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[PATCH 03/19] built-in add -p: show colored hunks by default

From
Johannes Schindelin via GitGitGadget <gitgitgadget@gmail.com>
Date
Dec 13, 2019, 08:07 UTC
Message-ID
<438e6519fb7e81c451ebba3ea9efffc26b4c7a17.1576224486.git.gitgitgadget@gmail.com>
In-Reply-To
<pull.173.git.1576224486.gitgitgadget@gmail.com>
From: Johannes Schindelin <johannes.schindelin@gmx.de>

Just like the Perl version, we now generate two diffs if `color.diff` is set: one with and one without color. Then we parse them in parallel and record which hunks start at which offsets in both.

Note that this is a (slight) deviation from the way the Perl version did it: we are no longer reading the output of `diff-files` line by line (which is more natural for Perl than for C), but in one go, and parse everything later, so we might just as well do it in synchrony.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 add-patch.c | 79 +++++++++++++++++++++++++++++++++++++++++------------
 1 file changed, 62 insertions(+), 17 deletions(-)
diff --git a/add-patch.c b/add-patch.c
index d1b1a080e4..79eefa9505 100644
--- a/add-patch.c
+++ b/add-patch.c
@@ -4,9 +4,10 @@
 #include "run-command.h"
 #include "argv-array.h"
 #include "pathspec.h"
+#include "color.h"
 
 struct hunk {
-	size_t start, end;
+	size_t start, end, colored_start, colored_end;
 	enum { UNDECIDED_HUNK = 0, SKIP_HUNK, USE_HUNK } use;
 };
 
@@ -15,7 +16,7 @@ struct add_p_state {
 	struct strbuf answer, buf;
 
 	/* parsed diff */
-	struct strbuf plain;
+	struct strbuf plain, colored;
 	struct hunk head;
 	struct hunk *hunk;
 	size_t hunk_nr, hunk_alloc;
@@ -39,26 +40,50 @@ static void setup_child_process(struct add_p_state *s,
 
 static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
 {
-	struct strbuf *plain = &s->plain;
+	struct argv_array args = ARGV_ARRAY_INIT;
+	struct strbuf *plain = &s->plain, *colored = NULL;
 	struct child_process cp = CHILD_PROCESS_INIT;
-	char *p, *pend;
-	size_t i;
+	char *p, *pend, *colored_p = NULL, *colored_pend = NULL;
+	size_t i, color_arg_index;
 	struct hunk *hunk = NULL;
 	int res;
 
 	/* Use `--no-color` explicitly, just in case `diff.color = always`. */
-	setup_child_process(s, &cp,
-			 "diff-files", "-p", "--no-color", "--", NULL);
+	argv_array_pushl(&args, "diff-files", "-p", "--no-color", "--", NULL);
+	color_arg_index = args.argc - 2;
 	for (i = 0; i < ps->nr; i++)
-		argv_array_push(&cp.args, ps->items[i].original);
+		argv_array_push(&args, ps->items[i].original);
 
+	setup_child_process(s, &cp, NULL);
+	cp.argv = args.argv;
 	res = capture_command(&cp, plain, 0);
-	if (res)
+	if (res) {
+		argv_array_clear(&args);
 		return error(_("could not parse diff"));
-	if (!plain->len)
+	}
+	if (!plain->len) {
+		argv_array_clear(&args);
 		return 0;
+	}
 	strbuf_complete_line(plain);
 
+	if (want_color_fd(1, -1)) {
+		struct child_process colored_cp = CHILD_PROCESS_INIT;
+
+		setup_child_process(s, &colored_cp, NULL);
+		xsnprintf((char *)args.argv[color_arg_index], 8, "--color");
+		colored_cp.argv = args.argv;
+		colored = &s->colored;
+		res = capture_command(&colored_cp, colored, 0);
+		argv_array_clear(&args);
+		if (res)
+			return error(_("could not parse colored diff"));
+		strbuf_complete_line(colored);
+		colored_p = colored->buf;
+		colored_pend = colored_p + colored->len;
+	}
+	argv_array_clear(&args);
+
 	/* parse hunks */
 	p = plain->buf;
 	pend = p + plain->len;
@@ -82,20 +107,37 @@ static int parse_diff(struct add_p_state *s, const struct pathspec *ps)
 			memset(hunk, 0, sizeof(*hunk));
 
 			hunk->start = p - plain->buf;
+			if (colored)
+				hunk->colored_start = colored_p - colored->buf;
 		}
 
 		p = eol == pend ? pend : eol + 1;
 		hunk->end = p - plain->buf;
+
+		if (colored) {
+			char *colored_eol = memchr(colored_p, '\n',
+						   colored_pend - colored_p);
+			if (colored_eol)
+				colored_p = colored_eol + 1;
+			else
+				colored_p = colored_pend;
+
+			hunk->colored_end = colored_p - colored->buf;
+		}
 	}
 
 	return 0;
 }
 
 static void render_hunk(struct add_p_state *s, struct hunk *hunk,
-			struct strbuf *out)
+			int colored, struct strbuf *out)
 {
-	strbuf_add(out, s->plain.buf + hunk->start,
-		   hunk->end - hunk->start);
+	if (colored)
+		strbuf_add(out, s->colored.buf + hunk->colored_start,
+			   hunk->colored_end - hunk->colored_start);
+	else
+		strbuf_add(out, s->plain.buf + hunk->start,
+			   hunk->end - hunk->start);
 }
 
 static void reassemble_patch(struct add_p_state *s, struct strbuf *out)
@@ -103,12 +145,12 @@ static void reassemble_patch(struct add_p_state *s, struct strbuf *out)
 	struct hunk *hunk;
 	size_t i;
 
