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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 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.ast;

import com.google.common.collect.ImmutableSet;

import java.util.Set;

/**
 * Any compiler pass which derives from this is able to skip
 * processing rules that contain specific property names.
 * 
 * TODO(user): Should we move these functions to the DefaultVisitController?
 */
public class SkippingTreeVisitor extends DefaultTreeVisitor {

    private boolean skipping = false;
    /**
     * The rules which contain any of these property names will be skipped,
     * if skipping is set to true.
     */
    final Set propertyNamesToSkip = ImmutableSet.of("display");
    // TODO(user): Possible more needed property names (which can trigger
    // hasLayout in IE): zoom, position, float

    /**
     * Constructor of a skipping tree visitor which sets the skipping property.
     *
     * @param skip
     */
    public SkippingTreeVisitor(boolean skip) {
        skipping = skip;
    }

    /**
     * This method checks if the given ruleset is safe to be changed.
     *
     * @return {@code false} if the ruleset is not safe to be modified (because
     * it contains any of the pre-defined property names when skipping is turned
     * on), true otherwise.
     */
    public boolean canModifyRuleset(CssRulesetNode ruleset) {
        // If skipping is on and the rule contains a property from the set : skip.
        if (skipping) {
            for (String propNameToSkip : propertyNamesToSkip) {
                for (CssNode child : ruleset.getDeclarations().childIterable()) {
                    if (!(child instanceof CssDeclarationNode)) {
                        continue;
                    }
                    CssDeclarationNode decl = (CssDeclarationNode) child;
                    if (decl.getPropertyName().getPropertyName().equals(propNameToSkip)) {
                        return false;
                    }
                }
            }
        }
        return true;
    }

    public boolean isSkipping() {
        return skipping;
    }

}