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