path: root/gdb/completer.c

/* Line completion stuff for GDB, the GNU debugger.
   Copyright 2000 Free Software Foundation, Inc.

   This file is part of GDB.

   This program 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 of the License, or
   (at your option) any later version.

   This program 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 this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include "defs.h"
#include "symtab.h"
#include "gdbtypes.h"
#include "expression.h"

/* FIXME: This is needed because of lookup_cmd_1().
   We should be calling a hook instead so we eliminate the CLI dependency. */
#include "gdbcmd.h"

/* Needed for rl_completer_word_break_characters() */
#include <readline/readline.h>

/* readline defines this.  */
#undef savestring

#include "completer.h"

/* Prototypes for local functions */

/* readline uses the word breaks for two things:
   (1) In figuring out where to point the TEXT parameter to the
   rl_completion_entry_function.  Since we don't use TEXT for much,
   it doesn't matter a lot what the word breaks are for this purpose, but
   it does affect how much stuff M-? lists.
   (2) If one of the matches contains a word break character, readline
   will quote it.  That's why we switch between
   gdb_completer_word_break_characters and
   gdb_completer_command_word_break_characters.  I'm not sure when
   we need this behavior (perhaps for funky characters in C++ symbols?).  */

/* Variables which are necessary for fancy command line editing.  */
static char *gdb_completer_word_break_characters =
" \t\n!@#$%^&*()+=|~`}{[]\"';:?/>.<,-";

/* When completing on command names, we remove '-' from the list of
   word break characters, since we use it in command names.  If the
   readline library sees one in any of the current completion strings,
   it thinks that the string needs to be quoted and automatically supplies
   a leading quote. */
static char *gdb_completer_command_word_break_characters =
" \t\n!@#$%^&*()+=|~`}{[]\"';:?/>.<,";

/* When completing on file names, we remove from the list of word
   break characters any characters that are commonly used in file
   names, such as '-', '+', '~', etc.  Otherwise, readline displays
   incorrect completion candidates.  */
static char *gdb_completer_file_name_break_characters = " \t\n*|\"';:?/><";

/* Characters that can be used to quote completion strings.  Note that we
   can't include '"' because the gdb C parser treats such quoted sequences
   as strings. */
static char *gdb_completer_quote_characters = "'";

/* Accessor for some completer data that may interest other files. */

char *
get_gdb_completer_word_break_characters (void)
{
  return gdb_completer_word_break_characters;
}

char *
get_gdb_completer_quote_characters (void)
{
  return gdb_completer_quote_characters;
}

/* Complete on filenames.  */
char **
filename_completer (char *text, char *word)
{
  /* From readline.  */
extern char *filename_completion_function (char *, int);
  int subsequent_name;
  char **return_val;
  int return_val_used;
  int return_val_alloced;

  return_val_used = 0;
  /* Small for testing.  */
  return_val_alloced = 1;
  return_val = (char **) xmalloc (return_val_alloced * sizeof (char *));

  subsequent_name = 0;
  while (1)
    {
      char *p;
      p = filename_completion_function (text, subsequent_name);
      if (return_val_used >= return_val_alloced)
	{
	  return_val_alloced *= 2;
	  return_val =
	    (char **) xrealloc (return_val,
				return_val_alloced * sizeof (char *));
	}
      if (p == NULL)
	{
	  return_val[return_val_used++] = p;
	  break;
	}
      /* We need to set subsequent_name to a non-zero value before the
	 continue line below, because otherwise, if the first file seen
	 by GDB is a backup file whose name ends in a `~', we will loop
	 indefinitely.  */
      subsequent_name = 1;
      /* Like emacs, don't complete on old versions.  Especially useful
         in the "source" command.  */
      if (p[strlen (p) - 1] == '~')
	continue;

      {
	char *q;
	if (word == text)
	  /* Return exactly p.  */
	  return_val[return_val_used++] = p;
	else if (word > text)
	  {
	    /* Return some portion of p.  */
	    q = xmalloc (strlen (p) + 5);
	    strcpy (q, p + (word - text));
	    return_val[return_val_used++] = q;
	    free (p);
	  }
	else
	  {
	    /* Return some of TEXT plus p.  */
	    q = xmalloc (strlen (p) + (text - word) + 5);
	    strncpy (q, word, text - word);
	    q[text - word] = '\0';
	    strcat (q, p);
	    return_val[return_val_used++] = q;
	    free (p);
	  }
      }
    }
#if 0
  /* There is no way to do this just long enough to affect quote inserting
     without also affecting the next completion.  This should be fixed in
     readline.  FIXME.  */
  /* Insure that readline does the right thing
     with respect to inserting quotes.  */
  rl_completer_word_break_characters = "";
#endif
  return return_val;
}

/* Here are some useful test cases for completion.  FIXME: These should
   be put in the test suite.  They should be tested with both M-? and TAB.

