Support for @mixin, @include and @extend

pkg/csslib/lib/src/tree.dart

Index: pkg/csslib/lib/src/tree.dart
diff --git a/pkg/csslib/lib/src/tree.dart b/pkg/csslib/lib/src/tree.dart
index e8411d31f8fabb185ab4bc46be89a65d032e4d27..370281e3b87f806b1336aa3955f7f7344ff86cb5 100644
--- a/pkg/csslib/lib/src/tree.dart
+++ b/pkg/csslib/lib/src/tree.dart
@@ -266,6 +266,12 @@ class NegationSelector extends SimpleSelector {
   visit(VisitorBase visitor) => visitor.visitNegationSelector(this);
 }
 
+class NoOp extends TreeNode {
+  NoOp() : super(null);
+
+  visit(VisitorBase visitor) => visitor.visitNoOp(this);
+}
+
 class StyleSheet extends TreeNode {
   /**
    * Contains charset, ruleset, directives (media, page, etc.), and selectors.
@@ -494,6 +500,53 @@ class VarDefinitionDirective extends Directive {
   visit(VisitorBase visitor) => visitor.visitVarDefinitionDirective(this);
 }
 
+class MixinDefinition extends Directive {
+  final String name;
+  final List definedArgs;
+  final bool varArgs;

[nweiz, 2013/09/18 22:40:54]

As with @content, don't include infrastructure for features that aren't
supported. You can add these once you actually support arguments.

[terry, 2013/10/09 03:40:33]

args supported.
On 2013/09/18 22:40:54, nweiz wrote:

+
+  MixinDefinition(this.name, this.definedArgs, this.varArgs, Span span)
+      : super(span);
+
+  visit(VisitorBase visitor) => visitor.visitMixinDefinition(this);
+}
+
+/** To support defining a SASS @mixin. */

[nweiz, 2013/09/18 22:40:54]

Only the first letter of "Sass" is capitalized.

These documentation comments are way too short. If I'm reading this as someone
who doesn't know what a mixin is, I'm completely befuddled. Actually explain
what a mixin is. Use complete sentences. If you have multiple classes for
similar things -- IncludeDirective vs IncludeMixinAtDeclaration, for example --
explain the difference.

[terry, 2013/10/09 03:40:33]

Ok, referenced web site no need to explain the Sass world again.
On 2013/09/18 22:40:54, nweiz wrote:

+class MixinRulesetDirective extends MixinDefinition {
+  final List<RuleSet> rulesets;
+
+  MixinRulesetDirective(String name, List args, bool varArgs, this.rulesets,
+      Span span) : super(name, args, varArgs, span);
+
+  visit(VisitorBase visitor) => visitor.visitMixinRulesetDirective(this);
+}
+
+class MixinDeclarationDirective extends MixinDefinition {
+  final DeclarationGroup declarations;
+
+  MixinDeclarationDirective(String name, List args, bool varArgs,
+      this.declarations, Span span) : super(name, args, varArgs, span);
+
+  visit(VisitorBase visitor) => visitor.visitMixinDeclarationDirective(this);
+}
+
+/** To support consuming a SASS mixin @include. */
+class IncludeDirective extends Directive {
+  final String name;
+  final List args;
+
+  IncludeDirective(this.name, this.args, Span span) : super(span);
+
+  visit(VisitorBase visitor) => visitor.visitIncludeDirective(this);
+}
+
+/** To support SASS @content. */
+class ContentDirective extends Directive {
+  ContentDirective(Span span) : super(span);
+
+  visit(VisitorBase visitor) => visitor.visitContentDirective(this);
+}
+
 class Declaration extends TreeNode {
   final Identifier _property;
   final Expression _expression;
@@ -544,6 +597,22 @@ class VarDefinition extends Declaration {
   visit(VisitorBase visitor) => visitor.visitVarDefinition(this);
 }
 
+/**
+ * Node for usage of @include mixin[(args,...)] found in a declaration group
+ * instead of at a ruleset (toplevel) e.g.,
+ * div {
+ *   @include mixin1;
+ * }
+ */
+class IncludeMixinAtDeclaration extends Declaration {
+  final IncludeDirective include;
+
+  IncludeMixinAtDeclaration(this.include, Span span)
+      : super(null, null, null, span);
+
+  visit(VisitorBase visitor) => visitor.visitIncludeMixinAtDeclaration(this);
+}
+
 class DeclarationGroup extends TreeNode {
   /** Can be either Declaration or RuleSet (if nested selector). */
   final List _declarations;