Stop running pub get at gclient sync time and fix build bugs

mojo/public/dart/third_party/csslib/lib/src/analyzer.dart

+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of csslib.parser;
+
+// TODO(terry): Add optimizing phase to remove duplicated selectors in the same
+//              selector group (e.g., .btn, .btn { color: red; }).  Also, look
+//              at simplifying selectors expressions too (much harder).
+// TODO(terry): Detect invalid directive usage.  All @imports must occur before
+//              all rules other than @charset directive.  Any @import directive
+//              after any non @charset or @import directive are ignored. e.g.,
+//                  @import "a.css";
+//                  div { color: red; }
+//                  @import "b.css";
+//              becomes:
+//                  @import "a.css";
+//                  div { color: red; }
+// <http://www.w3.org/TR/css3-syntax/#at-rules>
+
+/**
+ * Analysis phase will validate/fixup any new CSS feature or any SASS style
+ * feature.
+ */
+class Analyzer {
+  final List<StyleSheet> _styleSheets;
+  final Messages _messages;
+
+  Analyzer(this._styleSheets, this._messages);
+
+  // TODO(terry): Currently each feature walks the AST each time.  Once we have
+  //               our complete feature set consider benchmarking the cost and
+  //               possibly combine in one walk.
+  void run() {
+    // Expand top-level @include.
+    _styleSheets.forEach(
+        (styleSheet) => TopLevelIncludes.expand(_messages, _styleSheets));
+
+    // Expand @include in declarations.
+    _styleSheets.forEach(
+        (styleSheet) => DeclarationIncludes.expand(_messages, _styleSheets));
+
+    // Remove all @mixin and @include
+    _styleSheets.forEach((styleSheet) => MixinsAndIncludes.remove(styleSheet));
+
+    // Expand any nested selectors using selector desendant combinator to
+    // signal CSS inheritance notation.
+    _styleSheets.forEach((styleSheet) => new ExpandNestedSelectors()
+      ..visitStyleSheet(styleSheet)
+      ..flatten(styleSheet));
+
+    // Expand any @extend.
+    _styleSheets.forEach((styleSheet) {
+      var allExtends = new AllExtends()..visitStyleSheet(styleSheet);
+      new InheritExtends(_messages, allExtends)..visitStyleSheet(styleSheet);
+    });
+  }
+}
+
+/**
+ * Traverse all rulesets looking for nested ones.  If a ruleset is in a
+ * declaration group (implies nested selector) then generate new ruleset(s) at
+ * level 0 of CSS using selector inheritance syntax (flattens the nesting).
+ *
+ * How the AST works for a rule [RuleSet] and nested rules.  First of all a
+ * CSS rule [RuleSet] consist of a selector and a declaration e.g.,
+ *
+ *    selector {
+ *      declaration
+ *    }
+ *
+ * AST structure of a [RuleSet] is:
+ *
+ *    RuleSet
+ *       SelectorGroup
+ *         List<Selector>
+ *            List<SimpleSelectorSequence>
+ *              Combinator      // +, >, ~, DESCENDENT, or NONE
+ *              SimpleSelector  // class, id, element, namespace, attribute
+ *        DeclarationGroup
+ *          List                // Declaration or RuleSet
+ *
+ * For the simple rule:
+ *
+ *    div + span { color: red; }
+ *
+ * the AST [RuleSet] is:
+ *
+ *    RuleSet
+ *       SelectorGroup
+ *         List<Selector>
+ *          [0]
+ *            List<SimpleSelectorSequence>
+ *              [0] Combinator = COMBINATOR_NONE
+ *                  ElementSelector (name = div)
+ *              [1] Combinator = COMBINATOR_PLUS
+ *                  ElementSelector (name = span)
+ *        DeclarationGroup
+ *          List                // Declarations or RuleSets
+ *            [0]
+ *              Declaration (property = color, expression = red)
+ *
+ * Usually a SelectorGroup contains 1 Selector.  Consider the selectors:
+ *
+ *    div { color: red; }
+ *    a { color: red; }
+ *
+ * are equivalent to
+ *
+ *    div, a { color : red; }
+ *
+ * In the above the RuleSet would have a SelectorGroup with 2 selectors e.g.,
+ *
+ *    RuleSet
+ *       SelectorGroup
+ *         List<Selector>
+ *          [0]
+ *            List<SimpleSelectorSequence>
+ *              [0] Combinator = COMBINATOR_NONE
+ *                  ElementSelector (name = div)
+ *          [1]
+ *            List<SimpleSelectorSequence>
+ *              [0] Combinator = COMBINATOR_NONE
