/*******************************************************************************
* Copyright (c) 2012, 2015 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 java.util.List;
import org.eclipse.persistence.jpa.jpql.ExpressionTools;
import org.eclipse.persistence.jpa.jpql.WordParser;
/**
* The <b>EXTRACT</b> function extracts a date part from a date/time value. The date part can be
* <code>YEAR</code>, <code>MONTH</code>, <code>DAY</code>, <code>HOUR</code>, <code>MINUTE</code>,
* <code>SECOND</code>. Some databases may support other parts.
*
* <div><b>BNF:</b> <code>extract_expression ::= EXTRACT(date_part_literal [FROM] scalar_expression)</code></div>
* <p>
* date_part_literal ::= { MICROSECOND | SECOND | MINUTE | HOUR | DAY | WEEK | MONTH | QUARTER |
* YEAR | SECOND_MICROSECOND | MINUTE_MICROSECOND | MINUTE_SECOND |
* HOUR_MICROSECOND | HOUR_SECOND | HOUR_MINUTE | DAY_MICROSECOND |
* DAY_SECOND | DAY_MINUTE | DAY_HOUR | YEAR_MONTH, etc }
* </p>
*
* @version 2.5
* @since 2.4
* @author James Sutherland
*/
public final class ExtractExpression extends AbstractSingleEncapsulatedExpression {
/**
* The date part to extract from the date/time.
*/
private String datePart;
/**
* The actual <b>FROM</b> identifier found in the string representation of the JPQL query.
*/
private String fromIdentifier;
/**
* Determines whether a space was parsed after the date part.
*/
private boolean hasSpaceAfterDatePart;
/**
* Determines whether a space was parsed after the identifier <b>FROM</b>.
*/
private boolean hasSpaceAfterFrom;
/**
* Creates a new <code>ExtractExpression</code>.
*
* @param parent The parent of this expression
*/
public ExtractExpression(AbstractExpression parent) {
super(parent, EXTRACT);
}
/**
* {@inheritDoc}
*/
public void accept(ExpressionVisitor visitor) {
acceptUnknownVisitor(visitor);
}
/**
* {@inheritDoc}
*/
@Override
protected void addOrderedEncapsulatedExpressionTo(List<Expression> children) {
// Date part
if (hasDatePart()) {
children.add(buildStringExpression(datePart));
}
if (hasSpaceAfterDatePart) {
children.add(buildStringExpression(SPACE));
}
// 'FROM'
if (fromIdentifier != null) {
children.add(buildStringExpression(FROM));
}
if (hasSpaceAfterFrom) {
children.add(buildStringExpression(SPACE));
}
// Value
super.addOrderedEncapsulatedExpressionTo(children);
}
/**
* {@inheritDoc}
*/
@Override
public String getEncapsulatedExpressionQueryBNFId() {
return ScalarExpressionBNF.ID;
}
/**
* Returns the actual <b>FROM</b> identifier found in the string representation of the JPQL
* query, which has the actual case that was used.
*
* @return The <b>FROM</b> identifier that was actually parsed, or an empty string if it was not
* parsed
*/
public String getActualFromIdentifier() {
return (fromIdentifier != null) ? fromIdentifier : ExpressionTools.EMPTY_STRING;
}
/**
* Returns the date part that was parsed, it is used to extract a single part of a date/time,
* such as year, month, day, your, etc.
*
* @return The part of the date/time to retrieve
*/
public String getDatePart() {
return datePart;
}
/**
* {@inheritDoc}
*/
public JPQLQueryBNF getQueryBNF() {
return getQueryBNF(ExtractExpressionBNF.ID);
}
/**
* Determines whether the date part literal was parsed or not.
*
* @return <code>true</code> if the date part literal was parsed; <code>false</code> otherwise
*/
public boolean hasDatePart() {
return ExpressionTools.stringIsNotEmpty(datePart);
}
/**
* {@inheritDoc}
*/
@Override
public boolean hasEncapsulatedExpression() {
return hasDatePart() || (fromIdentifier != null) || hasExpression();
}
/**
* Determines whether the identifier <b>FROM</b> was part of the query.
*
* @return <code>true</code> if the identifier <b>FROM</b> was parsed; <code>false</code> otherwise
*/
public boolean hasFrom() {
return fromIdentifier != null;
}
/**
* Determines whether a whitespace was found after the date part literal.
*
* @return <code>true</code> if there was a whitespace after the date part literal;
* <code>false</code> otherwise
*/
public boolean hasSpaceAfterDatePart() {
return hasSpaceAfterDatePart;
}
/**
* Determines whether a whitespace was found after <b>FROM</b>.
*
* @return <code>true</code> if there was a whitespace after <b>FROM</b>; <code>false</code> otherwise
*/
public boolean hasSpaceAfterFrom() {
return hasSpaceAfterFrom;
}
/**
* {@inheritDoc}
*/
@Override
protected boolean isParsingComplete(WordParser wordParser, String word, Expression expression) {
return word.equalsIgnoreCase(FROM) ||
super.isParsingComplete(wordParser, word, expression);
}
/**
* {@inheritDoc}
*/
@Override
protected void parseEncapsulatedExpression(WordParser wordParser,
int whitespaceCount,
boolean tolerant) {
if (wordParser.isTail()) {
datePart = ExpressionTools.EMPTY_STRING;
return;
}
// Parse the date part
datePart = wordParser.word();
// Invalid date part, parse it as the scalar expression
if (tolerant &&
(isParsingComplete(wordParser, datePart, null) ||
datePart.indexOf(DOT) > -1 ||
datePart.charAt(0) == SINGLE_QUOTE ||
datePart.charAt(0) == DOUBLE_QUOTE ||
Character.isDigit(datePart.charAt(0)))) {
datePart = ExpressionTools.EMPTY_STRING;
hasSpaceAfterDatePart = whitespaceCount > 0;
}
else {
wordParser.moveForward(datePart);
hasSpaceAfterDatePart = wordParser.skipLeadingWhitespace() > 0;
}
// Parse 'FROM'
if (wordParser.startsWithIdentifier(FROM)) {
fromIdentifier = wordParser.moveForward(FROM);
hasSpaceAfterFrom = wordParser.skipLeadingWhitespace() > 0;
}
// Parse the value
super.parseEncapsulatedExpression(wordParser, whitespaceCount, tolerant);
}
/**
* {@inheritDoc}
*/
@Override
protected void removeEncapsulatedExpression() {
super.removeEncapsulatedExpression();
datePart = ExpressionTools.EMPTY_STRING;
fromIdentifier = null;
hasSpaceAfterFrom = false;
hasSpaceAfterDatePart = false;
}
/**
* {@inheritDoc}
*/
@Override
protected void toParsedTextEncapsulatedExpression(StringBuilder writer, boolean actual) {
// Date part
writer.append(datePart);
if (hasSpaceAfterDatePart) {
writer.append(SPACE);
}
// FROM
if (fromIdentifier != null) {
writer.append(actual ? fromIdentifier : FROM);
}
if (hasSpaceAfterFrom) {
writer.append(SPACE);
}
// Value
super.toParsedTextEncapsulatedExpression(writer, actual);
}
}