gdb/completer.h

   1 /* Header for GDB line completion.
   2    Copyright (C) 2000-2017 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  16
  17 #if !defined (COMPLETER_H)
  18 #define COMPLETER_H 1
  19
  20 #include "gdb_vecs.h"
  21 #include "command.h"
  22
  23 /* Types of functions in struct match_list_displayer.  */
  24
  25 struct match_list_displayer;
  26
  27 typedef void mld_crlf_ftype (const struct match_list_displayer *);
  28 typedef void mld_putch_ftype (const struct match_list_displayer *, int);
  29 typedef void mld_puts_ftype (const struct match_list_displayer *,
  30                              const char *);
  31 typedef void mld_flush_ftype (const struct match_list_displayer *);
  32 typedef void mld_erase_entire_line_ftype (const struct match_list_displayer *);
  33 typedef void mld_beep_ftype (const struct match_list_displayer *);
  34 typedef int mld_read_key_ftype (const struct match_list_displayer *);
  35
  36 /* Interface between CLI/TUI and gdb_match_list_displayer.  */
  37
  38 struct match_list_displayer
  39 {
  40   /* The screen dimensions to work with when displaying matches.  */
  41   int height, width;
  42
  43   /* Print cr,lf.  */
  44   mld_crlf_ftype *crlf;
  45
  46   /* Not "putc" to avoid issues where it is a stdio macro.  Sigh.  */
  47   mld_putch_ftype *putch;
  48
  49   /* Print a string.  */
  50   mld_puts_ftype *puts;
  51
  52   /* Flush all accumulated output.  */
  53   mld_flush_ftype *flush;
  54
  55   /* Erase the currently line on the terminal (but don't discard any text the
  56      user has entered, readline may shortly re-print it).  */
  57   mld_erase_entire_line_ftype *erase_entire_line;
  58
  59   /* Ring the bell.  */
  60   mld_beep_ftype *beep;
  61
  62   /* Read one key.  */
  63   mld_read_key_ftype *read_key;
  64 };
  65
  66 /* A list of completion candidates.  Each element is a malloc string,
  67    because ownership of the strings is transferred to readline, which
  68    calls free on each element.  */
  69 typedef std::vector<gdb::unique_xmalloc_ptr<char>> completion_list;
  70
  71 /* The result of a successful completion match.  When doing symbol
  72    comparison, we use the symbol search name for the symbol name match
  73    check, but the matched name that is shown to the user may be
  74    different.  For example, Ada uses encoded names for lookup, but
  75    then wants to decode the symbol name to show to the user, and also
  76    in some cases wrap the matched name in "<sym>" (meaning we can't
  77    always use the symbol's print name).  */
  78
  79 class completion_match
  80 {
  81 public:
  82   /* Get the completion match result.  See m_match/m_storage's
  83      descriptions.  */
  84   const char *match ()
  85   { return m_match; }
  86
  87   /* Set the completion match result.  See m_match/m_storage's
  88      descriptions.  */
  89   void set_match (const char *match)
  90   { m_match = match; }
  91
  92   /* Get temporary storage for generating a match result, dynamically.
  93      The built string is only good until the next clear() call.  I.e.,
  94      good until the next symbol comparison.  */
  95   std::string &storage ()
  96   { return m_storage; }
  97
  98   /* Prepare for another completion matching sequence.  */
  99   void clear ()
 100   {
 101     m_match = NULL;
 102     m_storage.clear ();
 103   }
 104
 105 private:
 106   /* The completion match result.  This can either be a pointer into
 107      M_STORAGE string, or it can be a pointer into the some other
 108      string that outlives the completion matching sequence (usually, a
 109      pointer to a symbol's name).  */
 110   const char *m_match;
 111
 112   /* Storage a symbol comparison routine can use for generating a
 113      match result, dynamically.  The built string is only good until
 114      the next clear() call.  I.e., good until the next symbol
 115      comparison.  */
 116   std::string m_storage;
 117 };
 118
 119 /* The result of a successful completion match, but for least common
 120    denominator (LCD) computation.  Some completers provide matches
 121    that don't start with the completion "word".  E.g., completing on
 122    "b push_ba" on a C++ program usually completes to
 123    std::vector<...>::push_back, std::string::push_back etc.  In such
 124    case, the symbol comparison routine will set the LCD match to point
 125    into the "push_back" substring within the symbol's name string.