+ *                  ElementSelector (name = a)
+ *        DeclarationGroup
+ *          List                // Declarations or RuleSets
+ *            [0]
+ *              Declaration (property = color, expression = red)
+ *
+ * For a nested rule e.g.,
+ *
+ *    div {
+ *      color : blue;
+ *      a { color : red; }
+ *    }
+ *
+ * Would map to the follow CSS rules:
+ *
+ *    div { color: blue; }
+ *    div a { color: red; }
+ *
+ * The AST for the former nested rule is:
+ *
+ *    RuleSet
+ *       SelectorGroup
+ *         List<Selector>
+ *          [0]
+ *            List<SimpleSelectorSequence>
+ *              [0] Combinator = COMBINATOR_NONE
+ *                  ElementSelector (name = div)
+ *        DeclarationGroup
+ *          List                // Declarations or RuleSets
+ *            [0]
+ *              Declaration (property = color, expression = blue)
+ *            [1]
+ *              RuleSet
+ *                SelectorGroup
+ *                  List<Selector>
+ *                    [0]
+ *                      List<SimpleSelectorSequence>
+ *                        [0] Combinator = COMBINATOR_NONE
+ *                            ElementSelector (name = a)
+ *                DeclarationGroup
+ *                  List                // Declarations or RuleSets
+ *                    [0]
+ *                      Declaration (property = color, expression = red)
+ *
+ * Nested rules is a terse mechanism to describe CSS inheritance.  The analyzer
+ * will flatten and expand the nested rules to it's flatten strucure.  Using the
+ * all parent [RuleSets] (selector expressions) and applying each nested
+ * [RuleSet] to the list of [Selectors] in a [SelectorGroup].
+ *
+ * Then result is a style sheet where all nested rules have been flatten and
+ * expanded.
+ */
+class ExpandNestedSelectors extends Visitor {
+  /** Parent [RuleSet] if a nested rule otherwise [:null:]. */
+  RuleSet _parentRuleSet;
+
+  /** Top-most rule if nested rules. */
+  SelectorGroup _topLevelSelectorGroup;
+
+  /** SelectorGroup at each nesting level. */
+  SelectorGroup _nestedSelectorGroup;
+
+  /** Declaration (sans the nested selectors). */
+  DeclarationGroup _flatDeclarationGroup;
+
+  /** Each nested selector get's a flatten RuleSet. */
+  List<RuleSet> _expandedRuleSets = [];
+
+  /** Maping of a nested rule set to the fully expanded list of RuleSet(s). */
+  final Map<RuleSet, List<RuleSet>> _expansions = new Map();
+
+  void visitRuleSet(RuleSet node) {
+    final oldParent = _parentRuleSet;
+
+    var oldNestedSelectorGroups = _nestedSelectorGroup;
+
+    if (_nestedSelectorGroup == null) {
+      // Create top-level selector (may have nested rules).
+      final newSelectors = node.selectorGroup.selectors.toList();
+      _topLevelSelectorGroup = new SelectorGroup(newSelectors, node.span);
+      _nestedSelectorGroup = _topLevelSelectorGroup;
+    } else {
+      // Generate new selector groups from the nested rules.
+      _nestedSelectorGroup = _mergeToFlatten(node);
+    }
+
+    _parentRuleSet = node;
+
+    super.visitRuleSet(node);
+
+    _parentRuleSet = oldParent;
+
+    // Remove nested rules; they're all flatten and in the _expandedRuleSets.
+    node.declarationGroup.declarations
+        .removeWhere((declaration) => declaration is RuleSet);
+
+    _nestedSelectorGroup = oldNestedSelectorGroups;
+
+    // If any expandedRuleSets and we're back at the top-level rule set then
+    // there were nested rule set(s).
+    if (_parentRuleSet == null) {
+      if (!_expandedRuleSets.isEmpty) {
+        // Remember ruleset to replace with these flattened rulesets.
+        _expansions[node] = _expandedRuleSets;
+        _expandedRuleSets = [];
+      }
+      assert(_flatDeclarationGroup == null);
+      assert(_nestedSelectorGroup == null);
+    }
+  }
+
+  /**
+   * Build up the list of all inherited sequences from the parent selector
+   * [node] is the current nested selector and it's parent is the last entry in
+   * the [_nestedSelectorGroup].
+   */
+  SelectorGroup _mergeToFlatten(RuleSet node) {
+    // Create a new SelectorGroup for this nesting level.
+    var nestedSelectors = _nestedSelectorGroup.selectors;
+    var selectors = node.selectorGroup.selectors;
+
+    // Create a merged set of previous parent selectors and current selectors.
