");

  DEFVAR (return_last_computed_value, 0.0, 0, return_last_computed_value,
    "if a function does not return any values explicitly, return the\n\
  last computed value");
}

static void
install_builtin_variables_7 (void)
{
  DEFVAR (save_precision, 15.0, 0, set_save_precision,
    "number of significant figures kept by the ASCII save command");

  DEFVAR (saving_history, 1.0, 0, saving_history,
    "save command history");

  DEFVAR (silent_functions, 0.0, 0, silent_functions,
    "suppress printing results in called functions");

  DEFVAR (split_long_rows, 1.0, 0, split_long_rows,
    "split long matrix rows instead of wrapping");

  DEFVAR (struct_levels_to_print, 2.0, 0, struct_levels_to_print,
    "number of levels of structure elements to print");

#ifdef USE_GNU_INFO
  DEFVAR (suppress_verbose_help_message, 0.0, 0, suppress_verbose_help_message,
    "suppress printing of message pointing to additional help in the\n\
help and usage functions");
#endif

  DEFCONSTX ("stdin", SBV_stdin, 0.0, 0, 0,
    "file number of the standard input stream");

  DEFCONSTX ("stdout", SBV_stderr, 1.0, 0, 0,
    "file number of the standard output stream");

  DEFCONSTX ("stderr", SBV_stderr, 2.0, 0, 0,
    "file number of the standard error stream");

  DEFVAR (treat_neg_dim_as_zero, 0.0, 0, treat_neg_dim_as_zero,
    "convert negative dimensions to zero");
}

static void
install_builtin_variables_8 (void)
{
  DEFVAR (warn_assign_as_truth_value, 1.0, 0, warn_assign_as_truth_value,
    "produce warning for assignments used as truth values");

  DEFVAR (warn_comma_in_global_decl, 1.0, 0, warn_comma_in_global_decl,
    "produce warning for commas in global declarations");

  DEFVAR (warn_divide_by_zero, 1.0, 0, warn_divide_by_zero,
    "on IEEE machines, allow divide by zero errors to be suppressed");

  DEFVAR (warn_function_name_clash, 1.0, 0, warn_function_name_clash,
    "produce warning if function name conflicts with file name");

  DEFVAR (warn_missing_semicolon, 0.0, 0, warn_missing_semicolon,
    "produce a warning if a statement in a function file is not
terminated with a semicolon");

  DEFVAR (whitespace_in_literal_matrix, "", 0, whitespace_in_literal_matrix,
    "control auto-insertion of commas and semicolons in literal matrices");
}

void
install_builtin_variables (void)
{
  install_builtin_variables_1 ();
  install_builtin_variables_2 ();
  install_builtin_variables_3 ();
  install_builtin_variables_4 ();
  install_builtin_variables_5 ();
  install_builtin_variables_6 ();
  install_builtin_variables_7 ();
  install_builtin_variables_8 ();

  symbols_of_syscalls ();
}

// Deleting names from the symbol tables.

DEFUN_TEXT (clear, args, ,
  "clear [-x] [name ...]\n\
\n\
Clear symbol(s) matching a list of globbing patterns.\n\
\n\
If no arguments are given, clear all user-defined variables and
functions.\n\
\n\
With -x, exclude the named variables")
{
  octave_value_list retval;

  int argc = args.length () + 1;

  string_vector argv = args.make_argv ("clear");

  if (error_state)
    return retval;

  // Always clear the local table, but don't clear currently compiled
  // functions unless we are at the top level.  (Allowing that to
  // happen inside functions would result in pretty odd behavior...)

  int clear_user_functions = (curr_sym_tab == top_level_sym_tab);

  if (argc == 1)
    {
      curr_sym_tab->clear ();
      global_sym_tab->clear (clear_user_functions);
    }
  else
    {
      int exclusive = 0;

      int idx = 1;

      if (argc > 1)
	{
	  if (argv[idx] == "-x")
	    exclusive = 1;
	}

      int lcount = 0;
      int gcount = 0;
      int fcount = 0;

      string_vector lvars;
      string_vector gvars;
      string_vector fcns;

      if (argc > 0)
	{
	  lvars = curr_sym_tab->list (lcount, 0, 0, 0,
				      SYMTAB_VARIABLES,
				      SYMTAB_LOCAL_SCOPE);

	  gvars = curr_sym_tab->list (gcount, 0, 0, 0,
				      SYMTAB_VARIABLES,
				      SYMTAB_GLOBAL_SCOPE);

	  fcns = global_sym_tab->list (fcount, 0, 0, 0,
				       symbol_def::USER_FUNCTION,
				       SYMTAB_ALL_SCOPES);
	}

      for (int k = idx; k < argc; k++)
	{
	  string patstr = argv[k];

	  if (! patstr.empty ())
	    {
	      glob_match pattern (patstr);

	      int i;
	      for (i = 0; i < lcount; i++)
		{
		  string nm = lvars[i];
		  int match = pattern.match (nm);
		  if ((exclusive && ! match) || (! exclusive && match))
		    curr_sym_tab->clear (nm);
		}

	      int count;
	      for (i = 0; i < gcount; i++)
		{
		  string nm = gvars[i];
		  int match = pattern.match (nm);
		  if ((exclusive && ! match) || (! exclusive && match))
		    {
		      count = curr_sym_tab->clear (nm);
		      if (count > 0)
			global_sym_tab->clear (nm, clear_user_functions);
		    }
		}

	      for (i = 0; i < fcount; i++)
		{
		  string nm = fcns[i];
		  int match = pattern.match (nm);
		  if ((exclusive && ! match) || (! exclusive && match))
		    {
		      count = curr_sym_tab->clear (nm);
		      global_sym_tab->clear (nm, clear_user_functions);
		    }
		}
	    }
	}
    }

  return retval;
}

/*
;;; Local Variables: ***
;;; mode: C++ ***
;;; End: ***
*/