 126    Also, in some cases, the symbol comparison routine will want to
 127    ignore parts of the symbol name for LCD purposes, such as for
 128    example symbols with abi tags in C++.  In such cases, the symbol
 129    comparison routine will set MARK_IGNORED_RANGE to mark the ignored
 130    substrings of the matched string.  The resulting LCD string with
 131    the ignored parts stripped out is computed at the end of a
 132    completion match sequence iff we had a positive match.  */
 133
 134 class completion_match_for_lcd
 135 {
 136 public:
 137   /* Get the resulting LCD, after a successful match.  */
 138   const char *match ()
 139   { return m_match; }
 140
 141   /* Set the match for LCD.  See m_match's description.  */
 142   void set_match (const char *match)
 143   { m_match = match; }
 144
 145   /* Mark the range between [BEGIN, END) as ignored.  */
 146   void mark_ignored_range (const char *begin, const char *end)
 147   { m_ignored_ranges.emplace_back (begin, end); }
 148
 149   /* Get the resulting LCD, after a successful match.  If there are
 150      ignored ranges, then this builds a new string with the ignored
 151      parts removed (and stores it internally).  As such, the result of
 152      this call is only good for the current completion match
 153      sequence.  */
 154   const char *finish ()
 155   {
 156     if (m_ignored_ranges.empty ())
 157       return m_match;
 158     else
 159       {
 160         m_finished_storage.clear ();
 161
 162         const char *prev = m_match;
 163         for (const auto &range : m_ignored_ranges)
 164           {
 165             m_finished_storage.append (prev, range.first);
 166             prev = range.second;
 167           }
 168         m_finished_storage.append (prev);
 169
 170         return m_finished_storage.c_str ();
 171       }
 172   }
 173
 174   /* Prepare for another completion matching sequence.  */
 175   void clear ()
 176   {
 177     m_match = NULL;
 178     m_ignored_ranges.clear ();
 179   }
 180
 181 private:
 182   /* The completion match result for LCD.  This is usually either a
 183      pointer into to a substring within a symbol's name, or to the
 184      storage of the pairing completion_match object.  */
 185   const char *m_match;
 186
 187   /* The ignored substring ranges within M_MATCH.  E.g., if we were
 188      looking for completion matches for C++ functions starting with
 189        "functio"
 190      and successfully match:
 191        "function[abi:cxx11](int)"
 192      the ignored ranges vector will contain an entry that delimits the
 193      "[abi:cxx11]" substring, such that calling finish() results in:
 194        "function(int)"
 195    */
 196   std::vector<std::pair<const char *, const char *>> m_ignored_ranges;
 197
 198   /* Storage used by the finish() method, if it has to compute a new
 199      string.  */
 200   std::string m_finished_storage;
 201 };
 202
 203 /* Convenience aggregate holding info returned by the symbol name
 204    matching routines (see symbol_name_matcher_ftype).  */
 205 struct completion_match_result
 206 {
 207   /* The completion match candidate.  */
 208   completion_match match;
 209
 210   /* The completion match, for LCD computation purposes.  */
 211   completion_match_for_lcd match_for_lcd;
 212
 213   /* Convenience that sets both MATCH and MATCH_FOR_LCD.  M_FOR_LCD is
 214      optional.  If not specified, defaults to M.  */
 215   void set_match (const char *m, const char *m_for_lcd = NULL)
 216   {
 217     match.set_match (m);
 218     if (m_for_lcd == NULL)
 219       match_for_lcd.set_match (m);
 220     else
 221       match_for_lcd.set_match (m_for_lcd);
 222   }
 223 };
 224
 225 /* The final result of a completion that is handed over to either
 226    readline or the "completion" command (which pretends to be
 227    readline).  Mainly a wrapper for a readline-style match list array,
 228    though other bits of info are included too.  */
 229
 230 struct completion_result
 231 {
 232   /* Create an empty result.  */
 233   completion_result ();
 234
 235   /* Create a result.  */
 236   completion_result (char **match_list, size_t number_matches,
 237                      bool completion_suppress_append);
 238
 239   /* Destroy a result.  */
 240   ~completion_result ();
 241
 242   DISABLE_COPY_AND_ASSIGN (completion_result);
 243
 244   /* Move a result.  */
 245   completion_result (completion_result &&rhs);
 246
 247   /* Release ownership of the match list array.  */
 248   char **release_match_list ();
 249
 250   /* Sort the match list.  */
 251   void sort_match_list ();
 252
 253 private:
 254   /* Destroy the match list array and its contents.  */
 255   void reset_match_list ();
 256
 257 public:
 258   /* (There's no point in making these fields private, since the whole
 259      point of this wrapper is to build data in the layout expected by
 260      readline.  Making them private would require adding getters for
 261      the "complete" command, which would expose the same
 262      implementation details anyway.)  */
 263
 264   /* The match list array, in the format that readline expects.
