help.cc

Go to the documentation of this file.

////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 1993-2025 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 (HAVE_CONFIG_H)
#  include "config.h"
#endif
 
#include <cstdlib>
#include <cstring>
 
#include <algorithm>
#include <fstream>
#include <istream>
#include <map>
#include <sstream>
#include <string>
 
#include "cmd-edit.h"
#include "file-ops.h"
#include "file-stat.h"
#include "lo-sysdep.h"
#include "oct-env.h"
#include "oct-locbuf.h"
#include "str-vec.h"
 
#include "Cell.h"
#include "builtin-defun-decls.h"
#include "defaults.h"
#include "defun.h"
#include "error.h"
#include "errwarn.h"
#include "help.h"
#include "input.h"
#include "interpreter-private.h"
#include "interpreter.h"
#include "load-path.h"
#include "ov-classdef.h"
#include "ov-fcn-handle.h"
#include "ov-usr-fcn.h"
#include "ovl.h"
#include "pager.h"
#include "parse.h"
#include "pathsearch.h"
#include "procstream.h"
#include "quit.h"
#include "sighandlers.h"
#include "symtab.h"
#include "unwind-prot.h"
#include "utils.h"
#include "variables.h"
#include "version.h"
 
#include "default-defs.h"
 
OCTAVE_BEGIN_NAMESPACE(octave)
 
const static char *const operators[] =
{
  "!",
  "~",
  "!=",
  "~=",
  R"(")",
  "#",
  "%",
  "#{",
  "%{",
  "#}",
  "%}",
  "...",
  "&",
  "&&",
  "'",
  "(",
  ")",
  "*",
  "^",
  "+",
  "++",
  ",",
  "-",
  "--",
  ".'",
  ".*",
  ".^",
  "./",
  "/",
  R"(.\)",
  R"(\)",
  ":",
  ";",
  "<",
  "<=",
  "=",
  "==",
  ">",
  ">=",
  "[",
  "]",
  "|",
  "||",
  nullptr
};
 
const static string_vector operator_names (operators);
 
static bool
looks_like_html (const std::string& msg)
{
  const std::size_t p1 = msg.find ('\n');
  std::string t = msg.substr (0, p1);
  // FIXME: this comparison should be case-insensitive
  const std::size_t p2 = t.find ("<html");
 
  return (p2 != std::string::npos);
}
 
static bool
looks_like_texinfo (const std::string& msg, std::size_t& p1)
{
  p1 = msg.find ('\n');
 
  std::string t = msg.substr (0, p1);
 
  if (p1 == std::string::npos)
    p1 = 0;
 
  std::size_t p2 = t.find ("-*- texinfo -*-");
 
  return (p2 != std::string::npos);
}
 
octave_value
help_system::built_in_docstrings_file (const octave_value_list& args,
                                       int nargout)
{
  return set_internal_variable (m_built_in_docstrings_file, args, nargout,
                                "built_in_docstrings_file", false);
}
 
octave_value
help_system::doc_cache_file (const octave_value_list& args, int nargout)
{
  return set_internal_variable (m_doc_cache_file, args, nargout,
                                "doc_cache_file", false);
}
 
octave_value
help_system::info_file (const octave_value_list& args, int nargout)
{
  return set_internal_variable (m_info_file, args, nargout,
                                "info_file", false);
}
 
octave_value
help_system::info_program (const octave_value_list& args, int nargout)
{
  return set_internal_variable (m_info_program, args, nargout,
                                "info_program", false);
}
 
octave_value
help_system::makeinfo_program (const octave_value_list& args, int nargout)
{
  return set_internal_variable (m_makeinfo_program, args, nargout,
                                "makeinfo_program", false);
}
 
octave_value
help_system::suppress_verbose_help_message (const octave_value_list& args,
    int nargout)
{
  return set_internal_variable (m_suppress_verbose_help_message, args,
                                nargout, "suppress_verbose_help_message");
}
 
octave_value
help_system::texi_macros_file (const octave_value_list& args, int nargout)
{
  return set_internal_variable (m_texi_macros_file, args, nargout,
                                "texi_macros_file", false);
}
 
std::string
help_system::raw_help (const std::string& nm, bool& symbol_found) const
{
  std::string h;
  std::string w;
  std::string f;
 
  bool found;
 
  found = raw_help_from_symbol_table (nm, h, w, symbol_found);
 
  if (! found)
    found = raw_help_from_file (nm, h, f, symbol_found);
 
  bool external_doc = h.compare (0, 12, "external-doc") == 0;
 
  if (! found || external_doc)
    {
      std::string tmp_nm = nm;
 
      if (external_doc && h.length () > 12 && h[12] == ':')
        tmp_nm = h.substr (13);
 
      raw_help_from_docstrings_file (tmp_nm, h, symbol_found);
    }
 
  return h;
}
 
bool
help_system::get_which_info_from_fcn (const std::string& name, const octave_value& ov_fcn, std::string& file, std::string& type) const
{
  file = "";
  type = "";
 
