package net.sf.saxon.expr;
import net.sf.saxon.event.ReceiverOptions;
import net.sf.saxon.event.SequenceReceiver;
import net.sf.saxon.event.SequenceOutputter;
import net.sf.saxon.instruct.DivisibleInstruction;
import net.sf.saxon.instruct.ValueOf;
import net.sf.saxon.om.*;
import net.sf.saxon.pattern.EmptySequenceTest;
import net.sf.saxon.pattern.NodeTest;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.type.*;
import net.sf.saxon.value.*;
import java.util.Stack;
/**
* An Atomizer is an expression corresponding essentially to the fn:data() function: it
* maps a sequence by replacing nodes with their typed values
*/
public final class Atomizer extends UnaryExpression implements DivisibleInstruction {
private boolean untyped = false; //set to true if it is known that the nodes being atomized will be untyped
private boolean singleValued = false; // set to true if all atomized nodes will atomize to a single atomic value
private ItemType operandItemType = null;
/**
* Constructor
* @param sequence the sequence to be atomized
* */
public Atomizer(Expression sequence) {
super(sequence);
sequence.setFlattened(true);
}
/**
* Simplify an expression
* @param visitor an expression visitor
*/
public Expression simplify(ExpressionVisitor visitor) throws XPathException {
computeSingleValued(visitor.getConfiguration().getTypeHierarchy());
operand = visitor.simplify(operand);
if (operand instanceof Literal) {
Value val = ((Literal)operand).getValue();
if (val instanceof SingletonItem && ((SingletonItem)val).getItem() instanceof FunctionItem) {
XPathException err = new XPathException("Cannot atomize a function item", "FOTY0013");
err.setLocator(this);
throw err;
}
if (val instanceof AtomicValue) {
return operand;
}
SequenceIterator iter = val.iterate();
while (true) {
// if all items in the sequence are atomic (they generally will be, since this is
// done at compile time), then return the sequence
Item i = iter.next();
if (i == null) {
return operand;
}
if (i instanceof NodeInfo) {
return this;
}
}
} else if (operand instanceof ValueOf && (((ValueOf)operand).getOptions()& ReceiverOptions.DISABLE_ESCAPING) == 0) {
// XSLT users tend to use ValueOf unnecessarily
return ((ValueOf)operand).convertToStringJoin(visitor.getStaticContext());
}
return this;
}
/**
* Type-check the expression
*/
public Expression typeCheck(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException {
untyped = !visitor.getExecutable().isSchemaAware();
operand = visitor.typeCheck(operand, contextItemType);
// If the configuration allows typed data, check whether the content type of these particular nodes is untyped
final TypeHierarchy th = visitor.getConfiguration().getTypeHierarchy();
computeSingleValued(th);
visitor.resetStaticProperties();
ItemType operandType = operand.getItemType(th);
if (th.isSubType(operandType, BuiltInAtomicType.ANY_ATOMIC)) {
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.setLocator(this);
throw err;
}
operand.setFlattened(true);
return this;
}
private void computeSingleValued(TypeHierarchy th) {
singleValued = untyped;
if (!singleValued) {
ItemType nodeType = operand.getItemType(th);
if (nodeType instanceof NodeTest) {
SchemaType st = ((NodeTest)nodeType).getContentType();
if (st == Untyped.getInstance() || st.isAtomicType()) {
singleValued = true;
}
}
}
}
/**
* Perform optimisation of an expression and its subexpressions.
* <p/>
* <p>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.</p>
*
* @param visitor an expression visitor
* @param contextItemType 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)
*/
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 (th.isSubType(operand.getItemType(th), BuiltInAtomicType.ANY_ATOMIC)) {
return operand;
}
if (operand instanceof ValueOf && (((ValueOf)operand).getOptions()& ReceiverOptions.DISABLE_ESCAPING) == 0) {
// XSLT users tend to use ValueOf unnecessarily
return ((ValueOf)operand).convertToStringJoin(visitor.getStaticContext());
}
}
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() {
Atomizer copy = new Atomizer(getBaseExpression().copy());
copy.untyped = untyped;
copy.singleValued = singleValued;
return copy;
}
/**
* Iterate over the sequence of values
*/
public SequenceIterator iterate(XPathContext context) throws XPathException {
SequenceIterator base = operand.iterate(context);
return getAtomizingIterator(base);
}
/**
* Evaluate as an Item. This should only be called if the Atomizer has cardinality zero-or-one,
* which will only be the case if the underlying expression has cardinality zero-or-one.
*/
public Item evaluateItem(XPathContext context) throws XPathException {
Item i = operand.evaluateItem(context);
if (i==null) {
return null;
}
if (i instanceof NodeInfo) {
return Value.asItem(((NodeInfo)i).atomize());
} else {
return i;
}
}
/**
* Process the instruction, without returning any tail calls
* @param context The dynamic context, giving access to the current node,
* the current variables, etc.
*/
public void process(XPathContext context) throws XPathException {
super.process(context); //To change body of overridden methods use File | Settings | File Templates.
