Buggy implementation of CSS @import.

lib/src/ast/css.dart

@@ -5,6 +5,7 @@
 export 'css/at_rule.dart';
 export 'css/comment.dart';
 export 'css/declaration.dart';
+export 'css/import.dart';
 export 'css/media_query.dart';
 export 'css/media_rule.dart';
 export 'css/node.dart';

lib/src/ast/css/import.dart

@@ -0,0 +1,18 @@
+// 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:source_span/source_span.dart';
+
+import '../../visitor/interface/css.dart';
+import 'node.dart';
+
+class CssImport extends CssNode {
+  final Uri url;
+
+  final FileSpan span;
+
+  CssImport(this.url, this.span);
+
+  /*=T*/ accept/*<T>*/(CssVisitor/*<T>*/ visitor) => visitor.visitImport(this);
+}

lib/src/ast/sass.dart

@@ -33,6 +33,7 @@ export 'sass/statement/import.dart';
 export 'sass/statement/include.dart';
 export 'sass/statement/media_rule.dart';
 export 'sass/statement/mixin_declaration.dart';
+export 'sass/statement/plain_import.dart';
 export 'sass/statement/return.dart';
 export 'sass/statement/style_rule.dart';
 export 'sass/statement/stylesheet.dart';

lib/src/ast/sass/statement/plain_import.dart

@@ -0,0 +1,22 @@
+// 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:source_span/source_span.dart';
+
+import '../../../visitor/interface/statement.dart';
+import '../expression/string.dart';
+import '../statement.dart';
+
+class PlainImport implements Statement {
+  final Uri url;
+
+  final FileSpan span;
+
+  PlainImport(this.url, this.span);
+
+  /*=T*/ accept/*<T>*/(StatementVisitor/*<T>*/ visitor) =>
+      visitor.visitPlainImport(this);
+
+  String toString() => "@import ${StringExpression.quoteText(url.toString())};";
+}

lib/src/parser.dart

@@ -395,17 +395,32 @@ class Parser {
     return new If(expression, children, _scanner.spanFrom(start));
   }
 
-  Import _import(LineScannerState start) {
+  Statement _import(LineScannerState start) {
     if (_inControlDirective) {
       _disallowedAtRule(start);
       return null;
+    }
+
+    // TODO: wrap error with a span
+    // TODO: parse supports clauses, url(), and query lists
+    var urlString = _string(static: true).text.asPlain;
+    var url = Uri.parse(urlString);
+    if (_isPlainImportUrl(urlString)) {
+      return new PlainImport(url, _scanner.spanFrom(start));
     } else {
-      // TODO: wrap error with a span
-      var url = Uri.parse(_string(static: true).text.asPlain);
       return new Import(url, _scanner.spanFrom(start));
     }
   }
 
+  bool _isPlainImportUrl(String url) {
+    if (url.length < "//".length) return false;
+
+    var first = url.codeUnitAt(0);
+    if (first == $slash) return url.codeUnitAt(1) == $slash;
+    if (first != $h) return false;
+    return url.startsWith("http://") || url.startsWith("https://");
+  }
+
   Include _include(LineScannerState start) {
     var name = _identifier();
     _ignoreComments();

lib/src/visitor/interface/css.dart

@@ -10,6 +10,7 @@ abstract class CssVisitor<T> extends SelectorVisitor<T>
     implements ValueVisitor<T> {
   T visitComment(CssComment node) => null;
   T visitDeclaration(CssDeclaration node) => null;
+  T visitImport(CssImport node) => null;
 
   T visitAtRule(CssAtRule node) {
     if (node.children == null) return null;

lib/src/visitor/interface/statement.dart

@@ -9,6 +9,7 @@ abstract class StatementVisitor<T> {
   T visitContent(Content node) => null;
   T visitExtendRule(ExtendRule node) => null;
   T visitImport(Import node) => null;
+  T visitPlainImport(PlainImport node) => null;
   T visitReturn(Return node) => null;
   T visitVariableDeclaration(VariableDeclaration node) => null;
 

lib/src/visitor/perform.dart

@@ -291,6 +291,9 @@ class PerformVisitor extends StatementVisitor
     return new CssMediaQuery(type, modifier: modifier, features: features);
   }
 
+  CssImport visitPlainImport(PlainImport node) =>
+      new CssImport(node.url, node.span);
+
   Value visitReturn(Return node) => node.expression.accept(this);
 
   void visitStyleRule(StyleRule node) {

lib/src/visitor/serialize.dart

@@ -95,6 +95,13 @@ class _SerializeCssVisitor extends CssVisitor {
     _visitChildren(node.children);
   }
 
+  void visitImport(CssImport node) {
+    _writeIndentation();
+    _buffer.write("@import ");
+    _visitString(node.url.toString());
+    _buffer.writeCharCode($semicolon);
+  }
+
   void visitMediaQuery(CssMediaQuery query) {
     if (query.modifier != null) {
       _buffer.write(query.modifier.value);