  if (ov_fcn.is_function ())
    {
      octave_function *fcn = ov_fcn.function_value ();
 
      if (fcn)
        {
          if (fcn->is_classdef_meta ())
            {
              octave_classdef_meta *meta_obj
                = dynamic_cast<octave_classdef_meta *> (fcn);
 
              file = meta_obj->file_name ();
 
              if (meta_obj->is_classdef_constructor ())
                type = "class constructor";
              else if (meta_obj->is_classdef_method ())
                type = "class method";
              else
                type = "classdef meta object";
            }
          else
            {
              file = fcn->fcn_file_name ();
 
              if (! file.empty ())
                type = ov_fcn.is_user_script () ? "script" : "function";
              else
                {
                  if (fcn->is_user_function ())
                    type = "command-line function";
                  else
                    {
                      file = fcn->src_file_name ();
                      type = "built-in function";
                    }
                }
            }
 
          return true;
        }
      else
        {
          // We might find a file that contains only a doc string.
 
          load_path& lp = m_interpreter.get_load_path ();
 
          file = lp.find_fcn_file (name);
 
          if (file.empty ())
            return false;
        }
    }
 
  return false;
}
 
// FIXME: There is a lot of duplication between the following function
// and help_system::raw_help_from_symbol_table.  Some refactoring would
// probably be useful.
 
std::string
help_system::which (const std::string& name,
                    std::string& type) const
{
  std::string file;
 
  if (name.empty ())
    return file;
 
  type = "";
 
  symbol_table& symtab = m_interpreter.get_symbol_table ();
 
  size_t pos = name.find ('.');
 
  if (pos == std::string::npos)
    {
      // Simple name.  If not found, continue looking for packages and
      // classes.
 
      octave_value ov_fcn = symtab.find_function (name);
 
      if (get_which_info_from_fcn (name, ov_fcn, file, type))
        return file;
    }
 
  // NAME contains '.' and must match the following pattern:
  //
  //   (package.)*(package|classname).(property|method)*
  //
  // Start by looking up the full name.  It could be either a package or
  // a class and we are done.  Otherwise, strip the final component and
  // lookup that name.  If it is a package, look for a function.  If it
  // is a class, look for a property or method.
 
  cdef_manager& cdm = m_interpreter.get_cdef_manager ();
 
  // FIXME: In the following search we may load classes.  Is that really
  // what we want, or should we just search the loadpath for
  // +pkga/+pkgb/classname/file.m, etc. and attempt to extract help text
  // without actually installing packages and classes into the fcn_info
  // table?
 
  // Is NAME a class?
 
  cdef_class cls = cdm.find_class (name, false, true);
 
  if (cls.ok ())
    {
      // FIXME: Return documentation for the class or the class
      // constructor?
 
      file = cls.file_name ();
      type = "classdef class";
 
      return file;
    }
 
  cdef_package pkg = cdm.find_package (name, false, true);
 
  if (pkg.ok ())
    {
      // FIXME: How to get the fill name of a package?
      file = pkg.get_name ();
      type = "package";
 
      return file;
    }
 
  // Strip final component (might be a property or method name).
 
  pos = name.rfind ('.');
  std::string prefix = name.substr (0, pos);
  std::string nm = name.substr (pos+1);
 
  // Is PREFIX the name of a class?
 
  cls = cdm.find_class (prefix, false, true);
 
  if (cls.ok ())
    {
      // FIXME: Should we only find public methods here?
 
      octave_value ov_meth = cls.get_method (nm);
 
      if (get_which_info_from_fcn (nm, ov_meth, file, type))
        return file;
 
      // FIXME: Should we only find public properties here?
 
      cdef_property prop = cls.find_property (nm);
 
      if (prop.ok ())
        {
          file = cls.file_name ();
          type = "class property";
 
          return file;
        }
    }
 
  // Or is PREFIX the name of a package?
 
  pkg = cdm.find_package (prefix, false, true);
 
  if (pkg.ok ())
    {
      octave_value ov_fcn = pkg.find (nm);
 
      if (get_which_info_from_fcn (nm, ov_fcn, file, type))
        return file;
    }
 
  // File query.
 
  load_path& lp = m_interpreter.get_load_path ();
 