 265      match_list[0] contains the common prefix.  The real match list
 266      starts at index 1.  The list is NULL terminated.  If there's only
 267      one match, then match_list[1] is NULL.  If there are no matches,
 268      then this is NULL.  */
 269   char **match_list;
 270   /* The number of matched completions in MATCH_LIST.  Does not
 271      include the NULL terminator or the common prefix.  */
 272   size_t number_matches;
 273
 274   /* Whether readline should suppress appending a whitespace, when
 275      there's only one possible completion.  */
 276   bool completion_suppress_append;
 277 };
 278
 279 /* Object used by completers to build a completion match list to hand
 280    over to readline.  It tracks:
 281
 282    - How many unique completions have been generated, to terminate
 283      completion list generation early if the list has grown to a size
 284      so large as to be useless.  This helps avoid GDB seeming to lock
 285      up in the event the user requests to complete on something vague
 286      that necessitates the time consuming expansion of many symbol
 287      tables.
 288
 289    - The completer's idea of least common denominator (aka the common
 290      prefix) between all completion matches to hand over to readline.
 291      Some completers provide matches that don't start with the
 292      completion "word".  E.g., completing on "b push_ba" on a C++
 293      program usually completes to std::vector<...>::push_back,
 294      std::string::push_back etc.  If all matches happen to start with
 295      "std::", then readline would figure out that the lowest common
 296      denominator is "std::", and thus would do a partial completion
 297      with that.  I.e., it would replace "push_ba" in the input buffer
 298      with "std::", losing the original "push_ba", which is obviously
 299      undesirable.  To avoid that, such completers pass the substring
 300      of the match that matters for common denominator computation as
 301      MATCH_FOR_LCD argument to add_completion.  The end result is
 302      passed to readline in gdb_rl_attempted_completion_function.
 303
 304    - The custom word point to hand over to readline, for completers
 305      that parse the input string in order to dynamically adjust
 306      themselves depending on exactly what they're completing.  E.g.,
 307      the linespec completer needs to bypass readline's too-simple word
 308      breaking algorithm.
 309 */
 310 class completion_tracker
 311 {
 312 public:
 313   completion_tracker ();
 314   ~completion_tracker ();
 315
 316   DISABLE_COPY_AND_ASSIGN (completion_tracker);
 317
 318   /* Add the completion NAME to the list of generated completions if
 319      it is not there already.  If too many completions were already
 320      found, this throws an error.  */
 321   void add_completion (gdb::unique_xmalloc_ptr<char> name,
 322                        completion_match_for_lcd *match_for_lcd = NULL);
 323
 324   /* Add all completions matches in LIST.  Elements are moved out of
 325      LIST.  */
 326   void add_completions (completion_list &&list);
 327
 328   /* Set the quote char to be appended after a unique completion is
 329      added to the input line.  Set to '\0' to clear.  See
 330      m_quote_char's description.  */
 331   void set_quote_char (int quote_char)
 332   { m_quote_char = quote_char; }
 333
 334   /* The quote char to be appended after a unique completion is added
 335      to the input line.  Returns '\0' if no quote char has been set.
