Support compiling to node.js.

bin/sass.dart

@@ -2,14 +2,13 @@
 // MIT-style license that can be found in the LICENSE file or at
 // https://opensource.org/licenses/MIT.
 
-import 'dart:io';
-
 import 'package:args/args.dart';
 import 'package:stack_trace/stack_trace.dart';
 import 'package:path/path.dart' as p;
 
 import 'package:sass/src/ast/sass.dart';
 import 'package:sass/src/exception.dart';
+import 'package:sass/src/io.dart';
 import 'package:sass/src/visitor/perform.dart';
 import 'package:sass/src/visitor/serialize.dart';
 
@@ -22,13 +21,11 @@ void main(List<String> args) {
         allowed: ['expanded'],
         defaultsTo: 'expanded')
     ..addFlag('color',
-        abbr: 'c',
-        help: 'Whether to emit terminal colors.',
-        defaultsTo: stdout.hasTerminal && !Platform.isWindows)
+        abbr: 'c', help: 'Whether to emit terminal colors.', defaultsTo: true)
     ..addFlag('trace', help: 'Print full Dart stack traces for exceptions.')
     ..addFlag('help',
         abbr: 'h', help: 'Print this usage information.', negatable: false);
-  var options = argParser.parse(args);
+  var options = argParser.parse(getArguments(args));
 
   if (options['help']) {
     print("Compile Sass to CSS.\n");
@@ -39,7 +36,7 @@ void main(List<String> args) {
 
   try {
     var file = options.rest.first;
-    var contents = new File(file).readAsStringSync();
+    var contents = readFile(file);
     var url = p.toUri(file);
     var sassTree = p.extension(file) == '.sass'
         ? new Stylesheet.parseSass(contents, url: url)
@@ -52,7 +49,7 @@ void main(List<String> args) {
 
     if (options['trace']) {
       stderr.writeln();
-      stderr.write(new Trace.from(stackTrace));
+      stderr.write(new Trace.from(stackTrace).toString());
       stderr.flush();
     }
 

lib/src/io.dart

@@ -0,0 +1,7 @@
+// Copyright 2016 Google Inc. Use of this source code is governed by an
+// MIT-style license that can be found in the LICENSE file or at
+// https://opensource.org/licenses/MIT.
+
+export 'io/interface.dart'
+    if (dart.library.io) 'io/vm.dart'
+    if (node) 'io/node.dart';

lib/src/io/interface.dart

@@ -0,0 +1,19 @@
+// Copyright 2016 Google Inc. Use of this source code is governed by an
+// MIT-style license that can be found in the LICENSE file or at
+// https://opensource.org/licenses/MIT.
+
+class Stderr {
+  void write(object) {}
+  void writeln([object]) {}
+  void flush() {}
+}
+
+Stderr get stderr => null;
+
+List<String> getArguments(List<String> mainArguments) => null;
+
+String readFile(String path) => null;
+
+bool fileExists(String path) => null;
+
+void exit(int exitCode) {}

lib/src/io/node.dart

@@ -0,0 +1,54 @@
+// Copyright 2016 Google Inc. Use of this source code is governed by an
+// MIT-style license that can be found in the LICENSE file or at
+// https://opensource.org/licenses/MIT.
+
+import 'package:js/js.dart';
+
+@JS()
+class _FS {
+  external String readFileSync(String path, String encoding);
+
+  external bool existsSync(String path);
+}
+
+@JS()
+class _Stderr {
+  external void write(String text);
+}
+
+class Stderr {
+  final _Stderr _stderr;
+
+  Stderr(this._stderr);
+
+  void write(object) => _stderr.write(object.toString());
+
+  void writeln([object]) {
+    if (object != null) _stderr.write("$object\n");
+  }
+
+  void flush() {}
+}
+
+@JS("require")
+external _FS _require(String name);
+
+final _fs = _require("fs");
+
+String readFile(String path) => _fs.readFileSync(path, 'utf8');
+
+bool fileExists(String path) => _fs.existsSync(path);
+
+@JS("process.stderr")
+external _Stderr get _stderr;
+
+final stderr = new Stderr(_stderr);
+
+@JS("process.argv")
+external List<String> get _arguments;
+
+List<String> getArguments(List<String> mainArguments) =>
+    _arguments.skip(2).toList();
+
+@JS("process.exit")
+external int exit(int exitCode);

