text: // This is an open source non-commercial project. Dear PVS-Studio, please check
  // it. PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
  
  /*
   * Code to handle tags and the tag stack
   */
  
  #include <assert.h>
  #include <inttypes.h>
  #include <stdbool.h>
  #include <string.h>
  
  #include "nvim/ascii.h"
  #include "nvim/buffer.h"
  #include "nvim/charset.h"
  #include "nvim/cursor.h"
  #include "nvim/edit.h"
  #include "nvim/eval.h"
  #include "nvim/ex_cmds.h"
  #include "nvim/ex_cmds2.h"
  #include "nvim/ex_docmd.h"
  #include "nvim/ex_getln.h"
  #include "nvim/file_search.h"
  #include "nvim/fileio.h"
  #include "nvim/fold.h"
  #include "nvim/garray.h"
  #include "nvim/if_cscope.h"
  #include "nvim/input.h"
  #include "nvim/mark.h"
  #include "nvim/mbyte.h"
  #include "nvim/memory.h"
  #include "nvim/message.h"
  #include "nvim/move.h"
  #include "nvim/option.h"
  #include "nvim/os/input.h"
  #include "nvim/os/os.h"
  #include "nvim/os/time.h"
  #include "nvim/os_unix.h"
  #include "nvim/path.h"
  #include "nvim/quickfix.h"
  #include "nvim/regexp.h"
  #include "nvim/screen.h"
  #include "nvim/search.h"
  #include "nvim/strings.h"
  #include "nvim/tag.h"
  #include "nvim/ui.h"
  #include "nvim/vim.h"
  #include "nvim/window.h"
  
  /*
   * Structure to hold pointers to various items in a tag line.
   */
  typedef struct tag_pointers {
    // filled in by parse_tag_line():
    char_u *tagname;  // start of tag name (skip "file:")
    char_u *tagname_end;  // char after tag name
    char_u *fname;   // first char of file name
    char_u *fname_end;  // char after file name
    char_u *command;  // first char of command
    // filled in by parse_match():
    char_u *command_end;  // first char after command
    char_u *tag_fname;  // file name of the tags file. This is used
    // when 'tr' is set.
    char_u *tagkind;  // "kind:" value
    char_u *tagkind_end;  // end of tagkind
    char_u *user_data;  // user_data string
    char_u *user_data_end;  // end of user_data
    linenr_T tagline;        // "line:" value
  } tagptrs_T;
  
  /*
   * Structure to hold info about the tag pattern being used.
   */
  typedef struct {
    char_u *pat;             // the pattern
    int len;                      // length of pat[]
    char_u *head;            // start of pattern head
    int headlen;                  // length of head[]
    regmatch_T regmatch;          // regexp program, may be NULL
  } pat_T;
  
  // The matching tags are first stored in one of the hash tables.  In
  // which one depends on the priority of the match.
  // ht_match[] is used to find duplicates, ga_match[] to keep them in sequence.
  // At the end, the matches from ga_match[] are concatenated, to make a list
  // sorted on priority.
  #define MT_ST_CUR       0               // static match in current file
  #define MT_GL_CUR       1               // global match in current file
  #define MT_GL_OTH       2               // global match in other file
  #define MT_ST_OTH       3               // static match in other file
  #define MT_IC_OFF       4               // add for icase match
  #define MT_RE_OFF       8               // add for regexp match
  #define MT_MASK         7               // mask for printing priority
  #define MT_COUNT        16
  
  static char *mt_names[MT_COUNT/2] =
  { "FSC", "F C", "F  ", "FS ", " SC", "  C", "   ", " S " };
  
  #define NOTAGFILE       99              // return value for jumpto_tag
  static char_u *nofile_fname = NULL;   // fname for NOTAGFILE error
  
  
  #ifdef INCLUDE_GENERATED_DECLARATIONS
  # include "tag.c.generated.h"
  #endif
  
  static char_u *bottommsg = (char_u *)N_("E555: at bottom of tag stack");
  static char_u *topmsg = (char_u *)N_("E556: at top of tag stack");
  static char_u *recurmsg
    = (char_u *)N_("E986: cannot modify the tag stack within tagfunc");
  static char_u *tfu_inv_ret_msg
    = (char_u *)N_("E987: invalid return value from tagfunc");
  
  static char_u *tagmatchname = NULL;   // name of last used tag
  
  /*
   * Tag for preview window is remembered separately, to avoid messing up the
   * normal tagstack.
   */
  static taggy_T ptag_entry = { NULL, { { 0, 0, 0 }, 0, 0, NULL }, 0, 0, NULL };
  
  static int tfu_in_use = false;  // disallow recursive call of tagfunc
  
  // Used instead of NUL to separate tag fields in the growarrays.
  #define TAG_SEP 0x02
  
  /// Jump to tag; handling of tag commands and tag stack
  ///
  /// *tag != NUL: ":tag {tag}", jump to new tag, add to tag stack
  ///
  /// type == DT_TAG:      ":tag [tag]", jump to newer position or same tag again
  /// type == DT_HELP:     like DT_TAG, but don't use regexp.
  /// type == DT_POP:      ":pop" or CTRL-T, jump to old position
  /// type == DT_NEXT:     jump to next match of same tag
  /// type == DT_PREV:     jump to previous match of same tag
  /// type == DT_FIRST:    jump to first match of same tag
  /// type == DT_LAST:     jump to last match of same tag
  /// type == DT_SELECT:   ":tselect [tag]", select tag from a list of all matches
  /// type == DT_JUMP:     ":tjump [tag]", jump to tag or select tag from a list
  /// type == DT_CSCOPE:   use cscope to find the tag
  /// type == DT_LTAG:     use location list for displaying tag matches
  /// type == DT_FREE:     free cached matches
  ///
  /// for cscope, returns true if we jumped to tag or aborted, false otherwise
  ///
  /// @param tag  tag (pattern) to jump to
  /// @param forceit  :ta with !
  /// @param verbose  print "tag not found" message
  bool do_tag(char_u *tag, int type, int count, int forceit, int verbose)
  {
    taggy_T *tagstack = curwin->w_tagstack;
    int tagstackidx = curwin->w_tagstackidx;
    int tagstacklen = curwin->w_tagstacklen;
    int cur_match = 0;
    int cur_fnum = curbuf->b_fnum;
    int oldtagstackidx = tagstackidx;
    int prevtagstackidx = tagstackidx;
    int prev_num_matches;
    int new_tag = false;
    int i;
    int ic;
    int no_regexp = false;
    int error_cur_match = 0;
    int save_pos = false;
    fmark_T saved_fmark;
    bool jumped_to_tag = false;
    int new_num_matches;
    char_u **new_matches;
    int use_tagstack;
    int skip_msg = false;
    char_u *buf_ffname = curbuf->b_ffname;  // name for priority computation
    int use_tfu = 1;
  
    // remember the matches for the last used tag
    static int num_matches = 0;
    static int max_num_matches = 0;             // limit used for match search
    static char_u **matches = NULL;
    static int flags;
  
    if (tfu_in_use) {
      emsg(_(recurmsg));
      return false;
    }
  
  #ifdef EXITFREE
    if (type == DT_FREE) {
      // remove the list of matches
      FreeWild(num_matches, matches);
      cs_free_tags();
      num_matches = 0;
      return false;
    }
  #endif
  
    if (type == DT_HELP) {
      type = DT_TAG;
      no_regexp = true;
      use_tfu = 0;
    }
  
    prev_num_matches = num_matches;
    free_string_option(nofile_fname);
    nofile_fname = NULL;
  
    clearpos(&saved_fmark.mark);          // shutup gcc 4.0
    saved_fmark.fnum = 0;
  
    // Don't add a tag to the tagstack if 'tagstack' has been reset.
    assert(tag != NULL);
    if (!p_tgst && *tag != NUL) {  // -V522
      use_tagstack = false;
      new_tag = true;
      if (g_do_tagpreview != 0) {
        tagstack_clear_entry(&ptag_entry);
        ptag_entry.tagname = vim_strsave(tag);
      }
    } else {
      if (g_do_tagpreview != 0) {
        use_tagstack = false;
      } else {
        use_tagstack = true;
      }
  
      // new pattern, add to the tag stack
      if (*tag != NUL
          && (type == DT_TAG || type == DT_SELECT || type == DT_JUMP
              || type == DT_LTAG
              || type == DT_CSCOPE
              )) {
        if (g_do_tagpreview != 0) {
          if (ptag_entry.tagname != NULL
              && STRCMP(ptag_entry.tagname, tag) == 0) {
            // Jumping to same tag: keep the current match, so that
            // the CursorHold autocommand example works.
            cur_match = ptag_entry.cur_match;
            cur_fnum = ptag_entry.cur_fnum;
          } else {
            tagstack_clear_entry(&ptag_entry);
            ptag_entry.tagname = vim_strsave(tag);
          }
        } else {
          /*
           * If the last used entry is not at the top, delete all tag
           * stack entries above it.
           */
          while (tagstackidx < tagstacklen) {
            tagstack_clear_entry(&tagstack[--tagstacklen]);
          }
  
          // if the tagstack is full: remove oldest entry
          if (++tagstacklen > TAGSTACKSIZE) {
            tagstacklen = TAGSTACKSIZE;
            tagstack_clear_entry(&tagstack[0]);
            for (i = 1; i < tagstacklen; i++) {
              tagstack[i - 1] = tagstack[i];
            }
            tagstackidx--;
          }
  
          // put the tag name in the tag stack
          tagstack[tagstackidx].tagname = vim_strsave(tag);
  
          curwin->w_tagstacklen = tagstacklen;
  
          save_pos = true;                // save the cursor position below
        }
  
        new_tag = true;
      } else {
        if (
            g_do_tagpreview != 0 ? ptag_entry.tagname == NULL :
            tagstacklen == 0) {
          // empty stack
          emsg(_(e_tagstack));
          goto end_do_tag;
        }
  
        if (type == DT_POP) {             // go to older position
          const bool old_KeyTyped = KeyTyped;
          if ((tagstackidx -= count) < 0) {
            emsg(_(bottommsg));
            if (tagstackidx + count == 0) {
              // We did [num]^T from the bottom of the stack
              tagstackidx = 0;
              goto end_do_tag;
            }
            // We weren't at the bottom of the stack, so jump all the
            // way to the bottom now.
            tagstackidx = 0;
          } else if (tagstackidx >= tagstacklen) {        // count == 0?
            emsg(_(topmsg));
            goto end_do_tag;
          }
  
          // Make a copy of the fmark, autocommands may invalidate the
          // tagstack before it's used.
          saved_fmark = tagstack[tagstackidx].fmark;
          if (saved_fmark.fnum != curbuf->b_fnum) {
            /*
             * Jump to other file. If this fails (e.g. because the
             * file was changed) keep original position in tag stack.
             */
            if (buflist_getfile(saved_fmark.fnum, saved_fmark.mark.lnum,
                                GETF_SETMARK, forceit) == FAIL) {
              tagstackidx = oldtagstackidx;              // back to old posn
              goto end_do_tag;
            }
            // A BufReadPost autocommand may jump to the '" mark, but
            // we don't what that here.
            curwin->w_cursor.lnum = saved_fmark.mark.lnum;
          } else {
            setpcmark();
            curwin->w_cursor.lnum = saved_fmark.mark.lnum;
          }
          curwin->w_cursor.col = saved_fmark.mark.col;
          curwin->w_set_curswant = true;
          check_cursor();
          if ((fdo_flags & FDO_TAG) && old_KeyTyped) {
            foldOpenCursor();
          }
  
          // remove the old list of matches
          FreeWild(num_matches, matches);
          cs_free_tags();
          num_matches = 0;
          tag_freematch();
          goto end_do_tag;
        }
  
        if (type == DT_TAG
            || type == DT_LTAG) {
          if (g_do_tagpreview != 0) {
            cur_match = ptag_entry.cur_match;
            cur_fnum = ptag_entry.cur_fnum;
          } else {
            // ":tag" (no argument): go to newer pattern
            save_pos = true;              // save the cursor position below
            if ((tagstackidx += count - 1) >= tagstacklen) {
              /*
               * Beyond the last one, just give an error message and
               * go to the last one.  Don't store the cursor
               * position.
               */
              tagstackidx = tagstacklen - 1;
              emsg(_(topmsg));
              save_pos = false;
            } else if (tagstackidx < 0) {         // must have been count == 0
              emsg(_(bottommsg));
              tagstackidx = 0;
              goto end_do_tag;
            }
            cur_match = tagstack[tagstackidx].cur_match;
            cur_fnum = tagstack[tagstackidx].cur_fnum;
          }
          new_tag = true;
        } else {                                // go to other matching tag
          // Save index for when selection is cancelled.
          prevtagstackidx = tagstackidx;
  
          if (g_do_tagpreview != 0) {
            cur_match = ptag_entry.cur_match;
            cur_fnum = ptag_entry.cur_fnum;
          } else {
            if (--tagstackidx < 0) {
              tagstackidx = 0;
            }
            cur_match = tagstack[tagstackidx].cur_match;
            cur_fnum = tagstack[tagstackidx].cur_fnum;
          }
          switch (type) {
          case DT_FIRST:
            cur_match = count - 1; break;
          case DT_SELECT:
          case DT_JUMP:
          case DT_CSCOPE:
          case DT_LAST:
            cur_match = MAXCOL - 1; break;
          case DT_NEXT:
            cur_match += count; break;
          case DT_PREV:
            cur_match -= count; break;
          }
          if (cur_match >= MAXCOL) {
            cur_match = MAXCOL - 1;
          } else if (cur_match < 0) {
            emsg(_("E425: Cannot go before first matching tag"));
            skip_msg = true;
            cur_match = 0;
            cur_fnum = curbuf->b_fnum;
          }
        }
      }
  
      if (g_do_tagpreview != 0) {
        if (type != DT_SELECT && type != DT_JUMP) {
          ptag_entry.cur_match = cur_match;
          ptag_entry.cur_fnum = cur_fnum;
        }
      } else {
        /*
         * For ":tag [arg]" or ":tselect" remember position before the jump.
         */
        saved_fmark = tagstack[tagstackidx].fmark;
        if (save_pos) {
          tagstack[tagstackidx].fmark.mark = curwin->w_cursor;
          tagstack[tagstackidx].fmark.fnum = curbuf->b_fnum;
        }
  
