Add a compressed output style and pipe it through to the executable

lib/sass.dart

@@ -9,11 +9,13 @@ import 'src/compile.dart' as c;
 import 'src/exception.dart';
 import 'src/importer.dart';
 import 'src/sync_package_resolver.dart';
+import 'src/visitor/serialize.dart';
 
 export 'src/callable.dart' show Callable, AsyncCallable;
 export 'src/importer.dart';
 export 'src/value.dart' show ListSeparator;
 export 'src/value/external/value.dart';
+export 'src/visitor/serialize.dart' show OutputStyle;
 
 /// Loads the Sass file at [path], compiles it to CSS, and returns the result.
 ///
@@ -38,19 +40,23 @@ export 'src/value/external/value.dart';
 /// Each [Callable] defines a top-level function that will be invoked when the
 /// given name is called from Sass.
 ///
+/// The [style] parameter controls the style of the resulting CSS.
+///
 /// Throws a [SassException] if conversion fails.
 String compile(String path,
     {bool color: false,
     Iterable<Importer> importers,
     Iterable<String> loadPaths,
     SyncPackageResolver packageResolver,
-    Iterable<Callable> functions}) {
+    Iterable<Callable> functions,
+    OutputStyle style}) {
   var result = c.compile(path,
       color: color,
       importers: importers,
       loadPaths: loadPaths,
       packageResolver: packageResolver,
-      functions: functions);
+      functions: functions,
+      style: style);
   return result.css;
 }
 
@@ -79,6 +85,8 @@ String compile(String path,
 /// Each [Callable] defines a top-level function that will be invoked when the
 /// given name is called from Sass.
 ///
+/// The [style] parameter controls the style of the resulting CSS.
+///
 /// The [url] indicates the location from which [source] was loaded. It may be a
 /// [String] or a [Uri]. If [importer] is passed, [url] must be passed as well
 /// and `importer.load(url)` should return `source`.
@@ -91,6 +99,7 @@ String compileString(String source,
     SyncPackageResolver packageResolver,
     Iterable<String> loadPaths,
     Iterable<Callable> functions,
+    OutputStyle style,
     Importer importer,
     url}) {
   var result = c.compileString(source,
@@ -100,6 +109,7 @@ String compileString(String source,
       packageResolver: packageResolver,
       loadPaths: loadPaths,
       functions: functions,
+      style: style,
       importer: importer,
       url: url);
   return result.css;
@@ -115,13 +125,15 @@ Future<String> compileAsync(String path,
     Iterable<AsyncImporter> importers,
     SyncPackageResolver packageResolver,
     Iterable<String> loadPaths,
-    Iterable<AsyncCallable> functions}) async {
+    Iterable<AsyncCallable> functions,
+    OutputStyle style}) async {
   var result = await c.compileAsync(path,
       color: color,
       importers: importers,
       loadPaths: loadPaths,
       packageResolver: packageResolver,
-      functions: functions);
+      functions: functions,
+      style: style);
   return result.css;
 }
 
@@ -137,6 +149,7 @@ Future<String> compileStringAsync(String source,
     SyncPackageResolver packageResolver,
     Iterable<String> loadPaths,
     Iterable<AsyncCallable> functions,
+    OutputStyle style,
     AsyncImporter importer,
     url}) async {
   var result = await c.compileStringAsync(source,
@@ -146,6 +159,7 @@ Future<String> compileStringAsync(String source,
       packageResolver: packageResolver,
       loadPaths: loadPaths,
       functions: functions,
+      style: style,
       importer: importer,
       url: url);
   return result.css;

lib/src/executable.dart

@@ -20,7 +20,7 @@ main(List<String> args) async {
     ..addOption('style',
         abbr: 's',
         help: 'Output style.',
-        allowed: ['expanded'],
+        allowed: ['expanded', 'compressed'],
         defaultsTo: 'expanded')
     ..addFlag('color', abbr: 'c', help: 'Whether to emit terminal colors.')
     ..addFlag('trace', help: 'Print full Dart stack traces for exceptions.')
@@ -59,19 +59,22 @@ main(List<String> args) async {
 
   var color =
       options.wasParsed('color') ? options['color'] as bool : hasTerminal;
+  var style = options['style'] == 'compressed'
+      ? OutputStyle.compressed
+      : OutputStyle.expanded;
   var asynchronous = options['async'] as bool;
   try {
     String css;
     if (stdinFlag) {
-      css = await _compileStdin(asynchronous: asynchronous);
+      css = await _compileStdin(style: style, asynchronous: asynchronous);
     } else {
       var input = options.rest.first;
       if (input == '-') {
-        css = await _compileStdin(asynchronous: asynchronous);
+        css = await _compileStdin(style: style, asynchronous: asynchronous);
       } else if (asynchronous) {
-        css = await compileAsync(input, color: color);
+        css = await compileAsync(input, color: color, style: style);
       } else {
-        css = compile(input, color: color);
+        css = compile(input, color: color, style: style);
       }
     }
 
@@ -135,13 +138,14 @@ Future<String> _loadVersion() async {
 
 /// Compiles Sass from standard input and returns the result.
 Future<String> _compileStdin(
-    {bool asynchronous: false, bool color: false}) async {
+    {bool color: false, OutputStyle style, bool asynchronous: false}) async {
   var text = await readStdin();
   var importer = new FilesystemImporter('.');
   if (asynchronous) {
-    return await compileStringAsync(text, color: color, importer: importer);
+    return await compileStringAsync(text,
+        color: color, style: style, importer: importer);
   } else {
-    return compileString(text, color: color, importer: importer);
+    return compileString(text, color: color, style: style, importer: importer);
   }
 }
 

lib/src/node.dart

@@ -239,6 +239,7 @@ NodeImporter _parseImporter(RenderOptions options, DateTime start) {
 /// Parse [style] into an [OutputStyle].
 OutputStyle _parseOutputStyle(String style) {
   if (style == null || style == 'expanded') return OutputStyle.expanded;
+  if (style == 'compressed') return OutputStyle.compressed;
   throw new ArgumentError('Unsupported output style "$style".');
 }
 

lib/src/visitor/serialize.dart

@@ -981,8 +981,21 @@ class _SerializeVisitor implements CssVisitor, ValueVisitor, SelectorVisitor {
 /// An enum of generated CSS styles.
 class OutputStyle {
   /// The standard CSS style, with each declaration on its own line.
+  ///
+  /// ```css
+  /// .sidebar {
+  ///   width: 100px;
+  /// }
+  /// ```
   static const expanded = const OutputStyle._("expanded");
 
+  /// A CSS style that produces as few bytes of output as possible.
+  ///
+  /// ```css
+  /// .sidebar{width:100px}
+  /// ```
+  static const compressed = const OutputStyle._("compressed");
+
   /// The name of the style.
   final String _name;