jpa/org.eclipse.persistence.jpa.jpql/src/main/java/org/eclipse/persistence/jpa/jpql/parser/AsOfClause.java - eclipselink - Git at Google

 /*
  * Copyright (c) 2012, 2021 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 v. 2.0 which is available at
  * http://www.eclipse.org/legal/epl-2.0,
  * or the Eclipse Distribution License v. 1.0 which is available at
  * http://www.eclipse.org/org/documents/edl-v10.php.
  *
  * SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
  */

 // Contributors:
 //     Oracle - initial API and implementation
 //
 package org.eclipse.persistence.jpa.jpql.parser;

 import java.util.Collection;
 import java.util.List;
 import org.eclipse.persistence.jpa.jpql.ExpressionTools;
 import org.eclipse.persistence.jpa.jpql.WordParser;

 /**
  * <p>An <code><b>AS OF</b></code> clause is part of a flashback query, which provides ways to view
  * past states of database objects, or to return database objects to a previous state, without using
  * traditional point-in-time recovery.
  * </p><p>
  * Specify <code><b>AS OF</b></code> to retrieve the single version of the rows returned by the
  * query at a particular change number (SCN) or timestamp. If you specify SCN, then the expression
  * must evaluate to a number. If you specify <code><b>TIMESTAMP</b></code>, then the expression must
  * evaluate to a timestamp value. Oracle Database returns rows as they existed at the specified
  * system change number or time.
  * </p>
  * <div><b>BNF:</b> <code>asof_clause ::= AS OF { SCN | TIMESTAMP } scalar_expression</code></div>
  *
  * @version 2.5
  * @since 2.5
  * @author Pascal Filion
  */
 public final class AsOfClause extends AbstractExpression {

     /**
      * The {@link Expression} representing the timestamp or change number.
      */
     private AbstractExpression expression;

     /**
      * Determines whether a whitespace was found after either <code><b>SCN</b></code> or
      * <code><b>TIMESTAMP</b></code>.
      */
     private boolean hasSpaceAfterCategory;

     /**
      * Determines whether a whitespace was found after <code><b>AS OF</b></code>.
      */
     private boolean hasSpaceAfterIdentifier;

     /**
      * The actual identifier found in the string representation of the JPQL query.
      */
     private String identifier;

     /**
      * The actual <code><b>SCN</b></code> identifier found in the string representation of the
      * JPQL query.
      */
     private String scnIdentifier;

     /**
      * The actual <code><b>TIMESTAMP</b></code> identifier found in the string representation of the
      * JPQL query.
      */
     private String timestampIdentifier;

     /**
      * Creates a new <code>AsOfClause</code>.
      *
      * @param parent The parent of this expression
      */
     public AsOfClause(AbstractExpression parent) {
         super(parent, AS_OF);
     }

     @Override
     public void accept(ExpressionVisitor visitor) {
         acceptUnknownVisitor(visitor);
     }

     @Override
     public void acceptChildren(ExpressionVisitor visitor) {
         getExpression().accept(visitor);
     }

     @Override
     protected void addChildrenTo(Collection<Expression> children) {
         children.add(getExpression());
     }

     @Override
     protected void addOrderedChildrenTo(List<Expression> children) {

         // 'AS OF'
         children.add(buildStringExpression(AS_OF));

         if (hasSpaceAfterIdentifier) {
             children.add(buildStringExpression(SPACE));
         }

         // 'SCN'
         if (scnIdentifier != null) {
             children.add(buildStringExpression(SCN));
         }
         // 'TIMESTAMP'
         else if (timestampIdentifier != null) {
             children.add(buildStringExpression(TIMESTAMP));
         }

         if (hasSpaceAfterCategory) {
             children.add(buildStringExpression(SPACE));
         }

         // Expression
         if (expression != null) {
             children.add(expression);
         }
     }

     @Override
     public JPQLQueryBNF findQueryBNF(Expression expression) {

         if ((this.expression != null) && this.expression.isAncestor(expression)) {
             return getQueryBNF(ScalarExpressionBNF.ID);
         }

         return super.findQueryBNF(expression);
     }

     /**
      * Returns the actual <b>AS OF</b> identifier found in the string representation of the JPQL
      * query, which has the actual case that was used.
      *
      * @return The <b>AS OF</b> identifier that was actually parsed
      */
     public String getActualIdentifier() {
         return identifier;
     }

