/*
 * Copyright 2004-2008 the original author or authors.
 *
 * 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 org.springframework.binding.expression.beanwrapper;

import org.springframework.beans.BeanWrapperImpl;
import org.springframework.beans.NullValueInNestedPathException;
import org.springframework.beans.propertyeditors.PropertiesEditor;
import org.springframework.binding.convert.ConversionExecutor;
import org.springframework.binding.convert.ConversionService;
import org.springframework.binding.convert.service.DefaultConversionService;
import org.springframework.binding.expression.Expression;
import org.springframework.binding.expression.ParserContext;
import org.springframework.binding.expression.ParserException;
import org.springframework.binding.expression.support.AbstractExpressionParser;

/**
 * An expression parser that parses BeanWrapper property expressions.
 *
 * @author Keith Donald
 */
public class BeanWrapperExpressionParser extends AbstractExpressionParser {

	private ConversionService conversionService;

	private boolean autoGrowNestedPaths = false;

	private int autoGrowCollectionLimit = Integer.MAX_VALUE;

	/**
	 * Creates a new expression parser that uses a {@link DefaultConversionService} to perform type conversion.
	 */
	public BeanWrapperExpressionParser() {
		this.conversionService = new DefaultConversionService();
	}

	/**
	 * Creates a new expression parser that uses the specified conversion service for type conversion.
	 * @param conversionService the conversion service to use
	 */
	public BeanWrapperExpressionParser(ConversionService conversionService) {
		this.conversionService = conversionService;
	}

	/**
	 * The conversion service to use to obtain {@link ConversionExecutor conversion executors} that will be adapted to
	 * {@link PropertiesEditor property editors} for use during a
	 * {@link BeanWrapperImpl#setPropertyValue(String, Object) set value} call. The default if not specified is an
	 * instance of {@link DefaultConversionService}.
	 */
	public ConversionService getConversionService() {
		return conversionService;
	}

	/**
	 * Sets the conversion service to use to obtain {@link ConversionExecutor conversion executors} that will be adapted
	 * to {@link PropertiesEditor property editors} for use during a
	 * {@link BeanWrapperImpl#setPropertyValue(String, Object) set value} call.
	 * @param conversionService the conversion service
	 */
	public void setConversionService(ConversionService conversionService) {
		this.conversionService = conversionService;
	}

	/**
	 * Set whether this BeanWrapper should attempt to "auto-grow" a nested path that contains a null value.
	 * <p>If "true", a null path location will be populated with a default object value and traversed
	 * instead of resulting in a {@link NullValueInNestedPathException}. Turning this flag on also
	 * enables auto-growth of collection elements when accessing an out-of-bounds index.
	 * <p>Default is "false" on a plain BeanWrapper.
	 */
	public void setAutoGrowNestedPaths(boolean autoGrowNestedPaths) {
		this.autoGrowNestedPaths = autoGrowNestedPaths;
	}

	/**
	 * Specify a limit for array and collection auto-growing.
	 * <p>Default is unlimited on a plain BeanWrapper.
	 */
	public void setAutoGrowCollectionLimit(int autoGrowCollectionLimit) {
		this.autoGrowCollectionLimit = autoGrowCollectionLimit;
	}

	protected Expression doParseExpression(String expressionString, ParserContext context) throws ParserException {
		BeanWrapperExpression expression = new BeanWrapperExpression(expressionString, conversionService);
		expression.setAutoGrowNestedPaths(autoGrowNestedPaths);
		expression.setAutoGrowCollectionLimit(autoGrowCollectionLimit);
		return expression;
	}
}