Allow conditional statements inside rulesets, including mixins.

This change allows for conditionally including properties within a ruleset or
mixin, like so:

@defmixin foo() {
  @if (COND) {
    bar: baz
  }
}

Previously, this would cause an IllegalStateException in the @defmixin case
from the precondition in CssConditionalRuleNode or an unknown @ rule in the
ruleset case.
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=118486801

src/com/google/common/css/compiler/ast/CssConditionalRuleNode.java

@@ -47,7 +47,7 @@ public CssConditionalRuleNode(Type type, CssLiteralNode name) {
    */
   public CssConditionalRuleNode(Type type, CssLiteralNode name,
                                 @Nullable CssBooleanExpressionNode condition,
-                                CssBlockNode block) {
+                                CssAbstractBlockNode block) {
     super(type, name, block);
     Preconditions.checkArgument(this.getType().isConditional());
     if (condition != null) {
@@ -98,9 +98,8 @@ void setCondition(CssBooleanExpressionNode condition) {
   }
 
   @Override
-  public CssBlockNode getBlock() {
-    // This type is ensured by the constructor.
-    return (CssBlockNode) super.getBlock();
+  public CssAbstractBlockNode getBlock() {
+    return super.getBlock();
   }
 
   // TODO(user): Make sure that the parameters list is made up of a single

src/com/google/common/css/compiler/ast/CssDeclarationBlockNode.java

@@ -19,15 +19,16 @@
 import com.google.common.collect.ImmutableList;
 
 /**
- * A {@link CssAbstractBlockNode} that contains only declarations and @-rules.
+ * A {@link CssAbstractBlockNode} that contains only declarations, @-rules,
+ * and conditional blocks.
  *
  * @author fbenz@google.com (Florian Benz)
  */
 public class CssDeclarationBlockNode extends CssAbstractBlockNode {
 
   private static final ImmutableList<Class<? extends CssNode>>
       VALID_NODE_CLASSES = ImmutableList.of(
-          CssDeclarationNode.class, CssAtRuleNode.class);
+          CssDeclarationNode.class, CssAtRuleNode.class, CssConditionalBlockNode.class);
 
   public CssDeclarationBlockNode() {
     super(true, VALID_NODE_CLASSES);

src/com/google/common/css/compiler/ast/CssTreeBuilder.java

@@ -61,7 +61,7 @@ enum State {
   private boolean treeIsConstructed = false;
 
   // TODO(user): Use Collections.asLifoQueue(new ArrayDeque()) for openBlocks
-  private List<CssBlockNode> openBlocks = null;
+  private List<CssAbstractBlockNode> openBlocks = null;
   private List<CssConditionalBlockNode> openConditionalBlocks = null;
   private CssDeclarationBlockNode declarationBlock = null;
   private CssDeclarationNode declaration = null;
@@ -114,11 +114,11 @@ private void startMainBody() {
     }
   }
 
-  private CssBlockNode getEnclosingBlock() {
+  private CssAbstractBlockNode getEnclosingBlock() {
     return openBlocks.get(openBlocks.size() - 1);
   }
 
-  private void pushEnclosingBlock(CssBlockNode block) {
+  private void pushEnclosingBlock(CssAbstractBlockNode block) {
     openBlocks.add(block);
   }
 

src/com/google/common/css/compiler/ast/DefaultVisitController.java

@@ -851,7 +851,7 @@ public void transitionToNextState() {
   @VisibleForTesting
   class VisitConditionalRuleChildrenState extends VisitReplaceChildrenState<CssNode> {
 
-    VisitConditionalRuleChildrenState(CssBlockNode block) {
+    VisitConditionalRuleChildrenState(CssAbstractBlockNode block) {
       super(block);
     }
   }

src/com/google/common/css/compiler/passes/CreateConditionalNodes.java

@@ -16,11 +16,10 @@
 
 package com.google.common.css.compiler.passes;
 
-import com.google.common.base.Preconditions;
 import com.google.common.collect.Lists;
 import com.google.common.css.SourceCodeLocation;
+import com.google.common.css.compiler.ast.CssAbstractBlockNode;
 import com.google.common.css.compiler.ast.CssAtRuleNode;
-import com.google.common.css.compiler.ast.CssBlockNode;
 import com.google.common.css.compiler.ast.CssBooleanExpressionNode;
 import com.google.common.css.compiler.ast.CssCompilerPass;
 import com.google.common.css.compiler.ast.CssConditionalBlockNode;
@@ -108,7 +107,7 @@ public void leaveUnknownAtRule(CssUnknownAtRuleNode node) {
   @Override
   public boolean enterRuleset(CssRulesetNode node) {
     activeBlockNode = null;
-    return false;
+    return true;
   }
 
