diff.c: second war on whitespace.

This adds DIFF_WHITESPACE color class (default = reverse red) to
colored diff output to let you catch common whitespace errors.

 - trailing whitespaces at the end of line
 - a space followed by a tab in the indent

Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/diff.c b/diff.c
index 443e24861ba1857822dbe8e3c831f8037e4e832e..2464238ccd6c94a53a0a73de476e33f7cc935ab9 100644 (file)
--- a/diff.c
+++ b/diff.c
@@ -20,12 +20,13 @@ static int diff_use_color_default;
 
 static char diff_colors[][COLOR_MAXLEN] = {
        "\033[m",       /* reset */
-       "",             /* normal */
-       "\033[1m",      /* bold */
-       "\033[36m",     /* cyan */
-       "\033[31m",     /* red */
-       "\033[32m",     /* green */
-       "\033[33m"      /* yellow */
+       "",             /* PLAIN (normal) */
+       "\033[1m",      /* METAINFO (bold) */
+       "\033[36m",     /* FRAGINFO (cyan) */
+       "\033[31m",     /* OLD (red) */
+       "\033[32m",     /* NEW (green) */
+       "\033[33m",     /* COMMIT (yellow) */
+       "\033[41m",     /* WHITESPACE (red background) */
 };
 
 static int parse_diff_color_slot(const char *var, int ofs)
@@ -42,6 +43,8 @@ static int parse_diff_color_slot(const char *var, int ofs)
                return DIFF_FILE_NEW;
        if (!strcasecmp(var+ofs, "commit"))
                return DIFF_COMMIT;
+       if (!strcasecmp(var+ofs, "whitespace"))
+               return DIFF_WHITESPACE;
        die("bad config variable '%s'", var);
 }
 
@@ -383,9 +386,89 @@ const char *diff_get_color(int diff_use_color, enum color_diff ix)
        return "";
 }
 
