001/*
002 * Copyright (C) 2009-2011 Mathias Doenitz
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.parboiled.matchers;
018
019import org.parboiled.MatcherContext;
020import org.parboiled.Rule;
021import org.parboiled.matchervisitors.MatcherVisitor;
022
023import java.util.List;
024
025import static org.parboiled.common.Preconditions.checkArgNotNull;
026
027/**
028 * A {@link Matcher} that executes all of its submatchers in sequence and only succeeds if all submatchers succeed.
029 */
030public class SequenceMatcher extends CustomDefaultLabelMatcher<SequenceMatcher> {
031
032    public SequenceMatcher(Rule[] subRules) {
033        super(checkArgNotNull(subRules, "subRules"), "Sequence");
034    }
035
036    public boolean match(MatcherContext context) {
037        Object valueStackSnapshot = context.getValueStack().takeSnapshot();
038
039        List<Matcher> children = getChildren();
040        int size = children.size();
041        for (int i = 0; i < size; i++) {
042            Matcher matcher = children.get(i);
043
044            // remember the current index in the context, so we can access it for building the current follower set
045            context.setIntTag(i);
046
047            if (!matcher.getSubContext(context).runMatcher()) {
048                // rule failed, so invalidate all stack actions the rule might have done
049                context.getValueStack().restoreSnapshot(valueStackSnapshot);
050                return false;
051            }
052        }
053        context.createNode();
054        return true;
055    }
056
057    public <R> R accept(MatcherVisitor<R> visitor) {
058        checkArgNotNull(visitor, "visitor");
059        return visitor.visit(this);
060    }
061
062}