  // For compatibility: "file." queries "file".
  if (name.size () > 1 && name[name.size () - 1] == '.')
    file = lp.find_file (name.substr (0, name.size () - 1));
  else
    file = lp.find_file (name);
 
  file = sys::env::make_absolute (file);
 
  if (! file.empty ())
    type = "file";
 
  return file;
}
 
std::string
help_system::which (const std::string& name) const
{
  std::string type;
 
  return which (name, type);
}
 
string_vector
help_system::make_name_list () const
{
  const static string_vector keywords
    = Fiskeyword ()(0).string_vector_value ();
 
  const static int key_len = keywords.numel ();
 
  symbol_table& symtab = m_interpreter.get_symbol_table ();
 
  const string_vector bif = symtab.built_in_function_names ();
  const int bif_len = bif.numel ();
 
  const string_vector cfl = symtab.cmdline_function_names ();
  const int cfl_len = cfl.numel ();
 
  const string_vector lcl = m_interpreter.variable_names ();
  const int lcl_len = lcl.numel ();
 
  load_path& lp = m_interpreter.get_load_path ();
 
  const string_vector ffl = lp.fcn_names ();
  const int ffl_len = ffl.numel ();
 
  const string_vector afl = m_interpreter.autoloaded_functions ();
  const int afl_len = afl.numel ();
 
  const string_vector lfl = local_functions ();
  const int lfl_len = lfl.numel ();
 
  const int total_len
    = key_len + bif_len + cfl_len + lcl_len + ffl_len + afl_len + lfl_len;
 
  string_vector list (total_len);
 
  // Put all the symbols in one big list.
 
  int j = 0;
  int i = 0;
 
  for (i = 0; i < key_len; i++)
    list[j++] = keywords[i];
 
  for (i = 0; i < bif_len; i++)
    list[j++] = bif[i];
 
  for (i = 0; i < cfl_len; i++)
    list[j++] = cfl[i];
 
  for (i = 0; i < lcl_len; i++)
    list[j++] = lcl[i];
 
  for (i = 0; i < ffl_len; i++)
    list[j++] = ffl[i];
 
  for (i = 0; i < afl_len; i++)
    list[j++] = afl[i];
 
  for (i = 0; i < lfl_len; i++)
    list[j++] = lfl[i];
 
  return list;
}
 
void
help_system::get_help_text (const std::string& name, std::string& text,
                            std::string& format) const
{
  bool symbol_found = false;
  text = raw_help (name, symbol_found);
 
  format = "Not found";
  if (symbol_found)
    {
      std::size_t idx = -1;
      if (text.empty ())
        {
          format = "Not documented";
        }
      else if (looks_like_texinfo (text, idx))
        {
          format = "texinfo";
          text.erase (0, idx);
        }
      else if (looks_like_html (text))
        {
          format = "html";
        }
      else
        {
          format = "plain text";
        }
    }
}
 
void
help_system::get_help_text_from_file (const std::string& fname,
                                      std::string& text,
                                      std::string& format) const
{
  bool symbol_found = false;
 
  std::string f;
 
  raw_help_from_file (fname, text, f, symbol_found);
 
  format = "Not found";
  if (symbol_found)
    {
      std::size_t idx = -1;
      if (text.empty ())
        {
          format = "Not documented";
        }
      else if (looks_like_texinfo (text, idx))
        {
          format = "texinfo";
          text.erase (0, idx);
        }
      else if (looks_like_html (text))
        {
          format = "html";
        }
      else
        {
          format = "plain text";
        }
    }
}
 
std::string
help_system::init_built_in_docstrings_file ()
{
  std::string df = sys::env::getenv ("OCTAVE_BUILT_IN_DOCSTRINGS_FILE");
 
  std::string dir_sep = sys::file_ops::dir_sep_str ();
 
  if (df.empty ())
    df = config::oct_etc_dir () + dir_sep + "built-in-docstrings";
 
  return df;
}
 
std::string
help_system::init_doc_cache_file ()
{
  std::string def_file = config::prepend_octave_home (OCTAVE_DOC_CACHE_FILE);
 
  std::string env_file = sys::env::getenv ("OCTAVE_DOC_CACHE_FILE");
 
  return (env_file.empty () ? def_file : env_file);
}
 
std::string
help_system::init_info_file ()
{
  std::string std_info_file = config::prepend_octave_home (OCTAVE_INFOFILE);
 
  std::string oct_info_file = sys::env::getenv ("OCTAVE_INFO_FILE");
 
  return (oct_info_file.empty () ? std_info_file : oct_info_file);
}
 
std::string
help_system::init_info_program ()
{
  std::string info_prog = sys::env::getenv ("OCTAVE_INFO_PROGRAM");
 
  if (info_prog.empty ())
    info_prog = "info";
 
  return info_prog;
}
 
std::string
help_system::init_texi_macros_file ()
{
  std::string def_file
    = config::prepend_octave_home (OCTAVE_TEXI_MACROS_FILE);
 
  std::string env_file = sys::env::getenv ("OCTAVE_TEXI_MACROS_FILE");
 
  return (env_file.empty () ? def_file : env_file);
}
 
// Return a vector of all functions from this file,
// for use in command line auto-completion.
string_vector
help_system::local_functions () const
{
  string_vector retval;
 
  tree_evaluator& tw = m_interpreter.get_evaluator ();
 
  octave_user_code *curr_fcn = tw.current_user_code ();
 
  if (! curr_fcn)
    return retval;
 
  // All subfunctions are listed in the top-level function of this file.
  // If curr_fcn is a subfunction, then there must be a parent and
  // curr_fcn will always be valid in and after executing this loop.
 
