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1 /*
2 * Copyright (C) 1984-2008 Mark Nudelman
3 *
4 * You may distribute under the terms of either the GNU General Public
5 * License or the Less License, as specified in the README file.
6 *
7 * For more information about less, or for information on how to
8 * contact the author, see the README file.
9 */
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 public void
28 match_brac(obrac, cbrac, forwdir, n)
29 register int obrac;
30 register int cbrac;
31 int forwdir;
32 int n;
33 {
34 register int c;
35 register int nest;
36 POSITION pos;
37 int (*chget)();
38
39 extern int ch_forw_get(), ch_back_get();
40
41 /*
42 * Seek to the line containing the open bracket.
43 * This is either the top or bottom line on the screen,
44 * depending on the type of bracket.
45 */
46 pos = position((forwdir) ? TOP : BOTTOM);
47 if (pos == NULL_POSITION || ch_seek(pos))
48 {
49 if (forwdir)
50 error("Nothing in top line", NULL_PARG);
51 else
52 error("Nothing in bottom line", NULL_PARG);
53 return;
54 }
55
56 /*
57 * Look thru the line to find the open bracket to match.
58 */
59 do
60 {
61 if ((c = ch_forw_get()) == '\n' || c == EOI)
62 {
63 if (forwdir)
64 error("No bracket in top line", NULL_PARG);
65 else
66 error("No bracket in bottom line", NULL_PARG);
67 return;
68 }
69 } while (c != obrac || --n > 0);
70
71 /*
72 * Position the file just "after" the open bracket
73 * (in the direction in which we will be searching).
74 * If searching forward, we are already after the bracket.
75 * If searching backward, skip back over the open bracket.
76 */
77 if (!forwdir)
78 (void) ch_back_get();
79
80 /*
81 * Search the file for the matching bracket.
82 */
83 chget = (forwdir) ? ch_forw_get : ch_back_get;
84 nest = 0;
85 while ((c = (*chget)()) != EOI)
86 {
87 if (c == obrac)
88 nest++;
89 else if (c == cbrac && --nest < 0)
90 {
91 /*
92 * Found the matching bracket.
93 * If searching backward, put it on the top line.
94 * If searching forward, put it on the bottom line.
95 */
96 jump_line_loc(ch_tell(), forwdir ? -1 : 1);
97 return;
98 }
99 }
100 error("No matching bracket", NULL_PARG);
101 }