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The Teamscale Custom Check API allows users to extend Teamscale by writing custom analyses that create findings.

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/*
 * Copyright (c) CQSE GmbH
 *
 * 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 eu.cqse.check.framework.util.tokens;

/**
 * Base class for token patterns. Handles resetting the token stream's position if the pattern did
 * not match and appending the patterns match to the match group, if a group index was set for this
 * pattern.
 */
public abstract class TokenPatternBase {

	/**
	 * The group index of this pattern or null if this pattern's match should not be
	 * appended to a group.
	 */
	private Integer groupIndex = null;

	/** @see #groupIndex */
	public void setGroupIndex(Integer groupIndex) {
		this.groupIndex = groupIndex;
	}

	/**
	 * Tries to match this pattern at the current position of the given stream. Returns a match object
	 * if successful, null otherwise. If the match was unsuccessful, the streams position
	 * is not modified.
	 */
	/* package */TokenPatternMatch matches(TokenStream stream) {
		int beforePosition = stream.getPosition();
		TokenPatternMatch match = matchesLocally(stream);
		if (match == null) {
			stream.setPosition(beforePosition);
		} else if (groupIndex != null) {
			match.appendToGroup(groupIndex, beforePosition, stream.getPosition());
		}
		return match;
	}

	/** Utility method to create an empty match object. */
	protected TokenPatternMatch createMatch(TokenStream stream) {
		return new TokenPatternMatch(stream.getTokens());
	}

	/**
	 * Tries to match this pattern at the current position of the given stream. Returns a match object
	 * if successful, null otherwise. May modify the stream's position.
	 */
	protected abstract TokenPatternMatch matchesLocally(TokenStream stream);
}