  while (curr_fcn->is_subfunction ())
    {
      symbol_scope pscope = curr_fcn->parent_fcn_scope ();
      curr_fcn = pscope.user_code ();
    }
 
  // Get subfunctions.
  const std::list<std::string> names = curr_fcn->subfunction_names ();
 
  std::size_t sz = names.size ();
  retval.resize (sz);
 
  // Loop over them.
  std::size_t i = 0;
  for (const auto& nm : names)
    retval(i++) = nm;
 
  return retval;
}
 
static bool
get_help_from_fcn (const std::string& fcn_nm, const octave_value& ov_fcn, std::string& help, std::string& what, bool& symbol_found)
{
  symbol_found = false;
 
  help = "";
  what = "";
 
  if (ov_fcn.is_function ())
    {
      octave_function *fcn = ov_fcn.function_value ();
 
      help = fcn->doc_string (fcn_nm);
      what = fcn->fcn_file_name ();
 
      if (help.empty () && ov_fcn.is_user_function ())
        {
          octave_user_function *ufcn = ov_fcn.user_function_value ();
 
          if (ufcn->is_classdef_constructor ())
            help = "undocumented constructor: ";
          else if (ufcn->is_classdef_method ())
            help = "undocumented method: ";
          else
            help = "undocumented function: ";
 
          help += ufcn->signature ();
        }
 
      if (what.empty ())
        what = fcn->is_user_function () ? "command-line function" : "built-in function";
 
      symbol_found = true;
    }
 
  return symbol_found;
}
 
bool
help_system::raw_help_for_class (const cdef_class& cls,
                                 const std::string& name,
                                 std::string& help, std::string& what,
                                 bool& symbol_found) const
{
  if (cls.ok ())
    {
      // Is the class documented?
      help = cls.doc_string ();
 
      if (! help.empty ())
        {
          what = "class";
 
          symbol_found = true;
          return true;
        }
 
      // Look for constructor.
      std::size_t pos = name.rfind ('.');
 
      if (pos != std::string::npos)
        {
          std::string nm = name.substr (pos+1);
 
          octave_value ov_meth = cls.get_method (nm);
 
          if (get_help_from_fcn (nm, ov_meth, help, what, symbol_found))
            {
              what = "constructor";
              return true;
            }
        }
 
      // No dot in name and class is undocumented.  Look for documented
      // constructor.
 
      octave_value ov_meth = cls.get_method (name);
 
      if (get_help_from_fcn (name, ov_meth, help, what, symbol_found))
        {
          what = "constructor";
          symbol_found = true;
          return true;
        }
 
      // We found a class, but no docstring for it and there is no
      // constructor explicitly defined.
 
      help = "default constructor: obj = " + name + " ()";
      what = "constructor";
      symbol_found = true;
      return true;
    }
 
  return false;
}
 
// FIXME: There is a lot of duplication between the following function
// and help_system::which.  Some refactoring would probably be useful.
 
bool
help_system::raw_help_from_symbol_table (const std::string& name, std::string& help, std::string& what, bool& symbol_found) const
{
  symbol_table& symtab = m_interpreter.get_symbol_table ();
 
  size_t pos = name.find ('.');
 
  if (pos == std::string::npos)
    {
      // Simple name.  If not found, continue looking for packages and
      // classes.
 
      octave_value ov_fcn = symtab.find_function (name);
 
      // FIXME: it seems like there is a lot of potential for confusion
      // because is_function can also return true for
      // octave_classdef_meta objects.
 
      if (! ov_fcn.is_classdef_meta ()
          && get_help_from_fcn (name, ov_fcn, help, what, symbol_found))
        return true;
    }
 
  // If NAME does not contain '.', then it should be a package or a
  // class name.
  //
  // If NAME contains '.' it should match the following pattern:
  //
  //   (package.)*(package|classname).(property|method)*
  //
  // Start by looking up the full name.  It could be either a package or
  // a class and we are done.  Otherwise, strip the final component and
  // lookup that name.  If it is a package, look for a function.  If it
  // is a class, look for a property or method.
 
  cdef_manager& cdm = m_interpreter.get_cdef_manager ();
 
  // FIXME: In the following search we may load classes.  Is that really
  // what we want, or should we just search the loadpath for
  // +pkga/+pkgb/classname/file.m, etc. and attempt to extract help text
  // without actually installing packages and classes into the fcn_info
  // table?
 
