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>

Documentation/git-grep.txt

@@ -14,6 +14,7 @@ SYNOPSIS
 	   [-E | --extended-regexp] [-G | --basic-regexp]
 	   [-F | --fixed-strings] [-n]
 	   [-l | --files-with-matches] [-L | --files-without-match]
+	   [-O | --open-files-in-pager]
 	   [-z | --null]
 	   [-c | --count] [--all-match] [-q | --quiet]
 	   [--max-depth <depth>]
@@ -104,6 +105,13 @@ OPTIONS
 	For better compatibility with 'git diff', `--name-only` is a
 	synonym for `--files-with-matches`.
 
+-O::
+--open-files-in-pager::
+	Open the matching files in the pager (not the output of 'grep').
+	If the pager happens to be "less" or "vi", and the user
+	specified only one pattern, the first file is positioned at
+	the first match automatically.
+
 -z::
 --null::
 	Output \0 instead of the character that normally follows a

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;
 }

git.c

@@ -329,7 +329,7 @@ static void handle_internal_command(int argc, const char **argv)
 		{ "fsck-objects", cmd_fsck, RUN_SETUP },
 		{ "gc", cmd_gc, RUN_SETUP },
 		{ "get-tar-commit-id", cmd_get_tar_commit_id },
-		{ "grep", cmd_grep, USE_PAGER },
+		{ "grep", cmd_grep },
 		{ "hash-object", cmd_hash_object },
 		{ "help", cmd_help },
 		{ "index-pack", cmd_index_pack },

t/lib-pager.sh

@@ -0,0 +1,15 @@
+#!/bin/sh
+
+test_expect_success 'determine default pager' '
+	test_might_fail git config --unset core.pager &&
+	less=$(
+		unset PAGER GIT_PAGER;
+		git var GIT_PAGER
+	) &&
+	test -n "$less"
+'
+
+if expr "$less" : '^[a-z][a-z]*$' >/dev/null
+then
+	test_set_prereq SIMPLEPAGER
+fi

t/t7006-pager.sh

@@ -3,6 +3,7 @@
 test_description='Test automatic use of a pager.'
 
 . ./test-lib.sh
+. "$TEST_DIRECTORY"/lib-pager.sh
 
 cleanup_fail() {
 	echo >&2 cleanup failed
@@ -158,21 +159,12 @@ test_expect_success 'color when writing to a file intended for a pager' '
 	colorful colorful.log
 '
 
-test_expect_success 'determine default pager' '
-	unset PAGER GIT_PAGER &&
-	test_might_fail git config --unset core.pager ||
-	cleanup_fail &&
-
-	less=$(git var GIT_PAGER) &&
-	test -n "$less"
-'
-
-if expr "$less" : '^[a-z][a-z]*$' >/dev/null && test_have_prereq TTY
+if test_have_prereq SIMPLEPAGER && test_have_prereq TTY
 then
-	test_set_prereq SIMPLEPAGER
+	test_set_prereq SIMPLEPAGERTTY
 fi
 
-test_expect_success SIMPLEPAGER 'default pager is used by default' '
+test_expect_success SIMPLEPAGERTTY 'default pager is used by default' '
 	unset PAGER GIT_PAGER &&
 	test_might_fail git config --unset core.pager &&
 	rm -f default_pager_used ||