   @Override
@@ -119,9 +118,7 @@ public boolean enterDefinition(CssDefinitionNode node) {
 
   private CssConditionalRuleNode createConditionalRuleNode(
       CssUnknownAtRuleNode node, String name) {
-    Preconditions.checkState(node.getBlock() == null
-        || node.getBlock() instanceof CssBlockNode);
-    CssBlockNode block = (CssBlockNode) node.getBlock();
+    CssAbstractBlockNode block = node.getBlock();
     if (block == null) {
       errorManager.report(new GssError("@" + name + " without block",
                                        node.getSourceCodeLocation()));

src/com/google/common/css/compiler/passes/PassRunner.java

@@ -96,6 +96,11 @@ public void runPasses(CssTree cssTree) {
     new ProcessRefiners(cssTree.getMutatingVisitController(), errorManager,
         job.simplifyCss).runPass();
 
+    // Eliminate conditional nodes.
+    new EliminateConditionalNodes(
+        cssTree.getMutatingVisitController(),
+        ImmutableSet.copyOf(job.trueConditionNames)).runPass();
+
     // Collect mixin definitions and replace mixins
     CollectMixinDefinitions collectMixinDefinitions =
         new CollectMixinDefinitions(cssTree.getMutatingVisitController(),
@@ -106,10 +111,6 @@ public void runPasses(CssTree cssTree) {
 
     new ProcessComponents<Object>(cssTree.getMutatingVisitController(),
         errorManager).runPass();
-    // Eliminate conditional nodes.
-    new EliminateConditionalNodes(
-        cssTree.getMutatingVisitController(),
-        ImmutableSet.copyOf(job.trueConditionNames)).runPass();
     // Collect constant definitions.
     CollectConstantDefinitions collectConstantDefinitionsPass =
         new CollectConstantDefinitions(cssTree);

tests/com/google/common/css/compiler/passes/CreateConditionalNodesTest.java

@@ -18,7 +18,9 @@
 
 import com.google.common.css.compiler.ast.CssConditionalBlockNode;
 import com.google.common.css.compiler.ast.CssConditionalRuleNode;
+import com.google.common.css.compiler.ast.CssDeclarationBlockNode;
 import com.google.common.css.compiler.ast.CssNode;
+import com.google.common.css.compiler.ast.CssRulesetNode;
 import com.google.common.css.compiler.ast.testing.NewFunctionalTestBase;
 
 /**
@@ -72,6 +74,26 @@ public void testCreateNestedConditionalBlockNode() throws Exception {
     assertEquals("[[d]{[e:[f]]}]", elseCondRuleIf.getBlock().toString());
   }
 
+  public void testCreateConditionalBlockNodeInRuleset() throws Exception {
+    parseAndRun("a {@if X {b: c} @else {d: e} }");
+    assertTrue(getFirstActualNode() instanceof CssRulesetNode);
+    CssRulesetNode ruleset = (CssRulesetNode) getFirstActualNode();
+    assertEquals("[a]{[[@if[X]{[b:[c]]}, @else[]{[d:[e]]}]]}", ruleset.toString());
+    CssDeclarationBlockNode declarationBlock = ruleset.getDeclarations();
+    assertEquals(1, declarationBlock.getChildren().size());
+    assertTrue(declarationBlock.getChildAt(0) instanceof CssConditionalBlockNode);
+    CssConditionalBlockNode condBlock = (CssConditionalBlockNode) declarationBlock.getChildAt(0);
+    assertEquals(2, condBlock.getChildren().size());
+    CssConditionalRuleNode condRuleIf = condBlock.getChildren().get(0);
+    CssConditionalRuleNode condRuleElse = condBlock.getChildren().get(1);
+    assertEquals("if", condRuleIf.getName().getValue());
+    assertEquals(1, condRuleIf.getParametersCount());
+    assertEquals("[b:[c]]", condRuleIf.getBlock().toString());
+    assertEquals("else", condRuleElse.getName().getValue());
+    assertEquals(0, condRuleElse.getParametersCount());
+    assertEquals("[d:[e]]", condRuleElse.getBlock().toString());
+  }
+
   public void testIfWithoutBlockError() throws Exception {
     parseAndRun("@if (X) ;", "@if without block");
   }