  // Is NAME a class?
 
  cdef_class cls = cdm.find_class (name, false, true);
 
  if (raw_help_for_class (cls, name, help, what, symbol_found))
    return true;
 
  cdef_package pkg = cdm.find_package (name, false, true);
 
  if (pkg.ok ())
    {
      help = "package " + name;
      what = "package";
 
      symbol_found = true;
      return true;
    }
 
  // Strip final component (might be a property or method name).
 
  pos = name.rfind ('.');
  std::string prefix = name.substr (0, pos);
  std::string nm = name.substr (pos+1);
 
  // Is PREFIX the name of a class?
 
  cls = cdm.find_class (prefix, false, true);
 
  bool found_class = cls.ok ();
 
  if (found_class)
    {
      // FIXME: Should we only find public methods here?
 
      octave_value ov_meth = cls.get_method (nm);
 
      if (get_help_from_fcn (nm, ov_meth, help, what, symbol_found))
        {
          what = "class method";
          return true;
        }
 
      // Found class but no method.  If the NM is the same as the name
      // of the class, then we have a default constructor.
 
      if (cls.get_name () == nm)
        {
          help = "default constructor: obj = " + nm + " ()";
          what = "constructor";
          symbol_found = true;
          return true;
        }
 
      // FIXME: Should we only find public properties here?
 
      cdef_property prop = cls.find_property (nm);
 
      if (prop.ok ())
        {
          // FIXME: is it supposed to be possible to document
          // properties?
 
          help = prop.doc_string ();
          what = "class property";
 
          symbol_found = true;
          return true;
        }
    }
 
  // Or is PREFIX the name of a package?
 
  pkg = cdm.find_package (prefix, false, true);
 
  if (pkg.ok ())
    {
      octave_value ov_fcn = pkg.find (nm);
 
      if (get_help_from_fcn (nm, ov_fcn, help, what, symbol_found))
        return true;
    }
 
  if (nm == "m" && raw_help_for_class (cls, prefix, help, what, symbol_found))
    return true;
 
  return false;
}
 
bool
help_system::raw_help_from_file (const std::string& nm,
                                 std::string& h, std::string& file,
                                 bool& symbol_found) const
{
  bool retval = false;
 
  h = get_help_from_file (nm, symbol_found, file);
 
  if (h.length () > 0)
    retval = true;
 
  return retval;
}
 
bool
help_system::raw_help_from_docstrings_file (const std::string& nm,
    std::string& h,
    bool& symbol_found) const
{
  typedef std::pair<std::streampos, std::streamoff> txt_limits_type;
  typedef std::map<std::string, txt_limits_type> help_txt_map_type;
 
  static help_txt_map_type help_txt_map;
  static bool initialized = false;
 
  h = "";
  symbol_found = false;
 
  // FIXME: Should we cache the timestamp of the file and reload the
  // offsets if it changes?  Or just warn about that?  Or just ignore
  // it, and assume it won't change?
 
  if (! initialized)
    {
      std::ifstream file = sys::ifstream (m_built_in_docstrings_file.c_str (),
                                          std::ios::in | std::ios::binary);
 
      if (! file)
        error ("failed to open docstrings file: %s",
               m_built_in_docstrings_file.c_str ());
 
      // Ignore header;
      file.ignore (std::numeric_limits<std::streamsize>::max(), 0x1d);
 
      if (file.eof ())
        error ("invalid built-in-docstrings file!");
 
      // FIXME: eliminate fixed buffer size.
      std::size_t bufsize = 1000;
      OCTAVE_LOCAL_BUFFER (char, buf, bufsize);
 
      while (! file.eof ())
        {
          std::string name;
          int i = 0;
          int c;
          while (file
                 && (c = file.get ()) != std::istream::traits_type::eof ())
            {
              if (c == '\n' || c == '\r')
                {
                  buf[i] = '\0';
                  name = buf;
                  break;
                }
              else
                buf[i++] = c;
            }
 
          // Skip @c FILENAME which is part of current DOCSTRINGS
          // syntax.  This may disappear if a specific format for
          // docstring files is developed.
          while (file
                 && (c = file.get ()) != std::istream::traits_type::eof ()
                 && c != '\n' && c != '\r')
            ; // skip text
 
          // skip newline characters
          while (file
                 && (c = file.get ()) != std::istream::traits_type::eof ()
                 && (c == '\n' || c == '\r'))
            ; // skip text
 
          file.unget ();
 
          // Position of beginning of help text.
          std::streampos beg = file.tellg ();
 
          // Skip help text.
          file.ignore (std::numeric_limits<std::streamsize>::max(), 0x1d);
 
          // Position of end of help text.
          std::streamoff len;
 
          if (! file.eof ())
            len = file.tellg () - beg - 1;
          else
            {
              file.seekg (0, file.end);
              len = file.tellg () - beg - 1;
              file.setstate (file.eofbit);  // reset eof flag
            }
 
          help_txt_map[name] = txt_limits_type (beg, len);
        }
 
      initialized = true;
    }
 
  help_txt_map_type::const_iterator it = help_txt_map.find (nm);
 
  if (it != help_txt_map.end ())
    {
      txt_limits_type txt_limits = it->second;
 
      std::streampos beg = txt_limits.first;
      std::streamoff len = txt_limits.second;
 
      std::ifstream file = sys::ifstream (m_built_in_docstrings_file.c_str (),
                                          std::ios::in | std::ios::binary);
 
      if (! file)
        error ("failed to open docstrings file: %s",
               m_built_in_docstrings_file.c_str ());
 
      file.seekg (beg);
 
      std::size_t txt_len = len;
      OCTAVE_LOCAL_BUFFER (char, buf, txt_len + 1);
 
      file.read (buf, txt_len);
 
      buf[txt_len] = '\0';
 
      h = buf;
 
      symbol_found = true;
    }
 
  return symbol_found;
}
 
// FIXME: It's not likely that this does the right thing now.
 
