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Saxon a complete and conformant implementation of the XSLT 2.0, XQuery 1.0, and XPath 2.0 Recommendations published on 23 January 2007 by W3C
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package net.sf.saxon.expr;
import net.sf.saxon.instruct.Choose;
import net.sf.saxon.om.StructuredQName;
import net.sf.saxon.om.ValueRepresentation;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.value.SequenceType;
import net.sf.saxon.value.MemoClosure;
import net.sf.saxon.value.Value;
import net.sf.saxon.type.ItemType;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
/**
* Assignation is an abstract superclass for the kinds of expression
* that declare range variables: for, some, and every.
*/
public abstract class Assignation extends Expression implements Binding {
protected int slotNumber = -999; // slot number for range variable
// (initialized to ensure a crash if no real slot is allocated)
protected Expression sequence; // the expression over which the variable ranges
protected Expression action; // the action performed for each value of the variable
protected StructuredQName variableName;
protected SequenceType requiredType;
//protected RangeVariable declaration;
/**
* Set the required type (declared type) of the variable
* @param requiredType the required type
*/
public void setRequiredType(SequenceType requiredType) {
this.requiredType = requiredType;
}
/**
* Set the name of the variable
* @param variableName the name of the variable
*/
public void setVariableQName(StructuredQName variableName) {
this.variableName = variableName;
}
/**
* Get the name of the variable
* @return the variable name, as a QName
*/
public StructuredQName getVariableQName() {
return variableName;
}
public StructuredQName getObjectName() {
return variableName;
}
/**
* Get the declared type of the variable
*
* @return the declared type
*/
public SequenceType getRequiredType() {
return requiredType;
}
/**
* If this is a local variable held on the local stack frame, return the corresponding slot number.
* In other cases, return -1.
*/
public int getLocalSlotNumber() {
return slotNumber;
}
/**
* Get the value of the range variable
*/
public ValueRepresentation evaluateVariable(XPathContext context) throws XPathException {
ValueRepresentation actual = context.evaluateLocalVariable(slotNumber);
if (actual instanceof MemoClosure && ((MemoClosure)actual).isFullyRead()) {
actual = ((MemoClosure)actual).materialize();
context.setLocalVariable(slotNumber, actual);
}
return actual;
}
/**
* Add the "return" or "satisfies" expression, and fix up all references to the
* range variable that occur within that expression
* @param action the expression that occurs after the "return" keyword of a "for"
* expression, the "satisfies" keyword of "some/every", or the ":=" operator of
* a "let" expression.
*
*
*/
public void setAction(Expression action) {
this.action = action;
adoptChildExpression(action);
}
/**
* Indicate whether the binding is local or global. A global binding is one that has a fixed
* value for the life of a query or transformation; any other binding is local.
*/
public final boolean isGlobal() {
return false;
}
/**
* Test whether it is permitted to assign to the variable using the saxon:assign
* extension element. This will only be for an XSLT global variable where the extra
* attribute saxon:assignable="yes" is present.
*/
public final boolean isAssignable() {
return false;
}
/**
* Check to ensure that this expression does not contain any inappropriate updating subexpressions.
* This check is overridden for those expressions that permit updating subexpressions.
*
* @throws net.sf.saxon.trans.XPathException
* if the expression has a non-permitted updateing subexpression
*/
public void checkForUpdatingSubexpressions() throws XPathException {
sequence.checkForUpdatingSubexpressions();
if (sequence.isUpdatingExpression()) {
XPathException err = new XPathException(
"Updating expression appears in a context where it is not permitted", "XUST0001");
err.setLocator(sequence);
throw err;
}
action.checkForUpdatingSubexpressions();
}
/**
* Determine whether this is an updating expression as defined in the XQuery update specification
* @return true if this is an updating expression
*/
public boolean isUpdatingExpression() {
return action.isUpdatingExpression();
}
/**
* Get the action expression
* @return the action expression (introduced by "return" or "satisfies")
*/
public Expression getAction() {
return action;
}
/**
* Set the "sequence" expression - the one to which the variable is bound
* @param sequence the expression to which the variable is bound
*/
public void setSequence(Expression sequence) {
this.sequence = sequence;
adoptChildExpression(sequence);
}
/**
* Get the "sequence" expression - the one to which the variable is bound
* @return the expression to which the variable is bound
*/
public Expression getSequence() {
return sequence;
}
/**
* Set the slot number for the range variable
* @param nr the slot number to be used
*/
public void setSlotNumber(int nr) {
slotNumber = nr;
}
/**
* Get the number of slots required. Normally 1, except for a FOR expression with an AT clause, where it is 2.
