/*
* 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.QName;
import org.exist.xquery.util.ExpressionDumper;
import org.exist.xquery.value.Item;
import org.exist.xquery.value.Sequence;
import org.exist.xquery.value.Type;
/**
* Implements an XQuery let-expression.
*
* @author Wolfgang Meier <wolfgang@exist-db.org>
*/
public class LetExpr extends BindingExpression {
public LetExpr(XQueryContext context) {
super(context);
}
@Override
public ClauseType getType() {
return ClauseType.LET;
}
/* (non-Javadoc)
* @see org.exist.xquery.BindingExpression#analyze(org.exist.xquery.Expression, int, org.exist.xquery.OrderSpec[])
*/
public void analyze(AnalyzeContextInfo contextInfo) throws XPathException {
super.analyze(contextInfo);
//Save the local variable stack
final LocalVariable mark = context.markLocalVariables(false);
try {
contextInfo.setParent(this);
final AnalyzeContextInfo varContextInfo = new AnalyzeContextInfo(contextInfo);
inputSequence.analyze(varContextInfo);
//Declare the iteration variable
final LocalVariable inVar = new LocalVariable(QName.parse(context, varName, null));
inVar.setSequenceType(sequenceType);
inVar.setStaticType(varContextInfo.getStaticReturnType());
context.declareVariableBinding(inVar);
//Reset the context position
context.setContextSequencePosition(0, null);
returnExpr.analyze(contextInfo);
} finally {
// restore the local variable stack
context.popLocalVariables(mark);
}
}
/* (non-Javadoc)
* @see org.exist.xquery.Expression#eval(org.exist.xquery.StaticContext, org.exist.dom.persistent.DocumentSet, org.exist.xquery.value.Sequence, org.exist.xquery.value.Item)
*/
public Sequence eval(Sequence contextSequence, Item contextItem)
throws XPathException {
if (context.getProfiler().isEnabled()){
context.getProfiler().start(this);
context.getProfiler().message(this, Profiler.DEPENDENCIES,
"DEPENDENCIES", Dependency.getDependenciesName(this.getDependencies()));
if (contextSequence != null)
{context.getProfiler().message(this, Profiler.START_SEQUENCES,
"CONTEXT SEQUENCE", contextSequence);}
if (contextItem != null)
{context.getProfiler().message(this, Profiler.START_SEQUENCES,
"CONTEXT ITEM", contextItem.toSequence());}
}
context.expressionStart(this);
context.pushDocumentContext();
try {
//Save the local variable stack
LocalVariable mark = context.markLocalVariables(false);
Sequence in;
LocalVariable var;
Sequence resultSequence = null;
try {
// evaluate input sequence
in = inputSequence.eval(contextSequence, null);
clearContext(getExpressionId(), in);
// Declare the iteration variable
var = createVariable(varName);
var.setSequenceType(sequenceType);
context.declareVariableBinding(var);
var.setValue(in);
if (sequenceType == null)
{var.checkType();} //Just because it makes conversions !
var.setContextDocs(inputSequence.getContextDocSet());
registerUpdateListener(in);
resultSequence = returnExpr.eval(contextSequence, null);
if (sequenceType != null) {
int actualCardinality;
if (var.getValue().isEmpty()) {actualCardinality = Cardinality.EMPTY;}
else if (var.getValue().hasMany()) {actualCardinality = Cardinality.MANY;}
else {actualCardinality = Cardinality.ONE;}
//Type.EMPTY is *not* a subtype of other types ; checking cardinality first
if (!Cardinality.checkCardinality(sequenceType.getCardinality(), actualCardinality))
{throw new XPathException(this, ErrorCodes.XPTY0004,
"Invalid cardinality for variable $" + varName +
". Expected " +
Cardinality.getDescription(sequenceType.getCardinality()) +
", got " + Cardinality.getDescription(actualCardinality), in);}
//TODO : ignore nodes right now ; they are returned as xs:untypedAtomicType
if (!Type.subTypeOf(sequenceType.getPrimaryType(), Type.NODE)) {
if (!var.getValue().isEmpty() && !Type.subTypeOf(var.getValue()
.getItemType(), sequenceType.getPrimaryType())) {
throw new XPathException(this, ErrorCodes.XPTY0004,
"Invalid type for variable $" + varName +
". Expected " + Type.getTypeName(sequenceType.getPrimaryType()) +
", got " +Type.getTypeName(var.getValue().getItemType()), in);
}
//Here is an attempt to process the nodes correctly
} else {
//Same as above : we probably may factorize
if (!var.getValue().isEmpty() && !Type.subTypeOf(var.getValue().getItemType(), sequenceType.getPrimaryType()))
{throw new XPathException(this, ErrorCodes.XPTY0004,
"Invalid type for variable $" + varName + ". Expected " +
Type.getTypeName(sequenceType.getPrimaryType()) + ", got " +
Type.getTypeName(var.getValue().getItemType()), in);}
}
}
} finally {
// Restore the local variable stack
context.popLocalVariables(mark, resultSequence);
}
clearContext(getExpressionId(), in);
if (context.getProfiler().isEnabled())
{context.getProfiler().end(this, "", resultSequence);}
if (resultSequence == null)
{return Sequence.EMPTY_SEQUENCE;}
if (!(resultSequence instanceof DeferredFunctionCall)) {
setActualReturnType(resultSequence.getItemType());
}
if (getPreviousClause() == null) {
resultSequence = postEval(resultSequence);
}
return resultSequence;
} finally {
context.popDocumentContext();
context.expressionEnd(this);
}
}
/* (non-Javadoc)
* @see org.exist.xquery.Expression#dump(org.exist.xquery.util.ExpressionDumper)
*/
public void dump(ExpressionDumper dumper) {
dumper.display("let ", line);
dumper.startIndent();
dumper.display("$").display(varName);
dumper.display(" := ");
inputSequence.dump(dumper);
dumper.endIndent();
//TODO : QuantifiedExpr
if (returnExpr instanceof LetExpr)
{dumper.display(", ");}
else
{dumper.nl().display("return ");}
dumper.startIndent();
returnExpr.dump(dumper);
dumper.endIndent();
}
public String toString() {
final StringBuilder result = new StringBuilder();
result.append("let ");
result.append("$").append(varName);
result.append(" := ");
result.append(inputSequence.toString());
result.append(" ");
//TODO : QuantifiedExpr
if (returnExpr instanceof LetExpr)
{result.append(", ");}
else
{result.append("return ");}
result.append(returnExpr.toString());
return result.toString();
}
public void accept(ExpressionVisitor visitor) {
visitor.visitLetExpression(this);
}
@Override
public boolean allowMixedNodesInReturn() {
return true;
}
}