     /**
      * Returns the actual <b>SCN</b> identifier found in the string representation of the JPQL query,
      * which has the actual case that was used.
      *
      * @return The <b>SCN</b> identifier that was actually parsed, or an empty string if it was not parsed
      */
     public String getActualScnIdentifier() {
         return (scnIdentifier != null) ? scnIdentifier : ExpressionTools.EMPTY_STRING;
     }

     /**
      * Returns the actual <b>TIMESTAMP</b> identifier found in the string representation of the JPQL
      * query, which has the actual case that was used.
      *
      * @return The <b>TIMESTAMP</b> identifier that was actually parsed, or an empty string if it was
      * not parsed
      */
     public String getActualTimestampIdentifier() {
         return (timestampIdentifier != null) ? timestampIdentifier : ExpressionTools.EMPTY_STRING;
     }

     /**
      * Returns the {@link Expression} representing the timestamp or change number.
      *
      * @return The {@link Expression} that was parsed representing the timestamp or change number
      */
     public Expression getExpression() {
         if (expression == null) {
             expression = buildNullExpression();
         }
         return expression;
     }

     @Override
     public JPQLQueryBNF getQueryBNF() {
         return getQueryBNF(AsOfClauseBNF.ID);
     }

     /**
      * Determines whether the {@link Expression} representing the timestamp or change number was
      * parsed or not.
      *
      * @return <code>true</code> if the timestamp or change number was parsed; <code>false</code> otherwise
      */
     public boolean hasExpression() {
         return expression != null &&
               !expression.isNull();
     }

     /**
      * Determines whether the identifier <b>SCN</b> was part of the query.
      *
      * @return <code>true</code> if the identifier <b>SCN</b> was parsed; <code>false</code> otherwise
      */
     public boolean hasScn() {
         return scnIdentifier != null;
     }

     /**
      * Determines whether a whitespace was found after either <b>SCN</b> or <code>TIMESTAMP</code>.
      *
      * @return <code>true</code> if there was a whitespace after <b>SCN</b> or <code>TIMESTAMP</code>;
      * <code>false</code> otherwise
      */
     public boolean hasSpaceAfterCategory() {
         return hasSpaceAfterCategory;
     }

     /**
      * Determines whether a whitespace was found after <b>AS OF</b>.
      *
      * @return <code>true</code> if there was a whitespace after <b>AS OF</b>; <code>false</code> otherwise
      */
     public boolean hasSpaceAfterIdentifier() {
         return hasSpaceAfterIdentifier;
     }

     /**
      * Determines whether the identifier <b>TIMESTAMP</b> was part of the query.
      *
      * @return <code>true</code> if the identifier <b>TIMESTAMP</b> was parsed; <code>false</code> otherwise
      */
     public boolean hasTimestamp() {
         return timestampIdentifier != null;
     }

     @Override
     protected void parse(WordParser wordParser, boolean tolerant) {

         // 'AS OF'
         identifier = wordParser.moveForwardIgnoreWhitespace(AS_OF);
         hasSpaceAfterIdentifier = wordParser.skipLeadingWhitespace() > 0;

         // 'SCN'
         if (wordParser.startsWithIdentifier(SCN)) {
             scnIdentifier = wordParser.moveForward(SCN);
             hasSpaceAfterCategory = wordParser.skipLeadingWhitespace() > 0;
         }
         // 'TIMESTAMP'
         else if (wordParser.startsWithIdentifier(TIMESTAMP)) {
             timestampIdentifier = wordParser.moveForward(TIMESTAMP);
             hasSpaceAfterCategory = wordParser.skipLeadingWhitespace() > 0;
         }

         // Expression
         expression = parse(wordParser, ScalarExpressionBNF.ID, tolerant);
     }

     @Override
     protected void toParsedText(StringBuilder writer, boolean actual) {

         // 'AS OF'
         writer.append(actual ? identifier : AS_OF);

         if (hasSpaceAfterIdentifier) {
             writer.append(SPACE);
         }

         // 'SCN'
         if (scnIdentifier != null) {
             writer.append(actual ? scnIdentifier : SCN);
         }

