diff.c: add dimming to moved line detection

Any lines inside a moved block of code are not interesting. Boundaries
of blocks are only interesting if they are next to another block of moved
code.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 121 insertions, 11 deletions

diff --git a/diff.c b/diff.c
index 79ea592388..4af73a7e0c 100644
--- a/diff.c
+++ b/diff.c
@@ -58,10 +58,14 @@ static char diff_colors[][COLOR_MAXLEN] = {
 	GIT_COLOR_YELLOW,	/* COMMIT */
 	GIT_COLOR_BG_RED,	/* WHITESPACE */
 	GIT_COLOR_NORMAL,	/* FUNCINFO */
-	GIT_COLOR_MAGENTA,	/* OLD_MOVED */
-	GIT_COLOR_BLUE,		/* OLD_MOVED ALTERNATIVE */
-	GIT_COLOR_CYAN,		/* NEW_MOVED */
-	GIT_COLOR_YELLOW,	/* NEW_MOVED ALTERNATIVE */
+	GIT_COLOR_BOLD_MAGENTA,	/* OLD_MOVED */
+	GIT_COLOR_BOLD_BLUE,	/* OLD_MOVED ALTERNATIVE */
+	GIT_COLOR_FAINT,	/* OLD_MOVED_DIM */
+	GIT_COLOR_FAINT_ITALIC,	/* OLD_MOVED_ALTERNATIVE_DIM */
+	GIT_COLOR_BOLD_CYAN,	/* NEW_MOVED */
+	GIT_COLOR_BOLD_YELLOW,	/* NEW_MOVED ALTERNATIVE */
+	GIT_COLOR_FAINT,	/* NEW_MOVED_DIM */
+	GIT_COLOR_FAINT_ITALIC,	/* NEW_MOVED_ALTERNATIVE_DIM */
 };
 
 static NORETURN void die_want_option(const char *option_name)
@@ -91,10 +95,18 @@ static int parse_diff_color_slot(const char *var)
 		return DIFF_FILE_OLD_MOVED;
 	if (!strcasecmp(var, "oldmovedalternative"))
 		return DIFF_FILE_OLD_MOVED_ALT;
+	if (!strcasecmp(var, "oldmoveddimmed"))
+		return DIFF_FILE_OLD_MOVED_DIM;
+	if (!strcasecmp(var, "oldmovedalternativedimmed"))
+		return DIFF_FILE_OLD_MOVED_ALT_DIM;
 	if (!strcasecmp(var, "newmoved"))
 		return DIFF_FILE_NEW_MOVED;
 	if (!strcasecmp(var, "newmovedalternative"))
 		return DIFF_FILE_NEW_MOVED_ALT;
+	if (!strcasecmp(var, "newmoveddimmed"))
+		return DIFF_FILE_NEW_MOVED_DIM;
+	if (!strcasecmp(var, "newmovedalternativedimmed"))
+		return DIFF_FILE_NEW_MOVED_ALT_DIM;
 	return -1;
 }
 
@@ -262,8 +274,10 @@ static int parse_color_moved(const char *arg)
 		return COLOR_MOVED_ZEBRA;
 	else if (!strcmp(arg, "default"))
 		return COLOR_MOVED_DEFAULT;
+	else if (!strcmp(arg, "dimmed_zebra"))
+		return COLOR_MOVED_ZEBRA_DIM;
 	else
-		return error(_("color moved setting must be one of 'no', 'default', 'zebra', 'plain'"));
+		return error(_("color moved setting must be one of 'no', 'default', 'zebra', 'dimmed_zebra', 'plain'"));
 }
 
 int git_diff_ui_config(const char *var, const char *value, void *cb)
@@ -649,6 +663,7 @@ enum diff_symbol {
 #define DIFF_SYMBOL_CONTENT_BLANK_LINE_EOF	(1<<16)
 #define DIFF_SYMBOL_MOVED_LINE			(1<<17)
 #define DIFF_SYMBOL_MOVED_LINE_ALT		(1<<18)
+#define DIFF_SYMBOL_MOVED_LINE_UNINTERESTING	(1<<19)
 #define DIFF_SYMBOL_CONTENT_WS_MASK (WSEH_NEW | WSEH_OLD | WSEH_CONTEXT | WS_RULE_MASK)
 