+    var newSelectors = [];
+    for (Selector selector in selectors) {
+      for (Selector nestedSelector in nestedSelectors) {
+        var seq = _mergeNestedSelector(nestedSelector.simpleSelectorSequences,
+            selector.simpleSelectorSequences);
+        newSelectors.add(new Selector(seq, node.span));
+      }
+    }
+
+    return new SelectorGroup(newSelectors, node.span);
+  }
+
+  /**
+   * Merge the nested selector sequences [current] to the [parent] sequences or
+   * substitue any & with the parent selector.
+   */
+  List<SimpleSelectorSequence> _mergeNestedSelector(
+      List<SimpleSelectorSequence> parent,
+      List<SimpleSelectorSequence> current) {
+
+    // If any & operator then the parent selector will be substituted otherwise
+    // the parent selector is pre-pended to the current selector.
+    var hasThis = current.any((s) => s.simpleSelector.isThis);
+
+    var newSequence = [];
+
+    if (!hasThis) {
+      // If no & in the sector group then prefix with the parent selector.
+      newSequence.addAll(parent);
+      newSequence.addAll(_convertToDescendentSequence(current));
+    } else {
+      for (var sequence in current) {
+        if (sequence.simpleSelector.isThis) {
+          // Substitue the & with the parent selector and only use a combinator
+          // descendant if & is prefix by a sequence with an empty name e.g.,
+          // "... + &", "&", "... ~ &", etc.
+          var hasPrefix = !newSequence.isEmpty &&
+              !newSequence.last.simpleSelector.name.isEmpty;
+          newSequence.addAll(
+              hasPrefix ? _convertToDescendentSequence(parent) : parent);
+        } else {
+          newSequence.add(sequence);
+        }
+      }
+    }
+
+    return newSequence;
+  }
+
+  /**
+   * Return selector sequences with first sequence combinator being a
+   * descendant.  Used for nested selectors when the parent selector needs to
+   * be prefixed to a nested selector or to substitute the this (&) with the
+   * parent selector.
+   */
+  List<SimpleSelectorSequence> _convertToDescendentSequence(
+      List<SimpleSelectorSequence> sequences) {
+    if (sequences.isEmpty) return sequences;
+
+    var newSequences = [];
+    var first = sequences.first;
+    newSequences.add(new SimpleSelectorSequence(
+        first.simpleSelector, first.span, TokenKind.COMBINATOR_DESCENDANT));
+    newSequences.addAll(sequences.skip(1));
+
+    return newSequences;
+  }
+
+  void visitDeclarationGroup(DeclarationGroup node) {
+    var span = node.span;
+
+    var currentGroup = new DeclarationGroup([], span);
+
+    var oldGroup = _flatDeclarationGroup;
+    _flatDeclarationGroup = currentGroup;
+
+    var expandedLength = _expandedRuleSets.length;
+
+    super.visitDeclarationGroup(node);
+
+    // We're done with the group.
+    _flatDeclarationGroup = oldGroup;
+
+    // No nested rule to process it's a top-level rule.
+    if (_nestedSelectorGroup == _topLevelSelectorGroup) return;
+
+    // If flatten selector's declaration is empty skip this selector, no need
+    // to emit an empty nested selector.
+    if (currentGroup.declarations.isEmpty) return;
+
+    var selectorGroup = _nestedSelectorGroup;
+
+    // Build new rule set from the nested selectors and declarations.
+    var newRuleSet = new RuleSet(selectorGroup, currentGroup, span);
+
+    // Place in order so outer-most rule is first.
+    if (expandedLength == _expandedRuleSets.length) {
+      _expandedRuleSets.add(newRuleSet);
+    } else {
+      _expandedRuleSets.insert(expandedLength, newRuleSet);
+    }
+  }
+
+  // Record all declarations in a nested selector (Declaration, VarDefinition
+  // and MarginGroup) but not the nested rule in the Declaration.
+
+  void visitDeclaration(Declaration node) {
+    if (_parentRuleSet != null) {
+      _flatDeclarationGroup.declarations.add(node);
+    }
+    super.visitDeclaration(node);
+  }
+
+  void visitVarDefinition(VarDefinition node) {
+    if (_parentRuleSet != null) {
+      _flatDeclarationGroup.declarations.add(node);
+    }
+    super.visitVarDefinition(node);
+  }
+
+  void visitExtendDeclaration(ExtendDeclaration node) {
+    if (_parentRuleSet != null) {
+      _flatDeclarationGroup.declarations.add(node);
+    }
+    super.visitExtendDeclaration(node);
+  }
+
+  void visitMarginGroup(MarginGroup node) {
+    if (_parentRuleSet != null) {
+      _flatDeclarationGroup.declarations.add(node);
+    }
+    super.visitMarginGroup(node);
+  }
+
+  /**
+   * Replace the rule set that contains nested rules with the flatten rule sets.
