[PATCH 1/2] builtin/blame: dim uninteresting metadata lines

[Stefan Beller <sbeller@google.com>]

When using git-blame lots of lines contain redundant information, for
example in hunks that consist of multiple lines, the metadata (commit
name, author, date) are repeated. A reader may not be interested in those,
so offer an option to color the information that is repeated from the
previous line differently. Both the command line option '--color-lines'
as well as a config option 'color.blame.colorLines' is provided.

Signed-off-by: Stefan Beller <sbeller@google.com>
---
 Documentation/config.txt |  5 +++++
 builtin/blame.c          | 42 ++++++++++++++++++++++++++++++++++++----
 color.h                  |  1 +
 t/t8012-blame-colors.sh  | 29 +++++++++++++++++++++++++++
 4 files changed, 73 insertions(+), 4 deletions(-)
 create mode 100755 t/t8012-blame-colors.sh

diff --git a/Documentation/config.txt b/Documentation/config.txt
index 2659153cb3..a223232263 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -1218,6 +1218,11 @@ color.status.<slot>::
 	status short-format), or
 	`unmerged` (files which have unmerged changes).
 
+color.blame.repeatedMeta::
+	Use the customized color for the part of git-blame output that
+	is repeated meta information per line (such as commit id,
+	author name, date and timezone). Defaults to dark gray.
+
 color.ui::
 	This variable determines the default value for variables such
 	as `color.diff` and `color.grep` that control the use of color
diff --git a/builtin/blame.c b/builtin/blame.c
index db38c0b307..b49fee70a9 100644
--- a/builtin/blame.c
+++ b/builtin/blame.c
@@ -7,6 +7,7 @@
 
 #include "cache.h"
 #include "config.h"
+#include "color.h"
 #include "builtin.h"
 #include "commit.h"
 #include "diff.h"
@@ -46,6 +47,7 @@ static int xdl_opts;
 static int abbrev = -1;
 static int no_whole_file_rename;
 static int show_progress;
+static char repeated_meta_color[COLOR_MAXLEN];
 
 static struct date_mode blame_date_mode = { DATE_ISO8601 };
 static size_t blame_date_width;
@@ -316,10 +318,11 @@ static const char *format_time(timestamp_t time, const char *tz_str,
 #define OUTPUT_PORCELAIN	010
 #define OUTPUT_SHOW_NAME	020
 #define OUTPUT_SHOW_NUMBER	040
-#define OUTPUT_SHOW_SCORE      0100
-#define OUTPUT_NO_AUTHOR       0200
+#define OUTPUT_SHOW_SCORE	0100
+#define OUTPUT_NO_AUTHOR	0200
 #define OUTPUT_SHOW_EMAIL	0400
-#define OUTPUT_LINE_PORCELAIN 01000
+#define OUTPUT_LINE_PORCELAIN 	01000
+#define OUTPUT_COLOR_LINE	02000
 
 static void emit_porcelain_details(struct blame_origin *suspect, int repeat)
 {
@@ -375,6 +378,7 @@ static void emit_other(struct blame_scoreboard *sb, struct blame_entry *ent, int
 	struct commit_info ci;
 	char hex[GIT_MAX_HEXSZ + 1];
 	int show_raw_time = !!(opt & OUTPUT_RAW_TIMESTAMP);
+	const char *color = "", *reset = "";
 
 	get_commit_info(suspect->commit, &ci, 1);
 	oid_to_hex_r(hex, &suspect->commit->object.oid);
@@ -384,6 +388,19 @@ static void emit_other(struct blame_scoreboard *sb, struct blame_entry *ent, int
 		char ch;
 		int length = (opt & OUTPUT_LONG_OBJECT_NAME) ? GIT_SHA1_HEXSZ : abbrev;
 
+		if (!(opt & OUTPUT_ANNOTATE_COMPAT)) {
+			if (opt & OUTPUT_COLOR_LINE) {
+				if (cnt > 0) {
+					color = repeated_meta_color;
+					reset = GIT_COLOR_RESET;
+				} else  {
+					color ="";
+					reset = "";
+				}
+			}
+			fputs(color, stdout);
+		}
+
 		if (suspect->commit->object.flags & UNINTERESTING) {
 			if (blank_boundary)
 				memset(hex, ' ', length);
@@ -433,6 +450,9 @@ static void emit_other(struct blame_scoreboard *sb, struct blame_entry *ent, int
 			printf(" %*d) ",
 			       max_digits, ent->lno + 1 + cnt);
 		}
+		if (!(opt & OUTPUT_ANNOTATE_COMPAT) &&
+		    (opt & OUTPUT_COLOR_LINE))
+			fputs(reset, stdout);
 		do {
 			ch = *cp++;
 			putchar(ch);
@@ -585,6 +605,8 @@ static const char *add_prefix(const char *prefix, const char *path)
 