+static void emit_line(const char *set, const char *reset, const char *line, int len)
+{
+       if (len > 0 && line[len-1] == '\n')
+               len--;
+       fputs(set, stdout);
+       fwrite(line, len, 1, stdout);
+       puts(reset);
+}
+
+static void emit_add_line(const char *reset, struct emit_callback *ecbdata, const char *line, int len)
+{
+       int col0 = ecbdata->nparents;
+       int last_tab_in_indent = -1;
+       int last_space_in_indent = -1;
+       int i;
+       int tail = len;
+       int need_highlight_leading_space = 0;
+       const char *ws = diff_get_color(ecbdata->color_diff, DIFF_WHITESPACE);
+       const char *set = diff_get_color(ecbdata->color_diff, DIFF_FILE_NEW);
+
+       if (!*ws) {
+               emit_line(set, reset, line, len);
+               return;
+       }
+
+       /* The line is a newly added line.  Does it have funny leading
+        * whitespaces?  In indent, SP should never precede a TAB.
+        */
+       for (i = col0; i < len; i++) {
+               if (line[i] == '\t') {
+                       last_tab_in_indent = i;
+                       if (0 <= last_space_in_indent)
+                               need_highlight_leading_space = 1;
+               }
+               else if (line[i] == ' ')
+                       last_space_in_indent = i;
+               else
+                       break;
+       }
+       fputs(set, stdout);
+       fwrite(line, col0, 1, stdout);
+       fputs(reset, stdout);
+       if (((i == len) || line[i] == '\n') && i != col0) {
+               /* The whole line was indent */
+               emit_line(ws, reset, line + col0, len - col0);
+               return;
+       }
+       i = col0;
+       if (need_highlight_leading_space) {
+               while (i < last_tab_in_indent) {
+                       if (line[i] == ' ') {
+                               fputs(ws, stdout);
+                               putchar(' ');
+                               fputs(reset, stdout);
+                       }
+                       else
+                               putchar(line[i]);
+                       i++;
+               }
+       }
+       tail = len - 1;
+       if (line[tail] == '\n' && i < tail)
+               tail--;
+       while (i < tail) {
+               if (!isspace(line[tail]))
+                       break;
+               tail--;
+       }
+       if ((i < tail && line[tail + 1] != '\n')) {
+               /* This has whitespace between tail+1..len */
+               fputs(set, stdout);
+               fwrite(line + i, tail - i + 1, 1, stdout);
+               fputs(reset, stdout);
+               emit_line(ws, reset, line + tail + 1, len - tail - 1);
+       }
+       else
+               emit_line(set, reset, line + i, len - i);
+}
+
 static void fn_out_consume(void *priv, char *line, unsigned long len)
 {
        int i;
+       int color;
        struct emit_callback *ecbdata = priv;
        const char *set = diff_get_color(ecbdata->color_diff, DIFF_METAINFO);
        const char *reset = diff_get_color(ecbdata->color_diff, DIFF_RESET);
@@ -403,45 +486,52 @@ static void fn_out_consume(void *priv, char *line, unsigned long len)
                ;
        if (2 <= i && i < len && line[i] == ' ') {
                ecbdata->nparents = i - 1;
-               set = diff_get_color(ecbdata->color_diff, DIFF_FRAGINFO);
+               emit_line(diff_get_color(ecbdata->color_diff, DIFF_FRAGINFO),
+                         reset, line, len);
+               return;
        }
-       else if (len < ecbdata->nparents)
+
+       if (len < ecbdata->nparents) {
                set = reset;
-       else {
-               int nparents = ecbdata->nparents;
-               int color = DIFF_PLAIN;
-               if (ecbdata->diff_words && nparents != 1)
-                       /* fall back to normal diff */
-                       free_diff_words_data(ecbdata);
-               if (ecbdata->diff_words) {
-                       if (line[0] == '-') {
-                               diff_words_append(line, len,
-                                               &ecbdata->diff_words->minus);
-                               return;
-                       } else if (line[0] == '+') {
-                               diff_words_append(line, len,
-                                               &ecbdata->diff_words->plus);
-                               return;
-                       }
-                       if (ecbdata->diff_words->minus.text.size ||
-                                       ecbdata->diff_words->plus.text.size)
-                               diff_words_show(ecbdata->diff_words);
-                       line++;
-                       len--;
-               } else
-                       for (i = 0; i < nparents && len; i++) {
-                               if (line[i] == '-')
-                                       color = DIFF_FILE_OLD;
-                               else if (line[i] == '+')
-                                       color = DIFF_FILE_NEW;
-                       }
-               set = diff_get_color(ecbdata->color_diff, color);
+               emit_line(reset, reset, line, len);
+               return;
        }
-       if (len > 0 && line[len-1] == '\n')
+
+       color = DIFF_PLAIN;
+       if (ecbdata->diff_words && ecbdata->nparents != 1)
+               /* fall back to normal diff */
+               free_diff_words_data(ecbdata);
+       if (ecbdata->diff_words) {
+               if (line[0] == '-') {
+                       diff_words_append(line, len,
+                                         &ecbdata->diff_words->minus);
+                       return;
+               } else if (line[0] == '+') {
+                       diff_words_append(line, len,
+                                         &ecbdata->diff_words->plus);
+                       return;
+               }
+               if (ecbdata->diff_words->minus.text.size ||
+                   ecbdata->diff_words->plus.text.size)
+                       diff_words_show(ecbdata->diff_words);
+               line++;
                len--;
-       fputs (set, stdout);
-       fwrite (line, len, 1, stdout);
-       puts (reset);
+               emit_line(set, reset, line, len);
+               return;
+       }
+       for (i = 0; i < ecbdata->nparents && len; i++) {
+               if (line[i] == '-')
+                       color = DIFF_FILE_OLD;
+               else if (line[i] == '+')
+                       color = DIFF_FILE_NEW;
+       }
+
+       if (color != DIFF_FILE_NEW) {
+               emit_line(diff_get_color(ecbdata->color_diff, color),
+                         reset, line, len);
+               return;
+       }
+       emit_add_line(reset, ecbdata, line, len);
 }
 
 static char *pprint_rename(const char *a, const char *b)

diff --git a/diff.h b/diff.h
index b60a02e627415d4edaf5056e7f95b519b7fe8fc0..3435fe7b3f868ff1cefd5a20a3409993ce0a413b 100644 (file)
--- a/diff.h
+++ b/diff.h
@@ -86,6 +86,7 @@ enum color_diff {
        DIFF_FILE_OLD = 4,
        DIFF_FILE_NEW = 5,
        DIFF_COMMIT = 6,
+       DIFF_WHITESPACE = 7,
 };
 const char *diff_get_color(int diff_use_color, enum color_diff ix);