   "show output-" "radix"
   "show output" "-radix"
   "p" ambiguous (commands starting with p--path, print, printf, etc.)
   "p "  ambiguous (all symbols)
   "info t foo" no completions
   "info t " no completions
   "info t" ambiguous ("info target", "info terminal", etc.)
   "info ajksdlfk" no completions
   "info ajksdlfk " no completions
   "info" " "
   "info " ambiguous (all info commands)
   "p \"a" no completions (string constant)
   "p 'a" ambiguous (all symbols starting with a)
   "p b-a" ambiguous (all symbols starting with a)
   "p b-" ambiguous (all symbols)
   "file Make" "file" (word break hard to screw up here)
   "file ../gdb.stabs/we" "ird" (needs to not break word at slash)
 */

/* Generate completions one by one for the completer.  Each time we are
   called return another potential completion to the caller.
   line_completion just completes on commands or passes the buck to the
   command's completer function, the stuff specific to symbol completion
   is in make_symbol_completion_list.

   TEXT is the caller's idea of the "word" we are looking at.

   MATCHES is the number of matches that have currently been collected from
   calling this completion function.  When zero, then we need to initialize,
   otherwise the initialization has already taken place and we can just
   return the next potential completion string.

   LINE_BUFFER is available to be looked at; it contains the entire text
   of the line.  POINT is the offset in that line of the cursor.  You
   should pretend that the line ends at POINT.

   Returns NULL if there are no more completions, else a pointer to a string
   which is a possible completion, it is the caller's responsibility to
   free the string.  */

char *
line_completion_function (char *text, int matches, char *line_buffer, int point)
{
  static char **list = (char **) NULL;	/* Cache of completions */
  static int index;		/* Next cached completion */
  char *output = NULL;
  char *tmp_command, *p;
  /* Pointer within tmp_command which corresponds to text.  */
  char *word;
  struct cmd_list_element *c, *result_list;

  if (matches == 0)
    {
      /* The caller is beginning to accumulate a new set of completions, so
         we need to find all of them now, and cache them for returning one at
         a time on future calls. */

      if (list)
	{
	  /* Free the storage used by LIST, but not by the strings inside.
	     This is because rl_complete_internal () frees the strings. */
	  free ((PTR) list);
	}
      list = 0;
      index = 0;

      /* Choose the default set of word break characters to break completions.
         If we later find out that we are doing completions on command strings
         (as opposed to strings supplied by the individual command completer
         functions, which can be any string) then we will switch to the
         special word break set for command strings, which leaves out the
         '-' character used in some commands.  */

      rl_completer_word_break_characters =
	gdb_completer_word_break_characters;

      /* Decide whether to complete on a list of gdb commands or on symbols. */
      tmp_command = (char *) alloca (point + 1);
      p = tmp_command;

      strncpy (tmp_command, line_buffer, point);
      tmp_command[point] = '\0';
      /* Since text always contains some number of characters leading up
         to point, we can find the equivalent position in tmp_command
         by subtracting that many characters from the end of tmp_command.  */
      word = tmp_command + point - strlen (text);

      if (point == 0)
	{
	  /* An empty line we want to consider ambiguous; that is, it
	     could be any command.  */
	  c = (struct cmd_list_element *) -1;
	  result_list = 0;
	}
      else
	{
	  c = lookup_cmd_1 (&p, cmdlist, &result_list, 1);
	}

      /* Move p up to the next interesting thing.  */
      while (*p == ' ' || *p == '\t')
	{
	  p++;
	}

      if (!c)
	{
	  /* It is an unrecognized command.  So there are no
	     possible completions.  */
	  list = NULL;
	}
      else if (c == (struct cmd_list_element *) -1)
	{
	  char *q;

