bin/less/brac.c

   1 /*
   2  * Copyright (C) 1984-2012  Mark Nudelman
   3  * Modified for use with illumos by Garrett D'Amore.
   4  * Copyright 2014 Garrett D'Amore <garrett@damore.org>
   5  *
   6  * You may distribute under the terms of either the GNU General Public
   7  * License or the Less License, as specified in the README file.
   8  *
   9  * For more information, see the README file.
  10  */
  11
  12 /*
  13  * Routines to perform bracket matching functions.
  14  */
  15
  16 #include "less.h"
  17 #include "position.h"
  18
  19 /*
  20  * Try to match the n-th open bracket
  21  *  which appears in the top displayed line (forwdir),
  22  * or the n-th close bracket
  23  *  which appears in the bottom displayed line (!forwdir).
  24  * The characters which serve as "open bracket" and
  25  * "close bracket" are given.
  26  */
  27 void
  28 match_brac(int obrac, int cbrac, int forwdir, int n)
  29 {
  30         int c;
  31         int nest;
  32         off_t pos;
  33         int (*chget)(void);
  34
  35         /*
  36          * Seek to the line containing the open bracket.
  37          * This is either the top or bottom line on the screen,
  38          * depending on the type of bracket.
  39          */
  40         pos = position((forwdir) ? TOP : BOTTOM);
  41         if (pos == -1 || ch_seek(pos)) {
  42                 if (forwdir)
  43                         error("Nothing in top line", NULL);
  44                 else
  45                         error("Nothing in bottom line", NULL);
  46                 return;
  47         }
  48
  49         /*
  50          * Look thru the line to find the open bracket to match.
  51          */
  52         do {
  53                 if ((c = ch_forw_get()) == '\n' || c == EOI) {
  54                         if (forwdir)
  55                                 error("No bracket in top line", NULL);
  56                         else
  57                                 error("No bracket in bottom line", NULL);
  58                         return;
  59                 }
  60         } while (c != obrac || --n > 0);
  61
  62         /*
  63          * Position the file just "after" the open bracket
  64          * (in the direction in which we will be searching).
  65          * If searching forward, we are already after the bracket.
  66          * If searching backward, skip back over the open bracket.
  67          */
  68         if (!forwdir)
  69                 (void) ch_back_get();
  70
  71         /*
  72          * Search the file for the matching bracket.
  73          */
  74         chget = (forwdir) ? ch_forw_get : ch_back_get;
  75         nest = 0;
  76         while ((c = (*chget)()) != EOI) {
  77                 if (c == obrac) {
  78                         nest++;
  79                 } else if (c == cbrac && --nest < 0) {
  80                         /*
  81                          * Found the matching bracket.
  82                          * If searching backward, put it on the top line.
  83                          * If searching forward, put it on the bottom line.
  84                          */
  85                         jump_line_loc(ch_tell(), forwdir ? -1 : 1);
  86                         return;
  87                 }
  88         }
  89         error("No matching bracket", NULL);
  90 }