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Closure Stylesheets is an extension to CSS that adds variables, functions, conditionals, and mixins to standard CSS. The tool also supports minification, linting, RTL flipping, and CSS class renaming.

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/*
 * Copyright 2011 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.annotations.VisibleForTesting;
import com.google.common.collect.Sets;
import com.google.common.css.SourceCodeLocation;
import com.google.common.css.compiler.ast.*;

import java.util.Set;

/**
 * Compiler pass that reports an error if a ruleset has two of the same
 * declarations that are not marked as alternate. This must be run before
 * the SplitRulesetNodes pass.
 *
 * @author [email protected] (Henry Wong)
 */
public class DisallowDuplicateDeclarations extends DefaultTreeVisitor
        implements CssCompilerPass {

    private static final String ERROR_STR =
            "Detected multiple identical, non-alternate declarations in the same "
                    + "ruleset. If this is intentional please use the /* @alternate */ "
                    + "annotation. ";

    private final VisitController visitController;
    private final ErrorManager errorManager;

    private final Set propertyNames = Sets.newHashSet();

    public DisallowDuplicateDeclarations(VisitController visitController,
                                         ErrorManager errorManager) {
        this.visitController = visitController;
        this.errorManager = errorManager;
    }

    @Override
    public boolean enterRuleset(CssRulesetNode node) {
        for (CssNode child : node.getDeclarations().childIterable()) {
            // CssPropertyNodes don't get their location set, so just use the
            // location of the containing parent.
            SourceCodeLocation location = node.getSourceCodeLocation();
            if (location == null && !node.getSelectors().isEmpty()) {
                // If the ruleset doesn't have a location set, then use location in the selector within.
                location = node.getSelectors().getChildAt(0).getSourceCodeLocation();
            }
            processDeclaration((CssDeclarationNode) child, location);
        }

        // Clear the map for future re-use
        propertyNames.clear();

        return true;
    }

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

    /**
     * Tests a given declaration to see whether or not it has a property name
     * that we've seen before.
     */
    @VisibleForTesting
    void processDeclaration(CssDeclarationNode declaration,
                            SourceCodeLocation location) {

        String propertyName = declaration.getPropertyName().getPropertyName();

        // The MarkRemovableRulesetNodes pass special cases these so there's no
        // reason to check them here.
        // TODO(henrywong): Move PROPERTIES_NOT_TO_BE_CHECKED somewhere else.
        if (MarkRemovableRulesetNodes.PROPERTIES_NOT_TO_BE_CHECKED
                .contains(propertyName)) {
            return;
        }

        // If the declaration is star-hacked then we make the star be part of
        // the property name to ensure that we do not consider hacked
        // declarations as overridden by the non-hacked ones.
        // TODO(henrywong): This is copied from MarkRemovableRulesetNodes. We
        // should refactor this logic probably.
        if (declaration.hasStarHack()) {
            propertyName = "*" + propertyName;
        }

        // Ignore rules w/ the @alternate annotation.
        if (PassUtil.hasAlternateAnnotation(declaration)) {
            return;
        }

        if (propertyNames.contains(propertyName)) {
            errorManager.report(new GssError(ERROR_STR + declaration, location));
        } else {
            propertyNames.add(propertyName);
        }
    }
}