Annotation of src/usr.bin/less/brac.c, Revision 1.4
1.1 etheisen 1: /*
1.4 ! millert 2: * Copyright (C) 1984-2002 Mark Nudelman
1.1 etheisen 3: *
1.4 ! millert 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.
1.1 etheisen 6: *
1.4 ! millert 7: * For more information about less, or for information on how to
! 8: * contact the author, see the README file.
1.1 etheisen 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)
1.4 ! millert 29: register int obrac;
! 30: register int cbrac;
1.1 etheisen 31: int forwdir;
32: int n;
33: {
1.4 ! millert 34: register int c;
! 35: register int nest;
1.1 etheisen 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: }