        // Curwin will change in the call to jumpto_tag() if ":stag" was
        // used or an autocommand jumps to another window; store value of
        // tagstackidx now.
        curwin->w_tagstackidx = tagstackidx;
        if (type != DT_SELECT && type != DT_JUMP) {
          curwin->w_tagstack[tagstackidx].cur_match = cur_match;
          curwin->w_tagstack[tagstackidx].cur_fnum = cur_fnum;
        }
      }
    }
  
    // When not using the current buffer get the name of buffer "cur_fnum".
    // Makes sure that the tag order doesn't change when using a remembered
    // position for "cur_match".
    if (cur_fnum != curbuf->b_fnum) {
      buf_T *buf = buflist_findnr(cur_fnum);
  
      if (buf != NULL) {
        buf_ffname = buf->b_ffname;
      }
    }
  
    /*
     * Repeat searching for tags, when a file has not been found.
     */
    for (;;) {
      int other_name;
      char_u *name;
  
      // When desired match not found yet, try to find it (and others).
      if (use_tagstack) {
        name = tagstack[tagstackidx].tagname;
      } else if (g_do_tagpreview != 0) {
        name = ptag_entry.tagname;
      } else {
        name = tag;
      }
      other_name = (tagmatchname == NULL || STRCMP(tagmatchname, name) != 0);
      if (new_tag
          || (cur_match >= num_matches && max_num_matches != MAXCOL)
          || other_name) {
        if (other_name) {
          xfree(tagmatchname);
          tagmatchname = vim_strsave(name);
        }
  
        if (type == DT_SELECT || type == DT_JUMP
            || type == DT_LTAG) {
          cur_match = MAXCOL - 1;
        }
        if (type == DT_TAG) {
          max_num_matches = MAXCOL;
        } else {
          max_num_matches = cur_match + 1;
        }
  
        // when the argument starts with '/', use it as a regexp
        if (!no_regexp && *name == '/') {
          flags = TAG_REGEXP;
          ++name;
        } else {
          flags = TAG_NOIC;
        }
  
        if (type == DT_CSCOPE) {
          flags = TAG_CSCOPE;
        }
        if (verbose) {
          flags |= TAG_VERBOSE;
        }
        if (!use_tfu) {
          flags |= TAG_NO_TAGFUNC;
        }
  
        if (find_tags(name, &new_num_matches, &new_matches, flags,
                      max_num_matches, buf_ffname) == OK
            && new_num_matches < max_num_matches) {
          max_num_matches = MAXCOL;  // If less than max_num_matches
                                     // found: all matches found.
        }
  
        // If there already were some matches for the same name, move them
        // to the start.  Avoids that the order changes when using
        // ":tnext" and jumping to another file.
        if (!new_tag && !other_name) {
          int j, k;
          int idx = 0;
          tagptrs_T tagp, tagp2;
  
          // Find the position of each old match in the new list.  Need
          // to use parse_match() to find the tag line.
          for (j = 0; j < num_matches; j++) {
            parse_match(matches[j], &tagp);
            for (i = idx; i < new_num_matches; ++i) {
              parse_match(new_matches[i], &tagp2);
              if (STRCMP(tagp.tagname, tagp2.tagname) == 0) {
                char_u *p = new_matches[i];
                for (k = i; k > idx; k--) {
                  new_matches[k] = new_matches[k - 1];
                }
                new_matches[idx++] = p;
                break;
              }
            }
          }
        }
        FreeWild(num_matches, matches);
        num_matches = new_num_matches;
        matches = new_matches;
      }
  
      if (num_matches <= 0) {
        if (verbose) {
          semsg(_("E426: tag not found: %s"), name);
        }
        g_do_tagpreview = 0;
      } else {
        bool ask_for_selection = false;
  
        if (type == DT_CSCOPE && num_matches > 1) {
          cs_print_tags();
          ask_for_selection = true;
        } else if (type == DT_TAG && *tag != NUL) {
          // If a count is supplied to the ":tag <name>" command, then
          // jump to count'th matching tag.
          cur_match = count > 0 ? count - 1 : 0;
        } else if (type == DT_SELECT || (type == DT_JUMP && num_matches > 1)) {
          print_tag_list(new_tag, use_tagstack, num_matches, matches);
          ask_for_selection = true;
        } else if (type == DT_LTAG) {
          if (add_llist_tags(tag, num_matches, matches) == FAIL) {
            goto end_do_tag;
          }
  
          cur_match = 0;                  // Jump to the first tag
        }
  
        if (ask_for_selection) {
          // Ask to select a tag from the list.
          i = prompt_for_number(NULL);
          if (i <= 0 || i > num_matches || got_int) {
            // no valid choice: don't change anything
            if (use_tagstack) {
              tagstack[tagstackidx].fmark = saved_fmark;
              tagstackidx = prevtagstackidx;
            }
            cs_free_tags();
            jumped_to_tag = true;
            break;
          }
          cur_match = i - 1;
        }
  
        if (cur_match >= num_matches) {
          // Avoid giving this error when a file wasn't found and we're
          // looking for a match in another file, which wasn't found.
          // There will be an emsg("file doesn't exist") below then.
          if ((type == DT_NEXT || type == DT_FIRST)
              && nofile_fname == NULL) {
            if (num_matches == 1) {
              emsg(_("E427: There is only one matching tag"));
            } else {
              emsg(_("E428: Cannot go beyond last matching tag"));
            }
            skip_msg = true;
          }
          cur_match = num_matches - 1;
        }
        if (use_tagstack) {
          tagptrs_T tagp2;
  
          tagstack[tagstackidx].cur_match = cur_match;
          tagstack[tagstackidx].cur_fnum = cur_fnum;
  
          // store user-provided data originating from tagfunc
          if (use_tfu && parse_match(matches[cur_match], &tagp2) == OK
              && tagp2.user_data) {
            XFREE_CLEAR(tagstack[tagstackidx].user_data);
            tagstack[tagstackidx].user_data = vim_strnsave(tagp2.user_data,
                                                           (size_t)(tagp2.user_data_end -
                                                                    tagp2.user_data));
          }
  
          tagstackidx++;
        } else if (g_do_tagpreview != 0) {
          ptag_entry.cur_match = cur_match;
          ptag_entry.cur_fnum = cur_fnum;
        }
  
        /*
         * Only when going to try the next match, report that the previous
         * file didn't exist.  Otherwise an emsg() is given below.
         */
        if (nofile_fname != NULL && error_cur_match != cur_match) {
          smsg(_("File \"%s\" does not exist"), nofile_fname);
        }
  
  
        ic = (matches[cur_match][0] & MT_IC_OFF);
        if (type != DT_TAG && type != DT_SELECT && type != DT_JUMP
            && type != DT_CSCOPE
            && (num_matches > 1 || ic)
            && !skip_msg) {
          // Give an indication of the number of matching tags
          snprintf((char *)IObuff, sizeof(IObuff), _("tag %d of %d%s"),
                   cur_match + 1,
                   num_matches,
                   max_num_matches != MAXCOL ? _(" or more") : "");
          if (ic) {
            STRCAT(IObuff, _("  Using tag with different case!"));
          }
          if ((num_matches > prev_num_matches || new_tag)
              && num_matches > 1) {
            if (ic) {
              msg_attr((const char *)IObuff, HL_ATTR(HLF_W));
            } else {
              msg((char *)IObuff);
            }
            msg_scroll = true;  // Don't overwrite this message.
          } else {
            give_warning(IObuff, ic);
          }
          if (ic && !msg_scrolled && msg_silent == 0) {
            ui_flush();
            os_delay(1007L, true);
          }
        }
  
        // Let the SwapExists event know what tag we are jumping to.
        vim_snprintf((char *)IObuff, IOSIZE, ":ta %s\r", name);
        set_vim_var_string(VV_SWAPCOMMAND, (char *)IObuff, -1);
  
        /*
         * Jump to the desired match.
         */
        i = jumpto_tag(matches[cur_match], forceit, type != DT_CSCOPE);
  
        set_vim_var_string(VV_SWAPCOMMAND, NULL, -1);
  
        if (i == NOTAGFILE) {
          // File not found: try again with another matching tag
          if ((type == DT_PREV && cur_match > 0)
              || ((type == DT_TAG || type == DT_NEXT
                   || type == DT_FIRST)
                  && (max_num_matches != MAXCOL
                      || cur_match < num_matches - 1))) {
            error_cur_match = cur_match;
            if (use_tagstack) {
              --tagstackidx;
            }
            if (type == DT_PREV) {
              --cur_match;
            } else {
              type = DT_NEXT;
              ++cur_match;
            }
            continue;
          }
          semsg(_("E429: File \"%s\" does not exist"), nofile_fname);
        } else {
          // We may have jumped to another window, check that
          // tagstackidx is still valid.
          if (use_tagstack && tagstackidx > curwin->w_tagstacklen) {
            tagstackidx = curwin->w_tagstackidx;
          }
          jumped_to_tag = true;
        }
      }
      break;
    }
  
  end_do_tag:
    // Only store the new index when using the tagstack and it's valid.
    if (use_tagstack && tagstackidx <= curwin->w_tagstacklen) {
      curwin->w_tagstackidx = tagstackidx;
    }
    postponed_split = 0;          // don't split next time
    g_do_tagpreview = 0;          // don't do tag preview next time
  
    return jumped_to_tag;
  }
  
  //
  // List all the matching tags.
  //
  static void print_tag_list(int new_tag, int use_tagstack, int num_matches, char_u **matches)
  {
    taggy_T *tagstack = curwin->w_tagstack;
    int tagstackidx = curwin->w_tagstackidx;
    int i;
    char_u *p;
    char_u *command_end;
    tagptrs_T tagp;
    int taglen;
    int attr;
  
    // Assume that the first match indicates how long the tags can
    // be, and align the file names to that.
    parse_match(matches[0], &tagp);
    taglen = (int)(tagp.tagname_end - tagp.tagname + 2);
    if (taglen < 18) {
      taglen = 18;
    }
    if (taglen > Columns - 25) {
      taglen = MAXCOL;
    }
    if (msg_col == 0) {
      msg_didout = false;     // overwrite previous message
    }
    msg_start();
    msg_puts_attr(_("  # pri kind tag"), HL_ATTR(HLF_T));
    msg_clr_eos();
    taglen_advance(taglen);
    msg_puts_attr(_("file\n"), HL_ATTR(HLF_T));
  
    for (i = 0; i < num_matches && !got_int; i++) {
      parse_match(matches[i], &tagp);
      if (!new_tag && (
                       (g_do_tagpreview != 0
                        && i == ptag_entry.cur_match)
                       || (use_tagstack
                           && i == tagstack[tagstackidx].cur_match))) {
        *IObuff = '>';
      } else {
        *IObuff = ' ';
      }
      vim_snprintf((char *)IObuff + 1, IOSIZE - 1,
                   "%2d %s ", i + 1,
                   mt_names[matches[i][0] & MT_MASK]);
      msg_puts((char *)IObuff);
      if (tagp.tagkind != NULL) {
        msg_outtrans_len(tagp.tagkind,
                         (int)(tagp.tagkind_end - tagp.tagkind));
      }
      msg_advance(13);
      msg_outtrans_len_attr(tagp.tagname,
                            (int)(tagp.tagname_end - tagp.tagname),
                            HL_ATTR(HLF_T));
      msg_putchar(' ');
      taglen_advance(taglen);
  
      // Find out the actual file name. If it is long, truncate
      // it and put "..." in the middle
      p = tag_full_fname(&tagp);
      if (p != NULL) {
        msg_outtrans_attr(p, HL_ATTR(HLF_D));
        XFREE_CLEAR(p);
      }
      if (msg_col > 0) {
        msg_putchar('\n');
      }
      if (got_int) {
        break;
      }
      msg_advance(15);
  
      // print any extra fields
      command_end = tagp.command_end;
      if (command_end != NULL) {
        p = command_end + 3;
        while (*p && *p != '\r' && *p != '\n') {
          while (*p == TAB) {
            p++;
          }
  
          // skip "file:" without a value (static tag)
          if (STRNCMP(p, "file:", 5) == 0 && ascii_isspace(p[5])) {
            p += 5;
            continue;
          }
          // skip "kind:<kind>" and "<kind>"
          if (p == tagp.tagkind
              || (p + 5 == tagp.tagkind
                  && STRNCMP(p, "kind:", 5) == 0)) {
            p = tagp.tagkind_end;
            continue;
          }
          // print all other extra fields
          attr = HL_ATTR(HLF_CM);
          while (*p && *p != '\r' && *p != '\n') {
            if (msg_col + ptr2cells(p) >= Columns) {
              msg_putchar('\n');
              if (got_int) {
                break;
              }
              msg_advance(15);
            }
            p = msg_outtrans_one(p, attr);
            if (*p == TAB) {
              msg_puts_attr(" ", attr);
              break;
            }
            if (*p == ':') {
              attr = 0;
            }
          }
        }
        if (msg_col > 15) {
          msg_putchar('\n');
          if (got_int) {
            break;
          }
          msg_advance(15);
        }
      } else {
        for (p = tagp.command;
             *p && *p != '\r' && *p != '\n';
             p++) {
        }
        command_end = p;
      }
  
      // Put the info (in several lines) at column 15.
      // Don't display "/^" and "?^".
      p = tagp.command;
      if (*p == '/' || *p == '?') {
        p++;
        if (*p == '^') {
          p++;
        }
      }
      // Remove leading whitespace from pattern
      while (p != command_end && ascii_isspace(*p)) {
        p++;
      }
  
      while (p != command_end) {
        if (msg_col + (*p == TAB ? 1 : ptr2cells(p)) > Columns) {
          msg_putchar('\n');
        }
        if (got_int) {
          break;
        }
        msg_advance(15);
  
        // skip backslash used for escaping a command char or
        // a backslash
        if (*p == '\\' && (*(p + 1) == *tagp.command
                           || *(p + 1) == '\\')) {
          p++;
        }
  
        if (*p == TAB) {
          msg_putchar(' ');
          p++;
        } else {
          p = msg_outtrans_one(p, 0);
        }
  
