filter: implement handling **

filter/filter.go

@@ -31,7 +31,39 @@ func Match(pattern, str string) (matched bool, err error) {
 	return match(patterns, strs)
 }
 
+func hasDoubleWildcard(list []string) (ok bool, pos int) {
+	for i, item := range list {
+		if item == "**" {
+			return true, i
+		}
+	}
+
+	return false, 0
+}
+
 func match(patterns, strs []string) (matched bool, err error) {
+	if ok, pos := hasDoubleWildcard(patterns); ok {
+		// gradually expand '**' into separate wildcards
+		for i := 0; i <= len(strs)-len(patterns)+1; i++ {
+			newPat := patterns[:pos]
+			for k := 0; k < i; k++ {
+				newPat = append(newPat, "*")
+			}
+			newPat = append(newPat, patterns[pos+1:]...)
+
+			matched, err := match(newPat, strs)
+			if err != nil {
+				return false, err
+			}
+
+			if matched {
+				return true, nil
+			}
+		}
+
+		return false, nil
+	}
+
 	if len(patterns) == 0 && len(strs) == 0 {
 		return true, nil
 	}

filter/filter_test.go

@@ -54,7 +54,21 @@ var matchTests = []struct {
 	{"*.c", "bar/baz/test.go", false},
 	{"sdk", "/foo/bar/sdk", true},
 	{"sdk", "/foo/bar/sdk/test/sdk_foo.go", true},
-	{"sdk/*/cpp/*/*vars*.html", "/usr/share/doc/libreoffice/sdk/docs/cpp/ref/a00517.html", false},
+	{
+		"sdk/*/cpp/*/*vars*.html",
+		"/usr/share/doc/libreoffice/sdk/docs/cpp/ref/a00517.html",
+		false,
+	},
+	{"foo/**/bar/*.go", "/home/user/foo/work/special/project/bar/test.go", true},
+	{"foo/**/bar/*.go", "/home/user/foo/bar/test.go", true},
+	{"foo/**/bar/*.go", "x/foo/bar/test.go", true},
+	{"foo/**/bar/*.go", "foo/bar/test.go", true},
+	{"foo/**/bar/*.go", "/home/user/foo/test.c", false},
+	{"foo/**/bar/*.go", "bar/foo/main.go", false},
+	{"foo/**/bar/*.go", "/foo/bar/main.go", true},
+	{"foo/**/bar/*.go", "bar/main.go", false},
+	{"foo/**/bar", "/home/user/foo/x/y/bar", true},
+	{"foo/**/bar", "/home/user/foo/x/y/bar/main.go", true},
 }
 
 func TestMatch(t *testing.T) {