 336      See m_quote_char's description.  */
 337   int quote_char () { return m_quote_char; }
 338
 339   /* Tell the tracker that the current completer wants to provide a
 340      custom word point instead of a list of a break chars, in the
 341      handle_brkchars phase.  Such completers must also compute their
 342      completions then.  */
 343   void set_use_custom_word_point (bool enable)
 344   { m_use_custom_word_point = enable; }
 345
 346   /* Whether the current completer computes a custom word point.  */
 347   bool use_custom_word_point () const
 348   { return m_use_custom_word_point; }
 349
 350   /* The custom word point.  */
 351   int custom_word_point () const
 352   { return m_custom_word_point; }
 353
 354   /* Set the custom word point to POINT.  */
 355   void set_custom_word_point (int point)
 356   { m_custom_word_point = point; }
 357
 358   /* Advance the custom word point by LEN.  */
 359   void advance_custom_word_point_by (size_t len);
 360
 361   /* Whether to tell readline to skip appending a whitespace after the
 362      completion.  See m_suppress_append_ws.  */
 363   bool suppress_append_ws () const
 364   { return m_suppress_append_ws; }
 365
 366   /* Set whether to tell readline to skip appending a whitespace after
 367      the completion.  See m_suppress_append_ws.  */
 368   void set_suppress_append_ws (bool suppress)
 369   { m_suppress_append_ws = suppress; }
 370
 371   /* Return true if we only have one completion, and it matches
 372      exactly the completion word.  I.e., completing results in what we
 373      already have.  */
 374   bool completes_to_completion_word (const char *word);
 375
 376   /* Get a reference to the shared (between all the multiple symbol
 377      name comparison calls) completion_match_result object, ready for
 378      another symbol name match sequence.  */
 379   completion_match_result &reset_completion_match_result ()
 380   {
 381     completion_match_result &res = m_completion_match_result;
 382
 383     /* Clear any previous match.  */
 384     res.match.clear ();
 385     res.match_for_lcd.clear ();
 386     return m_completion_match_result;
 387   }
 388
 389   /* True if we have any completion match recorded.  */
 390   bool have_completions () const
 391   { return !m_entries_vec.empty (); }
 392
 393   /* Discard the current completion match list and the current
 394      LCD.  */
 395   void discard_completions ();
 396
 397   /* Build a completion_result containing the list of completion
 398      matches to hand over to readline.  The parameters are as in
 399      rl_attempted_completion_function.  */
 400   completion_result build_completion_result (const char *text,
 401                                              int start, int end);
 402
 403 private:
 404
 405   /* Add the completion NAME to the list of generated completions if
 406      it is not there already.  If false is returned, too many
 407      completions were found.  */
 408   bool maybe_add_completion (gdb::unique_xmalloc_ptr<char> name,
 409                              completion_match_for_lcd *match_for_lcd);
 410
 411   /* Given a new match, recompute the lowest common denominator (LCD)
 412      to hand over to readline.  Normally readline computes this itself
 413      based on the whole set of completion matches.  However, some
 414      completers want to override readline, in order to be able to
 415      provide a LCD that is not really a prefix of the matches, but the
 416      lowest common denominator of some relevant substring of each
 417      match.  E.g., "b push_ba" completes to
 418      "std::vector<..>::push_back", "std::string::push_back", etc., and
 419      in this case we want the lowest common denominator to be
 420      "push_back" instead of "std::".  */
 421   void recompute_lowest_common_denominator (const char *new_match);
 422
 423   /* Completion match outputs returned by the symbol name matching
 424      routines (see symbol_name_matcher_ftype).  These results are only
 425      valid for a single match call.  This is here in order to be able
 426      to conveniently share the same storage among all the calls to the
 427      symbol name matching routines.  */
 428   completion_match_result m_completion_match_result;
 429
 430   /* The completion matches found so far, in a vector.  */
 431   completion_list m_entries_vec;
 432
 433   /* The completion matches found so far, in a hash table, for
 434      duplicate elimination as entries are added.  Otherwise the user
 435      is left scratching his/her head: readline and complete_command
 436      will remove duplicates, and if removal of duplicates there brings
 437      the total under max_completions the user may think gdb quit
 438      searching too early.  */
 439   htab_t m_entries_hash;
 440
 441   /* If non-zero, then this is the quote char that needs to be
 442      appended after completion (iff we have a unique completion).  We
 443      don't rely on readline appending the quote char as delimiter as
 444      then readline wouldn't append the ' ' after the completion.
 445      I.e., we want this:
 446
 447       before tab: "b 'function("
 448       after tab:  "b 'function()' "
 449   */
 450   int m_quote_char = '\0';
 451
 452   /* If true, the completer has its own idea of "word" point, and
 453      doesn't want to rely on readline computing it based on brkchars.
 454      Set in the handle_brkchars phase.  */
 455   bool m_use_custom_word_point = false;
 456
 457   /* The completer's idea of where the "word" we were looking at is
 458      relative to RL_LINE_BUFFER.  This is advanced in the
 459      handle_brkchars phase as the completer discovers potential
 460      completable words.  */
 461   int m_custom_word_point = 0;
 462
 463   /* If true, tell readline to skip appending a whitespace after the
 464      completion.  Automatically set if we have a unique completion
 465      that already has a space at the end.  A completer may also
 466      explicitly set this.  E.g., the linespec completer sets this when
 467      the completion ends with the ":" separator between filename and
 468      function name.  */
 469   bool m_suppress_append_ws = false;
 470
 471   /* Our idea of lowest common denominator to hand over to readline.
