/*
* eXist Open Source Native XML Database
* Copyright (C) 2001-06 Wolfgang M. Meier
* wolfgang@exist-db.org
* http://exist.sourceforge.net
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* $Id$
*/
package org.exist.xquery;
import org.exist.dom.DocumentSet;
import org.exist.xquery.util.ExpressionDumper;
import org.exist.xquery.value.Item;
import org.exist.xquery.value.Sequence;
import org.exist.xquery.value.Type;
/**
* XQuery if ... then ... else expression.
*
* @author wolf
*/
public class ConditionalExpression extends AbstractExpression implements RewritableExpression {
private Expression testExpr;
private Expression thenExpr;
private Expression elseExpr;
public ConditionalExpression(XQueryContext context, Expression testExpr,
Expression thenExpr, Expression elseExpr) {
super(context);
this.testExpr = testExpr.simplify();
this.thenExpr = thenExpr.simplify();
this.elseExpr = elseExpr.simplify();
}
/* (non-Javadoc)
* @see org.exist.xquery.AbstractExpression#getDependencies()
*/
public int getDependencies() {
return Dependency.CONTEXT_SET | Dependency.CONTEXT_ITEM;
}
public Expression getTestExpr() {
return testExpr;
}
public Expression getThenExpr() {
return thenExpr;
}
public Expression getElseExpr() {
return elseExpr;
}
/* (non-Javadoc)
* @see org.exist.xquery.AbstractExpression#getCardinality()
*/
public int getCardinality() {
return thenExpr.getCardinality() | elseExpr.getCardinality();
}
/* (non-Javadoc)
* @see org.exist.xquery.Expression#analyze(org.exist.xquery.Expression)
*/
public void analyze(AnalyzeContextInfo contextInfo) throws XPathException {
AnalyzeContextInfo myContextInfo = new AnalyzeContextInfo(contextInfo);
myContextInfo.setFlags(myContextInfo.getFlags() & (~IN_PREDICATE));
myContextInfo.setParent(this);
testExpr.analyze(myContextInfo);
// parent may have been modified by testExpr: set it again
myContextInfo.setParent(this);
thenExpr.analyze(myContextInfo);
myContextInfo.setParent(this);
elseExpr.analyze(myContextInfo);
}
/* (non-Javadoc)
* @see org.exist.xquery.Expression#eval(org.exist.dom.DocumentSet,
* org.exist.xquery.value.Sequence, org.exist.xquery.value.Item)
*/
public Sequence eval(Sequence contextSequence, Item contextItem) throws XPathException {
context.expressionStart(this);
final Sequence testSeq = testExpr.eval(contextSequence, contextItem);
try {
if (testSeq.effectiveBooleanValue()) {
return thenExpr.eval(contextSequence, contextItem);
} else {
return elseExpr.eval(contextSequence, contextItem);
}
} catch (final XPathException e) {
if (e.getLine() == 0)
{e.setLocation(line, column);}
throw e;
} finally {
context.expressionEnd(this);
}
}
/* (non-Javadoc)
* @see org.exist.xquery.Expression#preselect(org.exist.dom.DocumentSet)
*/
public DocumentSet preselect(DocumentSet in_docs) throws XPathException {
return in_docs;
}
/* (non-Javadoc)
* @see org.exist.xquery.Expression#dump(org.exist.xquery.util.ExpressionDumper)
*/
public void dump(ExpressionDumper dumper) {
dumper.display("if (");
dumper.startIndent();
testExpr.dump(dumper);
dumper.endIndent();
dumper.nl().display(") then");
dumper.startIndent();
thenExpr.dump(dumper);
dumper.endIndent();
dumper.nl().display("else");
dumper.startIndent();
elseExpr.dump(dumper);
dumper.endIndent();
}
public String toString() {
final StringBuilder result = new StringBuilder();
result.append("if ( ");
result.append(testExpr.toString());
result.append(" ) then ");
result.append(thenExpr.toString());
result.append(" else ");
result.append(elseExpr.toString());
return result.toString();
}
/* (non-Javadoc)
* @see org.exist.xquery.Expression#returnsType()
*/
public int returnsType() {
return Type.getCommonSuperType(thenExpr.returnsType(), elseExpr.returnsType());
}
/* (non-Javadoc)
* @see org.exist.xquery.AbstractExpression#resetState()
*/
public void resetState(boolean postOptimization) {
super.resetState(postOptimization);
testExpr.resetState(postOptimization);
thenExpr.resetState(postOptimization);
elseExpr.resetState(postOptimization);
}
public void accept(ExpressionVisitor visitor) {
visitor.visitConditional(this);
}
/* RewritableExpression API */
@Override
public void replace(Expression oldExpr, Expression newExpr) {
if (testExpr == oldExpr)
{testExpr = newExpr;}
else if (thenExpr == oldExpr)
{thenExpr = newExpr;}
else if (elseExpr == oldExpr)
{elseExpr = newExpr;}
}
@Override
public Expression getPrevious(Expression current) {
return null;
}
@Override
public Expression getFirst() {
return null;
}
@Override
public void remove(Expression oldExpr) throws XPathException {
//Nothing to do
}
/* END RewritableExpression API */
}