	  /* lookup_cmd_1 advances p up to the first ambiguous thing, but
	     doesn't advance over that thing itself.  Do so now.  */
	  q = p;
	  while (*q && (isalnum (*q) || *q == '-' || *q == '_'))
	    ++q;
	  if (q != tmp_command + point)
	    {
	      /* There is something beyond the ambiguous
	         command, so there are no possible completions.  For
	         example, "info t " or "info t foo" does not complete
	         to anything, because "info t" can be "info target" or
	         "info terminal".  */
	      list = NULL;
	    }
	  else
	    {
	      /* We're trying to complete on the command which was ambiguous.
	         This we can deal with.  */
	      if (result_list)
		{
		  list = complete_on_cmdlist (*result_list->prefixlist, p,
					      word);
		}
	      else
		{
		  list = complete_on_cmdlist (cmdlist, p, word);
		}
	      /* Insure that readline does the right thing with respect to
	         inserting quotes.  */
	      rl_completer_word_break_characters =
		gdb_completer_command_word_break_characters;
	    }
	}
      else
	{
	  /* We've recognized a full command.  */

	  if (p == tmp_command + point)
	    {
	      /* There is no non-whitespace in the line beyond the command.  */

	      if (p[-1] == ' ' || p[-1] == '\t')
		{
		  /* The command is followed by whitespace; we need to complete
		     on whatever comes after command.  */
		  if (c->prefixlist)
		    {
		      /* It is a prefix command; what comes after it is
		         a subcommand (e.g. "info ").  */
		      list = complete_on_cmdlist (*c->prefixlist, p, word);

		      /* Insure that readline does the right thing
		         with respect to inserting quotes.  */
		      rl_completer_word_break_characters =
			gdb_completer_command_word_break_characters;
		    }
		  else if (c->enums)
		    {
		      list = complete_on_enum (c->enums, p, word);
		      rl_completer_word_break_characters =
			gdb_completer_command_word_break_characters;
		    }
		  else
		    {
		      /* It is a normal command; what comes after it is
		         completed by the command's completer function.  */
		      list = (*c->completer) (p, word);
		      if (c->completer == filename_completer)
			rl_completer_word_break_characters =
			  gdb_completer_file_name_break_characters;
		    }
		}
	      else
		{
		  /* The command is not followed by whitespace; we need to
		     complete on the command itself.  e.g. "p" which is a
		     command itself but also can complete to "print", "ptype"
		     etc.  */
		  char *q;

		  /* Find the command we are completing on.  */
		  q = p;
		  while (q > tmp_command)
		    {
		      if (isalnum (q[-1]) || q[-1] == '-' || q[-1] == '_')
			--q;
		      else
			break;
		    }

		  list = complete_on_cmdlist (result_list, q, word);

		  /* Insure that readline does the right thing
		     with respect to inserting quotes.  */
		  rl_completer_word_break_characters =
		    gdb_completer_command_word_break_characters;
		}
	    }
	  else
	    {
	      /* There is non-whitespace beyond the command.  */

	      if (c->prefixlist && !c->allow_unknown)
		{
		  /* It is an unrecognized subcommand of a prefix command,
		     e.g. "info adsfkdj".  */
		  list = NULL;
		}
	      else if (c->enums)
		{
		  list = complete_on_enum (c->enums, p, word);
		}
	      else
		{
		  /* It is a normal command.  */
		  list = (*c->completer) (p, word);
		  if (c->completer == filename_completer)
		    rl_completer_word_break_characters =
		      gdb_completer_file_name_break_characters;
		}
	    }
	}
    }

  /* If we found a list of potential completions during initialization then
     dole them out one at a time.  The vector of completions is NULL
     terminated, so after returning the last one, return NULL (and continue
     to do so) each time we are called after that, until a new list is
     available. */

  if (list)
    {
      output = list[index];
      if (output)
	{
	  index++;
	}
    }

#if 0
  /* Can't do this because readline hasn't yet checked the word breaks
     for figuring out whether to insert a quote.  */
  if (output == NULL)
    /* Make sure the word break characters are set back to normal for the
       next time that readline tries to complete something.  */
    rl_completer_word_break_characters =
      gdb_completer_word_break_characters;
#endif

  return (output);
}
/* Skip over a possibly quoted word (as defined by the quote characters
   and word break characters the completer uses).  Returns pointer to the
   location after the "word". */

char *
skip_quoted (char *str)
{
  char quote_char = '\0';
  char *scan;

  for (scan = str; *scan != '\0'; scan++)
    {
      if (quote_char != '\0')
	{
	  /* Ignore everything until the matching close quote char */
	  if (*scan == quote_char)
	    {
	      /* Found matching close quote. */
	      scan++;
	      break;
	    }
	}
      else if (strchr (gdb_completer_quote_characters, *scan))
	{
	  /* Found start of a quoted string. */
	  quote_char = *scan;
	}
      else if (strchr (gdb_completer_word_break_characters, *scan))
	{
	  break;
	}
    }
  return (scan);
}