Introduce class completion_tracker & rewrite completion<->readline interaction

[deliverable/binutils-gdb.git] / gdb / completer.h

/* Header for GDB line completion.
   Copyright (C) 2000-2017 Free Software Foundation, Inc.

   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 3 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, see <http://www.gnu.org/licenses/>.  */

#if !defined (COMPLETER_H)
#define COMPLETER_H 1

#include "gdb_vecs.h"
#include "command.h"

/* Types of functions in struct match_list_displayer.  */

struct match_list_displayer;

typedef void mld_crlf_ftype (const struct match_list_displayer *);
typedef void mld_putch_ftype (const struct match_list_displayer *, int);
typedef void mld_puts_ftype (const struct match_list_displayer *,
			     const char *);
typedef void mld_flush_ftype (const struct match_list_displayer *);
typedef void mld_erase_entire_line_ftype (const struct match_list_displayer *);
typedef void mld_beep_ftype (const struct match_list_displayer *);
typedef int mld_read_key_ftype (const struct match_list_displayer *);

/* Interface between CLI/TUI and gdb_match_list_displayer.  */

struct match_list_displayer
{
  /* The screen dimensions to work with when displaying matches.  */
  int height, width;

  /* Print cr,lf.  */
  mld_crlf_ftype *crlf;

  /* Not "putc" to avoid issues where it is a stdio macro.  Sigh.  */
  mld_putch_ftype *putch;

  /* Print a string.  */
  mld_puts_ftype *puts;

  /* Flush all accumulated output.  */
  mld_flush_ftype *flush;

  /* Erase the currently line on the terminal (but don't discard any text the
     user has entered, readline may shortly re-print it).  */
  mld_erase_entire_line_ftype *erase_entire_line;

  /* Ring the bell.  */
  mld_beep_ftype *beep;

  /* Read one key.  */
  mld_read_key_ftype *read_key;
};

/* A list of completion candidates.  Each element is a malloc string,
   because ownership of the strings is transferred to readline, which
   calls free on each element.  */
typedef std::vector<gdb::unique_xmalloc_ptr<char>> completion_list;

/* The final result of a completion that is handed over to either
   readline or the "completion" command (which pretends to be
   readline).  Mainly a wrapper for a readline-style match list array,
   though other bits of info are included too.  */

struct completion_result
{
  /* Create an empty result.  */
  completion_result ();

  /* Create a result.  */
  completion_result (char **match_list, size_t number_matches,
		     bool completion_suppress_append);

  /* Destroy a result.  */
  ~completion_result ();

  /* Disable copying, since we don't need it.  */
  completion_result (const completion_result &rhs) = delete;
  void operator= (const completion_result &rhs) = delete;

  /* Move a result.  */
  completion_result (completion_result &&rhs);

  /* Release ownership of the match list array.  */
  char **release_match_list ();

  /* Sort the match list.  */
  void sort_match_list ();

private:
  /* Destroy the match list array and its contents.  */
  void reset_match_list ();

public:
  /* (There's no point in making these fields private, since the whole
     point of this wrapper is to build data in the layout expected by
     readline.  Making them private would require adding getters for
     the "complete" command, which would expose the same
     implementation details anyway.)  */

  /* The match list array, in the format that readline expects.
     match_list[0] contains the common prefix.  The real match list
     starts at index 1.  The list is NULL terminated.  If there's only
     one match, then match_list[1] is NULL.  If there are no matches,
     then this is NULL.  */
  char **match_list;
  /* The number of matched completions in MATCH_LIST.  Does not
     include the NULL terminator or the common prefix.  */
  size_t number_matches;

  /* Whether readline should suppress appending a whitespace, when
     there's only one possible completion.  */
  bool completion_suppress_append;
};

/* Object used by completers to build a completion match list to hand
   over to readline.  It tracks:

   - How many unique completions have been generated, to terminate
     completion list generation early if the list has grown to a size
     so large as to be useless.  This helps avoid GDB seeming to lock
     up in the event the user requests to complete on something vague
     that necessitates the time consuming expansion of many symbol
     tables.
*/
class completion_tracker
{
public:
  completion_tracker ();
  ~completion_tracker ();

  /* Disable copy.  */
  completion_tracker (const completion_tracker &rhs) = delete;
  void operator= (const completion_tracker &rhs) = delete;

