git-grep: support regexp

modules/git/grep.go

@@ -27,12 +27,20 @@ type GrepResult struct {
 	HighlightedRanges [][3]int
 }
 
+type grepMode int
+
+const (
+	FixedGrepMode grepMode = iota
+	FixedAnyGrepMode
+	RegExpGrepMode
+)
+
 type GrepOptions struct {
 	RefName           string
 	MaxResultLimit    int
 	MatchesPerFile    int
 	ContextLineNumber int
-	IsFuzzy           bool
+	Mode              grepMode
 	PathSpec          []setting.Glob
 }
 
@@ -75,11 +83,16 @@ func GrepSearch(ctx context.Context, repo *Repository, search string, opts GrepO
 	// -I skips binary files
 	cmd := NewCommand(ctx, "grep",
 		"-I", "--null", "--break", "--heading", "--column",
-		"--fixed-strings", "--line-number", "--ignore-case", "--full-name")
+		"--line-number", "--ignore-case", "--full-name")
+	if opts.Mode == RegExpGrepMode {
+		cmd.AddArguments("--perl-regexp")
+	} else {
+		cmd.AddArguments("--fixed-strings")
+	}
 	cmd.AddOptionValues("--context", fmt.Sprint(opts.ContextLineNumber))
 	cmd.AddOptionValues("--max-count", fmt.Sprint(opts.MatchesPerFile))
 	words := []string{search}
-	if opts.IsFuzzy {
+	if opts.Mode == FixedAnyGrepMode {
 		words = strings.Fields(search)
 	}
 	for _, word := range words {

modules/git/grep_test.go

@@ -201,3 +201,34 @@ func TestGrepRefs(t *testing.T) {
 	assert.Len(t, res, 1)
 	assert.Equal(t, "A", res[0].LineCodes[0])
 }
+
+func TestGrepCanHazRegexOnDemand(t *testing.T) {
+	tmpDir := t.TempDir()
+
+	err := InitRepository(DefaultContext, tmpDir, false, Sha1ObjectFormat.Name())
+	require.NoError(t, err)
+
+	gitRepo, err := openRepositoryWithDefaultContext(tmpDir)
+	require.NoError(t, err)
+	defer gitRepo.Close()
+
+	require.NoError(t, os.WriteFile(path.Join(tmpDir, "matching"), []byte("It's a match!"), 0o666))
+	require.NoError(t, os.WriteFile(path.Join(tmpDir, "not-matching"), []byte("Orisitamatch?"), 0o666))
+
+	err = AddChanges(tmpDir, true)
+	require.NoError(t, err)
+
+	err = CommitChanges(tmpDir, CommitChangesOptions{Message: "Add fixtures for regexp test"})
+	require.NoError(t, err)
+
+	// should find nothing by default...
+	res, err := GrepSearch(context.Background(), gitRepo, "\\bmatch\\b", GrepOptions{})
+	require.NoError(t, err)
+	assert.Empty(t, res)
+
+	// ... unless configured explicitly
+	res, err = GrepSearch(context.Background(), gitRepo, "\\bmatch\\b", GrepOptions{Mode: RegExpGrepMode})
+	require.NoError(t, err)
+	assert.Len(t, res, 1)
+	assert.Equal(t, "matching", res[0].Filename)
+}