/*******************************************************************************
* Copyright (c) 1998, 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 from Oracle TopLink
******************************************************************************/
package org.eclipse.persistence.internal.expressions;
import org.eclipse.persistence.expressions.*;
import org.eclipse.persistence.internal.sessions.AbstractSession;
import java.util.*;
/**
* This is used during the normalization process to allow for a single main expression traversal.
*/
public class ExpressionNormalizer {
/** A new root expression can be made from joins being added to the original expression. */
protected Expression additionalExpression;
/** The statement being normalized. */
protected SQLSelectStatement statement;
/** Subselect expressions found in the course of normalization. */
protected List<SubSelectExpression> subSelectExpressions;
/** The session being normalized in. */
protected AbstractSession session;
/** Used to maintain identity of cloned expressions. */
protected Map<Expression, Expression> clonedExpressions;
/**
* Used to trigger adding additional join operations etc to the expression being processed instead of at the end of the where clause.
* Useful for dealing with Treat within an Or clause, as the type expression needs to be appended within the OR condition rather AND'd
* to the entire thing.
*/
protected boolean addAdditionalExpressionsWithinCurrrentExpressionContext = false;
/** Local expression from joins being added to the original expression. */
protected Expression additionalLocalExpression;
public ExpressionNormalizer(SQLSelectStatement statement) {
this.statement = statement;
}
public Map<Expression, Expression> getClonedExpressions() {
return clonedExpressions;
}
public void setClonedExpressions(Map<Expression, Expression> clonedExpressions) {
this.clonedExpressions = clonedExpressions;
}
public void addAdditionalExpression(Expression theExpression) {
// This change puts a null check into every call, but is printing additional
// expressions in a meaningful order worth it?
additionalExpression = (additionalExpression == null) ? theExpression : additionalExpression.and(theExpression);
}
/**
* INTERNAL:
* Remember this subselect so that it can be normalized after the enclosing
* select statement is.
*/
public void addSubSelectExpression(SubSelectExpression subSelectExpression) {
if (this.subSelectExpressions == null) {
this.subSelectExpressions = new ArrayList(4);
}
if (!this.subSelectExpressions.contains(subSelectExpression)) {
this.subSelectExpressions.add(subSelectExpression);
}
}
public Expression getAdditionalExpression() {
return additionalExpression;
}
public AbstractSession getSession() {
return session;
}
public SQLSelectStatement getStatement() {
return statement;
}
/**
* INTERNAL:
* Were subselect expressions found while normalizing the selection criteria?
* Assumes underlying collection is initialized on first add.
*/
public boolean encounteredSubSelectExpressions() {
return (subSelectExpressions != null);
}
/**
* INTERNAL:
* Normalize all subselect expressions found in the course of normalizing the
* enclosing query.
* This method allows one to completely normalize the parent statement first
* (which should treat its sub selects as black boxes), and then normalize the
* subselects (which require full knowledge of the enclosing statement).
* This should make things clearer too,
* Assumes encounteredSubSelectExpressions() true.
* For CR#4223.
*/
public void normalizeSubSelects(Map clonedExpressions) {
for (SubSelectExpression next : this.subSelectExpressions) {
next.normalizeSubSelect(this, clonedExpressions);
}
}
public void setAdditionalExpression(Expression additionalExpression) {
this.additionalExpression = additionalExpression;
}
public void setSession(AbstractSession session) {
this.session = session;
}
public void setStatement(SQLSelectStatement statement) {
this.statement = statement;
}
/**
* Similar to addAdditionalExpression, this keeps a running expression used for joins so that they can be added locally within 'OR'
* predicates rather than to the entire where clause. If addAdditionalExpressionsWithinCurrrentExpressionContext is false, it will work
* the same as addAdditionalExpression
* @param theExpression
*/
public void addAdditionalLocalExpression(Expression theExpression) {
// This change puts a null check into every call, but is printing additional
// expressions in a meaningful order worth it?
if (addAdditionalExpressionsWithinCurrrentExpressionContext) {
additionalLocalExpression = (additionalLocalExpression == null) ? theExpression : additionalLocalExpression.and(theExpression);
} else {
additionalExpression = (additionalExpression == null) ? theExpression : additionalExpression.and(theExpression);
}
}
/**
* INTERNAL
* This will return the localExpression if isLogicalExpression is false, otherwise it will check the addAdditionalExpressionsWithinCurrrentExpressionContext
* flag and clear additionalLocalExpression once adding it to the localExpression.
* @param localExpression
* @param isLogicalExpression
* @return
*/
public Expression processAdditionalLocalExpressions(Expression localExpression, boolean isLogicalExpression) {
if (!isLogicalExpression || !addAdditionalExpressionsWithinCurrrentExpressionContext) {
return localExpression;
}
Expression expToReturn = localExpression.and(additionalLocalExpression);
additionalLocalExpression = null;
return expToReturn;
}
public boolean isAddAdditionalExpressionsWithinCurrrentExpressionContext() {
return addAdditionalExpressionsWithinCurrrentExpressionContext;
}
/**
* INTERNAL:
* Allows keeping track when the normalizer is within a logical OR statement, where additionalExpressions might need to be added to the local
* expression instead of at the end of the where clause.
* @param addAdditionalExpressionsWithinCurrrentExpressionContext
*/
public void setAddAdditionalExpressionsWithinCurrrentExpressionContext(
boolean addAdditionalExpressionsWithinCurrrentExpressionContext) {
this.addAdditionalExpressionsWithinCurrrentExpressionContext = addAdditionalExpressionsWithinCurrrentExpressionContext;
}
}