contrib/less/jump.c

   1 /*
   2  * Copyright (C) 1984-2014  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, see the README file.
   8  */
   9
  10
  11 /*
  12  * Routines which jump to a new location in the file.
  13  */
  14
  15 #include "less.h"
  16 #include "position.h"
  17
  18 extern int jump_sline;
  19 extern int squished;
  20 extern int screen_trashed;
  21 extern int sc_width, sc_height;
  22 extern int show_attn;
  23 extern int top_scroll;
  24
  25 /*
  26  * Jump to the end of the file.
  27  */
  28         public void
  29 jump_forw()
  30 {
  31         POSITION pos;
  32         POSITION end_pos;
  33
  34         if (ch_end_seek())
  35         {
  36                 error("Cannot seek to end of file", NULL_PARG);
  37                 return;
  38         }
  39         /*
  40          * Note; lastmark will be called later by jump_loc, but it fails
  41          * because the position table has been cleared by pos_clear below.
  42          * So call it here before calling pos_clear.
  43          */
  44         lastmark();
  45         /*
  46          * Position the last line in the file at the last screen line.
  47          * Go back one line from the end of the file
  48          * to get to the beginning of the last line.
  49          */
  50         pos_clear();
  51         end_pos = ch_tell();
  52         pos = back_line(end_pos);
  53         if (pos == NULL_POSITION)
  54                 jump_loc((POSITION)0, sc_height-1);
  55         else
  56         {
  57                 jump_loc(pos, sc_height-1);
  58                 if (position(sc_height-1) != end_pos)
  59                         repaint();
  60         }
  61 }
  62
  63 /*
  64  * Jump to the last buffered line in the file.
  65  */
  66         public void
  67 jump_forw_buffered()
  68 {
  69         if (ch_end_buffer_seek())
  70         {
  71                 error("Cannot seek to end of buffers", NULL_PARG);
  72                 return;
  73         }
  74         jump_line_loc(ch_tell(), sc_height-1);
  75 }
  76
  77 /*
  78  * Jump to line n in the file.
  79  */
  80         public void
  81 jump_back(linenum)
  82         LINENUM linenum;
  83 {
  84         POSITION pos;
  85         PARG parg;
  86
  87         /*
  88          * Find the position of the specified line.
  89          * If we can seek there, just jump to it.
  90          * If we can't seek, but we're trying to go to line number 1,
  91          * use ch_beg_seek() to get as close as we can.
  92          */
  93         pos = find_pos(linenum);
  94         if (pos != NULL_POSITION && ch_seek(pos) == 0)
  95         {
  96                 if (show_attn)
  97                         set_attnpos(pos);
  98                 jump_loc(pos, jump_sline);
  99         } else if (linenum <= 1 && ch_beg_seek() == 0)
 100         {
 101                 jump_loc(ch_tell(), jump_sline);
 102                 error("Cannot seek to beginning of file", NULL_PARG);
 103         } else
 104         {
 105                 parg.p_linenum = linenum;
 106                 error("Cannot seek to line number %n", &parg);
 107         }
 108 }
 109
 110 /*
 111  * Repaint the screen.
 112  */
 113         public void
 114 repaint()
 115 {
 116         struct scrpos scrpos;
 117         /*
 118          * Start at the line currently at the top of the screen
 119          * and redisplay the screen.
 120          */
 121         get_scrpos(&scrpos);
 122         pos_clear();
 123         jump_loc(scrpos.pos, scrpos.ln);
 124 }
 125
 126 /*
 127  * Jump to a specified percentage into the file.
 128  */
 129         public void
 130 jump_percent(percent, fraction)
 131         int percent;
 132         long fraction;
 133 {
 134         POSITION pos, len;
 135
 136         /*
 137          * Determine the position in the file
 138          * (the specified percentage of the file's length).
 139          */
 140         if ((len = ch_length()) == NULL_POSITION)
 141         {
 142                 ierror("Determining length of file", NULL_PARG);
 143                 ch_end_seek();
 144         }
 145         if ((len = ch_length()) == NULL_POSITION)
 146         {
 147                 error("Don't know length of file", NULL_PARG);
 148                 return;
 149         }
 150         pos = percent_pos(len, percent, fraction);
 151         if (pos >= len)
 152                 pos = len-1;
 153
 154         jump_line_loc(pos, jump_sline);
 155 }
 156
 157 /*
 158  * Jump to a specified position in the file.
 159  * Like jump_loc, but the position need not be
 160  * the first character in a line.
 161  */
 162         public void
 163 jump_line_loc(pos, sline)
 164         POSITION pos;
 165         int sline;
 166 {
 167         int c;
 168
 169         if (ch_seek(pos) == 0)
 170         {
 171                 /*
 172                  * Back up to the beginning of the line.
