grep: teach --untracked and --exclude-standard options

In a working tree of a git managed repository, "grep --untracked" would
find the specified patterns from files in untracked files in addition to
its usual behaviour of finding them in the tracked files.

By default, when working with "--no-index" option, "grep" does not pay
attention to .gitignore mechanism. "grep --no-index --exclude-standard"
can be used to tell the command to use .gitignore and stop reporting hits
from files that would be ignored. Also, when working without "--no-index",
"grep" honors .gitignore mechanism, and "grep --no-exclude-standard" can
be used to tell the command to include hits from files that are ignored.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-grep.txt

@@ -9,7 +9,7 @@ git-grep - Print lines matching a pattern
 SYNOPSIS
 --------
 [verse]
-'git grep' [--cached]
+'git grep' [--cached] [--untracked] [--exclude-standard]
 	   [-a | --text] [-I] [-i | --ignore-case] [-w | --word-regexp]
 	   [-v | --invert-match] [-h|-H] [--full-name]
 	   [-E | --extended-regexp] [-G | --basic-regexp]
@@ -36,6 +36,19 @@ OPTIONS
 	Instead of searching in the working tree files, check
 	the blobs registered in the index file.
 
+--untracked::
+	In addition to searching in the tracked files in the working
+	tree, search also in untracked files.
+
+--no-exclude-standard::
+	Also search in ignored files by not honoring the `.gitignore`
+	mechanism. Only useful with `--untracked`.
+
+--exclude-standard::
+	Do not pay attention to ignored files specified via the	`.gitignore`
+	mechanism.  Only useful when searching files in the current directory
+	with `--no-index`.
+
 -a::
 --text::
 	Process binary files as if they were text.

builtin-grep.c

@@ -646,12 +646,14 @@ static int grep_object(struct grep_opt *opt, const char **paths,
 	die("unable to grep from object of type %s", typename(obj->type));
 }
 
-static int grep_directory(struct grep_opt *opt, const char **paths)
+static int grep_directory(struct grep_opt *opt, const char **paths, int exc_std)
 {
 	struct dir_struct dir;
 	int i, hit = 0;
 
 	memset(&dir, 0, sizeof(dir));
+	if (exc_std)
+		setup_standard_excludes(&dir);
 
 	fill_directory(&dir, paths);
 	for (i = 0; i < dir.nr; i++) {
@@ -749,7 +751,7 @@ static int help_callback(const struct option *opt, const char *arg, int unset)
 int cmd_grep(int argc, const char **argv, const char *prefix)
 {
 	int hit = 0;
-	int cached = 0;
+	int cached = 0, untracked = 0, opt_exclude = -1;
 	int seen_dashdash = 0;
 	int external_grep_allowed__ignored;
 	struct grep_opt opt;
@@ -764,6 +766,10 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 		{ OPTION_BOOLEAN, 0, "index", &use_index, NULL,
 			"finds in contents not managed by git",
 			PARSE_OPT_NOARG | PARSE_OPT_NEGHELP },
+		OPT_BOOLEAN(0, "untracked", &untracked,
+			"search in both tracked and untracked files"),
+		OPT_SET_INT(0, "exclude-standard", &opt_exclude,
+			    "search also in ignored files", 1),
 		OPT_GROUP(""),
 		OPT_BOOLEAN('v', "invert-match", &opt.invert,
 			"show non-matching lines"),
@@ -950,18 +956,23 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 		paths[1] = NULL;
 	}
 
-	if (!use_index) {
+	if (!use_index && (untracked || cached))
+		die("--cached or --untracked cannot be used with --no-index.");
+
+	if (!use_index || untracked) {
 		int hit;
-		if (cached)
-			die("--cached cannot be used with --no-index.");
+		int use_exclude = (opt_exclude < 0) ? use_index : !!opt_exclude;
 		if (list.nr)
-			die("--no-index cannot be used with revs.");
-		hit = grep_directory(&opt, paths);
+			die("--no-index or --untracked cannot be used with revs.");
+		hit = grep_directory(&opt, paths, use_exclude);
 		if (use_threads)
 			hit |= wait_all();
 		return !hit;
 	}
 
+	if (0 <= opt_exclude)
+		die("--exclude or --no-exclude cannot be used for tracked contents.");
+
 	if (!list.nr) {
 		int hit;
 		if (!cached)

t/t7002-grep.sh

@@ -455,6 +455,23 @@ test_expect_success 'outside of git repository' '
 		test_must_fail git grep o &&
 		git grep --no-index o >../../actual.sub &&
 		test_cmp ../../expect.sub ../../actual.sub
+	) &&
+
+	echo ".*o*" >non/git/.gitignore &&
+	(
+		GIT_CEILING_DIRECTORIES="$(pwd)/non/git" &&
+		export GIT_CEILING_DIRECTORIES &&
+		cd non/git &&
+		test_must_fail git grep o &&
+		git grep --no-index --exclude-standard o >../actual.full &&
+		test_cmp ../expect.full ../actual.full &&
+
+		{
+			echo ".gitignore:.*o*"
+			cat ../expect.full
+		} >../expect.with.ignored &&
+		git grep --no-index --no-exclude o >../actual.full &&
+		test_cmp ../expect.with.ignored ../actual.full
 	)
 '
 
@@ -465,9 +482,12 @@ test_expect_success 'inside git repository but with --no-index' '
 	echo world >is/git/sub/file2 &&
 	echo ".*o*" >is/git/.gitignore &&
 	{
-		echo ".gitignore:.*o*" &&
 		echo file1:hello &&
 		echo sub/file2:world
+	} >is/expect.unignored &&
+	{
+		echo ".gitignore:.*o*" &&
+		cat is/expect.unignored
 	} >is/expect.full &&
 	: >is/expect.empty &&
 	echo file2:world >is/expect.sub
@@ -476,12 +496,24 @@ test_expect_success 'inside git repository but with --no-index' '
 		git init &&
 		test_must_fail git grep o >../actual.full &&
 		test_cmp ../expect.empty ../actual.full &&
+
+		git grep --untracked o >../actual.unignored &&
+		test_cmp ../expect.unignored ../actual.unignored &&
+
 		git grep --no-index o >../actual.full &&
 		test_cmp ../expect.full ../actual.full &&
+
+		git grep --no-index --exclude-standard o >../actual.unignored &&
+		test_cmp ../expect.unignored ../actual.unignored &&
+
 		cd sub &&
 		test_must_fail git grep o >../../actual.sub &&
 		test_cmp ../../expect.empty ../../actual.sub &&
+
 		git grep --no-index o >../../actual.sub &&
+		test_cmp ../../expect.sub ../../actual.sub &&
+
+		git grep --untracked o >../../actual.sub &&
 		test_cmp ../../expect.sub ../../actual.sub
 	)
 '