src/editor/wordproc.c

   1 /* wordproc.c - word-processor mode for the editor: does dynamic
   2                 paragraph formatting.
   3    Copyright (C) 1996 Paul Sheer
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 2 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program; if not, write to the Free Software
  17    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  18    02110-1301, USA.
  19  */
  20
  21 /** \file
  22  *  \brief Source: word-processor mode for the editor: does dynamic paragraph formatting
  23  *  \author Paul Sheer
  24  *  \date 1996
  25  */
  26
  27 #include <config.h>
  28
  29 #include <stdio.h>
  30 #include <stdarg.h>
  31 #include <sys/types.h>
  32 #include <unistd.h>
  33 #include <string.h>
  34 #include <ctype.h>
  35 #include <errno.h>
  36 #include <sys/stat.h>
  37
  38 #include <stdlib.h>
  39
  40 #include "lib/global.h"
  41
  42 #include "edit-impl.h"
  43 #include "edit-widget.h"
  44 #include "src/main.h"   /* option_tab_spacing */
  45
  46 #define tab_width option_tab_spacing
  47
  48 #define NO_FORMAT_CHARS_START "-+*\\,.;:&>"
  49 #define FONT_MEAN_WIDTH 1
  50
  51 static long
  52 line_start (WEdit *edit, long line)
  53 {
  54     long p, l;
  55
  56     l = edit->curs_line;
  57     p = edit->curs1;
  58
  59     if (line < l)
  60         p = edit_move_backward (edit, p, l - line);
  61     else if (line > l)
  62         p = edit_move_forward (edit, p, line - l, 0);
  63
  64     p = edit_bol (edit, p);
  65     while (strchr ("\t ", edit_get_byte (edit, p)))
  66         p++;
  67     return p;
  68 }
  69
  70 static int bad_line_start (WEdit * edit, long p)
  71 {
  72     int c;
  73     c = edit_get_byte (edit, p);
  74     if (c == '.') {             /* `...' is acceptable */
  75         if (edit_get_byte (edit, p + 1) == '.')
  76             if (edit_get_byte (edit, p + 2) == '.')
  77                 return 0;
  78         return 1;
  79     }
  80     if (c == '-') {
  81         if (edit_get_byte (edit, p + 1) == '-')
  82             if (edit_get_byte (edit, p + 2) == '-')
  83                 return 0;       /* `---' is acceptable */
  84         return 1;
  85     }
  86     if (strchr (NO_FORMAT_CHARS_START, c))
  87         return 1;
  88     return 0;
  89 }
  90
  91 /*
  92  * Find the start of the current paragraph for the purpose of formatting.
  93  * Return position in the file.
  94  */
  95 static long
  96 begin_paragraph (WEdit *edit, int force)
  97 {
  98     long i;
  99     for (i = edit->curs_line - 1; i >= 0; i--) {
 100         if (line_is_blank (edit, i)) {
 101             i++;
 102             break;
 103         }
 104         if (force) {
 105             if (bad_line_start (edit, line_start (edit, i))) {
 106                 i++;
 107                 break;
 108             }
 109         }
 110     }
 111     return edit_move_backward (edit, edit_bol (edit, edit->curs1),
 112                                edit->curs_line - i);
 113 }
 114
 115 /*
 116  * Find the end of the current paragraph for the purpose of formatting.
 117  * Return position in the file.
