tools/src/utils: Add location.go

Contains helpers for obtaining the source location of the caller

Bug: dawn:1342
Change-Id: I6eddf9140d10bc7889260392e04c3e2adec715d8
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/87220
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Ben Clayton <bclayton@google.com>

tools/src/utils/location.go

@@ -0,0 +1,39 @@
+// Copyright 2022 The Tint Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package utils
+
+import (
+	"fmt"
+	"path/filepath"
+	"runtime"
+)
+
+// ThisLine returns the filepath and line number of the calling function
+func ThisLine() string {
+	_, file, line, ok := runtime.Caller(1)
+	if !ok {
+		return ""
+	}
+	return fmt.Sprintf("%v:%v", file, line)
+}
+
+// ThisDir returns the directory of the caller function
+func ThisDir() string {
+	_, file, _, ok := runtime.Caller(1)
+	if !ok {
+		return ""
+	}
+	return filepath.Dir(file)
+}

tools/src/utils/location_test.go

@@ -0,0 +1,36 @@
+// Copyright 2022 The Tint Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package utils_test
+
+import (
+	"strings"
+	"testing"
+
+	"dawn.googlesource.com/dawn/tools/src/utils"
+)
+
+func TestThisLine(t *testing.T) {
+	td := utils.ThisLine()
+	if !strings.HasSuffix(td, "location_test.go:25") {
+		t.Errorf("TestThisLine() returned %v", td)
+	}
+}
+
+func TestThisDir(t *testing.T) {
+	td := utils.ThisDir()
+	if !strings.HasSuffix(td, "utils") {
+		t.Errorf("ThisDir() returned %v", td)
+	}
+}