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/*******************************************************************************
 * Copyright (c) 2006, 2013 Oracle and/or its affiliates. All rights reserved.
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
 * which accompanies this distribution.
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *     Oracle - initial API and implementation
 *
 ******************************************************************************/
package org.eclipse.persistence.jpa.jpql.parser;

import org.eclipse.persistence.jpa.jpql.WordParser;

/**
 * This factory is responsible to return the right literal expression.
 *
 * @see StringLiteral
 * @see InputParameter
 * @see NumericLiteral
 * @see KeywordExpression
 * @see StateFieldPathExpression
 * @see IdentificationVariable
 *
 * @version 2.5
 * @since 2.3
 * @author Pascal Filion
 */
public abstract class AbstractLiteralExpressionFactory extends ExpressionFactory {

	/**
	 * Creates a new AbstractLiteralExpressionFactory.
	 *
	 * @param id The unique identifier of this {@link ExpressionFactory}
	 */
	protected AbstractLiteralExpressionFactory(String id) {
		super(id);
	}

	/**
	 * Creates the actual {@link AbstractExpression} this factory manages.
	 *
	 * @param parent The parent {@link AbstractExpression}
	 * @param wordParser The text to parse based on the current position of the cursor
	 * @param word The current word being parsed
	 * @param expression During the parsing, it is possible the first part of an expression was
	 * parsed which needs to be used as a sub-expression of the newly created expression
	 * @return A new {@link AbstractExpression} representing the portion or the totality of the
	 * text held by {@link WordParser} starting at the cursor position
	 */
	protected abstract AbstractExpression buildExpression(AbstractExpression parent,
	                                                      WordParser wordParser,
	                                                      String word,
	                                                      AbstractExpression expression,
	                                                      boolean tolerant);

	/**
	 * {@inheritDoc}
	 */
	@Override
	protected AbstractExpression buildExpression(AbstractExpression parent,
	                                             WordParser wordParser,
	                                             String word,
	                                             JPQLQueryBNF queryBNF,
	                                             AbstractExpression expression,
	                                             boolean tolerant) {

		switch (wordParser.getWordType()) {

			case NUMERIC_LITERAL: {
				expression = new NumericLiteral(parent, word);
				expression.parse(wordParser, tolerant);
				return expression;
			}

			case STRING_LITERAL: {
				expression = new StringLiteral(parent, word);
				expression.parse(wordParser, tolerant);
				return expression;
			}

			case INPUT_PARAMETER: {
				expression = new InputParameter(parent, word);
				expression.parse(wordParser, tolerant);
				return expression;
			}
		}

		// Path expression
		if (word.indexOf(AbstractExpression.DOT) > -1) {
			char character = word.charAt(0);

			if ((expression != null) && (character == AbstractExpression.DOT)) {
				if (isCollection()) {
					expression = new CollectionValuedPathExpression(parent, expression, word);
				}
				else {
					expression = new StateFieldPathExpression(parent, expression, word);
				}
			}
			else {
				if (isCollection()) {
					expression = new CollectionValuedPathExpression(parent, word);
				}
				else {
					expression = new StateFieldPathExpression(parent, word);
				}
			}

			expression.parse(wordParser, tolerant);
			return expression;
		}

		// Checks for invalid JPQL queries
		ExpressionRegistry registry = getExpressionRegistry();

		if (tolerant && registry.isIdentifier(word)) {
			ExpressionFactory factory = registry.expressionFactoryForIdentifier(word);
			// TODO: Before creating the expression, check to make sure it's not a function: 'identifier('
			if (factory != null) {
				expression = factory.buildExpression(parent, wordParser, word, queryBNF, expression, tolerant);

				if (expression != null) {
					return new BadExpression(parent, expression);
				}
			}
		}

		return buildExpression(parent, wordParser, word, expression, tolerant);
	}

	/**
	 * Determines
	 *
	 * @return
	 */
	protected boolean isCollection() {
		return false;
	}
}