         // 'TIMESTAMP'
         if (timestampIdentifier != null) {
             writer.append(actual ? timestampIdentifier : TIMESTAMP);
         }

         if (hasSpaceAfterCategory) {
             writer.append(SPACE);
         }

         // Expression
         if (expression != null) {
             expression.toParsedText(writer, actual);
         }
     }
 }
	/*
	* Copyright (c) 2012, 2021 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 v. 2.0 which is available at
	* http://www.eclipse.org/legal/epl-2.0,
	* or the Eclipse Distribution License v. 1.0 which is available at
	* http://www.eclipse.org/org/documents/edl-v10.php.
	*
	* SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
	*/

	// Contributors:
	// Oracle - initial API and implementation
	//
	package org.eclipse.persistence.jpa.jpql.parser;

	import java.util.Collection;
	import java.util.List;
	import org.eclipse.persistence.jpa.jpql.ExpressionTools;
	import org.eclipse.persistence.jpa.jpql.WordParser;

	/**
	* <p>An <code><b>AS OF</b></code> clause is part of a flashback query, which provides ways to view
	* past states of database objects, or to return database objects to a previous state, without using
	* traditional point-in-time recovery.
	* </p><p>
	* Specify <code><b>AS OF</b></code> to retrieve the single version of the rows returned by the
	* query at a particular change number (SCN) or timestamp. If you specify SCN, then the expression
	* must evaluate to a number. If you specify <code><b>TIMESTAMP</b></code>, then the expression must
	* evaluate to a timestamp value. Oracle Database returns rows as they existed at the specified
	* system change number or time.
	* </p>
	* <div><b>BNF:</b> <code>asof_clause ::= AS OF { SCN \| TIMESTAMP } scalar_expression</code></div>
	*
	* @version 2.5
	* @since 2.5
	* @author Pascal Filion
	*/
	public final class AsOfClause extends AbstractExpression {

	/**
	* The {@link Expression} representing the timestamp or change number.
	*/
	private AbstractExpression expression;

	/**
	* Determines whether a whitespace was found after either <code><b>SCN</b></code> or
	* <code><b>TIMESTAMP</b></code>.
	*/
	private boolean hasSpaceAfterCategory;

	/**
	* Determines whether a whitespace was found after <code><b>AS OF</b></code>.
	*/
	private boolean hasSpaceAfterIdentifier;

	/**
	* The actual identifier found in the string representation of the JPQL query.
	*/
	private String identifier;

	/**
	* The actual <code><b>SCN</b></code> identifier found in the string representation of the
	* JPQL query.
	*/
	private String scnIdentifier;

	/**
	* The actual <code><b>TIMESTAMP</b></code> identifier found in the string representation of the
	* JPQL query.
	*/
	private String timestampIdentifier;

	/**
	* Creates a new <code>AsOfClause</code>.
	*
	* @param parent The parent of this expression
	*/
	public AsOfClause(AbstractExpression parent) {
	super(parent, AS_OF);
	}

	@Override
	public void accept(ExpressionVisitor visitor) {
	acceptUnknownVisitor(visitor);
	}

	@Override
	public void acceptChildren(ExpressionVisitor visitor) {
	getExpression().accept(visitor);
	}

	@Override
	protected void addChildrenTo(Collection<Expression> children) {
	children.add(getExpression());
	}

	@Override
	protected void addOrderedChildrenTo(List<Expression> children) {

	// 'AS OF'
	children.add(buildStringExpression(AS_OF));

	if (hasSpaceAfterIdentifier) {
	children.add(buildStringExpression(SPACE));
	}

	// 'SCN'
	if (scnIdentifier != null) {
	children.add(buildStringExpression(SCN));
	}
	// 'TIMESTAMP'
	else if (timestampIdentifier != null) {
	children.add(buildStringExpression(TIMESTAMP));
	}

	if (hasSpaceAfterCategory) {
	children.add(buildStringExpression(SPACE));
	}

	// Expression
	if (expression != null) {
	children.add(expression);
	}
	}

	@Override
	public JPQLQueryBNF findQueryBNF(Expression expression) {

	if ((this.expression != null) && this.expression.isAncestor(expression)) {
	return getQueryBNF(ScalarExpressionBNF.ID);
	}

	return super.findQueryBNF(expression);
	}

	/**
	* Returns the actual <b>AS OF</b> identifier found in the string representation of the JPQL
	* query, which has the actual case that was used.
	*
	* @return The <b>AS OF</b> identifier that was actually parsed
	*/
	public String getActualIdentifier() {
	return identifier;
	}