        // don't display the "$/;\"" and "$?;\""
        if (p == command_end - 2 && *p == '$'
            && *(p + 1) == *tagp.command) {
          break;
        }
        // don't display matching '/' or '?'
        if (p == command_end - 1 && *p == *tagp.command
            && (*p == '/' || *p == '?')) {
          break;
        }
      }
      if (msg_col) {
        msg_putchar('\n');
      }
      os_breakcheck();
    }
    if (got_int) {
      got_int = false;        // only stop the listing
    }
  }
  
  //
  // Add the matching tags to the location list for the current
  // window.
  //
  static int add_llist_tags(char_u *tag, int num_matches, char_u **matches)
  {
    list_T *list;
    char_u tag_name[128 + 1];
    char_u *fname;
    char_u *cmd;
    int i;
    char_u *p;
    tagptrs_T tagp;
  
    fname = xmalloc(MAXPATHL + 1);
    cmd = xmalloc(CMDBUFFSIZE + 1);
    list = tv_list_alloc(0);
  
    for (i = 0; i < num_matches; i++) {
      int len, cmd_len;
      long lnum;
      dict_T *dict;
  
      parse_match(matches[i], &tagp);
  
      // Save the tag name
      len = (int)(tagp.tagname_end - tagp.tagname);
      if (len > 128) {
        len = 128;
      }
      STRLCPY(tag_name, tagp.tagname, len + 1);
      tag_name[len] = NUL;
  
      // Save the tag file name
      p = tag_full_fname(&tagp);
      if (p == NULL) {
        continue;
      }
      STRLCPY(fname, p, MAXPATHL);
      XFREE_CLEAR(p);
  
      // Get the line number or the search pattern used to locate
      // the tag.
      lnum = 0;
      if (isdigit(*tagp.command)) {
        // Line number is used to locate the tag
        lnum = atol((char *)tagp.command);
      } else {
        char_u *cmd_start, *cmd_end;
  
        // Search pattern is used to locate the tag
  
        // Locate the end of the command
        cmd_start = tagp.command;
        cmd_end = tagp.command_end;
        if (cmd_end == NULL) {
          for (p = tagp.command;
               *p && *p != '\r' && *p != '\n'; p++) {
          }
          cmd_end = p;
        }
  
        // Now, cmd_end points to the character after the
        // command. Adjust it to point to the last
        // character of the command.
        cmd_end--;
  
        // Skip the '/' and '?' characters at the
        // beginning and end of the search pattern.
        if (*cmd_start == '/' || *cmd_start == '?') {
          cmd_start++;
        }
  
        if (*cmd_end == '/' || *cmd_end == '?') {
          cmd_end--;
        }
  
        len = 0;
        cmd[0] = NUL;
  
        // If "^" is present in the tag search pattern, then
        // copy it first.
        if (*cmd_start == '^') {
          STRCPY(cmd, "^");
          cmd_start++;
          len++;
        }
  
        // Precede the tag pattern with \V to make it very
        // nomagic.
        STRCAT(cmd, "\\V");
        len += 2;
  
        cmd_len = (int)(cmd_end - cmd_start + 1);
        if (cmd_len > (CMDBUFFSIZE - 5)) {
          cmd_len = CMDBUFFSIZE - 5;
        }
        snprintf((char *)cmd + len, (size_t)(CMDBUFFSIZE + 1 - len),
                 "%.*s", cmd_len, cmd_start);
        len += cmd_len;
  
        if (cmd[len - 1] == '$') {
          // Replace '$' at the end of the search pattern
          // with '\$'
          cmd[len - 1] = '\\';
          cmd[len] = '$';
          len++;
        }
  
        cmd[len] = NUL;
      }
  
      dict = tv_dict_alloc();
      tv_list_append_dict(list, dict);
  
      tv_dict_add_str(dict, S_LEN("text"), (const char *)tag_name);
      tv_dict_add_str(dict, S_LEN("filename"), (const char *)fname);
      tv_dict_add_nr(dict, S_LEN("lnum"), lnum);
      if (lnum == 0) {
        tv_dict_add_str(dict, S_LEN("pattern"), (const char *)cmd);
      }
    }
  
    vim_snprintf((char *)IObuff, IOSIZE, "ltag %s", tag);
    set_errorlist(curwin, list, ' ', IObuff, NULL);
  
    tv_list_free(list);
    XFREE_CLEAR(fname);
    XFREE_CLEAR(cmd);
  
    return OK;
  }
  
  /*
   * Free cached tags.
   */
  void tag_freematch(void)
  {
    XFREE_CLEAR(tagmatchname);
  }
  
  static void taglen_advance(int l)
  {
    if (l == MAXCOL) {
      msg_putchar('\n');
      msg_advance(24);
    } else {
      msg_advance(13 + l);
    }
  }
  
  /*
   * Print the tag stack
   */
  void do_tags(exarg_T *eap)
  {
    int i;
    char_u *name;
    taggy_T *tagstack = curwin->w_tagstack;
    int tagstackidx = curwin->w_tagstackidx;
    int tagstacklen = curwin->w_tagstacklen;
  
    // Highlight title
    msg_puts_title(_("\n  # TO tag         FROM line  in file/text"));
    for (i = 0; i < tagstacklen; ++i) {
      if (tagstack[i].tagname != NULL) {
        name = fm_getname(&(tagstack[i].fmark), 30);
        if (name == NULL) {           // file name not available
          continue;
        }
  
        msg_putchar('\n');
        vim_snprintf((char *)IObuff, IOSIZE, "%c%2d %2d %-15s %5ld  ",
                     i == tagstackidx ? '>' : ' ',
                     i + 1,
                     tagstack[i].cur_match + 1,
                     tagstack[i].tagname,
                     tagstack[i].fmark.mark.lnum);
        msg_outtrans(IObuff);
        msg_outtrans_attr(name, tagstack[i].fmark.fnum == curbuf->b_fnum
                          ? HL_ATTR(HLF_D) : 0);
        xfree(name);
      }
      ui_flush();                    // show one line at a time
    }
    if (tagstackidx == tagstacklen) {     // idx at top of stack
      msg_puts("\n>");
    }
  }
  
  
  /*
   * Compare two strings, for length "len", ignoring case the ASCII way.
   * return 0 for match, < 0 for smaller, > 0 for bigger
   * Make sure case is folded to uppercase in comparison (like for 'sort -f')
   */
  static int tag_strnicmp(char_u *s1, char_u *s2, size_t len)
  {
    int i;
  
    while (len > 0) {
      i = TOUPPER_ASC(*s1) - TOUPPER_ASC(*s2);
      if (i != 0) {
        return i;                         // this character different
      }
      if (*s1 == NUL) {
        break;                            // strings match until NUL
      }
      ++s1;
      ++s2;
      --len;
    }
    return 0;                             // strings match
  }
  
  
  /*
   * Extract info from the tag search pattern "pats->pat".
   */
  static void prepare_pats(pat_T *pats, int has_re)
  {
    pats->head = pats->pat;
    pats->headlen = pats->len;
    if (has_re) {
      // When the pattern starts with '^' or "\\<", binary searching can be
      // used (much faster).
      if (pats->pat[0] == '^') {
        pats->head = pats->pat + 1;
      } else if (pats->pat[0] == '\\' && pats->pat[1] == '<') {
        pats->head = pats->pat + 2;
      }
      if (pats->head == pats->pat) {
        pats->headlen = 0;
      } else {
        for (pats->headlen = 0; pats->head[pats->headlen] != NUL;
             ++pats->headlen) {
          if (vim_strchr((char_u *)(p_magic ? ".[~*\\$" : "\\$"),
                         pats->head[pats->headlen]) != NULL) {
            break;
          }
        }
      }
      if (p_tl != 0 && pats->headlen > p_tl) {    // adjust for 'taglength'
        pats->headlen = (int)p_tl;
      }
    }
  
    if (has_re) {
      pats->regmatch.regprog = vim_regcomp(pats->pat, p_magic ? RE_MAGIC : 0);
    } else {
      pats->regmatch.regprog = NULL;
    }
  }
  
  /// Call the user-defined function to generate a list of tags used by
  /// find_tags().
  ///
  /// Return OK if at least 1 tag has been successfully found,
  /// NOTDONE if the function returns v:null, and FAIL otherwise.
  ///
  /// @param pat  pattern supplied to the user-defined function
  /// @param ga  the tags will be placed here
  /// @param match_count  here the number of tags found will be placed
  /// @param flags  flags from find_tags (TAG_*)
  /// @param buf_ffname  name of buffer for priority
  static int find_tagfunc_tags(char_u *pat, garray_T *ga, int *match_count, int flags,
                               char_u *buf_ffname)
  {
    pos_T save_pos;
    list_T *taglist;
    int ntags = 0;
    int result = FAIL;
    typval_T args[4];
    typval_T rettv;
    char_u flagString[4];
    taggy_T *tag = &curwin->w_tagstack[curwin->w_tagstackidx];
  
    if (*curbuf->b_p_tfu == NUL) {
      return FAIL;
    }
  
    args[0].v_type = VAR_STRING;
    args[0].vval.v_string = pat;
    args[1].v_type = VAR_STRING;
    args[1].vval.v_string = flagString;
  
    // create 'info' dict argument
    dict_T *const d = tv_dict_alloc_lock(VAR_FIXED);
    if (tag->user_data != NULL) {
      tv_dict_add_str(d, S_LEN("user_data"), (const char *)tag->user_data);
    }
    if (buf_ffname != NULL) {
      tv_dict_add_str(d, S_LEN("buf_ffname"), (const char *)buf_ffname);
    }
  
    d->dv_refcount++;
    args[2].v_type = VAR_DICT;
    args[2].vval.v_dict = d;
  
    args[3].v_type = VAR_UNKNOWN;
  
    vim_snprintf((char *)flagString, sizeof(flagString),
                 "%s%s%s",
                 g_tag_at_cursor      ? "c": "",
                 flags & TAG_INS_COMP ? "i": "",
                 flags & TAG_REGEXP   ? "r": "");
  
    save_pos = curwin->w_cursor;
    result = call_vim_function(curbuf->b_p_tfu, 3, args, &rettv);
    curwin->w_cursor = save_pos;  // restore the cursor position
    d->dv_refcount--;
  
    if (result == FAIL) {
      return FAIL;
    }
    if (rettv.v_type == VAR_SPECIAL && rettv.vval.v_special == kSpecialVarNull) {
      tv_clear(&rettv);
      return NOTDONE;
    }
    if (rettv.v_type != VAR_LIST || !rettv.vval.v_list) {
      tv_clear(&rettv);
      emsg(_(tfu_inv_ret_msg));
      return FAIL;
    }
    taglist = rettv.vval.v_list;
  
    TV_LIST_ITER_CONST(taglist, li, {
      char_u *res_name;
      char_u *res_fname;
      char_u *res_cmd;
      char_u *res_kind;
      int has_extra = 0;
      int name_only = flags & TAG_NAMES;
  
      if (TV_LIST_ITEM_TV(li)->v_type != VAR_DICT) {
        emsg(_(tfu_inv_ret_msg));
        break;
      }
  
      size_t len = 2;
      res_name = NULL;
      res_fname = NULL;
      res_cmd = NULL;
      res_kind = NULL;
  
      TV_DICT_ITER(TV_LIST_ITEM_TV(li)->vval.v_dict, di, {
        const char_u *dict_key = di->di_key;
        typval_T *tv = &di->di_tv;
  
        if (tv->v_type != VAR_STRING || tv->vval.v_string == NULL) {
          continue;
        }
  
        len += STRLEN(tv->vval.v_string) + 1;   // Space for "\tVALUE"
        if (!STRCMP(dict_key, "name")) {
          res_name = tv->vval.v_string;
          continue;
        }
        if (!STRCMP(dict_key, "filename")) {
          res_fname = tv->vval.v_string;
          continue;
        }
        if (!STRCMP(dict_key, "cmd")) {
          res_cmd = tv->vval.v_string;
          continue;
        }
        has_extra = 1;
        if (!STRCMP(dict_key, "kind")) {
          res_kind = tv->vval.v_string;
          continue;
        }
        // Other elements will be stored as "\tKEY:VALUE"
        // Allocate space for the key and the colon
        len += STRLEN(dict_key) + 1;
      });
  
      if (has_extra) {
        len += 2;  // need space for ;"
      }
  
      if (!res_name || !res_fname || !res_cmd) {
        emsg(_(tfu_inv_ret_msg));
        break;
      }
  
      char_u *const mfp = name_only ? vim_strsave(res_name) : xmalloc(len + 2);
  
      if (!name_only) {
        char_u *p = mfp;
  
        *p++ = MT_GL_OTH + 1;   // mtt
        *p++ = TAG_SEP;     // no tag file name
  
        STRCPY(p, res_name);
        p += STRLEN(p);
  
        *p++ = TAB;
        STRCPY(p, res_fname);
        p += STRLEN(p);
  
        *p++ = TAB;
        STRCPY(p, res_cmd);
        p += STRLEN(p);
  
        if (has_extra) {
          STRCPY(p, ";\"");
          p += STRLEN(p);
  
          if (res_kind) {
            *p++ = TAB;
            STRCPY(p, res_kind);
            p += STRLEN(p);
          }
  
          TV_DICT_ITER(TV_LIST_ITEM_TV(li)->vval.v_dict, di, {
            const char_u *dict_key = di->di_key;
            typval_T *tv = &di->di_tv;
            if (tv->v_type != VAR_STRING || tv->vval.v_string == NULL) {
              continue;
            }
  
            if (!STRCMP(dict_key, "name")) {
              continue;
            }
            if (!STRCMP(dict_key, "filename")) {
              continue;
            }
            if (!STRCMP(dict_key, "cmd")) {
              continue;
            }
            if (!STRCMP(dict_key, "kind")) {
              continue;
            }
  
            *p++ = TAB;
            STRCPY(p, dict_key);
            p += STRLEN(p);
            STRCPY(p, ":");
            p += STRLEN(p);
            STRCPY(p, tv->vval.v_string);
            p += STRLEN(p);
          });
        }
      }
  
      // Add all matches because tagfunc should do filtering.
      ga_grow(ga, 1);
      ((char_u **)(ga->ga_data))[ga->ga_len++] = mfp;
      ntags++;
      result = OK;
    });
  
    tv_clear(&rettv);
  