  /* Add the completion NAME to the list of generated completions if
     it is not there already.  If too many completions were already
     found, this throws an error.  */
  void add_completion (gdb::unique_xmalloc_ptr<char> name);

  /* Add all completions matches in LIST.  Elements are moved out of
     LIST.  */
  void add_completions (completion_list &&list);

  /* True if we have any completion match recorded.  */
  bool have_completions () const
  { return !m_entries_vec.empty (); }

  /* Build a completion_result containing the list of completion
     matches to hand over to readline.  The parameters are as in
     rl_attempted_completion_function.  */
  completion_result build_completion_result (const char *text,
					     int start, int end);

private:

  /* Add the completion NAME to the list of generated completions if
     it is not there already.  If false is returned, too many
     completions were found.  */
  bool maybe_add_completion (gdb::unique_xmalloc_ptr<char> name);

  /* Given a new match, recompute the lowest common denominator (LCD)
     to hand over to readline.  */
  void recompute_lowest_common_denominator (const char *new_match);

  /* The completion matches found so far, in a vector.  */
  completion_list m_entries_vec;

  /* The completion matches found so far, in a hash table, for
     duplicate elimination as entries are added.  Otherwise the user
     is left scratching his/her head: readline and complete_command
     will remove duplicates, and if removal of duplicates there brings
     the total under max_completions the user may think gdb quit
     searching too early.  */
  htab_t m_entries_hash;

  /* Our idea of lowest common denominator to hand over to readline.  */
  char *m_lowest_common_denominator = NULL;

  /* If true, the LCD is unique.  I.e., all completion candidates had
     the same string.  */
  bool m_lowest_common_denominator_unique = false;
};

extern void gdb_display_match_list (char **matches, int len, int max,
				    const struct match_list_displayer *);

extern const char *get_max_completions_reached_message (void);

extern void complete_line (completion_tracker &tracker,
			   const char *text,
			   const char *line_buffer,
			   int point);

extern char **gdb_rl_attempted_completion_function (const char *text,
						    int start, int end);

extern void noop_completer (struct cmd_list_element *,
			    completion_tracker &tracker,
			    const char *, const char *);

extern void filename_completer (struct cmd_list_element *,
				completion_tracker &tracker,
				const char *, const char *);

extern void expression_completer (struct cmd_list_element *,
				  completion_tracker &tracker,
				  const char *, const char *);

extern void location_completer (struct cmd_list_element *,
				completion_tracker &tracker,
				const char *, const char *);

extern void symbol_completer (struct cmd_list_element *,
			      completion_tracker &tracker,
			      const char *, const char *);

extern void command_completer (struct cmd_list_element *,
			       completion_tracker &tracker,
			       const char *, const char *);

extern void signal_completer (struct cmd_list_element *,
			      completion_tracker &tracker,
			      const char *, const char *);

extern void reg_or_group_completer (struct cmd_list_element *,
				    completion_tracker &tracker,
				    const char *, const char *);

extern void reggroup_completer (struct cmd_list_element *,
				completion_tracker &tracker,
				const char *, const char *);

extern const char *get_gdb_completer_quote_characters (void);

extern char *gdb_completion_word_break_characters (void);

/* Set the word break characters array to BREAK_CHARS.  This function
   is useful as const-correct alternative to direct assignment to
   rl_completer_word_break_characters, which is "char *",
   not "const char *".  */
extern void set_rl_completer_word_break_characters (const char *break_chars);

/* Get the matching completer_handle_brkchars_ftype function for FN.
   FN is one of the core completer functions above (filename,
   location, symbol, etc.).  This function is useful for cases when
   the completer doesn't know the type of the completion until some
   calculation is done (e.g., for Python functions).  */

extern completer_handle_brkchars_ftype *
  completer_handle_brkchars_func_for_completer (completer_ftype *fn);

/* Exported to linespec.c */

extern const char *skip_quoted_chars (const char *, const char *,
				      const char *);

extern const char *skip_quoted (const char *);

/* Maximum number of candidates to consider before the completer
   bails by throwing MAX_COMPLETIONS_REACHED_ERROR.  Negative values
   disable limiting.  */

extern int max_completions;

#endif /* defined (COMPLETER_H) */