 173                  */
 174                 while ((c = ch_back_get()) != '\n' && c != EOI)
 175                         ;
 176                 if (c == '\n')
 177                         (void) ch_forw_get();
 178                 pos = ch_tell();
 179         }
 180         if (show_attn)
 181                 set_attnpos(pos);
 182         jump_loc(pos, sline);
 183 }
 184
 185 /*
 186  * Jump to a specified position in the file.
 187  * The position must be the first character in a line.
 188  * Place the target line on a specified line on the screen.
 189  */
 190         public void
 191 jump_loc(pos, sline)
 192         POSITION pos;
 193         int sline;
 194 {
 195         register int nline;
 196         POSITION tpos;
 197         POSITION bpos;
 198
 199         /*
 200          * Normalize sline.
 201          */
 202         sline = adjsline(sline);
 203
 204         if ((nline = onscreen(pos)) >= 0)
 205         {
 206                 /*
 207                  * The line is currently displayed.
 208                  * Just scroll there.
 209                  */
 210                 nline -= sline;
 211                 if (nline > 0)
 212                         forw(nline, position(BOTTOM_PLUS_ONE), 1, 0, 0);
 213                 else
 214                         back(-nline, position(TOP), 1, 0);
 215 #if HILITE_SEARCH
 216                 if (show_attn)
 217                         repaint_hilite(1);
 218 #endif
 219                 return;
 220         }
 221
 222         /*
 223          * Line is not on screen.
 224          * Seek to the desired location.
 225          */
 226         if (ch_seek(pos))
 227         {
 228                 error("Cannot seek to that file position", NULL_PARG);
 229                 return;
 230         }
 231
 232         /*
 233          * See if the desired line is before or after
 234          * the currently displayed screen.
 235          */
 236         tpos = position(TOP);
 237         bpos = position(BOTTOM_PLUS_ONE);
 238         if (tpos == NULL_POSITION || pos >= tpos)
 239         {
 240                 /*
 241                  * The desired line is after the current screen.
 242                  * Move back in the file far enough so that we can
 243                  * call forw() and put the desired line at the
 244                  * sline-th line on the screen.
 245                  */
 246                 for (nline = 0;  nline < sline;  nline++)
 247                 {
 248                         if (bpos != NULL_POSITION && pos <= bpos)
 249                         {
 250                                 /*
 251                                  * Surprise!  The desired line is
 252                                  * close enough to the current screen
 253                                  * that we can just scroll there after all.
 254                                  */
 255                                 forw(sc_height-sline+nline-1, bpos, 1, 0, 0);
 256 #if HILITE_SEARCH
 257                                 if (show_attn)
 258                                         repaint_hilite(1);
 259 #endif
 260                                 return;
 261                         }
 262                         pos = back_line(pos);
 263                         if (pos == NULL_POSITION)
 264                         {
 265                                 /*
 266                                  * Oops.  Ran into the beginning of the file.
 267                                  * Exit the loop here and rely on forw()
 268                                  * below to draw the required number of
 269                                  * blank lines at the top of the screen.
 270                                  */
 271                                 break;
 272                         }
 273                 }
 274                 lastmark();
 275                 squished = 0;
 276                 screen_trashed = 0;
 277                 forw(sc_height-1, pos, 1, 0, sline-nline);
 278         } else
 279         {
 280                 /*
 281                  * The desired line is before the current screen.
 282                  * Move forward in the file far enough so that we
 283                  * can call back() and put the desired line at the
 284                  * sline-th line on the screen.
 285                  */
 286                 for (nline = sline;  nline < sc_height - 1;  nline++)
 287                 {
 288                         pos = forw_line(pos);
 289                         if (pos == NULL_POSITION)
 290                         {
 291                                 /*
 292                                  * Ran into end of file.
 293                                  * This shouldn't normally happen,
 294                                  * but may if there is some kind of read error.
 295                                  */
 296                                 break;
 297                         }
 298 #if HILITE_SEARCH
 299                         pos = next_unfiltered(pos);
 300 #endif
 301                         if (pos >= tpos)
 302                         {
 303                                 /*
 304                                  * Surprise!  The desired line is
 305                                  * close enough to the current screen
 306                                  * that we can just scroll there after all.
 307                                  */
 308                                 back(nline+1, tpos, 1, 0);
 309 #if HILITE_SEARCH
 310                                 if (show_attn)
 311                                         repaint_hilite(1);
 312 #endif
 313                                 return;
 314                         }
 315                 }
 316                 lastmark();
 317                 if (!top_scroll)
 318                         clear();
 319                 else
 320                         home();
 321                 screen_trashed = 0;
 322                 add_back_pos(pos);
 323                 back(sc_height-1, pos, 1, 0);
 324         }
 325 }