    *match_count = ntags;
    return result;
  }
  
  /// find_tags() - search for tags in tags files
  ///
  /// Return FAIL if search completely failed (*num_matches will be 0, *matchesp
  /// will be NULL), OK otherwise.
  ///
  /// There is a priority in which type of tag is recognized.
  ///
  ///  6.  A static or global tag with a full matching tag for the current file.
  ///  5.  A global tag with a full matching tag for another file.
  ///  4.  A static tag with a full matching tag for another file.
  ///  3.  A static or global tag with an ignore-case matching tag for the
  ///      current file.
  ///  2.  A global tag with an ignore-case matching tag for another file.
  ///  1.  A static tag with an ignore-case matching tag for another file.
  ///
  /// Tags in an emacs-style tags file are always global.
  ///
  /// flags:
  /// TAG_HELP       only search for help tags
  /// TAG_NAMES      only return name of tag
  /// TAG_REGEXP     use "pat" as a regexp
  /// TAG_NOIC       don't always ignore case
  /// TAG_KEEP_LANG  keep language
  /// TAG_CSCOPE     use cscope results for tags
  /// TAG_NO_TAGFUNC do not call the 'tagfunc' function
  ///
  /// @param pat  pattern to search for
  /// @param num_matches  return: number of matches found
  /// @param matchesp  return: array of matches found
  /// @param mincount  MAXCOL: find all matches other: minimal number of matches */
  /// @param buf_ffname  name of buffer for priority
  int find_tags(char_u *pat, int *num_matches, char_u ***matchesp, int flags, int mincount,
                char_u *buf_ffname)
  {
    FILE *fp;
    char_u *lbuf;                     // line buffer
    int lbuf_size = LSIZE;                // length of lbuf
    char_u *tag_fname;                // name of tag file
    tagname_T tn;                         // info for get_tagfname()
    int first_file;                       // trying first tag file
    tagptrs_T tagp;
    bool did_open = false;                // did open a tag file
    bool stop_searching = false;          // stop when match found or error
    int retval = FAIL;                    // return value
    int is_static;                        // current tag line is static
    int is_current;                       // file name matches
    bool eof = false;                     // found end-of-file
    char_u *p;
    char_u *s;
    int i;
    int tag_file_sorted = NUL;            // !_TAG_FILE_SORTED value
    struct tag_search_info {      // Binary search file offsets
      off_T low_offset;           // offset for first char of first line that
                                  // could match
      off_T high_offset;          // offset of char after last line that could
                                  // match
      off_T curr_offset;          // Current file offset in search range
      off_T curr_offset_used;     // curr_offset used when skipping back
      off_T match_offset;         // Where the binary search found a tag
      int low_char;               // first char at low_offset
      int high_char;              // first char at high_offset
    } search_info;
    int tagcmp;
    off_T offset;
    int round;
    enum {
      TS_START,                   // at start of file
      TS_LINEAR,                  // linear searching forward, till EOF
      TS_BINARY,                // binary searching
      TS_SKIP_BACK,               // skipping backwards
      TS_STEP_FORWARD,  // stepping forwards
    }   state;                    // Current search state
  
    int cmplen;
    int match;                    // matches
    int match_no_ic = 0;          // matches with rm_ic == FALSE
    int match_re;                 // match with regexp
    int matchoff = 0;
    int save_emsg_off;
  
  
    char_u *mfp;
    garray_T ga_match[MT_COUNT];   // stores matches in sequence
    hashtab_T ht_match[MT_COUNT];  // stores matches by key
    hash_T hash = 0;
    int match_count = 0;                          // number of matches found
    char_u **matches;
    int mtt;
    int help_save;
    int help_pri = 0;
    char_u *help_lang_find = NULL;           // lang to be found
    char_u help_lang[3];                          // lang of current tags file
    char_u *saved_pat = NULL;                // copy of pat[]
    bool is_txt = false;
  
    pat_T orgpat;                         // holds unconverted pattern info
    vimconv_T vimconv;
  
    int findall = (mincount == MAXCOL || mincount == TAG_MANY);
    // find all matching tags
    bool sort_error = false;                      // tags file not sorted
    int linear;                                   // do a linear search
    bool sortic = false;                          // tag file sorted in nocase
    bool line_error = false;                      // syntax error
    int has_re = (flags & TAG_REGEXP);            // regexp used
    int help_only = (flags & TAG_HELP);
    int name_only = (flags & TAG_NAMES);
    int noic = (flags & TAG_NOIC);
    int get_it_again = FALSE;
    int use_cscope = (flags & TAG_CSCOPE);
    int verbose = (flags & TAG_VERBOSE);
    int use_tfu = ((flags & TAG_NO_TAGFUNC) == 0);
    int save_p_ic = p_ic;
  
    // Change the value of 'ignorecase' according to 'tagcase' for the
    // duration of this function.
    switch (curbuf->b_tc_flags ? curbuf->b_tc_flags : tc_flags) {
    case TC_FOLLOWIC:
      break;
    case TC_IGNORE:
      p_ic = true;
      break;
    case TC_MATCH:
      p_ic = false;
      break;
    case TC_FOLLOWSCS:
      p_ic = ignorecase(pat);
      break;
    case TC_SMART:
      p_ic = ignorecase_opt(pat, true, true);
      break;
    default:
      abort();
    }
  
    help_save = curbuf->b_help;
    orgpat.pat = pat;
    orgpat.regmatch.regprog = NULL;
    vimconv.vc_type = CONV_NONE;
  
    /*
     * Allocate memory for the buffers that are used
     */
    lbuf = xmalloc((size_t)lbuf_size);
    tag_fname = xmalloc(MAXPATHL + 1);
    for (mtt = 0; mtt < MT_COUNT; mtt++) {
      ga_init(&ga_match[mtt], sizeof(char_u *), 100);
      hash_init(&ht_match[mtt]);
    }
  
    STRCPY(tag_fname, "from cscope");             // for error messages
  
    /*
     * Initialize a few variables
     */
    if (help_only) {                              // want tags from help file
      curbuf->b_help = true;                      // will be restored later
    } else if (use_cscope) {
      // Make sure we don't mix help and cscope, confuses Coverity.
      help_only = false;
      curbuf->b_help = false;
    }
  
    orgpat.len = (int)STRLEN(pat);
    if (curbuf->b_help) {
      // When "@ab" is specified use only the "ab" language, otherwise
      // search all languages.
      if (orgpat.len > 3 && pat[orgpat.len - 3] == '@'
          && ASCII_ISALPHA(pat[orgpat.len - 2])
          && ASCII_ISALPHA(pat[orgpat.len - 1])) {
        saved_pat = vim_strnsave(pat, (size_t)orgpat.len - 3);
        help_lang_find = &pat[orgpat.len - 2];
        orgpat.pat = saved_pat;
        orgpat.len -= 3;
      }
    }
    if (p_tl != 0 && orgpat.len > p_tl) {         // adjust for 'taglength'
      orgpat.len = (int)p_tl;
    }
  
    save_emsg_off = emsg_off;
    emsg_off = TRUE;    // don't want error for invalid RE here
    prepare_pats(&orgpat, has_re);
    emsg_off = save_emsg_off;
    if (has_re && orgpat.regmatch.regprog == NULL) {
      goto findtag_end;
    }
  
    // This is only to avoid a compiler warning for using search_info
    // uninitialised.
    memset(&search_info, 0, 1);  // -V512
  
    if (*curbuf->b_p_tfu != NUL && use_tfu && !tfu_in_use) {
      tfu_in_use = true;
      retval = find_tagfunc_tags(pat, &ga_match[0], &match_count,
                                 flags, buf_ffname);
      tfu_in_use = false;
      if (retval != NOTDONE) {
        goto findtag_end;
      }
    }
  
    /*
     * When finding a specified number of matches, first try with matching
     * case, so binary search can be used, and try ignore-case matches in a
     * second loop.
     * When finding all matches, 'tagbsearch' is off, or there is no fixed
     * string to look for, ignore case right away to avoid going though the
     * tags files twice.
     * When the tag file is case-fold sorted, it is either one or the other.
     * Only ignore case when TAG_NOIC not used or 'ignorecase' set.
     */
    // Set a flag if the file extension is .txt
    if ((flags & TAG_KEEP_LANG)
        && help_lang_find == NULL
        && curbuf->b_fname != NULL
        && (i = (int)STRLEN(curbuf->b_fname)) > 4
        && STRICMP(curbuf->b_fname + i - 4, ".txt") == 0) {
      is_txt = true;
    }
    orgpat.regmatch.rm_ic = ((p_ic || !noic)
                             && (findall || orgpat.headlen == 0 || !p_tbs));
    for (round = 1; round <= 2; ++round) {
      linear = (orgpat.headlen == 0 || !p_tbs || round == 2);
  
      // Try tag file names from tags option one by one.
      for (first_file = true;
           use_cscope || get_tagfname(&tn, first_file, tag_fname) == OK;
           first_file = false) {
        // A file that doesn't exist is silently ignored.  Only when not a
        // single file is found, an error message is given (further on).
        if (use_cscope) {
          fp = NULL;  // avoid GCC warning
        } else {
          if (curbuf->b_help) {
            // Keep en if the file extension is .txt
            if (is_txt) {
              STRCPY(help_lang, "en");
            } else {
              // Prefer help tags according to 'helplang'.  Put the
              // two-letter language name in help_lang[].
              i = (int)STRLEN(tag_fname);
              if (i > 3 && tag_fname[i - 3] == '-') {
                STRCPY(help_lang, tag_fname + i - 2);
              } else {
                STRCPY(help_lang, "en");
              }
            }
  
            // When searching for a specific language skip tags files
            // for other languages.
            if (help_lang_find != NULL
                && STRICMP(help_lang, help_lang_find) != 0) {
              continue;
            }
  
            // For CTRL-] in a help file prefer a match with the same
            // language.
            if ((flags & TAG_KEEP_LANG)
                && help_lang_find == NULL
                && curbuf->b_fname != NULL
                && (i = (int)STRLEN(curbuf->b_fname)) > 4
                && curbuf->b_fname[i - 1] == 'x'
                && curbuf->b_fname[i - 4] == '.'
                && STRNICMP(curbuf->b_fname + i - 3, help_lang, 2) == 0) {
              help_pri = 0;
            } else {
              help_pri = 1;
              for (s = p_hlg; *s != NUL; ++s) {
                if (STRNICMP(s, help_lang, 2) == 0) {
                  break;
                }
                ++help_pri;
                if ((s = vim_strchr(s, ',')) == NULL) {
                  break;
                }
              }
              if (s == NULL || *s == NUL) {
                // Language not in 'helplang': use last, prefer English,
                // unless found already.
                help_pri++;
                if (STRICMP(help_lang, "en") != 0) {
                  ++help_pri;
                }
              }
            }
          }
  
          if ((fp = os_fopen((char *)tag_fname, "r")) == NULL) {
            continue;
          }
  
          if (p_verbose >= 5) {
            verbose_enter();
            smsg(_("Searching tags file %s"), tag_fname);
            verbose_leave();
          }
        }
        did_open = true;      // remember that we found at least one file
  
        state = TS_START;     // we're at the start of the file
  
        /*
         * Read and parse the lines in the file one by one
         */
        for (;;) {
          // check for CTRL-C typed, more often when jumping around
          if (state == TS_BINARY || state == TS_SKIP_BACK) {
            line_breakcheck();
          } else {
            fast_breakcheck();
          }
          if ((flags & TAG_INS_COMP)) {   // Double brackets for gcc
            ins_compl_check_keys(30, false);
          }
          if (got_int || compl_interrupted) {
            stop_searching = true;
            break;
          }
          // When mincount is TAG_MANY, stop when enough matches have been
          // found (for completion).
          if (mincount == TAG_MANY && match_count >= TAG_MANY) {
            stop_searching = true;
            retval = OK;
            break;
          }
          if (get_it_again) {
            goto line_read_in;
          }
          /*
           * For binary search: compute the next offset to use.
           */
          if (state == TS_BINARY) {
            offset = search_info.low_offset + ((search_info.high_offset
                                                - search_info.low_offset) / 2);
            if (offset == search_info.curr_offset) {
              break;              // End the binary search without a match.
            } else {
              search_info.curr_offset = offset;
            }
          } else if (state == TS_SKIP_BACK) {
            // Skipping back (after a match during binary search).
            search_info.curr_offset -= lbuf_size * 2;
            if (search_info.curr_offset < 0) {
              search_info.curr_offset = 0;
              rewind(fp);
              state = TS_STEP_FORWARD;
            }
          }
  
          /*
           * When jumping around in the file, first read a line to find the
           * start of the next line.
           */
          if (state == TS_BINARY || state == TS_SKIP_BACK) {
            // Adjust the search file offset to the correct position
            search_info.curr_offset_used = search_info.curr_offset;
            vim_fseek(fp, search_info.curr_offset, SEEK_SET);
            eof = vim_fgets(lbuf, lbuf_size, fp);
            if (!eof && search_info.curr_offset != 0) {
              // The explicit cast is to work around a bug in gcc 3.4.2
              // (repeated below).
              search_info.curr_offset = vim_ftell(fp);
              if (search_info.curr_offset == search_info.high_offset) {
                // oops, gone a bit too far; try from low offset
                vim_fseek(fp, search_info.low_offset, SEEK_SET);
                search_info.curr_offset = search_info.low_offset;
              }
              eof = vim_fgets(lbuf, lbuf_size, fp);
            }
            // skip empty and blank lines
            while (!eof && vim_isblankline(lbuf)) {
              search_info.curr_offset = vim_ftell(fp);
              eof = vim_fgets(lbuf, lbuf_size, fp);
            }
            if (eof) {
              // Hit end of file.  Skip backwards.
              state = TS_SKIP_BACK;
              search_info.match_offset = vim_ftell(fp);
              search_info.curr_offset = search_info.curr_offset_used;
              continue;
            }
          }
          /*
           * Not jumping around in the file: Read the next line.
           */
          else {
            // skip empty and blank lines
            do {
              eof = use_cscope
                ? cs_fgets(lbuf, lbuf_size)
                : vim_fgets(lbuf, lbuf_size, fp);
            } while (!eof && vim_isblankline(lbuf));
  
            if (eof) {
              break;                                  // end of file
            }
          }
  line_read_in:
  
          if (vimconv.vc_type != CONV_NONE) {
            char_u *conv_line;
            int len;
  
            // Convert every line.  Converting the pattern from 'enc' to
            // the tags file encoding doesn't work, because characters are
            // not recognized.
            conv_line = string_convert(&vimconv, lbuf, NULL);
            if (conv_line != NULL) {
              // Copy or swap lbuf and conv_line.
              len = (int)STRLEN(conv_line) + 1;
              if (len > lbuf_size) {
                xfree(lbuf);
                lbuf = conv_line;
                lbuf_size = len;
              } else {
                STRCPY(lbuf, conv_line);
                xfree(conv_line);
              }
            }
          }
  
  
          /*
           * When still at the start of the file, check for Emacs tags file
           * format, and for "not sorted" flag.
           */
          if (state == TS_START) {
            // The header ends when the line sorts below "!_TAG_".  When
            // case is folded lower case letters sort before "_".
            if (STRNCMP(lbuf, "!_TAG_", 6) <= 0
                || (lbuf[0] == '!' && ASCII_ISLOWER(lbuf[1]))) {
              if (STRNCMP(lbuf, "!_TAG_", 6) != 0) {
                // Non-header item before the header, e.g. "!" itself.
                goto parse_line;
              }
  
              /*
               * Read header line.
               */
              if (STRNCMP(lbuf, "!_TAG_FILE_SORTED\t", 18) == 0) {
                tag_file_sorted = lbuf[18];
              }
              if (STRNCMP(lbuf, "!_TAG_FILE_ENCODING\t", 20) == 0) {
                // Prepare to convert every line from the specified
                // encoding to 'encoding'.
                for (p = lbuf + 20; *p > ' ' && *p < 127; p++) {
                }
                *p = NUL;
                convert_setup(&vimconv, lbuf + 20, p_enc);
              }
  
              // Read the next line.  Unrecognized flags are ignored.
              continue;
            }
  
            // Headers ends.
  