* @return the number of slots required
*/
public int getRequiredSlots() {
return 1;
}
/**
* Simplify the expression
* @param visitor an expression visitor
*/
public Expression simplify(ExpressionVisitor visitor) throws XPathException {
sequence = visitor.simplify(sequence);
action = visitor.simplify(action);
return this;
}
/**
* Promote this expression if possible
*/
public Expression promote(PromotionOffer offer) throws XPathException {
Expression exp = offer.accept(this);
if (exp != null) {
return exp;
} else {
sequence = doPromotion(sequence, offer);
if (offer.action == PromotionOffer.INLINE_VARIABLE_REFERENCES ||
offer.action == PromotionOffer.UNORDERED ||
offer.action == PromotionOffer.REPLACE_CURRENT) {
action = doPromotion(action, offer);
} else if (offer.action == PromotionOffer.RANGE_INDEPENDENT ||
offer.action == PromotionOffer.FOCUS_INDEPENDENT) {
// Pass the offer to the action expression only if the action isn't dependent on the
// variable bound by this assignation
Binding[] savedBindingList = offer.bindingList;
offer.bindingList = extendBindingList(offer.bindingList);
action = doPromotion(action, offer);
offer.bindingList = savedBindingList;
}
return this;
}
}
/**
* Suppress validation on contained element constructors, on the grounds that the parent element
* is already performing validation. The default implementation does nothing.
*/
public void suppressValidation(int validationMode) {
action.suppressValidation(validationMode);
}
/**
* Extend an array of variable bindings to include the binding(s) defined in this expression
* @param in a set of variable bindings
* @return a set of variable bindings including all those supplied plus this one
*/
protected Binding[] extendBindingList(Binding[] in) {
Binding[] newBindingList;
if (in == null) {
newBindingList = new Binding[1];
} else {
newBindingList = new Binding[in.length + 1];
System.arraycopy(in, 0, newBindingList, 0, in.length);
}
newBindingList[newBindingList.length - 1] = this;
return newBindingList;
}
/**
* Promote a WHERE clause whose condition doesn't depend on the variable being bound.