 /*
@@ -933,6 +948,67 @@ static void mark_color_as_moved(struct diff_options *o,
 	free(pmb);
 }
 
+#define DIFF_SYMBOL_MOVED_LINE_ZEBRA_MASK \
+  (DIFF_SYMBOL_MOVED_LINE | DIFF_SYMBOL_MOVED_LINE_ALT)
+static void dim_moved_lines(struct diff_options *o)
+{
+	int n;
+	for (n = 0; n < o->emitted_symbols->nr; n++) {
+		struct emitted_diff_symbol *prev = (n != 0) ?
+				&o->emitted_symbols->buf[n - 1] : NULL;
+		struct emitted_diff_symbol *l = &o->emitted_symbols->buf[n];
+		struct emitted_diff_symbol *next =
+				(n < o->emitted_symbols->nr - 1) ?
+				&o->emitted_symbols->buf[n + 1] : NULL;
+
+		/* Not a plus or minus line? */
+		if (l->s != DIFF_SYMBOL_PLUS && l->s != DIFF_SYMBOL_MINUS)
+			continue;
+
+		/* Not a moved line? */
+		if (!(l->flags & DIFF_SYMBOL_MOVED_LINE))
+			continue;
+
+		/*
+		 * If prev or next are not a plus or minus line,
+		 * pretend they don't exist
+		 */
+		if (prev && prev->s != DIFF_SYMBOL_PLUS &&
+			    prev->s != DIFF_SYMBOL_MINUS)
+			prev = NULL;
+		if (next && next->s != DIFF_SYMBOL_PLUS &&
+			    next->s != DIFF_SYMBOL_MINUS)
+			next = NULL;
+
+		/* Inside a block? */
+		if ((prev &&
+		    (prev->flags & DIFF_SYMBOL_MOVED_LINE_ZEBRA_MASK) ==
+		    (l->flags & DIFF_SYMBOL_MOVED_LINE_ZEBRA_MASK)) &&
+		    (next &&
+		    (next->flags & DIFF_SYMBOL_MOVED_LINE_ZEBRA_MASK) ==
+		    (l->flags & DIFF_SYMBOL_MOVED_LINE_ZEBRA_MASK))) {
+			l->flags |= DIFF_SYMBOL_MOVED_LINE_UNINTERESTING;
+			continue;
+		}
+
+		/* Check if we are at an interesting bound: */
+		if (prev && (prev->flags & DIFF_SYMBOL_MOVED_LINE) &&
+		    (prev->flags & DIFF_SYMBOL_MOVED_LINE_ALT) !=
+		       (l->flags & DIFF_SYMBOL_MOVED_LINE_ALT))
+			continue;
+		if (next && (next->flags & DIFF_SYMBOL_MOVED_LINE) &&
+		    (next->flags & DIFF_SYMBOL_MOVED_LINE_ALT) !=
+		       (l->flags & DIFF_SYMBOL_MOVED_LINE_ALT))
+			continue;
+
+		/*
+		 * The boundary to prev and next are not interesting,
+		 * so this line is not interesting as a whole
+		 */
+		l->flags |= DIFF_SYMBOL_MOVED_LINE_UNINTERESTING;
+	}
+}
+
 static void emit_line_ws_markup(struct diff_options *o,
 				const char *set, const char *reset,
 				const char *line, int len, char sign,
@@ -1007,24 +1083,56 @@ static void emit_diff_symbol_from_struct(struct diff_options *o,
 				    flags & (DIFF_SYMBOL_CONTENT_WS_MASK), 0);
 		break;
 	case DIFF_SYMBOL_PLUS:
-		if (flags & DIFF_SYMBOL_MOVED_LINE_ALT)