lib/src/io/vm.dart

@@ -0,0 +1,15 @@
+// Copyright 2016 Google Inc. Use of this source code is governed by an
+// MIT-style license that can be found in the LICENSE file or at
+// https://opensource.org/licenses/MIT.
+
+import 'dart:io' as io;
+
+io.Stdout get stderr => io.stderr;
+
+List<String> getArguments(List<String> mainArguments) => mainArguments;
+
+String readFile(String path) => new io.File(path).readAsStringSync();
+
+bool fileExists(String path) => new io.File(path).existsSync();
+
+void exit(int exitCode) => io.exit(exitCode);

lib/src/visitor/perform.dart

@@ -2,7 +2,6 @@
 // MIT-style license that can be found in the LICENSE file or at
 // https://opensource.org/licenses/MIT.
 
-import 'dart:io';
 import 'dart:math' as math;
 
 import 'package:path/path.dart' as p;
@@ -17,6 +16,7 @@ import '../callable.dart';
 import '../environment.dart';
 import '../exception.dart';
 import '../extend/extender.dart';
+import '../io.dart';
 import '../utils.dart';
 import '../value.dart';
 import 'interface/statement.dart';
@@ -377,7 +377,7 @@ class PerformVisitor implements StatementVisitor, ExpressionVisitor<Value> {
     }
 
     return _importedFiles.putIfAbsent(path, () {
-      var contents = new File(path).readAsStringSync();
+      var contents = readFile(path);
       var url = p.toUri(path);
       return p.extension(path) == '.sass'
           ? new Stylesheet.parseSass(contents, url: url)
@@ -390,8 +390,8 @@ class PerformVisitor implements StatementVisitor, ExpressionVisitor<Value> {
 
   String _tryImportPath(String path) {
     var partial = p.join(p.dirname(path), "_${p.basename(path)}");
-    if (new File(partial).existsSync()) return partial;
-    if (new File(path).existsSync()) return path;
+    if (fileExists(partial)) return partial;
+    if (fileExists(path)) return path;
     return null;
   }
 

pubspec.yaml

@@ -17,6 +17,8 @@ dependencies:
   tuple: "^1.0.0"
 
 dev_dependencies:
-  test: "^0.12.0"
-  grinder: "^0.8.0"
   dart_style: "^0.2.9"
+  grinder: "^0.8.0"
+  js: "^0.6.0"
+  node_preamble: "^1.0.0"
+  test: "^0.12.0"

tool/grind.dart

@@ -2,14 +2,39 @@
 // MIT-style license that can be found in the LICENSE file or at
 // https://opensource.org/licenses/MIT.
 
+import 'dart:io';
+import 'dart:isolate';
+
 import 'package:grinder/grinder.dart';
+import 'package:node_preamble/preamble.dart' as preamble;
 
 main(args) => grind(args);
 
-@DefaultTask()
+@DefaultTask('Run the Dart formatter.')
 format() {
   Pub.run('dart_style',
       script: 'format',
       arguments: ['--overwrite']
         ..addAll(existingSourceDirs.map((dir) => dir.path)));
 }
+
+@Task('Build Dart snapshot.')
+snapshot() {
+  _ensureBuild();
+  Dart.run('bin/sass.dart', vmArgs: ['--snapshot=build/sass.dart.snapshot']);
+}
+
+@Task('Compile to JS.')
+js() {
+  _ensureBuild();
+  var destination = new File('build/sass.dart.js');
+  Dart2js.compile(new File('bin/sass.dart'),
+      outFile: destination, extraArgs: ['-Dnode=true']);
+  var text = destination.readAsStringSync();
+  destination.writeAsStringSync("${preamble.getPreamble()}\n$text");
+}
+
+/// Ensure that the `build/` directory exists.
+void _ensureBuild() {
+  new Directory('build').createSync(recursive: true);
+}