-	render_hunk(s, &s->head, out);
+	render_hunk(s, &s->head, 0, out);
 
 	for (i = 0; i < s->hunk_nr; i++) {
 		hunk = s->hunk + i;
 		if (hunk->use == USE_HUNK)
-			render_hunk(s, hunk, out);
+			render_hunk(s, hunk, 0, out);
 	}
 }
 
@@ -130,12 +172,13 @@ static int patch_update_file(struct add_p_state *s)
 	struct hunk *hunk;
 	char ch;
 	struct child_process cp = CHILD_PROCESS_INIT;
+	int colored = !!s->colored.len;
 
 	if (!s->hunk_nr)
 		return 0;
 
 	strbuf_reset(&s->buf);
-	render_hunk(s, &s->head, &s->buf);
+	render_hunk(s, &s->head, colored, &s->buf);
 	fputs(s->buf.buf, stdout);
 	for (;;) {
 		if (hunk_index >= s->hunk_nr)
@@ -162,7 +205,7 @@ static int patch_update_file(struct add_p_state *s)
 			break;
 
 		strbuf_reset(&s->buf);
-		render_hunk(s, hunk, &s->buf);
+		render_hunk(s, hunk, colored, &s->buf);
 		fputs(s->buf.buf, stdout);
 
 		strbuf_reset(&s->buf);
@@ -252,6 +295,7 @@ int run_add_p(struct repository *r, const struct pathspec *ps)
 					 NULL, NULL, NULL) < 0 ||
 	    parse_diff(&s, ps) < 0) {
 		strbuf_release(&s.plain);
+		strbuf_release(&s.colored);
 		return -1;
 	}
 
@@ -261,5 +305,6 @@ int run_add_p(struct repository *r, const struct pathspec *ps)
 	strbuf_release(&s.answer);
 	strbuf_release(&s.buf);
 	strbuf_release(&s.plain);
+	strbuf_release(&s.colored);
 	return 0;
 }

-- 
gitgitgadget
Previous: Johannes Schindelin via GitGitGadgetNext: Johannes Schindelin via GitGitGadget
Message 4 of 20 in “Implement the git add --patch backend in C”
  1. 00/19 Implement the git add --patch backend in CJohannes Schindelin via GitGitGadget, Dec 13, 2019
  2. 02/19 built-in add -i: wire up the new C code for the `patch` commandJohannes Schindelin via GitGitGadget, Dec 13, 2019
  3. 01/19 built-in add -i: start implementing the `patch` functionality in CJohannes Schindelin via GitGitGadget, Dec 13, 2019
  4. 03/19 built-in add -p: show colored hunks by defaultJohannes Schindelin via GitGitGadget, Dec 13, 2019
  5. 07/19 built-in add -p: support multi-file diffsJohannes Schindelin via GitGitGadget, Dec 13, 2019
  6. 06/19 built-in add -p: offer a helpful error message when hunk navigation failedJohannes Schindelin via GitGitGadget, Dec 13, 2019
  7. 10/19 built-in add -p: show different prompts for mode changes and deletionsJohannes Schindelin via GitGitGadget, Dec 13, 2019
  8. 09/19 built-in app -p: allow selecting a mode change as a "hunk"Johannes Schindelin via GitGitGadget, Dec 13, 2019
  9. 13/19 strbuf: add a helper function to call the editor "on an strbuf"Johannes Schindelin via GitGitGadget, Dec 13, 2019
  10. 12/19 built-in add -p: coalesce hunks after splitting themJohannes Schindelin via GitGitGadget, Dec 13, 2019
  11. 15/19 built-in add -p: implement the 'g' ("goto") commandJohannes Schindelin via GitGitGadget, Dec 13, 2019
  12. 14/19 built-in add -p: implement hunk editingJohannes Schindelin via GitGitGadget, Dec 13, 2019
  13. 11/19 built-in add -p: implement the hunk splitting featureJohannes Schindelin via GitGitGadget, Dec 13, 2019
  14. 19/19 built-in add -p: show helpful hint when nothing can be stagedJohannes Schindelin via GitGitGadget, Dec 13, 2019
  15. 18/19 built-in add -p: only show the applicable parts of the help textJohannes Schindelin via GitGitGadget, Dec 13, 2019
  16. 16/19 built-in add -p: implement the '/' ("search regex") commandJohannes Schindelin via GitGitGadget, Dec 13, 2019
  17. 17/19 built-in add -p: implement the 'q' ("quit") commandJohannes Schindelin via GitGitGadget, Dec 13, 2019
  18. 08/19 built-in add -p: handle deleted empty filesJohannes Schindelin via GitGitGadget, Dec 13, 2019
  19. 04/19 built-in add -p: adjust hunk headers as neededJohannes Schindelin via GitGitGadget, Dec 13, 2019
  20. 05/19 built-in add -p: color the prompt and the help textJohannes Schindelin via GitGitGadget, Dec 13, 2019

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