+		switch (flags & (DIFF_SYMBOL_MOVED_LINE |
+				 DIFF_SYMBOL_MOVED_LINE_ALT |
+				 DIFF_SYMBOL_MOVED_LINE_UNINTERESTING)) {
+		case DIFF_SYMBOL_MOVED_LINE |
+		     DIFF_SYMBOL_MOVED_LINE_ALT |
+		     DIFF_SYMBOL_MOVED_LINE_UNINTERESTING:
+			set = diff_get_color_opt(o, DIFF_FILE_NEW_MOVED_ALT_DIM);
+			break;
+		case DIFF_SYMBOL_MOVED_LINE |
+		     DIFF_SYMBOL_MOVED_LINE_ALT:
 			set = diff_get_color_opt(o, DIFF_FILE_NEW_MOVED_ALT);
-		else if (flags & DIFF_SYMBOL_MOVED_LINE)
+			break;
+		case DIFF_SYMBOL_MOVED_LINE |
+		     DIFF_SYMBOL_MOVED_LINE_UNINTERESTING:
+			set = diff_get_color_opt(o, DIFF_FILE_NEW_MOVED_DIM);
+			break;
+		case DIFF_SYMBOL_MOVED_LINE:
 			set = diff_get_color_opt(o, DIFF_FILE_NEW_MOVED);
-		else
+			break;
+		default:
 			set = diff_get_color_opt(o, DIFF_FILE_NEW);
+		}
 		reset = diff_get_color_opt(o, DIFF_RESET);
 		emit_line_ws_markup(o, set, reset, line, len, '+',
 				    flags & DIFF_SYMBOL_CONTENT_WS_MASK,
 				    flags & DIFF_SYMBOL_CONTENT_BLANK_LINE_EOF);
 		break;
 	case DIFF_SYMBOL_MINUS:
-		if (flags & DIFF_SYMBOL_MOVED_LINE_ALT)
+		switch (flags & (DIFF_SYMBOL_MOVED_LINE |
+				 DIFF_SYMBOL_MOVED_LINE_ALT |
+				 DIFF_SYMBOL_MOVED_LINE_UNINTERESTING)) {
+		case DIFF_SYMBOL_MOVED_LINE |
+		     DIFF_SYMBOL_MOVED_LINE_ALT |
+		     DIFF_SYMBOL_MOVED_LINE_UNINTERESTING:
+			set = diff_get_color_opt(o, DIFF_FILE_OLD_MOVED_ALT_DIM);
+			break;
+		case DIFF_SYMBOL_MOVED_LINE |
+		     DIFF_SYMBOL_MOVED_LINE_ALT:
 			set = diff_get_color_opt(o, DIFF_FILE_OLD_MOVED_ALT);
-		else if (flags & DIFF_SYMBOL_MOVED_LINE)
+			break;
+		case DIFF_SYMBOL_MOVED_LINE |
+		     DIFF_SYMBOL_MOVED_LINE_UNINTERESTING:
+			set = diff_get_color_opt(o, DIFF_FILE_OLD_MOVED_DIM);
+			break;
+		case DIFF_SYMBOL_MOVED_LINE:
 			set = diff_get_color_opt(o, DIFF_FILE_OLD_MOVED);
-		else
+			break;
+		default:
 			set = diff_get_color_opt(o, DIFF_FILE_OLD);
+		}
 		reset = diff_get_color_opt(o, DIFF_RESET);
 		emit_line_ws_markup(o, set, reset, line, len, '-',
 				    flags & DIFF_SYMBOL_CONTENT_WS_MASK, 0);
@@ -5420,6 +5528,8 @@ static void diff_flush_patch_all_file_pairs(struct diff_options *o)
 
 			add_lines_to_move_detection(o, &add_lines, &del_lines);
 			mark_color_as_moved(o, &add_lines, &del_lines);
+			if (o->color_moved == COLOR_MOVED_ZEBRA_DIM)
+				dim_moved_lines(o);
 
 			hashmap_free(&add_lines, 0);
 			hashmap_free(&del_lines, 0);