Preparation for diff-showing feature.

1 files changed, 44 insertions, 30 deletions

diff --git a/pw.c b/pw.c
index ae6545d..d1a652f 100644
--- a/pw.c
+++ b/pw.c
@@ -81,7 +81,8 @@ enum status_flags {
   stat_bkgnd =    0x0200, // running in the background
   stat_hlite =    0x0400, // running in the background
   stat_oneshot =  0x0800, // running in the background
-  stat_save =     stat_susp | stat_lino | stat_hlite
+  stat_diff =     0x1000, // highlight differences
+  stat_save =     stat_susp | stat_lino | stat_hlite | stat_diff
 };
 
 typedef enum execode {
@@ -93,7 +94,7 @@ typedef struct pwstate {
   int nlines, maxlines;
   int hpos;
   int vsplit1, vsplit2, vs2pos;
-  int hist;
+  int hist, prevhist;
   int columns;
   int tstop;
   unsigned stat;
@@ -384,38 +385,43 @@ static void clreol(int nl)
     putchar('\n');
 }
 
-static void hlon(void)
+static void hlon(int *phlite)
 {
-  printf("\033[7m");
+  if (!*phlite) {
+    printf("\033[7m");
+    *phlite = 1;
+  }
 }
 
-static void hloff(void)
+static void hloff(int *phlite)
 {
-  printf("\033[m");
+  if (*phlite) {
+    printf("\033[m");
+    *phlite = 0;
+  }
 }
 
-#define with_hl(pw, expr) do {                                                \
-  if ((pw)->stat & stat_hlite)                                                \
-    hlon();                                                                   \
-  expr;                                                                       \
-  if ((pw)->stat & stat_hlite)                                                \
-    hloff();                                                                  \
-} while (0)
-
-static void hlchar(pwstate *pw, int ch)
-{
-  with_hl(pw, putchar(ch));
-}
+#define with_hl(on, keep, hlite, expr)                                        \
+  do {                                                                        \
+    if (on)                                                                   \
+       hlon(&hlite);                                                          \
+    expr;                                                                     \
+    if (!keep)                                                                \
+       hloff(&hlite);                                                         \
+  } while (0)
 
-static void drawline(pwstate *pw, const char *line, int lineno)
+static void drawline(pwstate *pw, const char *line, int lineno, char *diffline)
 {
   const char *oline = line;
-  int olen = (int) dslen(line), len = olen;
+  int olen = (int) dslen(line), len = olen, pos = 0;
   int columns = pw->columns;
   int vsplit1 = pw->vsplit1;
   int vsplit2 = pw->vsplit2;
   int vs2pos = pw->vs2pos;
   int endmark = 0;
+  int hlpanel = (pw->stat & stat_hlite) != 0;
+  int hldiff = (pw->stat & stat_diff) != 0 && diffline != 0;
+  int hlite = 0;
 
   if (lineno >= 0)
     columns -= printf("%3d ", lineno);
@@ -449,7 +455,7 @@ static void drawline(pwstate *pw, const char *line, int lineno)
     int i = 0;
 
     if (vsplit1 || vs2pos) {
-      hlchar(pw, '|');
+      with_hl (hlpanel, hldiff, hlite, putchar('|'));
       i++;
     }
 
@@ -480,7 +486,7 @@ static void drawline(pwstate *pw, const char *line, int lineno)
     if (pw->hpos || vsplit1 || vsplit2) {
       pos += pw->hpos + 1;
       len -= pw->hpos + 1;
-      hlchar(pw, '>');
+      with_hl (hlpanel, hldiff, hlite, putchar('>'));
       columns--;
     }
     if (len < columns) {
@@ -489,14 +495,16 @@ static void drawline(pwstate *pw, const char *line, int lineno)
     } else {
       for (int i = 0; i < columns - 1; i++)
         putchar(line[pos + i]);
-      hlchar(pw, '<');
+      with_hl (hlpanel, hldiff, hlite, putchar('<'));
       putchar('\n');
     }
   } else {
     if (endmark)
-      hlchar(pw, '>');
+      with_hl (hlpanel, hldiff, hlite, putchar('>'));
     clreol(1);
   }
+
+  hloff(&hlite);
 }
 
 static void drawstatus(pwstate *pw)
@@ -602,7 +610,7 @@ static void redraw(pwstate *pw)
     printf("\r\033[%dA", snaplines[pw->hist]);
     if ((pw->stat & stat_lino) == 0) {
       for (int i = 0; i < snaplines[pw->hist]; i++)
-        drawline(pw, snapshot[pw->hist][i], -1);
+        drawline(pw, snapshot[pw->hist][i], -1, snapshot[pw->prevhist][i]);
     } else {
       int start = 1, step = 1;
       if (pw->stat & stat_htmode) {
@@ -610,7 +618,7 @@ static void redraw(pwstate *pw)
         step = -1;
       }
       for (int i = 0, l = start; i < snaplines[pw->hist]; i++, l += step)
-        drawline(pw, snapshot[pw->hist][i], l);
+        drawline(pw, snapshot[pw->hist][i], l, snapshot[pw->prevhist][i]);
     }
   } else {
     clrline(pw->stat);
@@ -1420,7 +1428,7 @@ int main(int argc, char **argv)
                                       snaplines[0] + 1);
               snapshot[0][snaplines[0]++] = dsref(line);
               clrline(pw.stat);
-              drawline(&pw, line, (pw.stat & stat_lino) ? 0: -1);
+              drawline(&pw, line, (pw.stat & stat_lino) ? 0: -1, 0);
               drawstatus(&pw);
             }
           }
@@ -1440,7 +1448,7 @@ int main(int argc, char **argv)
           pw.maxlines = ws.ws_row - 1;
         }
         if (maxed) {
-          pw.hist = 0;
+          pw.prevhist = pw.hist = 0;
           pw.circbuf = resizebuf(pw.circbuf, oldmax, pw.maxlines);
           snapshot[0] = resizebuf(snapshot[0], oldmax, pw.maxlines);
           if (pw.nlines > pw.maxlines)
@@ -1620,15 +1628,19 @@ int main(int argc, char **argv)
             pw.stat ^= stat_hlite;
             pw.stat |= stat_force;
             break;
+          case ctrl('d'):
+            pw.stat ^= stat_diff;
+            pw.stat |= stat_force;
+            break;
           case 'j':
             if (pw.hist > 0) {
-              pw.hist--;
+              pw.prevhist = pw.hist--;
               pw.stat |= stat_force;
             }
             break;
           case 'k':
             if (pw.hist < snhistsize - 1 && snapshot[pw.hist + 1]) {
-              pw.hist++;
+              pw.prevhist = pw.hist++;
               pw.stat |= stat_force;
             }
             break;
@@ -1706,6 +1718,8 @@ int main(int argc, char **argv)
                 free(snapshot[i]);
                 snapshot[i] = 0;
               }
+
+              pw.prevhist = 0;
             }
             break;
           case '#':