            /*
             * When there is no tag head, or ignoring case, need to do a
             * linear search.
             * When no "!_TAG_" is found, default to binary search.  If
             * the tag file isn't sorted, the second loop will find it.
             * When "!_TAG_FILE_SORTED" found: start binary search if
             * flag set.
             * For cscope, it's always linear.
             */
            if (linear || use_cscope) {
              state = TS_LINEAR;
            } else if (tag_file_sorted == NUL) {
              state = TS_BINARY;
            } else if (tag_file_sorted == '1') {
              state = TS_BINARY;
            } else if (tag_file_sorted == '2') {
              state = TS_BINARY;
              sortic = true;
              orgpat.regmatch.rm_ic = (p_ic || !noic);
            } else {
              state = TS_LINEAR;
            }
  
            if (state == TS_BINARY && orgpat.regmatch.rm_ic && !sortic) {
              // Binary search won't work for ignoring case, use linear
              // search.
              linear = true;
              state = TS_LINEAR;
            }
  
            // When starting a binary search, get the size of the file and
            // compute the first offset.
            if (state == TS_BINARY) {
              if (vim_fseek(fp, 0, SEEK_END) != 0) {
                // can't seek, don't use binary search
                state = TS_LINEAR;
              } else {
                // Get the tag file size.
                // Don't use lseek(), it doesn't work
                // properly on MacOS Catalina.
                const off_T filesize = vim_ftell(fp);
                vim_fseek(fp, 0, SEEK_SET);
  
                // Calculate the first read offset in the file.  Start
                // the search in the middle of the file.
                search_info.low_offset = 0;
                search_info.low_char = 0;
                search_info.high_offset = filesize;
                search_info.curr_offset = 0;
                search_info.high_char = 0xff;
              }
              continue;
            }
          }
  
  parse_line:
          // When the line is too long the NUL will not be in the
          // last-but-one byte (see vim_fgets()).
          // Has been reported for Mozilla JS with extremely long names.
          // In that case we need to increase lbuf_size.
          if (lbuf[lbuf_size - 2] != NUL && !use_cscope) {
            lbuf_size *= 2;
            xfree(lbuf);
            lbuf = xmalloc((size_t)lbuf_size);
            // this will try the same thing again, make sure the offset is
            // different
            search_info.curr_offset = 0;
            continue;
          }
  
          // Figure out where the different strings are in this line.
          // For "normal" tags: Do a quick check if the tag matches.
          // This speeds up tag searching a lot!
          if (orgpat.headlen) {
            tagp.tagname = lbuf;
            tagp.tagname_end = vim_strchr(lbuf, TAB);
            if (tagp.tagname_end == NULL) {
              // Corrupted tag line.
              line_error = true;
              break;
            }
  
            /*
             * Skip this line if the length of the tag is different and
             * there is no regexp, or the tag is too short.
             */
            cmplen = (int)(tagp.tagname_end - tagp.tagname);
            if (p_tl != 0 && cmplen > p_tl) {         // adjust for 'taglength'
              cmplen = (int)p_tl;
            }
            if (has_re && orgpat.headlen < cmplen) {
              cmplen = orgpat.headlen;
            } else if (state == TS_LINEAR && orgpat.headlen != cmplen) {
              continue;
            }
  
            if (state == TS_BINARY) {
              /*
               * Simplistic check for unsorted tags file.
               */
              i = (int)tagp.tagname[0];
              if (sortic) {
                i = TOUPPER_ASC(tagp.tagname[0]);
              }
              if (i < search_info.low_char || i > search_info.high_char) {
                sort_error = true;
              }
  
              /*
               * Compare the current tag with the searched tag.
               */
              if (sortic) {
                tagcmp = tag_strnicmp(tagp.tagname, orgpat.head,
                                      (size_t)cmplen);
              } else {
                tagcmp = STRNCMP(tagp.tagname, orgpat.head, cmplen);
              }
  
              /*
               * A match with a shorter tag means to search forward.
               * A match with a longer tag means to search backward.
               */
              if (tagcmp == 0) {
                if (cmplen < orgpat.headlen) {
                  tagcmp = -1;
                } else if (cmplen > orgpat.headlen) {
                  tagcmp = 1;
                }
              }
  
              if (tagcmp == 0) {
                // We've located the tag, now skip back and search
                // forward until the first matching tag is found.
                state = TS_SKIP_BACK;
                search_info.match_offset = search_info.curr_offset;
                continue;
              }
              if (tagcmp < 0) {
                search_info.curr_offset = vim_ftell(fp);
                if (search_info.curr_offset < search_info.high_offset) {
                  search_info.low_offset = search_info.curr_offset;
                  if (sortic) {
                    search_info.low_char =
                      TOUPPER_ASC(tagp.tagname[0]);
                  } else {
                    search_info.low_char = tagp.tagname[0];
                  }
                  continue;
                }
              }
              if (tagcmp > 0
                  && search_info.curr_offset != search_info.high_offset) {
                search_info.high_offset = search_info.curr_offset;
                if (sortic) {
                  search_info.high_char =
                    TOUPPER_ASC(tagp.tagname[0]);
                } else {
                  search_info.high_char = tagp.tagname[0];
                }
                continue;
              }
  
              // No match yet and are at the end of the binary search.
              break;
            } else if (state == TS_SKIP_BACK) {
              assert(cmplen >= 0);
              if (mb_strnicmp(tagp.tagname, orgpat.head, (size_t)cmplen) != 0) {
                state = TS_STEP_FORWARD;
              } else {
                // Have to skip back more.  Restore the curr_offset
                // used, otherwise we get stuck at a long line.
                search_info.curr_offset = search_info.curr_offset_used;
              }
              continue;
            } else if (state == TS_STEP_FORWARD) {
              assert(cmplen >= 0);
              if (mb_strnicmp(tagp.tagname, orgpat.head, (size_t)cmplen) != 0) {
                if ((off_T)vim_ftell(fp) > search_info.match_offset) {
                  break;                  // past last match
                } else {
                  continue;               // before first match
                }
              }
            } else {
              // skip this match if it can't match
              assert(cmplen >= 0);
            }
            if (mb_strnicmp(tagp.tagname, orgpat.head, (size_t)cmplen) != 0) {
              continue;
            }
  
            // Can be a matching tag, isolate the file name and command.
            tagp.fname = tagp.tagname_end + 1;
            tagp.fname_end = vim_strchr(tagp.fname, TAB);
            tagp.command = tagp.fname_end + 1;
            if (tagp.fname_end == NULL) {
              i = FAIL;
            } else {
              i = OK;
            }
          } else {
            i = parse_tag_line(lbuf,
                               &tagp);
          }
          if (i == FAIL) {
            line_error = true;
            break;
          }
  
          /*
           * First try matching with the pattern literally (also when it is
           * a regexp).
           */
          cmplen = (int)(tagp.tagname_end - tagp.tagname);
          if (p_tl != 0 && cmplen > p_tl) {           // adjust for 'taglength'
            cmplen = (int)p_tl;
          }
          // if tag length does not match, don't try comparing
          if (orgpat.len != cmplen) {
            match = FALSE;
          } else {
            if (orgpat.regmatch.rm_ic) {
              assert(cmplen >= 0);
              match = mb_strnicmp(tagp.tagname, orgpat.pat, (size_t)cmplen) == 0;
              if (match) {
                match_no_ic = (STRNCMP(tagp.tagname, orgpat.pat,
                                       cmplen) == 0);
              }
            } else {
              match = (STRNCMP(tagp.tagname, orgpat.pat, cmplen) == 0);
            }
          }
  
          /*
           * Has a regexp: Also find tags matching regexp.
           */
          match_re = FALSE;
          if (!match && orgpat.regmatch.regprog != NULL) {
            int cc;
  
            cc = *tagp.tagname_end;
            *tagp.tagname_end = NUL;
            match = vim_regexec(&orgpat.regmatch, tagp.tagname, (colnr_T)0);
            if (match) {
              matchoff = (int)(orgpat.regmatch.startp[0] - tagp.tagname);
              if (orgpat.regmatch.rm_ic) {
                orgpat.regmatch.rm_ic = FALSE;
                match_no_ic = vim_regexec(&orgpat.regmatch, tagp.tagname,
                                          (colnr_T)0);
                orgpat.regmatch.rm_ic = TRUE;
              }
            }
            *tagp.tagname_end = (char_u)cc;
            match_re = true;
          }
  
          // If a match is found, add it to ht_match[] and ga_match[].
          if (match) {
            size_t len = 0;
  
            if (use_cscope) {
              // Don't change the ordering, always use the same table.
              mtt = MT_GL_OTH;
            } else {
              // Decide in which array to store this match.
              is_current = test_for_current(tagp.fname, tagp.fname_end, tag_fname,
                                            buf_ffname);
              is_static = test_for_static(&tagp);
  
              // Decide in which of the sixteen tables to store this match.
              if (is_static) {
                if (is_current) {
                  mtt = MT_ST_CUR;
                } else {
                  mtt = MT_ST_OTH;
                }
              } else {
                if (is_current) {
                  mtt = MT_GL_CUR;
                } else {
                  mtt = MT_GL_OTH;
                }
              }
              if (orgpat.regmatch.rm_ic && !match_no_ic) {
                mtt += MT_IC_OFF;
              }
              if (match_re) {
                mtt += MT_RE_OFF;
              }
            }
  
            // Add the found match in ht_match[mtt] and ga_match[mtt].
            // Store the info we need later, which depends on the kind of
            // tags we are dealing with.
            if (help_only) {
  #define ML_EXTRA 3
              // Append the help-heuristic number after the tagname, for
              // sorting it later.  The heuristic is ignored for
              // detecting duplicates.
              // The format is {tagname}@{lang}NUL{heuristic}NUL
              *tagp.tagname_end = NUL;
              len = (size_t)(tagp.tagname_end - tagp.tagname);
              mfp = xmalloc(sizeof(char_u) + len + 10 + ML_EXTRA + 1);
  
              p = mfp;
              STRCPY(p, tagp.tagname);
              p[len] = '@';
              STRCPY(p + len + 1, help_lang);
              snprintf((char *)p + len + 1 + ML_EXTRA, 10, "%06d",
                       help_heuristic(tagp.tagname,
                                      match_re ? matchoff : 0, !match_no_ic)
                       + help_pri);
  
              *tagp.tagname_end = TAB;
            } else if (name_only) {
              if (get_it_again) {
                char_u *temp_end = tagp.command;
  
                if (*temp_end == '/') {
                  while (*temp_end && *temp_end != '\r'
                         && *temp_end != '\n'
                         && *temp_end != '$') {
                    temp_end++;
                  }
                }
  
                if (tagp.command + 2 < temp_end) {
                  len = (size_t)(temp_end - tagp.command - 2);
                  mfp = xmalloc(len + 2);
                  STRLCPY(mfp, tagp.command + 2, len + 1);
                } else {
                  mfp = NULL;
                }
                get_it_again = false;
              } else {
                len = (size_t)(tagp.tagname_end - tagp.tagname);
                mfp = xmalloc(sizeof(char_u) + len + 1);
                STRLCPY(mfp, tagp.tagname, len + 1);
  
                // if wanted, re-read line to get long form too
                if (State & INSERT) {
                  get_it_again = p_sft;
                }
              }
            } else {
              size_t tag_fname_len = STRLEN(tag_fname);
              // Save the tag in a buffer.
              // Use 0x02 to separate fields (Can't use NUL, because the
              // hash key is terminated by NUL).
              // Emacs tag: <mtt><tag_fname><0x02><ebuf><0x02><lbuf><NUL>
              // other tag: <mtt><tag_fname><0x02><0x02><lbuf><NUL>
              // without Emacs tags: <mtt><tag_fname><0x02><lbuf><NUL>
              // Here <mtt> is the "mtt" value plus 1 to avoid NUL.
              len = tag_fname_len + STRLEN(lbuf) + 3;
              mfp = xmalloc(sizeof(char_u) + len + 1);
              p = mfp;
              p[0] = (char_u)(mtt + 1);
              STRCPY(p + 1, tag_fname);
  #ifdef BACKSLASH_IN_FILENAME
              // Ignore differences in slashes, avoid adding
              // both path/file and path\file.
              slash_adjust(p + 1);
  #endif
              p[tag_fname_len + 1] = TAG_SEP;
              s = p + 1 + tag_fname_len + 1;
              STRCPY(s, lbuf);
            }
  
            if (mfp != NULL) {
              hashitem_T *hi;
  