+   */
+  void flatten(StyleSheet styleSheet) {
+    // TODO(terry): Iterate over topLevels instead of _expansions it's already
+    //              a map (this maybe quadratic).
+    _expansions.forEach((RuleSet ruleSet, List<RuleSet> newRules) {
+      var index = styleSheet.topLevels.indexOf(ruleSet);
+      if (index == -1) {
+        // Check any @media directives for nested rules and replace them.
+        var found = _MediaRulesReplacer.replace(styleSheet, ruleSet, newRules);
+        assert(found);
+      } else {
+        styleSheet.topLevels.insertAll(index + 1, newRules);
+      }
+    });
+    _expansions.clear();
+  }
+}
+
+class _MediaRulesReplacer extends Visitor {
+  RuleSet _ruleSet;
+  List<RuleSet> _newRules;
+  bool _foundAndReplaced = false;
+
+  /**
+   * Look for the [ruleSet] inside of an @media directive; if found then replace
+   * with the [newRules].  If [ruleSet] is found and replaced return true.
+   */
+  static bool replace(
+      StyleSheet styleSheet, RuleSet ruleSet, List<RuleSet> newRules) {
+    var visitor = new _MediaRulesReplacer(ruleSet, newRules);
+    visitor.visitStyleSheet(styleSheet);
+    return visitor._foundAndReplaced;
+  }
+
+  _MediaRulesReplacer(this._ruleSet, this._newRules);
+
+  visitMediaDirective(MediaDirective node) {
+    var index = node.rulesets.indexOf(_ruleSet);
+    if (index != -1) {
+      node.rulesets.insertAll(index + 1, _newRules);
+      _foundAndReplaced = true;
+    }
+  }
+}
+
+/**
+ * Expand all @include at the top-level the ruleset(s) associated with the
+ * mixin.
+ */
+class TopLevelIncludes extends Visitor {
+  StyleSheet _styleSheet;
+  final Messages _messages;
+  /** Map of variable name key to it's definition. */
+  final Map<String, MixinDefinition> map = new Map<String, MixinDefinition>();
+  MixinDefinition currDef;
+
+  static void expand(Messages messages, List<StyleSheet> styleSheets) {
+    new TopLevelIncludes(messages, styleSheets);
+  }
+
+  bool _anyRulesets(MixinRulesetDirective def) =>
+      def.rulesets.any((rule) => rule is RuleSet);
+
+  TopLevelIncludes(this._messages, List<StyleSheet> styleSheets) {
+    for (var styleSheet in styleSheets) {
+      visitTree(styleSheet);
+    }
+  }
+
+  void visitStyleSheet(StyleSheet ss) {
+    _styleSheet = ss;
+    super.visitStyleSheet(ss);
+    _styleSheet = null;
+  }
+
+  void visitIncludeDirective(IncludeDirective node) {
+    if (map.containsKey(node.name)) {
+      var mixinDef = map[node.name];
+      if (mixinDef is MixinRulesetDirective) {
+        _TopLevelIncludeReplacer.replace(
+            _messages, _styleSheet, node, mixinDef.rulesets);
+      } else if (currDef is MixinRulesetDirective && _anyRulesets(currDef)) {
+        // currDef is MixinRulesetDirective
+        MixinRulesetDirective mixinRuleset = currDef;
+        int index = mixinRuleset.rulesets.indexOf(node as dynamic);
+        mixinRuleset.rulesets.replaceRange(index, index + 1, [new NoOp()]);
+        _messages.warning(
+            'Using declaration mixin ${node.name} as top-level mixin',
+            node.span);
+      }
+    } else {
+      if (currDef is MixinRulesetDirective) {
+        MixinRulesetDirective rulesetDirect = currDef as MixinRulesetDirective;
+        var index = 0;
+        rulesetDirect.rulesets.forEach((entry) {
+          if (entry == node) {
+            rulesetDirect.rulesets.replaceRange(index, index + 1, [new NoOp()]);
+            _messages.warning('Undefined mixin ${node.name}', node.span);
+          }
+          index++;
+        });
+      }
+    }
+    super.visitIncludeDirective(node);
+  }
+
+  void visitMixinRulesetDirective(MixinRulesetDirective node) {
+    currDef = node;
+
+    super.visitMixinRulesetDirective(node);
+
+    // Replace with latest top-level mixin definition.
+    map[node.name] = node;
+    currDef = null;
+  }
+
+  void visitMixinDeclarationDirective(MixinDeclarationDirective node) {
+    currDef = node;
+
+    super.visitMixinDeclarationDirective(node);
+
+    // Replace with latest mixin definition.
