Mojom formatter incorporated in the mojom binary.

mojom/mojom_parser/fmt_cmd.go

Index: mojom/mojom_parser/fmt_cmd.go
diff --git a/mojom/mojom_parser/fmt_cmd.go b/mojom/mojom_parser/fmt_cmd.go
new file mode 100644
index 0000000000000000000000000000000000000000..e5251082622d62c951e49543711aabe4dd510fbb
--- /dev/null
+++ b/mojom/mojom_parser/fmt_cmd.go
@@ -0,0 +1,72 @@
+// 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.
+
+// This file contains fmtCmd which formats a .mojom file and outputs the
+// formatted mojom file to stdout.
+// The fmt command is invoked as follows:
+//
+//		mojom fmt [-w] <mojom_file>
+//
+//	If -w is specified and the formatted file is different from the original,
+//	the file is overwritten with the formatted version.
+package main
+
+import (
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"mojom/mojom_parser/formatter"
+	"os"
+	"path/filepath"
+)
+
+// fmtCmd implements the fmt command for the mojom tool.
+// The slice of strings |args| is the list of arguments passed on the command
+// line starting with the program name and followed by the invoked command.
+func fmtCmd(args []string) {
+	flagSet := flag.NewFlagSet("fmt", flag.ContinueOnError)
+	var overwrite bool
+	flagSet.BoolVar(&overwrite, "w", false,
+		"Overwrite the specified file with the formatted version if it is different from the original.")
+
+	printUsage := func() {
+		fmt.Fprintf(os.Stderr, "Usage: %s fmt [-w] <mojom_file>\n\n", filepath.Base(args[0]))
+		flagSet.PrintDefaults()
+	}
+
+	if err := flagSet.Parse(args[2:]); err != nil {
+		fmt.Fprintln(os.Stderr, err.Error())
+		os.Exit(1)
+	}
+
+	inputFileName := flagSet.Arg(0)
+	if inputFileName == "" {
+		fmt.Fprintln(os.Stderr, "No .mojom file given.")
+		printUsage()
+		os.Exit(1)
+	}
+
+	originalBytes, err := ioutil.ReadFile(inputFileName)
+	if err != nil {
+		ErrorExit(err.Error())
+	}
+
+	original := string(originalBytes[:])
+
+	var formatted string
+	formatted, err = formatter.FormatMojom(inputFileName, original)
+	if err != nil {
+		ErrorExit(err.Error())
+	}
+
+	if overwrite {
+		if formatted != original {
+			if err := ioutil.WriteFile(inputFileName, []byte(formatted), 0); err != nil {
+				ErrorExit(err.Error())
+			}
+		}
+	} else {
+		fmt.Print(formatted)
+	}
+}