grep: Add the option '--open-files-in-pager'

This adds an option to open the matching files in the pager, and if the
pager happens to be "less" (or "vi") and there is only one grep pattern,
it also jumps to the first match right away.

The short option was chose as '-O' to avoid clashes with GNU grep's
options (as suggested by Junio).

So, 'git grep -O abc' is a short form for 'less +/abc $(grep -l abc)'
except that it works also with spaces in file names, and it does not
start the pager if there was no matching file.

[jn: rebased and added tests; with error handling fix from Junio
squashed in]

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 73 insertions, 0 deletions

diff --git a/builtin/grep.c b/builtin/grep.c
index 2111212890..1e8b9465ed 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -11,6 +11,8 @@
 #include "tree-walk.h"
 #include "builtin.h"
 #include "parse-options.h"
+#include "string-list.h"
+#include "run-command.h"
 #include "userdiff.h"
 #include "grep.h"
 #include "quote.h"
@@ -556,6 +558,33 @@ static int grep_file(struct grep_opt *opt, const char *filename)
 	}
 }
 
+static void append_path(struct grep_opt *opt, const void *data, size_t len)
+{
+	struct string_list *path_list = opt->output_priv;
+
+	if (len == 1 && *(const char *)data == '\0')
+		return;
+	string_list_append(xstrndup(data, len), path_list);
+}
+
+static void run_pager(struct grep_opt *opt, const char *prefix)
+{
+	struct string_list *path_list = opt->output_priv;
+	const char **argv = xmalloc(sizeof(const char *) * (path_list->nr + 1));
+	int i, status;
+
+	for (i = 0; i < path_list->nr; i++)
+		argv[i] = path_list->items[i].string;
+	argv[path_list->nr] = NULL;
+
+	if (prefix && chdir(prefix))
+		die("Failed to chdir: %s", prefix);
+	status = run_command_v_opt(argv, RUN_USING_SHELL);
+	if (status)
+		exit(status);
+	free(argv);
+}
+
 static int grep_cache(struct grep_opt *opt, const char **paths, int cached)
 {
 	int hit = 0;
@@ -799,9 +828,11 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 	int cached = 0;
 	int seen_dashdash = 0;
 	int external_grep_allowed__ignored;
+	int show_in_pager = 0;
 	struct grep_opt opt;
 	struct object_array list = { 0, 0, NULL };
 	const char **paths = NULL;
+	struct string_list path_list = { NULL, 0, 0, 0 };
 	int i;
 	int dummy;
 	int nongit = 0, use_index = 1;
@@ -885,6 +916,8 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 		OPT_BOOLEAN(0, "all-match", &opt.all_match,
 			"show only matches from files that match all patterns"),
 		OPT_GROUP(""),
+		OPT_BOOLEAN('O', "open-files-in-pager", &show_in_pager,
+			"show matching files in the pager"),
 		OPT_BOOLEAN(0, "ext-grep", &external_grep_allowed__ignored,
 			    "allow calling of grep(1) (ignored by this build)"),
 		{ OPTION_CALLBACK, 0, "help-all", &options, NULL, "show usage",
@@ -960,6 +993,20 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 		argc--;
 	}
 
+	if (show_in_pager) {
+		const char *pager = git_pager(1);
+		if (!pager) {
+			show_in_pager = 0;
+		} else {
+			opt.name_only = 1;
+			opt.null_following_name = 1;
+			opt.output_priv = &path_list;
+			opt.output = append_path;
+			string_list_append(pager, &path_list);
+			use_threads = 0;
+		}
+	}
+
 	if (!opt.pattern_list)
 		die("no pattern given.");
 	if (!opt.fixed && opt.ignore_case)
@@ -1016,6 +1063,30 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 		paths[1] = NULL;
 	}
 
+	if (show_in_pager && (cached || list.nr))
+		die("--open-files-in-pager only works on the worktree");
+
+	if (show_in_pager && opt.pattern_list && !opt.pattern_list->next) {
+		const char *pager = path_list.items[0].string;
+		int len = strlen(pager);
+
+		if (len > 4 && is_dir_sep(pager[len - 5]))
+			pager += len - 4;
+
+		if (!strcmp("less", pager) || !strcmp("vi", pager)) {
+			struct strbuf buf = STRBUF_INIT;
+			strbuf_addf(&buf, "+/%s%s",
+					strcmp("less", pager) ? "" : "*",
+					opt.pattern_list->pattern);
+			string_list_append(buf.buf, &path_list);
+			strbuf_detach(&buf, NULL);
+		}
+	}
+
+	if (!show_in_pager)
+		setup_pager();
+
+
 	if (!use_index) {
 		if (cached)
 			die("--cached cannot be used with --no-index.");
@@ -1035,6 +1106,8 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 
 	if (use_threads)
 		hit |= wait_all();
+	if (hit && show_in_pager)
+		run_pager(&opt, prefix);
 	free_grep_patterns(&opt);
 	return !hit;
 }