+    map[node.name] = node;
+    currDef = null;
+  }
+}
+
+/** @include as a top-level with ruleset(s). */
+class _TopLevelIncludeReplacer extends Visitor {
+  final Messages _messages;
+  final IncludeDirective _include;
+  final List<RuleSet> _newRules;
+  bool _foundAndReplaced = false;
+
+  /**
+   * Look for the [ruleSet] inside of an @media directive; if found then replace
+   * with the [newRules].  If [ruleSet] is found and replaced return true.
+   */
+  static bool replace(Messages messages, StyleSheet styleSheet,
+      IncludeDirective include, List<RuleSet> newRules) {
+    var visitor = new _TopLevelIncludeReplacer(messages, include, newRules);
+    visitor.visitStyleSheet(styleSheet);
+    return visitor._foundAndReplaced;
+  }
+
+  _TopLevelIncludeReplacer(this._messages, this._include, this._newRules);
+
+  visitStyleSheet(StyleSheet node) {
+    var index = node.topLevels.indexOf(_include);
+    if (index != -1) {
+      node.topLevels.insertAll(index + 1, _newRules);
+      node.topLevels.replaceRange(index, index + 1, [new NoOp()]);
+      _foundAndReplaced = true;
+    }
+    super.visitStyleSheet(node);
+  }
+
+  void visitMixinRulesetDirective(MixinRulesetDirective node) {
+    var index = node.rulesets.indexOf(_include as dynamic);
+    if (index != -1) {
+      node.rulesets.insertAll(index + 1, _newRules);
+      // Only the resolve the @include once.
+      node.rulesets.replaceRange(index, index + 1, [new NoOp()]);
+      _foundAndReplaced = true;
+    }
+    super.visitMixinRulesetDirective(node);
+  }
+}
+
+/**
+ * Utility function to match an include to a list of either Declarations or
+ * RuleSets, depending on type of mixin (ruleset or declaration).  The include
+ * can be an include in a declaration or an include directive (top-level).
+ */
+int _findInclude(List list, var node) {
+  IncludeDirective matchNode =
+      (node is IncludeMixinAtDeclaration) ? node.include : node;
+
+  var index = 0;
+  for (var item in list) {
+    var includeNode = (item is IncludeMixinAtDeclaration) ? item.include : item;
+    if (includeNode == matchNode) return index;
+    index++;
+  }
+  return -1;
+}
+
+/**
+ * Stamp out a mixin with the defined args substituted with the user's
+ * parameters.
+ */
+class CallMixin extends Visitor {
+  final MixinDefinition mixinDef;
+  List _definedArgs;
+  Expressions _currExpressions;
+  int _currIndex = -1;
+
+  final varUsages = new Map<String, Map<Expressions, Set<int>>>();
+
+  /** Only var defs with more than one expression (comma separated). */
+  final Map<String, VarDefinition> varDefs;
+
+  CallMixin(this.mixinDef, [this.varDefs]) {
+    if (mixinDef is MixinRulesetDirective) {
+      visitMixinRulesetDirective(mixinDef);
+    } else {
+      visitMixinDeclarationDirective(mixinDef);
+    }
+  }
+
+  /**
+   * Given a mixin's defined arguments return a cloned mixin defintion that has
+   * replaced all defined arguments with user's supplied VarUsages.
+   */
+  MixinDefinition transform(List callArgs) {
+    // TODO(terry): Handle default arguments and varArgs.
+    // Transform mixin with callArgs.
+    for (var index = 0; index < _definedArgs.length; index++) {
+      var definedArg = _definedArgs[index];
+      VarDefinition varDef;
+      if (definedArg is VarDefinition) {
+        varDef = definedArg;
+      } else if (definedArg is VarDefinitionDirective) {
+        VarDefinitionDirective varDirective = definedArg;
+        varDef = varDirective.def;
+      }
+      var callArg = callArgs[index];
+
+      // Is callArg a var definition with multi-args (expressions > 1).
+      var defArgs = _varDefsAsCallArgs(callArg);
+      if (defArgs.isNotEmpty) {
+        // Replace call args with the var def parameters.