string_vector
make_name_list ()
{
  help_system& help_sys = __get_help_system__ ();
 
  return help_sys.make_name_list ();
}
 
DEFMETHOD (get_help_text, interp, args, ,
           doc: /* -*- texinfo -*-
@deftypefn {} {[@var{text}, @var{format}] =} get_help_text (@var{name})
Return the raw help text of function @var{name}.
 
The raw help text is returned in @var{text} and the format in @var{format}.
The format is a string which is one of @qcode{"texinfo"}, @qcode{"html"}, or
@w{@qcode{"plain text"}}.
@seealso{get_help_text_from_file}
@end deftypefn */)
{
  if (args.length () != 1)
    print_usage ();
 
  const std::string name = args(0).xstring_value ("get_help_text: NAME must be a string");
 
  help_system& help_sys = interp.get_help_system ();
 
  std::string text, format;
 
  help_sys.get_help_text (name, text, format);
 
  return ovl (text, format);
}
 
DEFMETHOD (get_help_text_from_file, interp, args, ,
           doc: /* -*- texinfo -*-
@deftypefn {} {[@var{text}, @var{format}] =} get_help_text_from_file (@var{fname})
Return the raw help text from the file @var{fname}.
 
The raw help text is returned in @var{text} and the format in @var{format}.
The format is a string which is one of @qcode{"texinfo"}, @qcode{"html"}, or
@w{@qcode{"plain text"}}.
@seealso{get_help_text}
@end deftypefn */)
{
  if (args.length () != 1)
    print_usage ();
 
  const std::string fname = args(0).xstring_value ("get_help_text_from_file: NAME must be a string");
 
  help_system& help_sys = interp.get_help_system ();
 
  std::string text, format;
 
  help_sys.get_help_text_from_file (fname, text, format);
 
  return ovl (text, format);
}
 
// Return a cell array of strings containing the names of all operators.
 
DEFUN (__operators__, , ,
       doc: /* -*- texinfo -*-
@deftypefn {} {@var{cstr} =} __operators__ ()
Return a cell array of strings of all possible Octave operators.
@end deftypefn */)
{
  return ovl (Cell (operator_names));
}
 
// Return a cell array of strings containing the names of all keywords.
// iskeyword() function is located in lex.ll and is based on what the parser
// thinks is a keyword.
 
DEFALIAS (__keywords__, iskeyword)
 
// Return a cell array of strings with the names of all builtin functions.
 
DEFMETHOD (__builtins__, interp, , ,
           doc: /* -*- texinfo -*-
@deftypefn {} {} __builtins__ ()
Return a cell array of all builtin (compiled) functions available to Octave.
@end deftypefn */)
{
  symbol_table& symtab = interp.get_symbol_table ();
 
  const string_vector bif = symtab.built_in_function_names ();
 
  return ovl (Cell (bif));
}
 
DEFMETHOD (localfunctions, interp, args, ,
           doc: /* -*- texinfo -*-
@deftypefn {} {@var{subfcn_list} =} localfunctions ()
Return a list of all local functions, i.e., subfunctions, within the current
file.
 
The return value is a column cell array of function handles to all local
functions accessible from the function from which @code{localfunctions} is
called.  Nested functions are @emph{not} included in the list.
 
If the call is from the command line, an anonymous function, or a script,
the return value is an empty cell array.
 
@seealso{functions}
@end deftypefn */)
{
  if (args.length () != 0)
    print_usage ();
 
  Cell retval;
 
  // Find the main function we are in.
  tree_evaluator& tw = interp.get_evaluator ();
  octave_user_code *caller = tw.debug_user_code ();
 
  if (! caller)
    return ovl (retval);
 
  symbol_scope scope = caller->scope ();
 
  return ovl (Cell (scope.localfunctions ()));
}
 
/*
%!test
%! f = tempname (tempdir (), "oct_");
%! [~, fcn_name] = fileparts (f);
%! f = [f ".m"];
%! save_path = path ();
%! unwind_protect
%!   addpath (tempdir ());
%!   fid = fopen (f, "w+");
%!   fprintf (fid, "function z = %s\n z = localfunctions; end\n", fcn_name);
%!   fprintf (fid, "function z = b(x)\n z = x+1; end\n");
%!   fprintf (fid, "function z = c(x)\n z = 2*x; end\n");
%!   fclose (fid);
%!   d = eval (fcn_name);
%!   assert (size (d), [2, 1]);
%!   assert (d{1} (3), 4);
%!   assert (d{2} (3), 6);
%! unwind_protect_cleanup
%!   unlink (f);
%!   path (save_path);
%! end_unwind_protect
*/
 