              // Don't add identical matches.
              // Add all cscope tags, because they are all listed.
              // "mfp" is used as a hash key, there is a NUL byte to end
              // the part that matters for comparing, more bytes may
              // follow after it.  E.g. help tags store the priority
              // after the NUL.
              if (use_cscope) {
                hash++;
              } else {
                hash = hash_hash(mfp);
              }
              hi = hash_lookup(&ht_match[mtt], (const char *)mfp,
                               STRLEN(mfp), hash);
              if (HASHITEM_EMPTY(hi)) {
                hash_add_item(&ht_match[mtt], hi, mfp, hash);
                ga_grow(&ga_match[mtt], 1);
                ((char_u **)(ga_match[mtt].ga_data))
                [ga_match[mtt].ga_len++] = mfp;
                match_count++;
              } else {
                // duplicate tag, drop it
                xfree(mfp);
              }
            }
          }
          if (use_cscope && eof) {
            break;
          }
        }   // forever
  
        if (line_error) {
          semsg(_("E431: Format error in tags file \"%s\""), tag_fname);
          if (!use_cscope) {
            semsg(_("Before byte %" PRId64), (int64_t)vim_ftell(fp));
          }
          stop_searching = true;
          line_error = false;
        }
  
        if (!use_cscope) {
          fclose(fp);
        }
        if (vimconv.vc_type != CONV_NONE) {
          convert_setup(&vimconv, NULL, NULL);
        }
  
        tag_file_sorted = NUL;
        if (sort_error) {
          semsg(_("E432: Tags file not sorted: %s"), tag_fname);
          sort_error = false;
        }
  
        /*
         * Stop searching if sufficient tags have been found.
         */
        if (match_count >= mincount) {
          retval = OK;
          stop_searching = true;
        }
  
        if (stop_searching || use_cscope) {
          break;
        }
      }   // end of for-each-file loop
  
      if (!use_cscope) {
        tagname_free(&tn);
      }
  
      // stop searching when already did a linear search, or when TAG_NOIC
      // used, and 'ignorecase' not set or already did case-ignore search
      if (stop_searching || linear || (!p_ic && noic) || orgpat.regmatch.rm_ic) {
        break;
      }
      if (use_cscope) {
        break;
      }
      orgpat.regmatch.rm_ic = TRUE;       // try another time while ignoring case
    }
  
    if (!stop_searching) {
      if (!did_open && verbose) {         // never opened any tags file
        emsg(_("E433: No tags file"));
      }
      retval = OK;                // It's OK even when no tag found
    }
  
  findtag_end:
    xfree(lbuf);
    vim_regfree(orgpat.regmatch.regprog);
    xfree(tag_fname);
  
    /*
     * Move the matches from the ga_match[] arrays into one list of
     * matches.  When retval == FAIL, free the matches.
     */
    if (retval == FAIL) {
      match_count = 0;
    }
  
    if (match_count > 0) {
      matches = xmalloc((size_t)match_count * sizeof(char_u *));
    } else {
      matches = NULL;
    }
    match_count = 0;
    for (mtt = 0; mtt < MT_COUNT; mtt++) {
      for (i = 0; i < ga_match[mtt].ga_len; i++) {
        mfp = ((char_u **)(ga_match[mtt].ga_data))[i];
        if (matches == NULL) {
          xfree(mfp);
        } else {
          if (!name_only) {
            // Change mtt back to zero-based.
            *mfp = (char_u)(*mfp - 1);
  
            // change the TAG_SEP back to NUL
            for (p = mfp + 1; *p != NUL; p++) {
              if (*p == TAG_SEP) {
                *p = NUL;
              }
            }
          }
          matches[match_count++] = mfp;
        }
      }
  
      ga_clear(&ga_match[mtt]);
      hash_clear(&ht_match[mtt]);
    }
  
    *matchesp = matches;
    *num_matches = match_count;
  
    curbuf->b_help = help_save;
    xfree(saved_pat);
  
    p_ic = save_p_ic;
  
    return retval;
  }
  
  static garray_T tag_fnames = GA_EMPTY_INIT_VALUE;
  
  /*
   * Callback function for finding all "tags" and "tags-??" files in
   * 'runtimepath' doc directories.
   */
  static void found_tagfile_cb(char_u *fname, void *cookie)
  {
    char_u *const tag_fname = vim_strsave(fname);
  
  #ifdef BACKSLASH_IN_FILENAME
    slash_adjust(tag_fname);
  #endif
    simplify_filename(tag_fname);
    GA_APPEND(char_u *, &tag_fnames, tag_fname);
  }
  
  #if defined(EXITFREE)
  void free_tag_stuff(void)
  {
    ga_clear_strings(&tag_fnames);
    do_tag(NULL, DT_FREE, 0, 0, 0);
    tag_freematch();
  
    tagstack_clear_entry(&ptag_entry);
  }
  
  #endif
  
  /// Get the next name of a tag file from the tag file list.
  /// For help files, use "tags" file only.
  ///
  /// @param tnp  holds status info
  /// @param first  TRUE when first file name is wanted
  /// @param buf  pointer to buffer of MAXPATHL chars
  ///
  /// @return  FAIL if no more tag file names, OK otherwise.
  int get_tagfname(tagname_T *tnp, int first, char_u *buf)
  {
    char_u *fname = NULL;
    char_u *r_ptr;
  
    if (first) {
      memset(tnp, 0, sizeof(tagname_T));
    }
  
    if (curbuf->b_help) {
      /*
       * For help files it's done in a completely different way:
       * Find "doc/tags" and "doc/tags-??" in all directories in
       * 'runtimepath'.
       */
      if (first) {
        ga_clear_strings(&tag_fnames);
        ga_init(&tag_fnames, (int)sizeof(char_u *), 10);
        do_in_runtimepath((char_u *)"doc/tags doc/tags-??", DIP_ALL,
                          found_tagfile_cb, NULL);
      }
  
      if (tnp->tn_hf_idx >= tag_fnames.ga_len) {
        // Not found in 'runtimepath', use 'helpfile', if it exists and
        // wasn't used yet, replacing "help.txt" with "tags".
        if (tnp->tn_hf_idx > tag_fnames.ga_len || *p_hf == NUL) {
          return FAIL;
        }
        ++tnp->tn_hf_idx;
        STRCPY(buf, p_hf);
        STRCPY(path_tail(buf), "tags");
  #ifdef BACKSLASH_IN_FILENAME
        slash_adjust(buf);
  #endif
        simplify_filename(buf);
  
        for (int i = 0; i < tag_fnames.ga_len; i++) {
          if (STRCMP(buf, ((char_u **)(tag_fnames.ga_data))[i]) == 0) {
            return FAIL;  // avoid duplicate file names
          }
        }
      } else {
        STRLCPY(buf, ((char_u **)(tag_fnames.ga_data))[tnp->tn_hf_idx++],
                MAXPATHL);
      }
      return OK;
    }
  
    if (first) {
      // Init.  We make a copy of 'tags', because autocommands may change
      // the value without notifying us.
      tnp->tn_tags = vim_strsave((*curbuf->b_p_tags != NUL)
          ? curbuf->b_p_tags : p_tags);
      tnp->tn_np = tnp->tn_tags;
    }
  
    /*
     * Loop until we have found a file name that can be used.
     * There are two states:
     * tnp->tn_did_filefind_init == FALSE: setup for next part in 'tags'.
     * tnp->tn_did_filefind_init == TRUE: find next file in this part.
     */
    for (;;) {
      if (tnp->tn_did_filefind_init) {
        fname = vim_findfile(tnp->tn_search_ctx);
        if (fname != NULL) {
          break;
        }
  
        tnp->tn_did_filefind_init = FALSE;
      } else {
        char_u *filename = NULL;
  
        // Stop when used all parts of 'tags'.
        if (*tnp->tn_np == NUL) {
          vim_findfile_cleanup(tnp->tn_search_ctx);
          tnp->tn_search_ctx = NULL;
          return FAIL;
        }
  
        /*
         * Copy next file name into buf.
         */
        buf[0] = NUL;
        (void)copy_option_part(&tnp->tn_np, buf, MAXPATHL - 1, " ,");
  
        r_ptr = vim_findfile_stopdir(buf);
        // move the filename one char forward and truncate the
        // filepath with a NUL
        filename = path_tail(buf);
        STRMOVE(filename + 1, filename);
        *filename++ = NUL;
  
        tnp->tn_search_ctx = vim_findfile_init(buf, filename,
                                               r_ptr, 100,
                                               FALSE,                   // don't free visited list
                                               FINDFILE_FILE,           // we search for a file
                                               tnp->tn_search_ctx, TRUE, curbuf->b_ffname);
        if (tnp->tn_search_ctx != NULL) {
          tnp->tn_did_filefind_init = TRUE;
        }
      }
    }
  
    STRCPY(buf, fname);
    xfree(fname);
    return OK;
  }
  
  /*
   * Free the contents of a tagname_T that was filled by get_tagfname().
   */
  void tagname_free(tagname_T *tnp)
  {
    xfree(tnp->tn_tags);
    vim_findfile_cleanup(tnp->tn_search_ctx);
    tnp->tn_search_ctx = NULL;
    ga_clear_strings(&tag_fnames);
  }
  
  /// Parse one line from the tags file. Find start/end of tag name, start/end of
  /// file name and start of search pattern.
  ///
  /// If is_etag is TRUE, tagp->fname and tagp->fname_end are not set.
  ///
  /// @param lbuf  line to be parsed
  ///
  /// @return  FAIL if there is a format error in this line, OK otherwise.
  static int parse_tag_line(char_u *lbuf, tagptrs_T *tagp)
  {
    char_u *p;
  
    // Isolate the tagname, from lbuf up to the first white
    tagp->tagname = lbuf;
    p = vim_strchr(lbuf, TAB);
    if (p == NULL) {
      return FAIL;
    }
    tagp->tagname_end = p;
  
    // Isolate file name, from first to second white space
    if (*p != NUL) {
      ++p;
    }
    tagp->fname = p;
    p = vim_strchr(p, TAB);
    if (p == NULL) {
      return FAIL;
    }
    tagp->fname_end = p;
  
    // find start of search command, after second white space
    if (*p != NUL) {
      ++p;
    }
    if (*p == NUL) {
      return FAIL;
    }
    tagp->command = p;
  
    return OK;
  }
  
  /*
   * Check if tagname is a static tag
   *
   * Static tags produced by the older ctags program have the format:
   *      'file:tag  file  /pattern'.
   * This is only recognized when both occurrence of 'file' are the same, to
   * avoid recognizing "string::string" or ":exit".
   *
   * Static tags produced by the new ctags program have the format:
   *      'tag  file  /pattern/;"<Tab>file:'          "
   *
   * Return TRUE if it is a static tag and adjust *tagname to the real tag.
   * Return FALSE if it is not a static tag.
   */
  static bool test_for_static(tagptrs_T *tagp)
  {
    char_u *p;
  
    // Check for new style static tag ":...<Tab>file:[<Tab>...]"
    p = tagp->command;
    while ((p = vim_strchr(p, '\t')) != NULL) {
      ++p;
      if (STRNCMP(p, "file:", 5) == 0) {
        return TRUE;
      }
    }
  
    return FALSE;
  }
  
  // Returns the length of a matching tag line.
  static size_t matching_line_len(const char_u *const lbuf)
  {
    const char_u *p = lbuf + 1;
  
    // does the same thing as parse_match()
    p += STRLEN(p) + 1;
    return (size_t)(p - lbuf) + STRLEN(p);
  }
  
  /// Parse a line from a matching tag.  Does not change the line itself.
  ///
  /// The line that we get looks like this:
  /// Emacs tag: <mtt><tag_fname><NUL><ebuf><NUL><lbuf>
  /// other tag: <mtt><tag_fname><NUL><NUL><lbuf>
  /// without Emacs tags: <mtt><tag_fname><NUL><lbuf>
  ///
  /// @param lbuf  input: matching line
  /// @param tagp  output: pointers into the line
  ///
  /// @return  OK or FAIL.
  static int parse_match(char_u *lbuf, tagptrs_T *tagp)
  {
    int retval;
    char_u *p;
    char_u *pc, *pt;
  
    tagp->tag_fname = lbuf + 1;
    lbuf += STRLEN(tagp->tag_fname) + 2;
  
    // Find search pattern and the file name for non-etags.
    retval = parse_tag_line(lbuf,
                            tagp);
  
    tagp->tagkind = NULL;
    tagp->user_data = NULL;
    tagp->tagline = 0;
    tagp->command_end = NULL;
  
    if (retval == OK) {
      // Try to find a kind field: "kind:<kind>" or just "<kind>"
      p = tagp->command;
      if (find_extra(&p) == OK) {
        tagp->command_end = p;
        if (p > tagp->command && p[-1] == '|') {
          tagp->command_end = p - 1;  // drop trailing bar
        }
        p += 2;  // skip ";\""
        if (*p++ == TAB) {
          // Accept ASCII alphabetic kind characters and any multi-byte
          // character.
          while (ASCII_ISALPHA(*p) || utfc_ptr2len(p) > 1) {
            if (STRNCMP(p, "kind:", 5) == 0) {
              tagp->tagkind = p + 5;
            } else if (STRNCMP(p, "user_data:", 10) == 0) {
              tagp->user_data = p + 10;
            } else if (STRNCMP(p, "line:", 5) == 0) {
              tagp->tagline = atoi((char *)p + 5);
            }
            if (tagp->tagkind != NULL && tagp->user_data != NULL) {
              break;
            }
  
            pc = vim_strchr(p, ':');
            pt = vim_strchr(p, '\t');
            if (pc == NULL || (pt != NULL && pc > pt)) {
              tagp->tagkind = p;
            }
            if (pt == NULL) {
              break;
            }
            p = pt;
            MB_PTR_ADV(p);
          }
        }
      }
      if (tagp->tagkind != NULL) {
        for (p = tagp->tagkind;
             *p && *p != '\t' && *p != '\r' && *p != '\n';
             MB_PTR_ADV(p)) {
        }
        tagp->tagkind_end = p;
      }
      if (tagp->user_data != NULL) {
        for (p = tagp->user_data;
             *p && *p != '\t' && *p != '\r' && *p != '\n';
             MB_PTR_ADV(p)) {
        }
        tagp->user_data_end = p;
      }
    }
    return retval;
  }
  