+        callArgs.insertAll(index, defArgs);
+        callArgs.removeAt(index + defArgs.length);
+        callArg = callArgs[index];
+      }
+
+      var expressions = varUsages[varDef.definedName];
+      expressions.forEach((k, v) {
+        for (var usagesIndex in v) {
+          k.expressions.replaceRange(usagesIndex, usagesIndex + 1, callArg);
+        }
+      });
+    }
+
+    // Clone the mixin
+    return mixinDef.clone();
+  }
+
+  /** Rip apart var def with multiple parameters. */
+  List<List<TreeNode>> _varDefsAsCallArgs(var callArg) {
+    var defArgs = [];
+    if (callArg is List && callArg[0] is VarUsage) {
+      var varDef = varDefs[callArg[0].name];
+      var expressions = varDef.expression.expressions;
+      assert(expressions.length > 1);
+      for (var expr in expressions) {
+        if (expr is! OperatorComma) {
+          defArgs.add([expr]);
+        }
+      }
+    }
+    return defArgs;
+  }
+
+  void visitExpressions(Expressions node) {
+    var oldExpressions = _currExpressions;
+    var oldIndex = _currIndex;
+
+    _currExpressions = node;
+    for (_currIndex = 0; _currIndex < node.expressions.length; _currIndex++) {
+      node.expressions[_currIndex].visit(this);
+    }
+
+    _currIndex = oldIndex;
+    _currExpressions = oldExpressions;
+  }
+
+  void _addExpression(Map<Expressions, Set<int>> expressions) {
+    var indexSet = new Set<int>();
+    indexSet.add(_currIndex);
+    expressions[_currExpressions] = indexSet;
+  }
+
+  void visitVarUsage(VarUsage node) {
+    assert(_currIndex != -1);
+    assert(_currExpressions != null);
+    if (varUsages.containsKey(node.name)) {
+      Map<Expressions, Set<int>> expressions = varUsages[node.name];
+      Set<int> allIndexes = expressions[_currExpressions];
+      if (allIndexes == null) {
+        _addExpression(expressions);
+      } else {
+        allIndexes.add(_currIndex);
+      }
+    } else {
+      var newExpressions = new Map<Expressions, Set<int>>();
+      _addExpression(newExpressions);
+      varUsages[node.name] = newExpressions;
+    }
+    super.visitVarUsage(node);
+  }
+
+  void visitMixinDeclarationDirective(MixinDeclarationDirective node) {
+    _definedArgs = node.definedArgs;
+    super.visitMixinDeclarationDirective(node);
+  }
+
+  void visitMixinRulesetDirective(MixinRulesetDirective node) {
+    _definedArgs = node.definedArgs;
+    super.visitMixinRulesetDirective(node);
+  }
+}
+
+/** Expand all @include inside of a declaration associated with a mixin. */
+class DeclarationIncludes extends Visitor {
+  StyleSheet _styleSheet;
+  final Messages _messages;
+  /** Map of variable name key to it's definition. */
+  final Map<String, MixinDefinition> map = new Map<String, MixinDefinition>();
+  /** Cache of mixin called with parameters. */
+  final Map<String, CallMixin> callMap = new Map<String, CallMixin>();
+  MixinDefinition currDef;
+  DeclarationGroup currDeclGroup;
+
+  /** Var definitions with more than 1 expression. */
+  final Map<String, VarDefinition> varDefs = new Map<String, VarDefinition>();
+
+  static void expand(Messages messages, List<StyleSheet> styleSheets) {
+    new DeclarationIncludes(messages, styleSheets);
+  }
+
+  DeclarationIncludes(this._messages, List<StyleSheet> styleSheets) {
+    for (var styleSheet in styleSheets) {
+      visitTree(styleSheet);
+    }
+  }
+
+  bool _allIncludes(rulesets) =>
+      rulesets.every((rule) => rule is IncludeDirective || rule is NoOp);
+
+  CallMixin _createCallDeclMixin(MixinDefinition mixinDef) {
+    callMap.putIfAbsent(mixinDef.name,
+        () => callMap[mixinDef.name] = new CallMixin(mixinDef, varDefs));
+    return callMap[mixinDef.name];
+  }
+
+  void visitStyleSheet(StyleSheet ss) {
+    _styleSheet = ss;
+    super.visitStyleSheet(ss);
+    _styleSheet = null;
+  }
+
+  void visitDeclarationGroup(DeclarationGroup node) {
+    currDeclGroup = node;
+    super.visitDeclarationGroup(node);
+    currDeclGroup = null;
+  }
+
+  void visitIncludeMixinAtDeclaration(IncludeMixinAtDeclaration node) {
+    if (map.containsKey(node.include.name)) {
+      var mixinDef = map[node.include.name];
+
+      // Fix up any mixin that is really a Declaration but has includes.
