com.google.common.css.compiler.passes.CreateConditionalNodes Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of closure-stylesheets Show documentation
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.
There is a newer version: 1.8.0
Show newest version
/*
 * 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.Lists;
import com.google.common.css.SourceCodeLocation;
import com.google.common.css.compiler.ast.*;

import java.util.List;
import java.util.Stack;

/**
 * A compiler pass that replaces each {@code @if}, {@code @elseif}, and
 * {@code @else} {@link CssUnknownAtRuleNode} with appropriate conditional
 * nodes ({@link CssConditionalBlockNode} and {@link CssConditionalRuleNode}).
 */
public class CreateConditionalNodes extends DefaultTreeVisitor
        implements CssCompilerPass {

    private final MutatingVisitController visitController;
    private final ErrorManager errorManager;
    private final Stack stack =
            new Stack<>();
    private CssConditionalBlockNode activeBlockNode = null;

    private static final String IF_NAME = CssAtRuleNode.Type.IF.getCanonicalName();
    private static final String ELSEIF_NAME = CssAtRuleNode.Type.ELSEIF.getCanonicalName();
    private static final String ELSE_NAME = CssAtRuleNode.Type.ELSE.getCanonicalName();

    public CreateConditionalNodes(MutatingVisitController visitController,
                                  ErrorManager errorManager) {
        this.visitController = visitController;
        this.errorManager = errorManager;
    }

    @Override
    public boolean enterUnknownAtRule(CssUnknownAtRuleNode node) {
        String name = node.getName().getValue();
        if (name.equals(IF_NAME)) {
            CssConditionalBlockNode condBlock = new CssConditionalBlockNode(node.getComments());
            condBlock.setSourceCodeLocation(node.getSourceCodeLocation());
            stack.push(condBlock);
        } else if (name.equals(ELSEIF_NAME) || name.equals(ELSE_NAME)) {
            if (activeBlockNode == null) {
                errorManager.report(new GssError("@" + name + " without previous @" + IF_NAME,
                        node.getSourceCodeLocation()));
                visitController.removeCurrentNode();
                return false;
            }
            stack.push(activeBlockNode);
        }
        activeBlockNode = null;
        return true;
    }

    @Override
    public void leaveUnknownAtRule(CssUnknownAtRuleNode node) {
        String name = node.getName().getValue();
        if (name.equals(IF_NAME)
                || name.equals(ELSEIF_NAME)
                || name.equals(ELSE_NAME)) {
            activeBlockNode = stack.pop();
            CssConditionalRuleNode conditionalNode = createConditionalRuleNode(node, name);
            activeBlockNode.addChildToBack(conditionalNode);
            updateLocation(activeBlockNode);
            if (name.equals(IF_NAME)) {
                visitController.replaceCurrentBlockChildWith(
                        Lists.newArrayList((CssNode) activeBlockNode), false);
            } else {
                visitController.removeCurrentNode();
                if (name.equals(ELSE_NAME)) {
                    activeBlockNode = null;
                }
            }
        }
    }

    @Override
    public boolean enterRuleset(CssRulesetNode node) {
        activeBlockNode = null;
        return true;
    }

    @Override
    public boolean enterDefinition(CssDefinitionNode node) {
        activeBlockNode = null;
        return true;
    }

    private CssConditionalRuleNode createConditionalRuleNode(
            CssUnknownAtRuleNode node, String name) {
        CssAbstractBlockNode block = node.getBlock();
        if (block == null) {
            errorManager.report(new GssError("@" + name + " without block",
                    node.getSourceCodeLocation()));
        }

        List params = node.getParameters();
        CssBooleanExpressionNode condition = null;
        if (!name.equals(ELSE_NAME)) {
            if (!params.isEmpty()) {
                if (params.size() > 1) {
                    errorManager.report(new GssError("@" + name + " with too many parameters",
                            node.getSourceCodeLocation()));
                }
                CssValueNode param = params.get(0);
                if (param instanceof CssBooleanExpressionNode) {
                    condition = (CssBooleanExpressionNode) param;
                } else {
                    condition = new CssBooleanExpressionNode(CssBooleanExpressionNode.Type.CONSTANT,
                            param.getValue(), param.getSourceCodeLocation());
                }
            } else {
                errorManager.report(new GssError("@" + name + " without condition",
                        node.getSourceCodeLocation()));
            }
        } else {
            if (!params.isEmpty()) {
                errorManager.report(new GssError("@" + ELSE_NAME + " with too many parameters",
                        node.getSourceCodeLocation()));
            }
        }

        CssConditionalRuleNode rulenode = new CssConditionalRuleNode(
                CssAtRuleNode.Type.valueOf(name.toUpperCase()), node.getName(), condition, block);
        rulenode.setComments(node.getComments());
        rulenode.setSourceCodeLocation(node.getSourceCodeLocation());
        return rulenode;
    }

    /**
     * Assigns a new SourceCodeLocation to the BlockNode which starts at the
     * BlockNode's first child's beginning location point and ends at the
     * last child's ending location point.
     */
    private void updateLocation(CssConditionalBlockNode blockNode) {
        SourceCodeLocation firstLocation = blockNode.getSourceCodeLocation();
        SourceCodeLocation lastLocation = blockNode.getLastChild().getSourceCodeLocation();
        SourceCodeLocation mergedLocation = new SourceCodeLocation(
                firstLocation.getSourceCode(),
                firstLocation.getBeginCharacterIndex(),
                firstLocation.getBeginLineNumber(),
                firstLocation.getBeginIndexInLine(),
                lastLocation.getEndCharacterIndex(),
                lastLocation.getEndLineNumber(),
                lastLocation.getEndIndexInLine());
        blockNode.setSourceCodeLocation(mergedLocation);
    }

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