src/usr.bin/less/line.c - diff

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Diff for /src/usr.bin/less/line.c between version 1.22 and 1.23

-version 1.22, 2017/04/02 23:02:06
+version 1.23, 2019/02/24 04:54:36
 Line 15
 Line 15
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   * in preparation for output to the screen.
   */
+ #include <wchar.h>
  #include "charset.h"
  #include "less.h"
-Line 373
+Line 375
 Line 373
 Line 375
   * attribute sequence to be inserted, so this must be taken into account.
   */
  static int
- pwidth(LWCHAR ch, int a, LWCHAR prev_ch)
+ pwidth(wchar_t ch, int a, wchar_t prev_ch)
  {
          int w;
-         if (ch == '\b')
+         /*
-                 /*
+          * In case of a backspace, back up by the width of the previous
-                  * Backspace moves backwards one or two positions.
+          * character.  If that is non-printable (for example another
-                  * XXX - Incorrect if several '\b' in a row.
+          * backspace) or zero width (for example a combining accent),
-                  */
+          * the terminal may actually back up to a character even further
-                 return ((utf_mode && is_wide_char(prev_ch)) ? -2 : -1);
+          * back, but we no longer know how wide that may have been.
+          * The best guess possible at this point is that it was
-         if (!utf_mode || is_ascii_char(ch)) {
+          * hopefully width one.
-                 if (control_char((char)ch)) {
+          */
-                         /*
+         if (ch == L'\b') {
-                          * Control characters do unpredictable things,
+                 w = wcwidth(prev_ch);
-                          * so we don't even try to guess; say it doesn't move.
+                 if (w <= 0)
-                          * This can only happen if the -r flag is in effect.
+                         w = 1;
-                          */
+                 return (-w);
-                         return (0);
-                 }
-         } else {
-                 if (is_composing_char(ch) || is_combining_char(prev_ch, ch)) {
-                         /*
-                          * Composing and combining chars take up no space.
-                          *
-                          * Some terminals, upon failure to compose a
-                          * composing character with the character(s) that
-                          * precede(s) it will actually take up one column
-                          * for the composing character; there isn't much
-                          * we could do short of testing the (complex)
-                          * composition process ourselves and printing
-                          * a binary representation when it fails.
-                          */
-                         return (0);
-                 }
          }
+         w = wcwidth(ch);
          /*
+          * Non-printable characters can get here if the -r flag is in
+          * effect, and possibly in some other situations (XXX check that!).
+          * Treat them as zero width.
+          * That may not always match their actual behaviour,
+          * but there is no reasonable way to be more exact.
+          */
+         if (w == -1)
+                 w = 0;
+         /*
+          * Combining accents take up no space.
+          * Some terminals, upon failure to compose them with the
+          * characters that precede them, will actually take up one column
+          * for the combining accent; there isn't much we could do short
+          * of testing the (complex) composition process ourselves and
+          * printing a binary representation when it fails.
+          */
+         if (w == 0)
+                 return (0);
+         /*
           * Other characters take one or two columns,
           * plus the width of any attribute enter/exit sequence.
           */
-         w = 1;
-         if (is_wide_char(ch))
-                 w++;
          if (curr > 0 && !is_at_equiv(attr[curr-1], a))
                  w += attr_ewidth(attr[curr-1]);
          if ((apply_at_specials(a) != AT_NORMAL) &&