 118  */
 119 static long
 120 end_paragraph (WEdit *edit, int force)
 121 {
 122     int i;
 123     for (i = edit->curs_line + 1; i <= edit->total_lines; i++) {
 124         if (line_is_blank (edit, i)) {
 125             i--;
 126             break;
 127         }
 128         if (force)
 129             if (bad_line_start (edit, line_start (edit, i))) {
 130                 i--;
 131                 break;
 132             }
 133     }
 134     return edit_eol (edit,
 135                      edit_move_forward (edit, edit_bol (edit, edit->curs1),
 136                                         i - edit->curs_line, 0));
 137 }
 138
 139 static unsigned char *
 140 get_paragraph (WEdit *edit, long p, long q, int indent, int *size)
 141 {
 142     unsigned char *s, *t;
 143 #if 0
 144     t = g_try_malloc ((q - p) + 2 * (q - p) / option_word_wrap_line_length +
 145                   10);
 146 #else
 147     t = g_try_malloc (2 * (q - p) + 100);
 148 #endif
 149     if (t == NULL)
 150         return NULL;
 151     for (s = t; p < q; p++, s++) {
 152         if (indent)
 153             if (edit_get_byte (edit, p - 1) == '\n')
 154                 while (strchr ("\t ", edit_get_byte (edit, p)))
 155                     p++;
 156         *s = edit_get_byte (edit, p);
 157     }
 158     *size = (unsigned long) s - (unsigned long) t;
 159     t[*size] = '\n';
 160     return t;
 161 }
 162
 163 static inline void
 164 strip_newlines (unsigned char *t, int size)
 165 {
 166     unsigned char *p = t;
 167     while (size-- != 0) {
 168         if (*p == '\n')
 169             *p = ' ';
 170         p++;
 171     }
 172 }
 173
 174 /*
 175    This function calculates the number of chars in a line specified to length l in pixels
 176  */
 177 static inline int
 178 next_tab_pos (int x)
 179 {
 180     return x += tab_width - x % tab_width;
 181 }
 182
 183 static inline int
 184 line_pixel_length (unsigned char *t, long b, int l)
 185 {
 186     int x = 0, c, xn = 0;
 187     for (;;) {
 188         c = t[b];
 189         switch (c) {
 190         case '\n':
 191             return b;
 192         case '\t':
 193             xn = next_tab_pos (x);
 194             break;
 195         default:
 196             xn = x + 1;
 197             break;
 198         }
 199         if (xn > l)
 200             break;
 201         x = xn;
 202         b++;
 203     }
 204     return b;
 205 }
 206
 207 static int
 208 next_word_start (unsigned char *t, int q, int size)
 209 {
 210     int i;
 211     int saw_ws = 0;
 212
 213     for (i = q; i < size; i++) {
 214         switch (t[i]) {
 215         case '\n':
 216             return -1;
 217         case '\t':
 218         case ' ':
 219             saw_ws = 1;
 220             break;
 221         default:
 222             if (saw_ws != 0)
 223                 return i;
 224             break;
 225         }
 226     }
 227     return -1;
 228 }
 229
 230 /* find the start of a word */
 231 static inline int
 232 word_start (unsigned char *t, int q, int size)
 233 {
 234     int i = q;
 235     if (t[q] == ' ' || t[q] == '\t')
 236         return next_word_start (t, q, size);
 237     for (;;) {
 238         int c;
 239         if (!i)
 240             return -1;
 241         c = t[i - 1];
 242         if (c == '\n')
 243             return -1;
 244         if (c == ' ' || c == '\t')
 245             return i;
 246         i--;
 247     }
 248 }
 249
 250 /* replaces ' ' with '\n' to properly format a paragraph */
 251 static inline void
 252 format_this (unsigned char *t, int size, int indent)
 253 {
 254     int q = 0, ww;
 255     strip_newlines (t, size);
 256     ww = option_word_wrap_line_length * FONT_MEAN_WIDTH - indent;
 257     if (ww < FONT_MEAN_WIDTH * 2)
 258         ww = FONT_MEAN_WIDTH * 2;
 259     for (;;) {
 260         int p;
 261         q = line_pixel_length (t, q, ww);
 262         if (q > size)
 263             break;
 264         if (t[q] == '\n')