* This rewrites an expression of the form
*
* let $i := SEQ return if (C) then R else ()
* to the form:
* if (C) then (let $i := SEQ return R) else ()
*
* @param positionBinding the binding of the position variable if any
* @return an expression in which terms from the WHERE clause that can be extracted have been extracted
*/
protected Expression promoteWhereClause(Binding positionBinding) {
if (Choose.isSingleBranchChoice(action)) {
//IfExpression ifex = (IfExpression)action;
Expression condition = ((Choose)action).getConditions()[0];
Binding[] bindingList;
if (positionBinding == null) {
bindingList = new Binding[] {this};
} else {
bindingList = new Binding[] {this, positionBinding};
}
List list = new ArrayList(5);
Expression promotedCondition = null;
BooleanExpression.listAndComponents(condition, list);
for (int i = list.size() - 1; i >= 0; i--) {
Expression term = (Expression) list.get(i);
if (!ExpressionTool.dependsOnVariable(term, bindingList)) {
if (promotedCondition == null) {
promotedCondition = term;
} else {
promotedCondition = new BooleanExpression(term, Token.AND, promotedCondition);
}
list.remove(i);
}
}
if (promotedCondition != null) {
if (list.isEmpty()) {
// the whole if() condition has been promoted
Expression oldThen = ((Choose)action).getActions()[0];
setAction(oldThen);
return Choose.makeConditional(condition, this);
} else {
// one or more terms of the if() condition have been promoted
Expression retainedCondition = (Expression) list.get(0);
for (int i = 1; i < list.size(); i++) {
retainedCondition = new BooleanExpression(retainedCondition, Token.AND, (Expression) list.get(i));
}
((Choose)action).getConditions()[0] = retainedCondition;
Expression newIf = Choose.makeConditional(
promotedCondition, this, Literal.makeEmptySequence());
ExpressionTool.copyLocationInfo(this, newIf);
return newIf;
}
}
}
return null;
}
/**
* Get the immediate subexpressions of this expression
*/
public Iterator iterateSubExpressions() {
return new PairIterator(sequence, action);
}
/**
* Replace one subexpression by a replacement subexpression
* @param original the original subexpression
* @param replacement the replacement subexpression
* @return true if the original subexpression is found
*/
public boolean replaceSubExpression(Expression original, Expression replacement) {
boolean found = false;
if (sequence == original) {
sequence = replacement;
found = true;
}
if (action == original) {
action = replacement;
found = true;
}
return found;
}
/**
* 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.
*
* 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.
*
* @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 varPath = sequence.addToPathMap(pathMap, pathMapNodeSet);
pathMap.registerPathForVariable(this, varPath);
return action.addToPathMap(pathMap, pathMapNodeSet);
}
// Following methods implement the VariableDeclaration interface, in relation to the range
// variable
// public int getVariableNameCode() {
// return nameCode;
// }
// public int getVariableFingerprint() {
// return nameCode & 0xfffff;
// }
/**
* Get the display name of the range variable, for diagnostics only
* @return the lexical QName of the range variable
*/
public String getVariableName() {
if (variableName == null) {
return "zz:var" + hashCode();
} else {
return variableName.getDisplayName();
}
}
/**
* Refine the type information associated with this variable declaration. This is useful when the
* type of the variable has not been explicitly declared (which is common); the variable then takes
* a static type based on the type of the expression to which it is bound. The effect of this call
* is to update the static expression type for all references to this variable.
* @param type the inferred item type of the expression to which the variable is bound
* @param cardinality the inferred cardinality of the expression to which the variable is bound
* @param constantValue the constant value to which the variable is bound (null if there is no constant value)
* @param properties other static properties of the expression to which the variable is bound
* @param visitor an expression visitor to provide context information
* @param currentExpression the expression that binds the variable
*/
public void refineTypeInformation(ItemType type, int cardinality,
Value constantValue, int properties,
ExpressionVisitor visitor,
Assignation currentExpression) {
List references = new ArrayList();
ExpressionTool.gatherVariableReferences(currentExpression.getAction(), this, references);
for (Iterator iter=references.iterator(); iter.hasNext();) {
BindingReference ref = (BindingReference)iter.next();
if (ref instanceof VariableReference) {
((VariableReference)ref).refineVariableType(type, cardinality, constantValue, properties, visitor);
visitor.resetStaticProperties();
ExpressionTool.resetPropertiesWithinSubtree(currentExpression);
}
}
}
/**
* Get the value of the range variable
*/
// public ValueRepresentation evaluateVariable(XPathContext context) throws XPathException {
//// if (slotNumber == -999) {
//// display(10, context.getController().getNamePool(), System.err);
//// }
// ValueRepresentation actual = context.evaluateLocalVariable(slotNumber);
// if (actual instanceof MemoClosure && ((MemoClosure)actual).isFullyRead()) {
// actual = ((MemoClosure)actual).materialize();
// context.setLocalVariable(slotNumber, actual);
// }
// return actual;
// }
}
//
// 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.
//