	/**
	* Returns the actual <b>SCN</b> identifier found in the string representation of the JPQL query,
	* which has the actual case that was used.
	*
	* @return The <b>SCN</b> identifier that was actually parsed, or an empty string if it was not parsed
	*/
	public String getActualScnIdentifier() {
	return (scnIdentifier != null) ? scnIdentifier : ExpressionTools.EMPTY_STRING;
	}

	/**
	* Returns the actual <b>TIMESTAMP</b> identifier found in the string representation of the JPQL
	* query, which has the actual case that was used.
	*
	* @return The <b>TIMESTAMP</b> identifier that was actually parsed, or an empty string if it was
	* not parsed
	*/
	public String getActualTimestampIdentifier() {
	return (timestampIdentifier != null) ? timestampIdentifier : ExpressionTools.EMPTY_STRING;
	}

	/**
	* Returns the {@link Expression} representing the timestamp or change number.
	*
	* @return The {@link Expression} that was parsed representing the timestamp or change number
	*/
	public Expression getExpression() {
	if (expression == null) {
	expression = buildNullExpression();
	}
	return expression;
	}

	@Override
	public JPQLQueryBNF getQueryBNF() {
	return getQueryBNF(AsOfClauseBNF.ID);
	}

	/**
	* Determines whether the {@link Expression} representing the timestamp or change number was
	* parsed or not.
	*
	* @return <code>true</code> if the timestamp or change number was parsed; <code>false</code> otherwise
	*/
	public boolean hasExpression() {
	return expression != null &&
	!expression.isNull();
	}

	/**
	* Determines whether the identifier <b>SCN</b> was part of the query.
	*
	* @return <code>true</code> if the identifier <b>SCN</b> was parsed; <code>false</code> otherwise
	*/
	public boolean hasScn() {
	return scnIdentifier != null;
	}

	/**
	* Determines whether a whitespace was found after either <b>SCN</b> or <code>TIMESTAMP</code>.
	*
	* @return <code>true</code> if there was a whitespace after <b>SCN</b> or <code>TIMESTAMP</code>;
	* <code>false</code> otherwise
	*/
	public boolean hasSpaceAfterCategory() {
	return hasSpaceAfterCategory;
	}

	/**
	* Determines whether a whitespace was found after <b>AS OF</b>.
	*
	* @return <code>true</code> if there was a whitespace after <b>AS OF</b>; <code>false</code> otherwise
	*/
	public boolean hasSpaceAfterIdentifier() {
	return hasSpaceAfterIdentifier;
	}

	/**
	* Determines whether the identifier <b>TIMESTAMP</b> was part of the query.
	*
	* @return <code>true</code> if the identifier <b>TIMESTAMP</b> was parsed; <code>false</code> otherwise
	*/
	public boolean hasTimestamp() {
	return timestampIdentifier != null;
	}

	@Override
	protected void parse(WordParser wordParser, boolean tolerant) {

	// 'AS OF'
	identifier = wordParser.moveForwardIgnoreWhitespace(AS_OF);
	hasSpaceAfterIdentifier = wordParser.skipLeadingWhitespace() > 0;

	// 'SCN'
	if (wordParser.startsWithIdentifier(SCN)) {
	scnIdentifier = wordParser.moveForward(SCN);
	hasSpaceAfterCategory = wordParser.skipLeadingWhitespace() > 0;
	}
	// 'TIMESTAMP'
	else if (wordParser.startsWithIdentifier(TIMESTAMP)) {
	timestampIdentifier = wordParser.moveForward(TIMESTAMP);
	hasSpaceAfterCategory = wordParser.skipLeadingWhitespace() > 0;
	}

	// Expression
	expression = parse(wordParser, ScalarExpressionBNF.ID, tolerant);
	}

	@Override
	protected void toParsedText(StringBuilder writer, boolean actual) {

	// 'AS OF'
	writer.append(actual ? identifier : AS_OF);

	if (hasSpaceAfterIdentifier) {
	writer.append(SPACE);
	}

	// 'SCN'
	if (scnIdentifier != null) {
	writer.append(actual ? scnIdentifier : SCN);
	}

	// 'TIMESTAMP'
	if (timestampIdentifier != null) {
	writer.append(actual ? timestampIdentifier : TIMESTAMP);
	}

	if (hasSpaceAfterCategory) {
	writer.append(SPACE);
	}

	// Expression
	if (expression != null) {
	expression.toParsedText(writer, actual);
	}
	}
	}