 265             break;
 266         p = word_start (t, q, size);
 267         if (p == -1)
 268             q = next_word_start (t, q, size);   /* Return the end of the word if the beginning
 269                                                    of the word is at the beginning of a line
 270                                                    (i.e. a very long word) */
 271         else
 272             q = p;
 273         if (q == -1)    /* end of paragraph */
 274             break;
 275         if (q)
 276             t[q - 1] = '\n';
 277     }
 278 }
 279
 280 static inline void
 281 replace_at (WEdit * edit, long q, int c)
 282 {
 283     edit_cursor_move (edit, q - edit->curs1);
 284     edit_delete (edit, 1);
 285     edit_insert_ahead (edit, c);
 286 }
 287
 288 /* replaces a block of text */
 289 static inline void
 290 put_paragraph (WEdit * edit, unsigned char *t, long p, int indent, int size)
 291 {
 292     long cursor;
 293     int i, c = 0;
 294     cursor = edit->curs1;
 295     if (indent)
 296         while (strchr ("\t ", edit_get_byte (edit, p)))
 297             p++;
 298     for (i = 0; i < size; i++, p++) {
 299         if (i && indent) {
 300             if (t[i - 1] == '\n' && c == '\n') {
 301                 while (strchr ("\t ", edit_get_byte (edit, p)))
 302                     p++;
 303             } else if (t[i - 1] == '\n') {
 304                 long curs;
 305                 edit_cursor_move (edit, p - edit->curs1);
 306                 curs = edit->curs1;
 307                 edit_insert_indent (edit, indent);
 308                 if (cursor >= curs)
 309                     cursor += edit->curs1 - p;
 310                 p = edit->curs1;
 311             } else if (c == '\n') {
 312                 edit_cursor_move (edit, p - edit->curs1);
 313                 while (strchr ("\t ", edit_get_byte (edit, p))) {
 314                     edit_delete (edit, 1);
 315                     if (cursor > edit->curs1)
 316                         cursor--;
 317                 }
 318                 p = edit->curs1;
 319             }
 320         }
 321         c = edit_get_byte (edit, p);
 322         if (c != t[i])
 323             replace_at (edit, p, t[i]);
 324     }
 325     edit_cursor_move (edit, cursor - edit->curs1);      /* restore cursor position */
 326 }
 327
 328 static inline int
 329 test_indent (WEdit * edit, long p, long q)
 330 {
 331     int indent;
 332     indent = edit_indent_width (edit, p++);
 333     if (!indent)
 334         return 0;
 335     for (; p < q; p++)
 336         if (edit_get_byte (edit, p - 1) == '\n')
 337             if (indent != edit_indent_width (edit, p))
 338                 return 0;
 339     return indent;
 340 }
 341
 342 void
 343 format_paragraph (WEdit *edit, int force)
 344 {
 345     long p, q;
 346     int size;
 347     unsigned char *t;
 348     int indent = 0;
 349     if (option_word_wrap_line_length < 2)
 350         return;
 351     if (line_is_blank (edit, edit->curs_line))
 352         return;
 353     p = begin_paragraph (edit, force);
 354     q = end_paragraph (edit, force);
 355     indent = test_indent (edit, p, q);
 356     t = get_paragraph (edit, p, q, indent, &size);
 357     if (!t)
 358         return;
 359     if (!force) {
 360         int i;
 361         if (strchr (NO_FORMAT_CHARS_START, *t)) {
 362             g_free (t);
 363             return;
 364         }
 365         for (i = 0; i < size - 1; i++) {
 366             if (t[i] == '\n') {
 367                 if (strchr (NO_FORMAT_CHARS_START "\t ", t[i + 1])) {
 368                     g_free (t);
 369                     return;
 370                 }
 371             }
 372         }
 373     }
 374     format_this (t, q - p, indent);
 375     put_paragraph (edit, t, p, indent, size);
 376     g_free (t);
 377
 378     /* Scroll left as much as possible to show the formatted paragraph */
 379     edit_scroll_left (edit, -edit->start_col);
 380 }