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////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2015 Saxonica Limited.
// This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
// If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
// This Source Code Form is "Incompatible With Secondary Licenses", as defined by the Mozilla Public License, v. 2.0.
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
package net.sf.saxon.expr;
import net.sf.saxon.expr.parser.*;
import net.sf.saxon.lib.ConversionRules;
import net.sf.saxon.om.*;
import net.sf.saxon.trace.ExpressionPresenter;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.tree.iter.EmptyIterator;
import net.sf.saxon.type.*;
import net.sf.saxon.value.AtomicValue;
import net.sf.saxon.value.Cardinality;
import net.sf.saxon.value.SequenceType;
/**
* Expression class for a cast to a List type
*/
public class CastToList extends UnaryExpression {
private ListType targetType;
private boolean allowEmpty;
public CastToList(Expression source, ListType targetType, boolean allowEmpty) {
super(source);
this.targetType = targetType;
this.allowEmpty = allowEmpty;
}
public boolean isAllowEmpty() {
return allowEmpty;
}
public ListType getTargetType() {
return targetType;
}
public NamespaceResolver getNamespaceResolver() {
return getRetainedStaticContext();
}
protected OperandRole getOperandRole() {
return OperandRole.SINGLE_ATOMIC;
}
/**
* Type-check the expression
*/
/*@NotNull*/
public Expression typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) throws XPathException {
typeCheckChildren(visitor, contextInfo);
SequenceType atomicType = SequenceType.makeSequenceType(
BuiltInAtomicType.STRING,
allowEmpty ? StaticProperty.ALLOWS_ZERO_OR_ONE : StaticProperty.EXACTLY_ONE);
RoleDiagnostic role = new RoleDiagnostic(RoleDiagnostic.TYPE_OP, "cast as", 0);
//role.setSourceLocator(this);
Expression operand = TypeChecker.staticTypeCheck(getBaseExpression(), atomicType, false, role, visitor);
setBaseExpression(operand);
final TypeHierarchy th = getConfiguration().getTypeHierarchy();
boolean maybeString = th.relationship(operand.getItemType(), BuiltInAtomicType.STRING) != TypeHierarchy.DISJOINT;
boolean maybeUntyped = th.relationship(operand.getItemType(), BuiltInAtomicType.UNTYPED_ATOMIC) != TypeHierarchy.DISJOINT;
if (!maybeString && !maybeUntyped) {
XPathException err = new XPathException("Casting to list requires an xs:string or xs:untypedAtomic operand");
err.setErrorCode("XPTY0004");
err.setLocation(getLocation());
err.setIsTypeError(true);
throw err;
}
if (operand instanceof Literal) {
GroundedValue literalOperand = ((Literal) operand).getValue();
if (literalOperand instanceof AtomicValue) {
try {
SequenceIterator seq = iterate(visitor.getStaticContext().makeEarlyEvaluationContext());
return Literal.makeLiteral(SequenceTool.toGroundedValue(seq));
} catch (XPathException err) {
err.maybeSetErrorCode("FORG0001");
err.setLocation(getLocation());
err.setIsTypeError(true);
throw err;
}
}
if (literalOperand.getLength() == 0) {
if (allowEmpty) {
return operand;
} else {
XPathException err = new XPathException("Cast can never succeed: the operand must not be an empty sequence");
err.setErrorCode("XPTY0004");
err.setLocation(getLocation());
err.setIsTypeError(true);
throw err;
}
}
}
return this;
}
/**
* Perform optimisation of an expression and its subexpressions.
*
* This method is called after all references to functions and variables have been resolved
* to the declaration of the function or variable, and after all type checking has been done.
*
* @param visitor an expression visitor
* @param contextInfo the static type of "." at the point where this expression is invoked.
* The parameter is set to null if it is known statically that the context item will be undefined.