DEFMETHOD (__which__, interp, args, ,
           doc: /* -*- texinfo -*-
@deftypefn {} {@var{var_struct} =} __which__ (@var{name}, @dots{})
Undocumented internal function.
@end deftypefn */)
{
  help_system& help_sys = interp.get_help_system ();
 
  string_vector argv = args.make_argv ();
 
  int nargin = argv.numel ();
 
  octave_map m (dim_vector (1, nargin));
 
  Cell names (1, nargin);
  Cell files (1, nargin);
  Cell types (1, nargin);
 
  for (int i = 0; i < nargin; i++)
    {
      std::string name = argv[i];
 
      std::string type;
 
      std::string file = help_sys.which (name, type);
 
      names(i) = name;
      files(i) = file;
      types(i) = type;
    }
 
  m.assign ("name", names);
  m.assign ("file", files);
  m.assign ("type", types);
 
  return ovl (m);
}
 
// Return a cell array of strings containing the names of all
// functions available in DIRECTORY.  If no directory is given, search
// the current path.
 
DEFMETHOD (__list_functions__, interp, args, ,
           doc: /* -*- texinfo -*-
@deftypefn  {} {@var{retval} =} __list_functions__ ()
@deftypefnx {} {@var{retval} =} __list_functions__ (@var{directory})
Return a list of all functions (.m and .oct functions) in the load path.
 
If the optional argument @var{directory} is given then list only the functions
in that directory.
@seealso{path}
@end deftypefn */)
{
  octave_value retval;
 
  load_path& lp = interp.get_load_path ();
 
  if (args.length () == 0)
    {
      // Get list of all functions
      string_vector ffl = lp.fcn_names ();
      string_vector afl = interp.autoloaded_functions ();
 
      retval = Cell (ffl.append (afl));
    }
  else
    {
      std::string dir = args(0).xstring_value ("__list_functions__: DIRECTORY argument must be a string");
 
      string_vector fl = lp.files (dir, true);
 
      // Return a sorted list with unique entries (in case of .m and .oct
      // versions of the same function in a given directory, for example).
      fl.sort (true);
 
      retval = Cell (fl);
    }
 
  return retval;
}
 
DEFMETHOD (built_in_docstrings_file, interp, args, nargout,
           doc: /* -*- texinfo -*-
@deftypefn  {} {@var{val} =} built_in_docstrings_file ()
@deftypefnx {} {@var{old_val} =} built_in_docstrings_file (@var{new_val})
@deftypefnx {} {@var{old_val} =} built_in_docstrings_file (@var{new_val}, "local")
Query or set the internal variable that specifies the name of the
file containing docstrings for built-in Octave functions.
 
The default value is
@file{@var{octave-home}/share/octave/@var{version}/etc/built-in-docstrings},
in which @var{octave-home} is the root directory of the Octave installation,
and @var{version} is the Octave version number.  The default value may be
overridden by the environment variable
@w{@env{OCTAVE_BUILT_IN_DOCSTRINGS_FILE}}, or the command line argument
@option{--built-in-docstrings-file FNAME}.
 
Note: This variable is only used when Octave is initializing itself.
Modifying it during a running session of Octave will have no effect.
@end deftypefn */)
{
  help_system& help_sys = interp.get_help_system ();
 
  return help_sys.built_in_docstrings_file (args, nargout);
}
 
DEFMETHOD (doc_cache_file, interp, args, nargout,
           doc: /* -*- texinfo -*-
@deftypefn  {} {@var{val} =} doc_cache_file ()
@deftypefnx {} {@var{old_val} =} doc_cache_file (@var{new_val})
@deftypefnx {} {@var{old_val} =} doc_cache_file (@var{new_val}, "local")
Query or set the internal variable that specifies the name of the
Octave documentation cache file.
 
A cache file significantly improves the performance of the @code{lookfor}
command.  The default value is
@file{@var{octave-home}/share/octave/@var{version}/etc/doc-cache},
in which @var{octave-home} is the root directory of the Octave installation,
and @var{version} is the Octave version number.
The default value may be overridden by the environment variable
@w{@env{OCTAVE_DOC_CACHE_FILE}}, or the command line argument
@option{--doc-cache-file FNAME}.
 
When called from inside a function with the @qcode{"local"} option, the
variable is changed locally for the function and any subroutines it calls.
The original variable value is restored when exiting the function.
@seealso{doc_cache_create, lookfor, info_program, doc, help, makeinfo_program}
@seealso{lookfor}
@end deftypefn */)
{
  help_system& help_sys = interp.get_help_system ();
 
  return help_sys.doc_cache_file (args, nargout);
}
 
DEFMETHOD (info_file, interp, args, nargout,
           doc: /* -*- texinfo -*-
@deftypefn  {} {@var{val} =} info_file ()
@deftypefnx {} {@var{old_val} =} info_file (@var{new_val})
@deftypefnx {} {@var{old_val} =} info_file (@var{new_val}, "local")
Query or set the internal variable that specifies the name of the
Octave info file.
 
