io.vertigo.commons.parser.AbstractRule Maven / Gradle / Ivy

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/**
 * vertigo - simple java starter
 *
 * Copyright (C) 2013, KleeGroup, [email protected] (http://www.kleegroup.com)
 * KleeGroup, Centre d'affaire la Boursidiere - BP 159 - 92357 Le Plessis Robinson Cedex - France
 *
 * 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 io.vertigo.commons.parser;

import io.vertigo.lang.Assertion;

/**
 * Une règle peut être vue comme
 * - la création d'une règle principale
 * - la gestion du résultat du parsing
 *
 * @author pchretien
 * @param Type of the product text parsing
 */
public abstract class AbstractRule implements Rule {
	private Rule mainRule;

	protected final Rule getMainRule() {
		if (mainRule == null) {
			mainRule = createMainRule();
		}
		return mainRule;
	}

	protected abstract Rule createMainRule();

	/** {@inheritDoc} */
	@Override
	public String getExpression() {
		return getMainRule().getExpression();
	}

	protected abstract R handle(M parsing);

	@Override
	public final Parser createParser() {
		return new Parser() {
			private R result;

			/** {@inheritDoc} */
			@Override
			public int parse(final String text, final int start) throws NotFoundException {
				final Parser parser = getMainRule().createParser();
				final int end = parser.parse(text, start);
				//---
				result = handle(parser.get());
				//---
				return end;
			}

			@Override
			public R get() {
				Assertion.checkNotNull(result);
				return result;
			}
		};
	}
}