com.google.common.css.compiler.passes.CreateConstantReferences.java Source code

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Here is the source code for com.google.common.css.compiler.passes.CreateConstantReferences.java

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/*
 * Copyright 2009 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.css.compiler.passes;

import com.google.common.collect.ImmutableList;
import com.google.common.css.compiler.ast.CssCompilerPass;
import com.google.common.css.compiler.ast.CssConstantReferenceNode;
import com.google.common.css.compiler.ast.CssLiteralNode;
import com.google.common.css.compiler.ast.CssMixinDefinitionNode;
import com.google.common.css.compiler.ast.CssNode;
import com.google.common.css.compiler.ast.CssRootNode;
import com.google.common.css.compiler.ast.CssValueNode;
import com.google.common.css.compiler.ast.DefaultTreeVisitor;
import com.google.common.css.compiler.ast.MutatingVisitController;

/**
 * A compiler pass that transforms each upper-cased {@link CssLiteralNode} to
 * a {@link CssConstantReferenceNode}.
 *
 * @author fbenz@google.com (Florian Benz)
 */
public class CreateConstantReferences extends DefaultTreeVisitor implements CssCompilerPass {

    private final MutatingVisitController visitController;
    private CssNode globalScope;
    private CssNode currentScope;

    public CreateConstantReferences(MutatingVisitController visitController) {
        this.visitController = visitController;
    }

    @Override
    public void leaveValueNode(CssValueNode node) {
        if (!(node instanceof CssLiteralNode) || !CssConstantReferenceNode.isDefinitionReference(node.getValue())) {
            return;
        }
        CssConstantReferenceNode ref = new CssConstantReferenceNode(node.getValue(), node.getSourceCodeLocation());
        visitController.replaceCurrentBlockChildWith(ImmutableList.of(ref), false);
        CssNode scope = determineScope(ref);
        ref.setScope(scope);
    }

    @Override
    public void leaveArgumentNode(CssValueNode node) {
        leaveValueNode(node);
    }

    @Override
    public boolean enterTree(CssRootNode node) {
        globalScope = node;
        return true;
    }

    @Override
    public boolean enterMixinDefinition(CssMixinDefinitionNode node) {
        currentScope = node;
        return true;
    }

    @Override
    public void leaveMixinDefinition(CssMixinDefinitionNode node) {
        currentScope = globalScope;
    }

    /**
     * Returns the scope of the given reference.
     */
    private CssNode determineScope(CssConstantReferenceNode ref) {
        if (currentScope instanceof CssMixinDefinitionNode) {
            CssMixinDefinitionNode mixinDef = (CssMixinDefinitionNode) currentScope;
            // Search for a matching argument.
            for (CssValueNode arg : mixinDef.getArguments().getChildren()) {
                if (arg.getValue().equals(ref.getValue())) {
                    return currentScope;
                }
            }
        }
        return globalScope;
    }

    @Override
    public void runPass() {
        visitController.startVisit(this);
    }
}