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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 2012 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.css.SourceCodeLocation;
import com.google.common.css.compiler.ast.*;

/**
 * Build up an s-expression corresponding to the AST for debugging purposes.
 */
public class SExprPrintingVisitor extends DefaultTreeVisitor implements UniformVisitor {

    private final CodeBuffer buffer;
    private final boolean includeHashCodes;
    private final boolean withLocationAnnotation;

    /**
     * A S-Expr printer for {@link CssNode} instances.
     *
     * @param includeHashCodes       boolean switch to include hash code for node or not.
     * @param withLocationAnnotation boolean switch to include source code location or not.
     */
    public SExprPrintingVisitor(
            CodeBuffer buffer, boolean includeHashCodes, boolean withLocationAnnotation) {
        this.buffer = buffer;
        this.includeHashCodes = includeHashCodes;
        this.withLocationAnnotation = withLocationAnnotation;
    }

    @Override
    public void enter(CssNode node) {
        if (includeHashCodes) {
            buffer.append(String.format("(%s@%d ", node.getClass().getName(), node.hashCode()));
        } else {
            buffer.append(String.format("(%s ", node.getClass().getName()));
        }

        if (withLocationAnnotation) {
            SourceCodeLocation loc = node.getSourceCodeLocation();
            if (loc == null) {
                loc = SourceCodeLocation.getUnknownLocation();
            }
            buffer.append(String.format(":scl-unknown %s ", loc.isUnknown()));
        }
    }

    @Override
    public void leave(CssNode node) {
        buffer.deleteLastCharIfCharIs(' ');
        buffer.append(')');
    }

    /**
     * Called between adjacent nodes in a media type list
     */
    @Override
    public boolean enterMediaTypeListDelimiter(CssNodesListNode node) {
        super.enterMediaTypeListDelimiter(node);
        // this very special state does not represent a node
        buffer.append("(MediaTypeListDelimiter");
        return true;
    }

    /**
     * Called between adjacent nodes in a media type list
     */
    @Override
    public void leaveMediaTypeListDelimiter(CssNodesListNode node) {
        // this very special state does not represent a node
        buffer.append(')');
        super.leaveMediaTypeListDelimiter(node);
    }

    /**
     * Called between values in a {@code CssCompositeValueNode}
     */
    @Override
    public boolean enterCompositeValueNodeOperator(CssCompositeValueNode parent) {
        super.enterCompositeValueNodeOperator(parent);
        // this very special state does not represent a node
        buffer.append("(CompositeValueNodeOperator ");
        buffer.append(parent.getOperator().name());
        return true;
    }

    /**
     * Called between values in a {@code CssCompositeValueNode}
     */
    @Override
    public void leaveCompositeValueNodeOperator(CssCompositeValueNode parent) {
        buffer.append(')');
        super.leaveCompositeValueNodeOperator(parent);
    }

    @Override
    public boolean enterValueNode(CssValueNode n) {
        super.enterValueNode(n);
        buffer.append(n + " ");
        return true;
    }

    @Override
    public void leaveValueNode(CssValueNode n) {
        super.leaveValueNode(n);
    }
}