+      if (mixinDef is MixinRulesetDirective) {
+        if (!_allIncludes(mixinDef.rulesets) && currDeclGroup != null) {
+          var index = _findInclude(currDeclGroup.declarations, node);
+          if (index != -1) {
+            currDeclGroup.declarations.replaceRange(
+                index, index + 1, [new NoOp()]);
+          }
+          _messages.warning(
+              "Using top-level mixin ${node.include.name} as a declaration",
+              node.span);
+        } else {
+          // We're a list of @include(s) inside of a mixin ruleset - convert
+          // to a list of IncludeMixinAtDeclaration(s).
+          var origRulesets = mixinDef.rulesets;
+          var rulesets = [];
+          if (origRulesets.every((ruleset) => ruleset is IncludeDirective)) {
+            origRulesets.forEach((ruleset) {
+              rulesets
+                  .add(new IncludeMixinAtDeclaration(ruleset, ruleset.span));
+            });
+            _IncludeReplacer.replace(_styleSheet, node, rulesets);
+          }
+        }
+      }
+
+      if (mixinDef.definedArgs.length > 0 && node.include.args.length > 0) {
+        var callMixin = _createCallDeclMixin(mixinDef);
+        mixinDef = callMixin.transform(node.include.args);
+      }
+
+      if (mixinDef is MixinDeclarationDirective) {
+        _IncludeReplacer.replace(
+            _styleSheet, node, mixinDef.declarations.declarations);
+      }
+    } else {
+      _messages.warning("Undefined mixin ${node.include.name}", node.span);
+    }
+
+    super.visitIncludeMixinAtDeclaration(node);
+  }
+
+  void visitIncludeDirective(IncludeDirective node) {
+    if (map.containsKey(node.name)) {
+      var mixinDef = map[node.name];
+      if (currDef is MixinDeclarationDirective &&
+          mixinDef is MixinDeclarationDirective) {
+        _IncludeReplacer.replace(
+            _styleSheet, node, mixinDef.declarations.declarations);
+      } else if (currDef is MixinDeclarationDirective) {
+        var decls =
+            (currDef as MixinDeclarationDirective).declarations.declarations;
+        var index = _findInclude(decls, node);
+        if (index != -1) {
+          decls.replaceRange(index, index + 1, [new NoOp()]);
+        }
+      }
+    }
+
+    super.visitIncludeDirective(node);
+  }
+
+  void visitMixinRulesetDirective(MixinRulesetDirective node) {
+    currDef = node;
+
+    super.visitMixinRulesetDirective(node);
+
+    // Replace with latest top-level mixin definition.
+    map[node.name] = node;
+    currDef = null;
+  }
+
+  void visitMixinDeclarationDirective(MixinDeclarationDirective node) {
+    currDef = node;
+
+    super.visitMixinDeclarationDirective(node);
+
+    // Replace with latest mixin definition.
+    map[node.name] = node;
+    currDef = null;
+  }
+
+  void visitVarDefinition(VarDefinition node) {
+    // Only record var definitions that have multiple expressions (comma
+    // separated for mixin parameter substitution.
+    var exprs = (node.expression as Expressions).expressions;
+    if (exprs.length > 1) {
+      varDefs[node.definedName] = node;
+    }
+    super.visitVarDefinition(node);
+  }
+
+  void visitVarDefinitionDirective(VarDefinitionDirective node) {
+    visitVarDefinition(node.def);
+  }
+}
+
+/** @include as a top-level with ruleset(s). */
+class _IncludeReplacer extends Visitor {
+  final _include;
+  final List<Declaration> _newDeclarations;
+  bool _foundAndReplaced = false;
+
+  /**
+   * Look for the [ruleSet] inside of a @media directive; if found then replace
+   * with the [newRules].
+   */
+  static void replace(
+      StyleSheet ss, var include, List<Declaration> newDeclarations) {
+    var visitor = new _IncludeReplacer(include, newDeclarations);
+    visitor.visitStyleSheet(ss);
+  }
+
+  _IncludeReplacer(this._include, this._newDeclarations);
+
+  void visitDeclarationGroup(DeclarationGroup node) {
+    var index = _findInclude(node.declarations, _include);
+    if (index != -1) {
+      node.declarations.insertAll(index + 1, _newDeclarations);
+      // Change @include to NoOp so it's processed only once.
+      node.declarations.replaceRange(index, index + 1, [new NoOp()]);
+      _foundAndReplaced = true;
+    }
+    super.visitDeclarationGroup(node);
+  }
+}
+
+/**
+ * Remove all @mixin and @include and any NoOp used as placeholder for @include.
