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An OSGi bundle for Saxon-HE
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2013 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.Configuration;
import net.sf.saxon.expr.parser.ExpressionVisitor;
import net.sf.saxon.expr.parser.PathMap;
import net.sf.saxon.expr.parser.RoleLocator;
import net.sf.saxon.om.*;
import net.sf.saxon.pattern.NodeKindTest;
import net.sf.saxon.pattern.NodeTest;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.type.*;
import net.sf.saxon.value.AtomicValue;
import net.sf.saxon.value.ObjectValue;
import net.sf.saxon.value.StringValue;
import java.util.List;
/**
* A SingletonAtomizer combines the functions of an Atomizer and a CardinalityChecker: it is used to
* atomize a sequence of nodes, checking that the result of the atomization contains zero or one atomic
* values. Note that the input may be a sequence of nodes or atomic values, even though the result must
* contain at most one atomic value.
*/
public final class SingletonAtomizer extends UnaryExpression {
private boolean allowEmpty;
private RoleLocator role;
/**
* Constructor
* @param sequence the sequence to be atomized
* @param role contains information about where the expression appears, for use in any error message
* @param allowEmpty true if the result sequence is allowed to be empty.
*/
public SingletonAtomizer(Expression sequence, RoleLocator role, boolean allowEmpty) {
super(sequence);
this.allowEmpty = allowEmpty;
this.role = role;
}
/**
* Simplify an expression
* @param visitor an expression visitor
*/
/*@NotNull*/
public Expression simplify(ExpressionVisitor visitor) throws XPathException {
operand = visitor.simplify(operand);
if (operand instanceof Literal && ((Literal)(operand)).getValue() instanceof AtomicValue) {
return operand;
}
return this;
}
/**
* Type-check the expression
*/
/*@NotNull*/
public Expression typeCheck(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) throws XPathException {
operand = visitor.typeCheck(operand, contextItemType);
visitor.resetStaticProperties();
if (Literal.isEmptySequence(operand)) {
if (!allowEmpty) {
typeError("An empty sequence is not allowed as the " +
role.getMessage(), role.getErrorCode(), null);
}
return operand;
}
final TypeHierarchy th = visitor.getConfiguration().getTypeHierarchy();
ItemType operandType = operand.getItemType(th);
if (operandType.isPlainType()) {
return operand;
}
if (!operandType.isAtomizable()) {
XPathException err;
if (operandType instanceof FunctionItemType) {
err = new XPathException(
"Cannot atomize a function item", "FOTY0013");
} else {
err = new XPathException(
"Cannot atomize an element that is defined in the schema to have element-only content", "FOTY0012");
}
err.setIsTypeError(true);
err.setLocator(this);
throw err;
}
return this;
}
/*@NotNull*/
public Expression optimize(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) throws XPathException {
Expression exp = super.optimize(visitor, contextItemType);
if (exp == this) {
final TypeHierarchy th = visitor.getConfiguration().getTypeHierarchy();
if (operand.getItemType(th).isPlainType()) {
return operand;
}
return this;
} else {
return exp;
}
}
/**
* Determine the special properties of this expression
* @return {@link 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() {
return new SingletonAtomizer(getBaseExpression().copy(), role, allowEmpty);
}
/**
* Get the RoleLocator (used to construct error messages)
* @return the role locator
*/
public RoleLocator getRole() {
return role;
}
/*@Nullable*/ public PathMap.PathMapNodeSet addToPathMap(PathMap pathMap, PathMap.PathMapNodeSet pathMapNodeSet) {
PathMap.PathMapNodeSet result = operand.addToPathMap(pathMap, pathMapNodeSet);
if (result != null) {
TypeHierarchy th = getExecutable().getConfiguration().getTypeHierarchy();
ItemType operandItemType = operand.getItemType(th);
if (th.relationship(NodeKindTest.ELEMENT, operandItemType) != TypeHierarchy.DISJOINT ||
th.relationship(NodeKindTest.DOCUMENT, operandItemType) != TypeHierarchy.DISJOINT) {
result.setAtomized();
}
}
return null;
}
/**
* Evaluate as an Item. This should only be called if a singleton or empty sequence is required;
* it throws a type error if the underlying sequence is multi-valued.
*/
public AtomicValue evaluateItem(XPathContext context) throws XPathException {
int found = 0;
AtomicValue result = null;
SequenceIterator iter = operand.iterate(context);
while (true) {
Item item = iter.next();
if (item == null) {
break;
}
if (item instanceof AtomicValue) {
if (found++ > 0) {
typeError(
"A sequence of more than one item is not allowed as the " +
role.getMessage(), role.getErrorCode(), context);
}
result = (AtomicValue)item;
} else if (item instanceof FunctionItem) {
typeError("A function item cannot appear as the " +
role.getMessage(), "FOTY0013", context);
} else if (item instanceof ObjectValue) {
return new StringValue(item.getStringValue());
} else {
AtomicSequence value = ((NodeInfo)item).atomize();
found += SequenceTool.getLength(value);
if (found > 1) {
typeError(
"A sequence of more than one item is not allowed as the " +
role.getMessage(), role.getErrorCode(), context);
}
result = value.head();
}
}
if (found == 0 && !allowEmpty) {
typeError("An empty sequence is not allowed as the " +
role.getMessage(), role.getErrorCode(), null);
}
return result;
}
/**
* Determine the data type of the items returned by the expression, if possible
* @return a value such as Type.STRING, Type.BOOLEAN, Type.NUMBER. For this class, the
* result is always an atomic type, but it might be more specific.
* @param th the type hierarchy cache
*/
/*@NotNull*/
public ItemType getItemType(TypeHierarchy th) {
boolean isSchemaAware = true;
try {
isSchemaAware = getExecutable().isSchemaAware();
} catch (NullPointerException err) {
// ultra-cautious code in case expression container has not been set
if (!th.getConfiguration().isLicensedFeature(Configuration.LicenseFeature.SCHEMA_VALIDATION)) {
isSchemaAware = false;
}
}
ItemType in = operand.getItemType(th);
if (in.isPlainType()) {
return in;
} else if (in instanceof NodeTest) {
if (in instanceof ErrorType) {
return in;
}
int kinds = ((NodeTest)in).getNodeKindMask();
if (!isSchemaAware) {
// Some node-kinds always have a typed value that's a string
if ((kinds | STRING_KINDS) == STRING_KINDS) {
return BuiltInAtomicType.STRING;
}
// Some node-kinds are always untyped atomic; some are untypedAtomic provided that the configuration
// is untyped
if ((kinds | UNTYPED_IF_UNTYPED_KINDS) == UNTYPED_IF_UNTYPED_KINDS) {
return BuiltInAtomicType.UNTYPED_ATOMIC;
}
} else {
if ((kinds | UNTYPED_KINDS) == UNTYPED_KINDS) {
return BuiltInAtomicType.UNTYPED_ATOMIC;
}
}
return in.getAtomizedItemType();
} else if (in instanceof ExternalObjectType) {
return in.getAtomizedItemType();
}
return BuiltInAtomicType.ANY_ATOMIC;
}
/**
* Node kinds whose typed value is always a string
*/
private static final int STRING_KINDS =
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