* If the type of the context item is not known statically, the argument is set to
* {@link net.sf.saxon.type.Type#ITEM_TYPE}
* @return the original expression, rewritten if appropriate to optimize execution
* @throws net.sf.saxon.trans.XPathException
* if an error is discovered during this phase
* (typically a type error)
*/
/*@NotNull*/
public Expression optimize(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) throws XPathException {
Expression e2 = super.optimize(visitor, contextInfo);
if (e2 != this) {
return e2;
}
// if the operand can't be empty, then set allowEmpty to false to provide more information for analysis
if (!Cardinality.allowsZero(getBaseExpression().getCardinality())) {
allowEmpty = false;
resetLocalStaticProperties();
}
return this;
}
/**
* Get the static cardinality of the expression
*/
public int computeCardinality() {
return StaticProperty.ALLOWS_ZERO_OR_MORE;
}
/**
* Get the static type of the expression
*
*
*
* /*@NotNull
*/
public ItemType getItemType() {
try {
if (targetType.getItemType() instanceof ItemType) {
return (ItemType) targetType.getItemType();
}
} catch (MissingComponentException e) {
//
}
return BuiltInAtomicType.ANY_ATOMIC;
}
/**
* Determine the special properties of this expression
*
* @return {@link net.sf.saxon.expr.StaticProperty#NON_CREATIVE}.
*/
public int computeSpecialProperties() {
int p = super.computeSpecialProperties();
return p | StaticProperty.NON_CREATIVE;
}
/**
* Copy an expression. This makes a deep copy.
*
* @return the copy of the original expression
*/
/*@NotNull*/
public Expression copy() {
CastToList c = new CastToList(getBaseExpression().copy(), targetType, allowEmpty);
ExpressionTool.copyLocationInfo(this, c);
c.setRetainedStaticContext(getRetainedStaticContext());
return c;
}
/**
* An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process().
* This method indicates which of these methods is provided directly. The other methods will always be available
* indirectly, using an implementation that relies on one of the other methods.
*
* @return the implementation method, for example {@link #ITERATE_METHOD} or {@link #EVALUATE_METHOD} or
* {@link #PROCESS_METHOD}
*/
@Override
public int getImplementationMethod() {
return ITERATE_METHOD;
}
/**
* Evaluate the expression
*/
public SequenceIterator iterate(XPathContext context) throws XPathException {
AtomicValue value = (AtomicValue) getBaseExpression().evaluateItem(context);
if (value == null) {
if (allowEmpty) {
return EmptyIterator.emptyIterator();
} else {
XPathException e = new XPathException("Cast does not allow an empty sequence");
e.setXPathContext(context);
e.setLocation(getLocation());
e.setErrorCode("XPTY0004");
throw e;
}
}
return cast(value.getStringValueCS(), targetType, getRetainedStaticContext(),
context.getConfiguration().getConversionRules()).iterate();
}
/**
* Cast a string value to a list type
*
* @param value the input string value
* @param targetType the target list type
* @param nsResolver the namespace context, needed if the type is namespace-sensitive
* @param rules the conversion rules
* @return the sequence of atomic values that results from the conversion
* @throws XPathException if the conversion fails
*/
public static AtomicSequence cast(CharSequence value, ListType targetType, final NamespaceResolver nsResolver, final ConversionRules rules)
throws XPathException {
ValidationFailure failure = targetType.validateContent(value, nsResolver, rules);
if (failure != null) {
throw failure.makeException();
}
return targetType.getTypedValue(value, nsResolver, rules);
}
/**
* Is this expression the same as another expression?
*/
public boolean equals(Object other) {
return super.equals(other) &&
other instanceof CastToList &&
targetType == ((CastToList) other).targetType &&
allowEmpty == ((CastToList) other).allowEmpty &&
ExpressionTool.equalOrNull(getRetainedStaticContext(), ((CastToList)other).getRetainedStaticContext());
}
/**
* get HashCode for comparing two expressions.
*/
@Override
public int hashCode() {
return super.hashCode() ^ targetType.hashCode();
}
/**
* The toString() method for an expression attempts to give a representation of the expression
* in an XPath-like form, but there is no guarantee that the syntax will actually be true XPath.
* In the case of XSLT instructions, the toString() method gives an abstracted view of the syntax
*/
public String toString() {
return targetType.getEQName() + "(" + getBaseExpression().toString() + ")";
}
@Override
public String toShortString() {
return targetType.getDisplayName() + "(" + getBaseExpression().toShortString() + ")";
}
/**
* Diagnostic print of expression structure. The abstract expression tree
* is written to the supplied output destination.
*/
public void export(ExpressionPresenter out) {
out.startElement("castToList", this);
out.emitAttribute("as", targetType.toString());
getBaseExpression().export(out);
out.endElement();
}
}
// Copyright (c) 2011-2012 Saxonica Limited. All rights reserved.
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