The default value is
@file{@var{octave-home}/share/info/octave.info}, in
which @var{octave-home} is the root directory of the Octave installation.
The default value may be overridden by the environment variable
@w{@env{OCTAVE_INFO_FILE}}, or the command line argument
@option{--info-file FNAME}.
 
When called from inside a function with the @qcode{"local"} option, the
variable is changed locally for the function and any subroutines it calls.
The original variable value is restored when exiting the function.
@seealso{info_program, doc, help, makeinfo_program}
@end deftypefn */)
{
  help_system& help_sys = interp.get_help_system ();
 
  return help_sys.info_file (args, nargout);
}
 
DEFMETHOD (info_program, interp, args, nargout,
           doc: /* -*- texinfo -*-
@deftypefn  {} {@var{val} =} info_program ()
@deftypefnx {} {@var{old_val} =} info_program (@var{new_val})
@deftypefnx {} {@var{old_val} =} info_program (@var{new_val}, "local")
Query or set the internal variable that specifies the name of the
info program to run.
 
The default value is @file{info}.  The default value may be
overridden by the environment variable @w{@env{OCTAVE_INFO_PROGRAM}}, or the
command line argument @option{--info-program NAME}.
 
When called from inside a function with the @qcode{"local"} option, the
variable is changed locally for the function and any subroutines it calls.
The original variable value is restored when exiting the function.
@seealso{info_file, doc, help, makeinfo_program}
@end deftypefn */)
{
  help_system& help_sys = interp.get_help_system ();
 
  return help_sys.info_program (args, nargout);
}
 
DEFMETHOD (makeinfo_program, interp, args, nargout,
           doc: /* -*- texinfo -*-
@deftypefn  {} {@var{val} =} makeinfo_program ()
@deftypefnx {} {@var{old_val} =} makeinfo_program (@var{new_val})
@deftypefnx {} {@var{old_val} =} makeinfo_program (@var{new_val}, "local")
Query or set the internal variable that specifies the name of the
program that Octave runs to format help text containing
Texinfo markup commands.
 
The default value is @code{makeinfo}.
 
When called from inside a function with the @qcode{"local"} option, the
variable is changed locally for the function and any subroutines it calls.
The original variable value is restored when exiting the function.
@seealso{texi_macros_file, info_file, info_program, doc, help}
@end deftypefn */)
{
  help_system& help_sys = interp.get_help_system ();
 
  return help_sys.makeinfo_program (args, nargout);
}
 
DEFMETHOD (suppress_verbose_help_message, interp, args, nargout,
           doc: /* -*- texinfo -*-
@deftypefn  {} {@var{val} =} suppress_verbose_help_message ()
@deftypefnx {} {@var{old_val} =} suppress_verbose_help_message (@var{new_val})
@deftypefnx {} {@var{old_val} =} suppress_verbose_help_message (@var{new_val}, "local")
Query or set the internal variable that controls whether Octave
will add additional help information to the end of the output from
the @code{help} command and usage messages for built-in commands.
 
When called from inside a function with the @qcode{"local"} option, the
variable is changed locally for the function and any subroutines it calls.
The original variable value is restored when exiting the function.
@end deftypefn */)
{
  help_system& help_sys = interp.get_help_system ();
 
  return help_sys.suppress_verbose_help_message (args, nargout);
}
 
DEFMETHOD (texi_macros_file, interp, args, nargout,
           doc: /* -*- texinfo -*-
@deftypefn  {} {@var{val} =} texi_macros_file ()
@deftypefnx {} {@var{old_val} =} texi_macros_file (@var{new_val})
@deftypefnx {} {@var{old_val} =} texi_macros_file (@var{new_val}, "local")
Query or set the internal variable that specifies the name of the
file containing Texinfo macros that are prepended to documentation strings
before they are passed to makeinfo.
 
The default value is
@file{@var{octave-home}/share/octave/@var{version}/etc/macros.texi},
in which @var{octave-home} is the root directory of the Octave installation,
and @var{version} is the Octave version number.
The default value may be overridden by the environment variable
@w{@env{OCTAVE_TEXI_MACROS_FILE}}, or the command line argument
@option{--texi-macros-file FNAME}.
 
When called from inside a function with the @qcode{"local"} option, the
variable is changed locally for the function and any subroutines it calls.
The original variable value is restored when exiting the function.
@seealso{makeinfo_program}
@end deftypefn */)
{
  help_system& help_sys = interp.get_help_system ();
 
  return help_sys.texi_macros_file (args, nargout);
}
 
OCTAVE_END_NAMESPACE(octave)