 472      See intro.  */
 473   char *m_lowest_common_denominator = NULL;
 474
 475   /* If true, the LCD is unique.  I.e., all completions had the same
 476      MATCH_FOR_LCD substring, even if the completions were different.
 477      For example, if "break function<tab>" found "a::function()" and
 478      "b::function()", the LCD will be "function()" in both cases and
 479      so we want to tell readline to complete the line with
 480      "function()", instead of showing all the possible
 481      completions.  */
 482   bool m_lowest_common_denominator_unique = false;
 483 };
 484
 485 extern void gdb_display_match_list (char **matches, int len, int max,
 486                                     const struct match_list_displayer *);
 487
 488 extern const char *get_max_completions_reached_message (void);
 489
 490 extern void complete_line (completion_tracker &tracker,
 491                            const char *text,
 492                            const char *line_buffer,
 493                            int point);
 494
 495 /* Find the bounds of the word in TEXT for completion purposes, and
 496    return a pointer to the end of the word.  Calls the completion
 497    machinery for a handle_brkchars phase (using TRACKER) to figure out
 498    the right work break characters for the command in TEXT.
 499    QUOTE_CHAR, if non-null, is set to the opening quote character if
 500    we found an unclosed quoted substring, '\0' otherwise.  */
 501 extern const char *completion_find_completion_word (completion_tracker &tracker,
 502                                                     const char *text,
 503                                                     int *quote_char);
 504
 505
 506 /* Assuming TEXT is an expression in the current language, find the
 507    completion word point for TEXT, emulating the algorithm readline
 508    uses to find the word point, using the current language's word
 509    break characters.  */
 510
 511 const char *advance_to_expression_complete_word_point
 512   (completion_tracker &tracker, const char *text);
 513
 514 extern char **gdb_rl_attempted_completion_function (const char *text,
 515                                                     int start, int end);
 516
 517 extern void noop_completer (struct cmd_list_element *,
 518                             completion_tracker &tracker,
 519                             const char *, const char *);
 520
 521 extern void filename_completer (struct cmd_list_element *,
 522                                 completion_tracker &tracker,
 523                                 const char *, const char *);
 524
 525 extern void expression_completer (struct cmd_list_element *,
 526                                   completion_tracker &tracker,
 527                                   const char *, const char *);
 528
 529 extern void location_completer (struct cmd_list_element *,
 530                                 completion_tracker &tracker,
 531                                 const char *, const char *);
 532
 533 extern void symbol_completer (struct cmd_list_element *,
 534                               completion_tracker &tracker,
 535                               const char *, const char *);
 536
 537 extern void command_completer (struct cmd_list_element *,
 538                                completion_tracker &tracker,
 539                                const char *, const char *);
 540
 541 extern void signal_completer (struct cmd_list_element *,
 542                               completion_tracker &tracker,
 543                               const char *, const char *);
 544
 545 extern void reg_or_group_completer (struct cmd_list_element *,
 546                                     completion_tracker &tracker,
 547                                     const char *, const char *);
 548
 549 extern void reggroup_completer (struct cmd_list_element *,
 550                                 completion_tracker &tracker,
 551                                 const char *, const char *);
 552
 553 extern const char *get_gdb_completer_quote_characters (void);
 554
 555 extern char *gdb_completion_word_break_characters (void);
 556
 557 /* Set the word break characters array to BREAK_CHARS.  This function
 558    is useful as const-correct alternative to direct assignment to
 559    rl_completer_word_break_characters, which is "char *",
 560    not "const char *".  */
 561 extern void set_rl_completer_word_break_characters (const char *break_chars);
 562
 563 /* Get the matching completer_handle_brkchars_ftype function for FN.
 564    FN is one of the core completer functions above (filename,
 565    location, symbol, etc.).  This function is useful for cases when
 566    the completer doesn't know the type of the completion until some
 567    calculation is done (e.g., for Python functions).  */
 568
 569 extern completer_handle_brkchars_ftype *
 570   completer_handle_brkchars_func_for_completer (completer_ftype *fn);
 571
 572 /* Exported to linespec.c */
 573
 574 /* Return a list of all source files whose names begin with matching
 575    TEXT.  */
 576 extern completion_list complete_source_filenames (const char *text);
 577
 578 /* Complete on expressions.  Often this means completing on symbol
 579    names, but some language parsers also have support for completing
 580    field names.  */
 581 extern void complete_expression (completion_tracker &tracker,
 582                                  const char *text, const char *word);
 583
 584 extern const char *skip_quoted_chars (const char *, const char *,
 585                                       const char *);
 586
 587 extern const char *skip_quoted (const char *);
 588
 589 /* Maximum number of candidates to consider before the completer
 590    bails by throwing MAX_COMPLETIONS_REACHED_ERROR.  Negative values
 591    disable limiting.  */
 592
 593 extern int max_completions;
 594
 595 #endif /* defined (COMPLETER_H) */