t/t7811-grep-open.sh

@@ -0,0 +1,154 @@
+#!/bin/sh
+
+test_description='git grep --open-files-in-pager
+'
+
+. ./test-lib.sh
+. "$TEST_DIRECTORY"/lib-pager.sh
+unset PAGER GIT_PAGER
+
+test_expect_success 'setup' '
+	test_commit initial grep.h "
+enum grep_pat_token {
+	GREP_PATTERN,
+	GREP_PATTERN_HEAD,
+	GREP_PATTERN_BODY,
+	GREP_AND,
+	GREP_OPEN_PAREN,
+	GREP_CLOSE_PAREN,
+	GREP_NOT,
+	GREP_OR,
+};" &&
+
+	test_commit add-user revision.c "
+	}
+	if (seen_dashdash)
+		read_pathspec_from_stdin(revs, &sb, prune);
+	strbuf_release(&sb);
+}
+
+static void add_grep(struct rev_info *revs, const char *ptn, enum grep_pat_token what)
+{
+	append_grep_pattern(&revs->grep_filter, ptn, \"command line\", 0, what);
+" &&
+
+	mkdir subdir &&
+	test_commit subdir subdir/grep.c "enum grep_pat_token" &&
+
+	test_commit uninteresting unrelated "hello, world" &&
+
+	echo GREP_PATTERN >untracked
+'
+
+test_expect_success SIMPLEPAGER 'git grep -O' '
+	cat >$less <<-\EOF &&
+	#!/bin/sh
+	printf "%s\n" "$@" >pager-args
+	EOF
+	chmod +x $less &&
+	cat >expect.less <<-\EOF &&
+	+/*GREP_PATTERN
+	grep.h
+	EOF
+	echo grep.h >expect.notless &&
+	>empty &&
+
+	PATH=.:$PATH git grep -O GREP_PATTERN >out &&
+	{
+		test_cmp expect.less pager-args ||
+		test_cmp expect.notless pager-args
+	} &&
+	test_cmp empty out
+'
+
+test_expect_success 'git grep -O --cached' '
+	test_must_fail git grep --cached -O GREP_PATTERN >out 2>msg &&
+	grep open-files-in-pager msg
+'
+
+test_expect_success 'git grep -O --no-index' '
+	rm -f expect.less pager-args out &&
+	cat >expect <<-\EOF &&
+	grep.h
+	untracked
+	EOF
+	>empty &&
+
+	(
+		GIT_PAGER='\''printf "%s\n" >pager-args'\'' &&
+		export GIT_PAGER &&
+		git grep --no-index -O GREP_PATTERN >out
+	) &&
+	test_cmp expect pager-args &&
+	test_cmp empty out
+'
+
+test_expect_success 'setup: fake "less"' '
+	cat >less <<-\EOF
+	#!/bin/sh
+	printf "%s\n" "$@" >actual
+	EOF
+'
+
+test_expect_success 'git grep -O jumps to line in less' '
+	cat >expect <<-\EOF &&
+	+/*GREP_PATTERN
+	grep.h
+	EOF
+	>empty &&
+
+	GIT_PAGER=./less git grep -O GREP_PATTERN >out &&
+	test_cmp expect actual &&
+	test_cmp empty out
+'
+
+test_expect_success 'modified file' '
+	rm -f actual &&
+	cat >less <<-\EOF &&
+	#!/bin/sh
+	printf "%s\n" "$@" >actual
+	EOF
+	chmod +x $less &&
+	cat >expect <<-\EOF &&
+	+/*enum grep_pat_token
+	grep.h
+	revision.c
+	subdir/grep.c
+	unrelated
+	EOF
+	>empty &&
+
+	echo "enum grep_pat_token" >unrelated &&
+	test_when_finished "git checkout HEAD unrelated" &&
+	GIT_PAGER=./less git grep -F -O "enum grep_pat_token" >out &&
+	test_cmp expect actual &&
+	test_cmp empty out
+'
+
+test_expect_success 'run from subdir' '
+	rm -f actual &&
+	echo grep.c >expect &&
+	>empty &&
+
+	(
+		cd subdir &&
+		export GIT_PAGER &&
+		GIT_PAGER='\''printf "%s\n" >../args'\'' &&
+		git grep -O "enum grep_pat_token" >../out &&
+		GIT_PAGER="pwd >../dir; :" &&
+		git grep -O "enum grep_pat_token" >../out2
+	) &&
+	case $(cat dir) in
+	*subdir)
+		: good
+		;;
+	*)
+		false
+		;;
+	esac &&
+	test_cmp expect args &&
+	test_cmp empty out &&
+	test_cmp empty out2
+'
+
+test_done