  /*
   * Find out the actual file name of a tag.  Concatenate the tags file name
   * with the matching tag file name.
   * Returns an allocated string.
   */
  static char_u *tag_full_fname(tagptrs_T *tagp)
  {
    int c = *tagp->fname_end;
    *tagp->fname_end = NUL;
    char_u *fullname = expand_tag_fname(tagp->fname, tagp->tag_fname, false);
    *tagp->fname_end = (char_u)c;
  
    return fullname;
  }
  
  /// Jump to a tag that has been found in one of the tag files
  ///
  /// @param lbuf_arg  line from the tags file for this tag
  /// @param forceit  :ta with !
  /// @param keep_help  keep help flag (FALSE for cscope)
  ///
  /// @return  OK for success, NOTAGFILE when file not found, FAIL otherwise.
  static int jumpto_tag(const char_u *lbuf_arg, int forceit, int keep_help)
  {
    int save_magic;
    bool save_p_ws;
    int save_p_scs, save_p_ic;
    linenr_T save_lnum;
    char_u *str;
    char_u *pbuf;                    // search pattern buffer
    char_u *pbuf_end;
    char_u *tofree_fname = NULL;
    char_u *fname;
    tagptrs_T tagp;
    int retval = FAIL;
    int getfile_result = GETFILE_UNUSED;
    int search_options;
    win_T *curwin_save = NULL;
    char_u *full_fname = NULL;
    const bool old_KeyTyped = KeyTyped;       // getting the file may reset it
    const int l_g_do_tagpreview = g_do_tagpreview;
    const size_t len = matching_line_len(lbuf_arg) + 1;
    char_u *lbuf = xmalloc(len);
    memmove(lbuf, lbuf_arg, len);
  
    pbuf = xmalloc(LSIZE);
  
    // parse the match line into the tagp structure
    if (parse_match(lbuf, &tagp) == FAIL) {
      tagp.fname_end = NULL;
      goto erret;
    }
  
    // truncate the file name, so it can be used as a string
    *tagp.fname_end = NUL;
    fname = tagp.fname;
  
    // copy the command to pbuf[], remove trailing CR/NL
    str = tagp.command;
    for (pbuf_end = pbuf; *str && *str != '\n' && *str != '\r';) {
      *pbuf_end++ = *str++;
      if (pbuf_end - pbuf + 1 >= LSIZE) {
        break;
      }
    }
    *pbuf_end = NUL;
  
    {
      /*
       * Remove the "<Tab>fieldname:value" stuff; we don't need it here.
       */
      str = pbuf;
      if (find_extra(&str) == OK) {
        pbuf_end = str;
        *pbuf_end = NUL;
      }
    }
  
    /*
     * Expand file name, when needed (for environment variables).
     * If 'tagrelative' option set, may change file name.
     */
    fname = expand_tag_fname(fname, tagp.tag_fname, true);
    tofree_fname = fname;         // free() it later
  
    /*
     * Check if the file with the tag exists before abandoning the current
     * file.  Also accept a file name for which there is a matching BufReadCmd
     * autocommand event (e.g., http://sys/file).
     */
    if (!os_path_exists(fname)
        && !has_autocmd(EVENT_BUFREADCMD, fname,
                        NULL)) {
      retval = NOTAGFILE;
      xfree(nofile_fname);
      nofile_fname = vim_strsave(fname);
      goto erret;
    }
  
    ++RedrawingDisabled;
  
  
    if (l_g_do_tagpreview != 0) {
      postponed_split = 0;        // don't split again below
      curwin_save = curwin;       // Save current window
  
      /*
       * If we are reusing a window, we may change dir when
       * entering it (autocommands) so turn the tag filename
       * into a fullpath
       */
      if (!curwin->w_p_pvw) {
        full_fname = (char_u *)FullName_save((char *)fname, FALSE);
        fname = full_fname;
  
        /*
         * Make the preview window the current window.
         * Open a preview window when needed.
         */
        prepare_tagpreview(true);
      }
    }
  
    // If it was a CTRL-W CTRL-] command split window now.  For ":tab tag"
    // open a new tab page.
    if (postponed_split && (swb_flags & (SWB_USEOPEN | SWB_USETAB))) {
      buf_T *const existing_buf = buflist_findname_exp(fname);
  
      if (existing_buf != NULL) {
        const win_T *wp = NULL;
  
        if (swb_flags & SWB_USEOPEN) {
          wp = buf_jump_open_win(existing_buf);
        }
  
        // If 'switchbuf' contains "usetab": jump to first window in any tab
        // page containing "existing_buf" if one exists
        if (wp == NULL && (swb_flags & SWB_USETAB)) {
          wp = buf_jump_open_tab(existing_buf);
        }
  
        // We've switched to the buffer, the usual loading of the file must
        // be skipped.
        if (wp != NULL) {
          getfile_result = GETFILE_SAME_FILE;
        }
      }
    }
    if (getfile_result == GETFILE_UNUSED
        && (postponed_split || cmdmod.tab != 0)) {
      if (win_split(postponed_split > 0 ? postponed_split : 0,
                    postponed_split_flags) == FAIL) {
        RedrawingDisabled--;
        goto erret;
      }
      RESET_BINDING(curwin);
    }
  
    if (keep_help) {
      // A :ta from a help file will keep the b_help flag set.  For ":ptag"
      // we need to use the flag from the window where we came from.
      if (l_g_do_tagpreview != 0) {
        keep_help_flag = curwin_save->w_buffer->b_help;
      } else {
        keep_help_flag = curbuf->b_help;
      }
    }
  
    if (getfile_result == GETFILE_UNUSED) {
      // Careful: getfile() may trigger autocommands and call jumpto_tag()
      // recursively.
      getfile_result = getfile(0, fname, NULL, true, (linenr_T)0, forceit);
    }
    keep_help_flag = false;
  
    if (GETFILE_SUCCESS(getfile_result)) {    // got to the right file
      curwin->w_set_curswant = true;
      postponed_split = 0;
  
      save_magic = p_magic;
      p_magic = false;            // always execute with 'nomagic'
      // Save value of no_hlsearch, jumping to a tag is not a real search
      const bool save_no_hlsearch = no_hlsearch;
  
      /*
       * If 'cpoptions' contains 't', store the search pattern for the "n"
       * command.  If 'cpoptions' does not contain 't', the search pattern
       * is not stored.
       */
      if (vim_strchr(p_cpo, CPO_TAGPAT) != NULL) {
        search_options = 0;
      } else {
        search_options = SEARCH_KEEP;
      }
  
      /*
       * If the command is a search, try here.
       *
       * Reset 'smartcase' for the search, since the search pattern was not
       * typed by the user.
       * Only use do_search() when there is a full search command, without
       * anything following.
       */
      str = pbuf;
      if (pbuf[0] == '/' || pbuf[0] == '?') {
        str = skip_regexp(pbuf + 1, pbuf[0], FALSE, NULL) + 1;
      }
      if (str > pbuf_end - 1) {   // search command with nothing following
        save_p_ws = p_ws;
        save_p_ic = p_ic;
        save_p_scs = p_scs;
        p_ws = true;              // need 'wrapscan' for backward searches
        p_ic = FALSE;             // don't ignore case now
        p_scs = FALSE;
        save_lnum = curwin->w_cursor.lnum;
        if (tagp.tagline > 0) {
          // start search before line from "line:" field
          curwin->w_cursor.lnum = tagp.tagline - 1;
        } else {
          // start search before first line
          curwin->w_cursor.lnum = 0;
        }
        if (do_search(NULL, pbuf[0], pbuf[0], pbuf + 1, (long)1,
                      search_options, NULL)) {
          retval = OK;
        } else {
          int found = 1;
          int cc;
  
          /*
           * try again, ignore case now
           */
          p_ic = true;
          if (!do_search(NULL, pbuf[0], pbuf[0], pbuf + 1, (long)1,
                         search_options, NULL)) {
            // Failed to find pattern, take a guess: "^func  ("
            found = 2;
            (void)test_for_static(&tagp);
            cc = *tagp.tagname_end;
            *tagp.tagname_end = NUL;
            snprintf((char *)pbuf, LSIZE, "^%s\\s\\*(", tagp.tagname);
            if (!do_search(NULL, '/', '/', pbuf, (long)1, search_options, NULL)) {
              // Guess again: "^char * \<func  ("
              snprintf((char *)pbuf, LSIZE, "^\\[#a-zA-Z_]\\.\\*\\<%s\\s\\*(",
                       tagp.tagname);
              if (!do_search(NULL, '/', '/', pbuf, (long)1,
                             search_options, NULL)) {
                found = 0;
              }
            }
            *tagp.tagname_end = (char_u)cc;
          }
          if (found == 0) {
            emsg(_("E434: Can't find tag pattern"));
            curwin->w_cursor.lnum = save_lnum;
          } else {
            /*
             * Only give a message when really guessed, not when 'ic'
             * is set and match found while ignoring case.
             */
            if (found == 2 || !save_p_ic) {
              msg(_("E435: Couldn't find tag, just guessing!"));
              if (!msg_scrolled && msg_silent == 0) {
                ui_flush();
                os_delay(1010L, true);
              }
            }
            retval = OK;
          }
        }
        p_ws = save_p_ws;
        p_ic = save_p_ic;  // -V519
        p_scs = save_p_scs;
  
        // A search command may have positioned the cursor beyond the end
        // of the line.  May need to correct that here.
        check_cursor();
      } else {
        const int save_secure = secure;
  
        // Setup the sandbox for executing the command from the tags file.
        secure = 1;
        sandbox++;
        curwin->w_cursor.lnum = 1;  // start command in line 1
        do_cmdline_cmd((char *)pbuf);
        retval = OK;
  
        // When the command has done something that is not allowed make sure
        // the error message can be seen.
        if (secure == 2) {
          wait_return(true);
        }
        secure = save_secure;
        sandbox--;
      }
  
      p_magic = save_magic;
      // restore no_hlsearch when keeping the old search pattern
      if (search_options) {
        set_no_hlsearch(save_no_hlsearch);
      }
  
      // Return OK if jumped to another file (at least we found the file!).
      if (getfile_result == GETFILE_OPEN_OTHER) {
        retval = OK;
      }
  
      if (retval == OK) {
        /*
         * For a help buffer: Put the cursor line at the top of the window,
         * the help subject will be below it.
         */
        if (curbuf->b_help) {
          set_topline(curwin, curwin->w_cursor.lnum);
        }
        if ((fdo_flags & FDO_TAG) && old_KeyTyped) {
          foldOpenCursor();
        }
      }
  
      if (l_g_do_tagpreview != 0
          && curwin != curwin_save && win_valid(curwin_save)) {
        // Return cursor to where we were
        validate_cursor();
        redraw_later(curwin, VALID);
        win_enter(curwin_save, true);
      }
  
      RedrawingDisabled--;
    } else {
      RedrawingDisabled--;
      if (postponed_split) {              // close the window
        win_close(curwin, false, false);
        postponed_split = 0;
      }
    }
  
  erret:
    g_do_tagpreview = 0;  // For next time
    xfree(lbuf);
    xfree(pbuf);
    xfree(tofree_fname);
    xfree(full_fname);
  
    return retval;
  }
  
  // If "expand" is true, expand wildcards in fname.
  // If 'tagrelative' option set, change fname (name of file containing tag)
  // according to tag_fname (name of tag file containing fname).
  // Returns a pointer to allocated memory.
  static char_u *expand_tag_fname(char_u *fname, char_u *const tag_fname, const bool expand)
  {
    char_u *p;
    char_u *expanded_fname = NULL;
    expand_T xpc;
  
    /*
     * Expand file name (for environment variables) when needed.
     */
    if (expand && path_has_wildcard(fname)) {
      ExpandInit(&xpc);
      xpc.xp_context = EXPAND_FILES;
      expanded_fname = ExpandOne(&xpc, fname, NULL,
                                 WILD_LIST_NOTFOUND|WILD_SILENT, WILD_EXPAND_FREE);
      if (expanded_fname != NULL) {
        fname = expanded_fname;
      }
    }
  
    char_u *retval;
    if ((p_tr || curbuf->b_help)
        && !vim_isAbsName(fname)
        && (p = path_tail(tag_fname)) != tag_fname) {
      retval = xmalloc(MAXPATHL);
      STRCPY(retval, tag_fname);
      STRLCPY(retval + (p - tag_fname), fname,
              MAXPATHL - (p - tag_fname));
      /*
       * Translate names like "src/a/../b/file.c" into "src/b/file.c".
       */
      simplify_filename(retval);
    } else {
      retval = vim_strsave(fname);
    }
  
    xfree(expanded_fname);
  
    return retval;
  }
  
  /*
   * Check if we have a tag for the buffer with name "buf_ffname".
   * This is a bit slow, because of the full path compare in path_full_compare().
   * Return TRUE if tag for file "fname" if tag file "tag_fname" is for current
   * file.
   */
  static int test_for_current(char_u *fname, char_u *fname_end, char_u *tag_fname, char_u *buf_ffname)
  {
    int c;
    int retval = FALSE;
    char_u *fullname;
  
    if (buf_ffname != NULL) {     // if the buffer has a name
      {
        c = *fname_end;
        *fname_end = NUL;
      }
      fullname = expand_tag_fname(fname, tag_fname, true);
      retval = (path_full_compare(fullname, buf_ffname, true, true)
                & kEqualFiles);
      xfree(fullname);
      *fname_end = (char_u)c;
    }
  
    return retval;
  }
  
  /*
   * Find the end of the tagaddress.
   * Return OK if ";\"" is following, FAIL otherwise.
   */
  static int find_extra(char_u **pp)
  {
    char_u *str = *pp;
    char_u first_char = **pp;
  
    // Repeat for addresses separated with ';'
    for (;;) {
      if (ascii_isdigit(*str)) {
        str = skipdigits(str + 1);
      } else if (*str == '/' || *str == '?') {
        str = skip_regexp(str + 1, *str, false, NULL);
        if (*str != first_char) {
          str = NULL;
        } else {
          str++;
        }
      } else {
        // not a line number or search string, look for terminator.
        str = (char_u *)strstr((char *)str, "|;\"");
        if (str != NULL) {
          str++;
          break;
        }
      }
      if (str == NULL || *str != ';'
          || !(ascii_isdigit(str[1]) || str[1] == '/' || str[1] == '?')) {
        break;
      }
      str++;  // skip ';'
      first_char = *str;
    }
  
    if (str != NULL && STRNCMP(str, ";\"", 2) == 0) {
      *pp = str;
      return OK;
    }
    return FAIL;
  }
  