 static int git_blame_config(const char *var, const char *value, void *cb)
 {
+	int *output_option = cb;
+
 	if (!strcmp(var, "blame.showroot")) {
 		show_root = git_config_bool(var, value);
 		return 0;
@@ -607,6 +629,13 @@ static int git_blame_config(const char *var, const char *value, void *cb)
 		parse_date_format(value, &blame_date_mode);
 		return 0;
 	}
+	if (!strcmp(var, "color.blame.repeatedlines")) {
+		if (color_parse_mem(value, strlen(value), repeated_meta_color))
+			warning(_("invalid color '%s' in color.blame.repeatedLines"),
+				value);
+		*output_option |= OUTPUT_COLOR_LINE;
+		return 0;
+	}
 
 	if (git_diff_heuristic_config(var, value, cb) < 0)
 		return -1;
@@ -690,6 +719,7 @@ int cmd_blame(int argc, const char **argv, const char *prefix)
 		OPT_BIT('s', NULL, &output_option, N_("Suppress author name and timestamp (Default: off)"), OUTPUT_NO_AUTHOR),
 		OPT_BIT('e', "show-email", &output_option, N_("Show author email instead of name (Default: off)"), OUTPUT_SHOW_EMAIL),
 		OPT_BIT('w', NULL, &xdl_opts, N_("Ignore whitespace differences"), XDF_IGNORE_WHITESPACE),
+		OPT_BIT(0, "color-lines", &output_option, N_("color redundant metadata from previous line differently"), OUTPUT_COLOR_LINE),
 
 		/*
 		 * The following two options are parsed by parse_revision_opt()
@@ -949,8 +979,12 @@ int cmd_blame(int argc, const char **argv, const char *prefix)
 
 	blame_coalesce(&sb);
 
-	if (!(output_option & OUTPUT_PORCELAIN))
+	if (!(output_option & OUTPUT_PORCELAIN)) {
 		find_alignment(&sb, &output_option);
+		if (!*repeated_meta_color &&
+		    (output_option & OUTPUT_COLOR_LINE))
+			strcpy(repeated_meta_color, GIT_COLOR_DARK);
+	}
 
 	output(&sb, output_option);
 	free((void *)sb.final_buf);
diff --git a/color.h b/color.h
index cd0bcedd08..196be16058 100644
--- a/color.h
+++ b/color.h
@@ -30,6 +30,7 @@ struct strbuf;
 #define GIT_COLOR_BLUE		"\033[34m"
 #define GIT_COLOR_MAGENTA	"\033[35m"
 #define GIT_COLOR_CYAN		"\033[36m"
+#define GIT_COLOR_DARK		"\033[1;30m"
 #define GIT_COLOR_BOLD_RED	"\033[1;31m"
 #define GIT_COLOR_BOLD_GREEN	"\033[1;32m"
 #define GIT_COLOR_BOLD_YELLOW	"\033[1;33m"
diff --git a/t/t8012-blame-colors.sh b/t/t8012-blame-colors.sh
new file mode 100755
index 0000000000..bb0fe20e76
--- /dev/null
+++ b/t/t8012-blame-colors.sh
@@ -0,0 +1,29 @@
+#!/bin/sh
+
+test_description='colored git blame'
+. ./test-lib.sh
+
+PROG='git blame -c'
+. "$TEST_DIRECTORY"/annotate-tests.sh
+
+test_expect_success 'colored blame colors contiguous lines' '
+	git blame --abbrev=12 --color-lines hello.c >actual.raw &&
+	test_decode_color <actual.raw >actual &&
+	grep "<BOLD;BLACK>" <actual >darkened &&
+	grep "(F" darkened > F.expect &&
+	grep "(H" darkened > H.expect &&
+	test_line_count = 2 F.expect &&
+	test_line_count = 3 H.expect
+'
+
+test_expect_success 'colored blame colors contiguous lines via config' '
+	git -c color.blame.repeatedLines=yellow blame --abbrev=12 hello.c >actual.raw &&
+	test_decode_color <actual.raw >actual &&
+	grep "<YELLOW>" <actual >darkened &&
+	grep "(F" darkened > F.expect &&
+	grep "(H" darkened > H.expect &&
+	test_line_count = 2 F.expect &&
+	test_line_count = 3 H.expect
+'
+
+test_done
-- 
2.17.0.484.g0c8726318c-goog