A mojom .d generator.

mojom/mojom_parser/generators/common/util.go

Index: mojom/mojom_parser/generators/common/util.go
diff --git a/mojom/mojom_parser/generators/common/util.go b/mojom/mojom_parser/generators/common/util.go
new file mode 100644
index 0000000000000000000000000000000000000000..05444d3f5a6d46a2bd1bde5caf7712770cfd3c7d
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+++ b/mojom/mojom_parser/generators/common/util.go
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+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package common
+
+import (
+	"log"
+	"os"
+	"path"
+	"path/filepath"
+)
+
+// OutputWriterByFilePath returns |Writer| that writes to a file whose relative
+// path from config.OutputDir() is equivalent to the relative path from
+// config.SrcRootPath() to fileName. Also, the extension of the file is changed
+// from ".mojom" to |ext|.
+//
+// e.g. If
+// ext = ".d"
+// fileName = /alpha/beta/gamma/file.mojom
+// SrcRootPath = /alpha/
+// OutputDir = /some/output/path/
+//
+// The writer writes to /some/output/path/beta/gamma/file.d
+func OutputWriterByFilePath(fileName string, config GeneratorConfig, ext string) Writer {
+	fileName = changeExt(fileName, ext)
+	outPath := outputFileByFilePath(fileName, config)
+
+	return createAndOpen(outPath)
+}
+
+// outputFileByFilePath computes a file path such that the relative path
+// from config.SrcRootPath() to the returned path is equivalent to the relative
+// path from config.SrcRootPath() to fileName.
+//
+// e.g. If
+// fileName = /alpha/beta/gamma/file.mojom
+// SrcRootPath = /alpha/
+// OutputDir = /some/output/path/
+//
+// The returned path is /some/output/path/beta/gamma/file.mojom
+func outputFileByFilePath(fileName string, config GeneratorConfig) string {
+	var err error
+	relFileName, err := filepath.Rel(config.SrcRootPath(), fileName)
+	if err != nil {
+		log.Fatalln(err.Error())
+	}
+	return filepath.Join(config.OutputDir(), relFileName)
+}
+
+// createAndOpen opens for writing the specified file. If the file or any part
+// of the directory structure in its path does not exist, they are created.
+func createAndOpen(outPath string) (file Writer) {
+	// Create the directory that will contain the output.
+	outDir := path.Dir(outPath)
+	if err := os.MkdirAll(outDir, os.ModeDir|0770); err != nil && !os.IsExist(err) {
+		log.Fatalln(err.Error())
+	}
+
+	var err error
+	file, err = os.OpenFile(outPath, os.O_WRONLY, 0660)
+	if err != nil {
+		log.Fatalln(err.Error())
+	}
+
+	return
+}
+
+// changeExt changes the extension of a file to the specified extension.
+func changeExt(fileName string, ext string) string {
+	return fileName[:len(fileName)-len(filepath.Ext(fileName))] + ext
+}