+ */
+class MixinsAndIncludes extends Visitor {
+  static void remove(StyleSheet styleSheet) {
+    new MixinsAndIncludes()..visitStyleSheet(styleSheet);
+  }
+
+  bool _nodesToRemove(node) =>
+      node is IncludeDirective || node is MixinDefinition || node is NoOp;
+
+  void visitStyleSheet(StyleSheet ss) {
+    var index = ss.topLevels.length;
+    while (--index >= 0) {
+      if (_nodesToRemove(ss.topLevels[index])) {
+        ss.topLevels.removeAt(index);
+      }
+    }
+    super.visitStyleSheet(ss);
+  }
+
+  void visitDeclarationGroup(DeclarationGroup node) {
+    var index = node.declarations.length;
+    while (--index >= 0) {
+      if (_nodesToRemove(node.declarations[index])) {
+        node.declarations.removeAt(index);
+      }
+    }
+    super.visitDeclarationGroup(node);
+  }
+}
+
+/** Find all @extend to create inheritance. */
+class AllExtends extends Visitor {
+  final Map<String, List<SelectorGroup>> inherits =
+      new Map<String, List<SelectorGroup>>();
+
+  SelectorGroup _currSelectorGroup;
+  int _currDeclIndex;
+  List<int> _extendsToRemove = [];
+
+  void visitRuleSet(RuleSet node) {
+    var oldSelectorGroup = _currSelectorGroup;
+    _currSelectorGroup = node.selectorGroup;
+
+    super.visitRuleSet(node);
+
+    _currSelectorGroup = oldSelectorGroup;
+  }
+
+  void visitExtendDeclaration(ExtendDeclaration node) {
+    var inheritName = "";
+    for (var selector in node.selectors) {
+      inheritName += selector.toString();
+    }
+    if (inherits.containsKey(inheritName)) {
+      inherits[inheritName].add(_currSelectorGroup);
+    } else {
+      inherits[inheritName] = [_currSelectorGroup];
+    }
+
+    // Remove this @extend
+    _extendsToRemove.add(_currDeclIndex);
+
+    super.visitExtendDeclaration(node);
+  }
+
+  void visitDeclarationGroup(DeclarationGroup node) {
+    var oldDeclIndex = _currDeclIndex;
+
+    var decls = node.declarations;
+    for (_currDeclIndex = 0; _currDeclIndex < decls.length; _currDeclIndex++) {
+      decls[_currDeclIndex].visit(this);
+    }
+
+    if (_extendsToRemove.isNotEmpty) {
+      var removeTotal = _extendsToRemove.length - 1;
+      for (var index = removeTotal; index >= 0; index--) {
+        decls.removeAt(_extendsToRemove[index]);
+      }
+      _extendsToRemove.clear();
+    }
+
+    _currDeclIndex = oldDeclIndex;
+  }
+}
+
+// TODO(terry): Need to handle merging selector sequences
+// TODO(terry): Need to handle @extend-Only selectors.
+// TODO(terry): Need to handle !optional glag.
+/**
+ * Changes any selector that matches @extend.
+ */
+class InheritExtends extends Visitor {
+  final Messages _messages;
+  final AllExtends _allExtends;
+
+  InheritExtends(this._messages, this._allExtends);
+
+  void visitSelectorGroup(SelectorGroup node) {
+    for (var selectorsIndex = 0;
+        selectorsIndex < node.selectors.length;
+        selectorsIndex++) {
+      var selectors = node.selectors[selectorsIndex];
+      var isLastNone = false;
+      var selectorName = "";
+      for (var index = 0;
+          index < selectors.simpleSelectorSequences.length;
+          index++) {
+        var simpleSeq = selectors.simpleSelectorSequences[index];
+        var namePart = simpleSeq.simpleSelector.toString();
+        selectorName = (isLastNone) ? (selectorName + namePart) : namePart;
+        List<SelectorGroup> matches = _allExtends.inherits[selectorName];
+        if (matches != null) {
+          for (var match in matches) {
+            // Create a new group.
+            var newSelectors = selectors.clone();
+            var newSeq = match.selectors[0].clone();
+            if (isLastNone) {
+              // Add the inherited selector.
+              node.selectors.add(newSeq);
+            } else {
+              // Replace the selector sequence to the left of the pseudo class
+              // or pseudo element.
+
+              // Make new selector seq combinator the same as the original.
+              var orgCombinator =
+                  newSelectors.simpleSelectorSequences[index].combinator;
+              newSeq.simpleSelectorSequences[0].combinator = orgCombinator;
+
+              newSelectors.simpleSelectorSequences.replaceRange(
+                  index, index + 1, newSeq.simpleSelectorSequences);
+              node.selectors.add(newSelectors);
+            }
+            isLastNone = false;
+          }
+        } else {
+          isLastNone = simpleSeq.isCombinatorNone;
+        }
+      }
+    }
+    super.visitSelectorGroup(node);
+  }
+}