package net.sf.saxon.expr;
import net.sf.saxon.Configuration;
import net.sf.saxon.instruct.Executable;
import net.sf.saxon.om.Item;
import net.sf.saxon.om.NodeInfo;
import net.sf.saxon.om.SequenceIterator;
import net.sf.saxon.pattern.EmptySequenceTest;
import net.sf.saxon.pattern.NodeTest;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.type.BuiltInAtomicType;
import net.sf.saxon.type.ItemType;
import net.sf.saxon.type.Type;
import net.sf.saxon.type.TypeHierarchy;
import net.sf.saxon.value.AtomicValue;
import net.sf.saxon.value.Value;
/**
* 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
*/
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
*/
public Expression typeCheck(ExpressionVisitor visitor, ItemType 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();
if (operand.getItemType(th).isAtomicType()) {
return operand;
}
return this;
}
public Expression optimize(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException {
Expression exp = super.optimize(visitor, contextItemType);
if (exp == this) {
final TypeHierarchy th = visitor.getConfiguration().getTypeHierarchy();
if (operand.getItemType(th).isAtomicType()) {
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
*/
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;
}
public PathMap.PathMapNodeSet addToPathMap(PathMap pathMap, PathMap.PathMapNodeSet pathMapNodeSet) {
PathMap.PathMapNodeSet result = operand.addToPathMap(pathMap, pathMapNodeSet);
if (result != null) {
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 Item evaluateItem(XPathContext context) throws XPathException {
int found = 0;
Item 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 = item;
} else {
Value value = ((NodeInfo)item).atomize();
found += value.getLength();
if (found > 1) {
typeError(
"A sequence of more than one item is not allowed as the " +
role.getMessage(), role.getErrorCode(), context);
}
result = value.itemAt(0);
}
}
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
*/
public ItemType getItemType(TypeHierarchy th) {
boolean isSchemaAware = true;
Executable exec = getExecutable();
if (exec != null && !exec.getConfiguration().isSchemaAware(Configuration.XML_SCHEMA)) {
isSchemaAware = false;
}
ItemType in = operand.getItemType(th);
if (in.isAtomicType()) {
return in;
}
if (in instanceof NodeTest) {
if (in instanceof EmptySequenceTest) {
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();
// SchemaType schemaType = ((NodeTest)in).getContentType();
// if (schemaType instanceof SimpleType) {
// return ((SimpleType)schemaType).getCommonAtomicType();
// } else if (((ComplexType)schemaType).isSimpleContent()) {
// return ((ComplexType)schemaType).getSimpleContentType().getCommonAtomicType();
// } else if (schemaType instanceof AnyType) {
// // AnyType includes AnySimpleType as a subtype, so the atomized value can be any atomic type
// // including untypedAtomic
// return BuiltInAtomicType.ANY_ATOMIC;
// } else {
// // if a complex type with complex content (other than AnyType) can be atomized at all,
// // then it will return untypedAtomic values
// return BuiltInAtomicType.UNTYPED_ATOMIC;
// }
}
return BuiltInAtomicType.ANY_ATOMIC;
}
/**
* Node kinds whose typed value is always a string
*/
private static final int STRING_KINDS =
(1<<Type.NAMESPACE) | (1<<Type.COMMENT) | (1<<Type.PROCESSING_INSTRUCTION);
/**
* Node kinds whose typed value is always untypedAtomic
*/
private static final int UNTYPED_KINDS =
(1<<Type.TEXT) | (1<<Type.DOCUMENT);
/**
* Node kinds whose typed value is untypedAtomic if the configuration is untyped
*/
private static final int UNTYPED_IF_UNTYPED_KINDS =
(1<<Type.TEXT) | (1<<Type.ELEMENT) | (1<<Type.DOCUMENT) | (1<<Type.ATTRIBUTE);
/**
* Determine the static cardinality of the expression
*/
public int computeCardinality() {
if (allowEmpty) {
return StaticProperty.ALLOWS_ZERO_OR_ONE;
} else {
return StaticProperty.EXACTLY_ONE;
}
}
/**
* Give a string representation of the expression name for use in diagnostics
* @return the expression name, as a string
*/
protected String displayExpressionName() {
return "atomizeSingleton";
}
}
//
// The contents of this file are subject to the Mozilla Public License Version 1.0 (the "License");
// you may not use this file except in compliance with the License. You may obtain a copy of the
// License at http://www.mozilla.org/MPL/
//
// Software distributed under the License is distributed on an "AS IS" basis,
// WITHOUT WARRANTY OF ANY KIND, either express or implied.
// See the License for the specific language governing rights and limitations under the License.
//
// The Original Code is: all this file.
//
// The Initial Developer of the Original Code is Michael H. Kay
//
// Portions created by (your name) are Copyright (C) (your legal entity). All Rights Reserved.
//
// Contributor(s): none.
//