  //
  // Free a single entry in a tag stack
  //
  static void tagstack_clear_entry(taggy_T *item)
  {
    XFREE_CLEAR(item->tagname);
    XFREE_CLEAR(item->user_data);
  }
  
  /// @param tagnames  expand tag names
  int expand_tags(int tagnames, char_u *pat, int *num_file, char_u ***file)
  {
    int i;
    int extra_flag;
    char_u *name_buf;
    size_t name_buf_size = 100;
    tagptrs_T t_p;
    int ret;
  
    name_buf = xmalloc(name_buf_size);
  
    if (tagnames) {
      extra_flag = TAG_NAMES;
    } else {
      extra_flag = 0;
    }
    if (pat[0] == '/') {
      ret = find_tags(pat + 1, num_file, file,
                      TAG_REGEXP | extra_flag | TAG_VERBOSE | TAG_NO_TAGFUNC,
                      TAG_MANY, curbuf->b_ffname);
    } else {
      ret = find_tags(pat, num_file, file,
                      TAG_REGEXP | extra_flag | TAG_VERBOSE | TAG_NO_TAGFUNC | TAG_NOIC,
                      TAG_MANY, curbuf->b_ffname);
    }
    if (ret == OK && !tagnames) {
      // Reorganize the tags for display and matching as strings of:
      // "<tagname>\0<kind>\0<filename>\0"
      for (i = 0; i < *num_file; i++) {
        size_t len;
  
        parse_match((*file)[i], &t_p);
        len = (size_t)(t_p.tagname_end - t_p.tagname);
        if (len > name_buf_size - 3) {
          char_u *buf;
  
          name_buf_size = len + 3;
          buf = xrealloc(name_buf, name_buf_size);
          name_buf = buf;
        }
  
        memmove(name_buf, t_p.tagname, len);
        name_buf[len++] = 0;
        name_buf[len++] = (t_p.tagkind != NULL && *t_p.tagkind)
                                                     ? *t_p.tagkind : 'f';
        name_buf[len++] = 0;
        memmove((*file)[i] + len, t_p.fname, (size_t)(t_p.fname_end - t_p.fname));
        (*file)[i][len + (size_t)(t_p.fname_end - t_p.fname)] = 0;
        memmove((*file)[i], name_buf, len);
      }
    }
    xfree(name_buf);
    return ret;
  }
  
  
  /// Add a tag field to the dictionary "dict".
  /// Return OK or FAIL.
  ///
  /// @param start  start of the value
  /// @param end  after the value; can be NULL
  static int add_tag_field(dict_T *dict, const char *field_name, const char_u *start,
                           const char_u *end)
    FUNC_ATTR_NONNULL_ARG(1, 2)
  {
    int len = 0;
    int retval;
  
    // Check that the field name doesn't exist yet.
    if (tv_dict_find(dict, field_name, -1) != NULL) {
      if (p_verbose > 0) {
        verbose_enter();
        smsg(_("Duplicate field name: %s"), field_name);
        verbose_leave();
      }
      return FAIL;
    }
    char_u *buf = xmalloc(MAXPATHL);
    if (start != NULL) {
      if (end == NULL) {
        end = start + STRLEN(start);
        while (end > start && (end[-1] == '\r' || end[-1] == '\n')) {
          --end;
        }
      }
      len = (int)(end - start);
      if (len > MAXPATHL - 1) {
        len = MAXPATHL - 1;
      }
      STRLCPY(buf, start, len + 1);
    }
    buf[len] = NUL;
    retval = tv_dict_add_str(dict, field_name, STRLEN(field_name),
                             (const char *)buf);
    xfree(buf);
    return retval;
  }
  
  /// Add the tags matching the specified pattern "pat" to the list "list"
  /// as a dictionary. Use "buf_fname" for priority, unless NULL.
  int get_tags(list_T *list, char_u *pat, char_u *buf_fname)
  {
    int num_matches, i, ret;
    char_u **matches;
    char_u *full_fname;
    dict_T *dict;
    tagptrs_T tp;
    bool is_static;
  
    ret = find_tags(pat, &num_matches, &matches,
                    TAG_REGEXP | TAG_NOIC, MAXCOL, buf_fname);
    if (ret == OK && num_matches > 0) {
      for (i = 0; i < num_matches; ++i) {
        int parse_result = parse_match(matches[i], &tp);
  
        // Avoid an unused variable warning in release builds.
        (void)parse_result;
        assert(parse_result == OK);
  
        is_static = test_for_static(&tp);
  
        // Skip pseudo-tag lines.
        if (STRNCMP(tp.tagname, "!_TAG_", 6) == 0) {
          xfree(matches[i]);
          continue;
        }
  
        dict = tv_dict_alloc();
        tv_list_append_dict(list, dict);
  
        full_fname = tag_full_fname(&tp);
        if (add_tag_field(dict, "name", tp.tagname, tp.tagname_end) == FAIL
            || add_tag_field(dict, "filename", full_fname, NULL) == FAIL
            || add_tag_field(dict, "cmd", tp.command, tp.command_end) == FAIL
            || add_tag_field(dict, "kind", tp.tagkind,
                             tp.tagkind ? tp.tagkind_end : NULL) == FAIL
            || tv_dict_add_nr(dict, S_LEN("static"), is_static) == FAIL) {
          ret = FAIL;
        }
  
        xfree(full_fname);
  
        if (tp.command_end != NULL) {
          for (char_u *p = tp.command_end + 3;
               *p != NUL && *p != '\n' && *p != '\r';
               MB_PTR_ADV(p)) {
            if (p == tp.tagkind
                || (p + 5 == tp.tagkind && STRNCMP(p, "kind:", 5) == 0)) {
              // skip "kind:<kind>" and "<kind>"
              p = tp.tagkind_end - 1;
            } else if (STRNCMP(p, "file:", 5) == 0) {
              // skip "file:" (static tag)
              p += 4;
            } else if (!ascii_iswhite(*p)) {
              char_u *s, *n;
              int len;
  
              // Add extra field as a dict entry.  Fields are
              // separated by Tabs.
              n = p;
              while (*p != NUL && *p >= ' ' && *p < 127 && *p != ':') {
                ++p;
              }
              len = (int)(p - n);
              if (*p == ':' && len > 0) {
                s = ++p;
                while (*p != NUL && *p >= ' ') {
                  ++p;
                }
                n[len] = NUL;
                if (add_tag_field(dict, (char *)n, s, p) == FAIL) {
                  ret = FAIL;
                }
                n[len] = ':';
              } else {
                // Skip field without colon.
                while (*p != NUL && *p >= ' ') {
                  ++p;
                }
              }
              if (*p == NUL) {
                break;
              }
            }
          }
        }
  
        xfree(matches[i]);
      }
      xfree(matches);
    }
    return ret;
  }
  
  // Return information about 'tag' in dict 'retdict'.
  static void get_tag_details(taggy_T *tag, dict_T *retdict)
  {
    list_T *pos;
    fmark_T *fmark;
  
    tv_dict_add_str(retdict, S_LEN("tagname"), (const char *)tag->tagname);
    tv_dict_add_nr(retdict, S_LEN("matchnr"), tag->cur_match + 1);
    tv_dict_add_nr(retdict, S_LEN("bufnr"), tag->cur_fnum);
    if (tag->user_data) {
      tv_dict_add_str(retdict, S_LEN("user_data"), (const char *)tag->user_data);
    }
  
    pos = tv_list_alloc(4);
    tv_dict_add_list(retdict, S_LEN("from"), pos);
  
    fmark = &tag->fmark;
    tv_list_append_number(pos,
                          (varnumber_T)(fmark->fnum != -1 ? fmark->fnum : 0));
    tv_list_append_number(pos, (varnumber_T)fmark->mark.lnum);
    tv_list_append_number(pos, (varnumber_T)(fmark->mark.col == MAXCOL
                                             ? MAXCOL : fmark->mark.col + 1));
    tv_list_append_number(pos, (varnumber_T)fmark->mark.coladd);
  }
  
  // Return the tag stack entries of the specified window 'wp' in dictionary
  // 'retdict'.
  void get_tagstack(win_T *wp, dict_T *retdict)
  {
    list_T *l;
    int i;
    dict_T *d;
  
    tv_dict_add_nr(retdict, S_LEN("length"), wp->w_tagstacklen);
    tv_dict_add_nr(retdict, S_LEN("curidx"), wp->w_tagstackidx + 1);
    l = tv_list_alloc(2);
    tv_dict_add_list(retdict, S_LEN("items"), l);
  
    for (i = 0; i < wp->w_tagstacklen; i++) {
      d = tv_dict_alloc();
      tv_list_append_dict(l, d);
      get_tag_details(&wp->w_tagstack[i], d);
    }
  }
  
  // Free all the entries in the tag stack of the specified window
  static void tagstack_clear(win_T *wp)
  {
    // Free the current tag stack
    for (int i = 0; i < wp->w_tagstacklen; i++) {
      tagstack_clear_entry(&wp->w_tagstack[i]);
    }
    wp->w_tagstacklen = 0;
    wp->w_tagstackidx = 0;
  }
  
  // Remove the oldest entry from the tag stack and shift the rest of
  // the entries to free up the top of the stack.
  static void tagstack_shift(win_T *wp)
  {
    taggy_T *tagstack = wp->w_tagstack;
    tagstack_clear_entry(&tagstack[0]);
    for (int i = 1; i < wp->w_tagstacklen; i++) {
      tagstack[i - 1] = tagstack[i];
    }
    wp->w_tagstacklen--;
  }
  
  // Push a new item to the tag stack
  static void tagstack_push_item(win_T *wp, char_u *tagname, int cur_fnum, int cur_match, pos_T mark,
                                 int fnum, char_u *user_data)
  {
    taggy_T *tagstack = wp->w_tagstack;
    int idx = wp->w_tagstacklen;  // top of the stack
  
    // if the tagstack is full: remove the oldest entry
    if (idx >= TAGSTACKSIZE) {
      tagstack_shift(wp);
      idx = TAGSTACKSIZE - 1;
    }
  
    wp->w_tagstacklen++;
    tagstack[idx].tagname = tagname;
    tagstack[idx].cur_fnum = cur_fnum;
    tagstack[idx].cur_match = cur_match;
    if (tagstack[idx].cur_match < 0) {
      tagstack[idx].cur_match = 0;
    }
    tagstack[idx].fmark.mark = mark;
    tagstack[idx].fmark.fnum = fnum;
    tagstack[idx].user_data = user_data;
  }
  
  // Add a list of items to the tag stack in the specified window
  static void tagstack_push_items(win_T *wp, list_T *l)
  {
    listitem_T *li;
    dictitem_T *di;
    dict_T *itemdict;
    char_u *tagname;
    pos_T mark;
    int fnum;
  
    // Add one entry at a time to the tag stack
    for (li = tv_list_first(l); li != NULL; li = TV_LIST_ITEM_NEXT(l, li)) {
      if (TV_LIST_ITEM_TV(li)->v_type != VAR_DICT
          || TV_LIST_ITEM_TV(li)->vval.v_dict == NULL) {
        continue;  // Skip non-dict items
      }
      itemdict = TV_LIST_ITEM_TV(li)->vval.v_dict;
  
      // parse 'from' for the cursor position before the tag jump
      if ((di = tv_dict_find(itemdict, "from", -1)) == NULL) {
        continue;
      }
      if (list2fpos(&di->di_tv, &mark, &fnum, NULL, false) != OK) {
        continue;
      }
      if ((tagname = (char_u *)tv_dict_get_string(itemdict, "tagname", true))
          == NULL) {
        continue;
      }
  
      if (mark.col > 0) {
        mark.col--;
      }
      tagstack_push_item(wp,
                         tagname,
                         (int)tv_dict_get_number(itemdict, "bufnr"),
                         (int)tv_dict_get_number(itemdict, "matchnr") - 1,
                         mark, fnum,
                         (char_u *)tv_dict_get_string(itemdict, "user_data", true));
    }
  }
  
  // Set the current index in the tag stack. Valid values are between 0
  // and the stack length (inclusive).
  static void tagstack_set_curidx(win_T *wp, int curidx)
  {
    wp->w_tagstackidx = curidx;
    if (wp->w_tagstackidx < 0) {  // sanity check
      wp->w_tagstackidx = 0;
    }
    if (wp->w_tagstackidx > wp->w_tagstacklen) {
      wp->w_tagstackidx = wp->w_tagstacklen;
    }
  }
  
  // Set the tag stack entries of the specified window.
  // 'action' is set to one of:
  //    'a' for append
  //    'r' for replace
  //    't' for truncate
  int set_tagstack(win_T *wp, const dict_T *d, int action)
    FUNC_ATTR_NONNULL_ARG(1)
  {
    dictitem_T *di;
    list_T *l = NULL;
  
    // not allowed to alter the tag stack entries from inside tagfunc
    if (tfu_in_use) {
      emsg(_(recurmsg));
      return FAIL;
    }
  
    if ((di = tv_dict_find(d, "items", -1)) != NULL) {
      if (di->di_tv.v_type != VAR_LIST) {
        emsg(_(e_listreq));
        return FAIL;
      }
      l = di->di_tv.vval.v_list;
    }
  
    if ((di = tv_dict_find(d, "curidx", -1)) != NULL) {
      tagstack_set_curidx(wp, (int)tv_get_number(&di->di_tv) - 1);
    }
    if (action == 't') {  // truncate the stack
      taggy_T *const tagstack = wp->w_tagstack;
      const int tagstackidx = wp->w_tagstackidx;
      int tagstacklen = wp->w_tagstacklen;
      // delete all the tag stack entries above the current entry
      while (tagstackidx < tagstacklen) {
        tagstack_clear_entry(&tagstack[--tagstacklen]);
      }
      wp->w_tagstacklen = tagstacklen;
    }
  
    if (l != NULL) {
      if (action == 'r') {  // replace the stack
        tagstack_clear(wp);
      }
  
      tagstack_push_items(wp, l);
      // set the current index after the last entry
      wp->w_tagstackidx = wp->w_tagstacklen;
    }
  
    return OK;
  }
  