}
/**
* 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) {
operandItemType = operand.getItemType(th);
return getAtomizedItemType(operand, untyped, th);
}
/**
* Compute the type that will result from atomizing the result of a given expression
* @param operand the given expression
* @param alwaysUntyped true if it is known that nodes will always be untyped
* @param th the type hierarchy cache
* @return the item type of the result of evaluating the operand expression, after atomization
*/
public static ItemType getAtomizedItemType(Expression operand, boolean alwaysUntyped, TypeHierarchy th) {
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 (alwaysUntyped) {
// 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();
}
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 (untyped || singleValued) {
return operand.getCardinality();
} else {
if (Cardinality.allowsMany(operand.getCardinality())) {
return StaticProperty.ALLOWS_ZERO_OR_MORE;
}
ItemType in = operandItemType;
if (in == null) {
try {
in = operand.getItemType(getContainer().getExecutable().getConfiguration().getTypeHierarchy());
} catch (NullPointerException npe) {
return StaticProperty.ALLOWS_ZERO_OR_MORE;
}
}
if (in.isAtomicType()) {
return operand.getCardinality();
}
if (in instanceof NodeTest) {
SchemaType schemaType = ((NodeTest)in).getContentType();
if (schemaType.isAtomicType()) {
// can return at most one atomic value per node
return operand.getCardinality();
}
}
return StaticProperty.ALLOWS_ZERO_OR_MORE;
}
}
/**
* Add a representation of this expression to a PathMap. The PathMap captures a map of the nodes visited
* by an expression in a source tree.
* <p/>
* <p>The default implementation of this method assumes that an expression does no navigation other than
* the navigation done by evaluating its subexpressions, and that the subexpressions are evaluated in the
* same context as the containing expression. The method must be overridden for any expression
* where these assumptions do not hold. For example, implementations exist for AxisExpression, ParentExpression,
* and RootExpression (because they perform navigation), and for the doc(), document(), and collection()
* functions because they create a new navigation root. Implementations also exist for PathExpression and
* FilterExpression because they have subexpressions that are evaluated in a different context from the
* calling expression.</p>
*
* @param pathMap the PathMap to which the expression should be added
* @param pathMapNodeSet the PathMapNodeSet to which the paths embodied in this expression should be added
* @return the pathMapNodeSet representing the points in the source document that are both reachable by this
* expression, and that represent possible results of this expression. For an expression that does
* navigation, it represents the end of the arc in the path map that describes the navigation route. For other
* expressions, it is the same as the input pathMapNode.
*/
public PathMap.PathMapNodeSet addToPathMap(PathMap pathMap, PathMap.PathMapNodeSet pathMapNodeSet) {
PathMap.PathMapNodeSet result = operand.addToPathMap(pathMap, pathMapNodeSet);
if (result != null) {
result.setAtomized();
}
return null;
}
/**
* Get an iterator that returns the result of atomizing the sequence delivered by the supplied
* iterator
* @param base the supplied iterator, the input to atomization
* @return an iterator that returns atomic values, the result of the atomization
*/
public static SequenceIterator getAtomizingIterator(SequenceIterator base) throws XPathException {
if (base instanceof AxisIterator) {
return new AxisAtomizingIterator((AxisIterator)base);
}
if ((base.getProperties() & SequenceIterator.LAST_POSITION_FINDER) != 0) {
int count = ((LastPositionFinder)base).getLastPosition();
if (count == 0) {
return EmptyIterator.getInstance();
} else if (count == 1) {
Item first = base.next();
return first.getTypedValue();
}
}
return new MappingIterator(base, AtomizingFunction.getInstance());
}
/**
* In streaming mode, process the first half of the instruction (for example, to start a new document or element)
* @param contextStack
* @param state a stack on which the instruction can save state information during the call on processLeft()
*/
public void processLeft(Stack<XPathContext> contextStack, Stack state) throws XPathException {
XPathContext context = contextStack.peek();
SequenceReceiver out = context.getReceiver();
state.push(out);
SequenceOutputter out2 = new SequenceOutputter();
out2.setPipelineConfiguration(out.getPipelineConfiguration());
context.setReceiver(out2);
int annotation = ((NodeInfo)context.getContextItem()).getTypeAnnotation();
state.push(annotation);
}
/**
* In streaming mode, process the right half of the instruction (for example, to end a new document or element)
* Note that unlike other divisible instructions this one doesn't push the result to the current output
* destination, it leaves a sequenceIterator over the result on the stack.
* @param contextStack
* @param state a stack on which the instruction can save state information during the call on processLeft()
*/
public void processRight(Stack<XPathContext> contextStack, Stack state) throws XPathException {
XPathContext context = contextStack.peek();
int annotation = (Integer)state.pop();
CharSequence value = ((SequenceOutputter)context.getReceiver()).getFirstItem().getStringValueCS();
SchemaType type = context.getConfiguration().getSchemaType(annotation);
SequenceReceiver out = (SequenceReceiver)state.pop();
context.setReceiver(out);
if (type.isComplexType()) {
if (((ComplexType)type).isMixedContent()) {
SequenceIterator iter = SingletonIterator.makeIterator(new UntypedAtomicValue(value));
state.push(iter);
} else {
throw new XPathException("Cannot atomize element with element-only content");
}
} else {
// TODO: handle namespace-sensitive types
if (((SimpleType)type).isNamespaceSensitive()) {
throw new XPathException("Cannot yet do streaming of content with namespace-sensitive element types");
}
SequenceIterator iter = ((SimpleType)type).getTypedValue(value, null, context.getConfiguration().getNameChecker());
state.push(iter);
}
}
/**
* Diagnostic print of expression structure. The abstract expression tree
* is written to the supplied output destination.
*/
public String displayExpressionName() {
return "atomize";
}
/**
* Implement the mapping function. This is stateless, so there is a singleton instance.
*/
public static class AtomizingFunction implements MappingFunction {
/**
* Private constructor, ensuring that everyone uses the singleton instance
*/
private AtomizingFunction(){}
private static final AtomizingFunction theInstance = new AtomizingFunction();
/**
* Get the singleton instance
* @return the singleton instance of this mapping function
*/
public static AtomizingFunction getInstance() {
return theInstance;
}
public SequenceIterator map(Item item) throws XPathException {
if (item instanceof NodeInfo) {
return item.getTypedValue();
} else {
return SingletonIterator.makeIterator(item);
}
}
}
}
//
// 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.
//