net.sf.saxon.functions
Class Idref

java.lang.Object
  extended by net.sf.saxon.expr.Expression
      extended by net.sf.saxon.expr.FunctionCall
          extended by net.sf.saxon.functions.SystemFunction
              extended by net.sf.saxon.functions.Idref
All Implemented Interfaces:
Serializable, SourceLocator, EvaluableItem, SequenceIterable, InstructionInfoProvider

public class Idref
extends SystemFunction

See Also:
Serialized Form

Field Summary
 
Fields inherited from class net.sf.saxon.expr.Expression
EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD
 
Constructor Summary
Idref()
           
 
Method Summary
 PathMap.PathMapNodeSet addToPathMap(PathMap pathMap, PathMap.PathMapNodeSet pathMapNodeSet)
          Add a representation of a doc() call or similar function to a PathMap.
 void checkArguments(ExpressionVisitor visitor)
          Method called during static type checking
 int computeSpecialProperties()
          Get the static properties of this expression (other than its type).
static SequenceIterator getIdrefMultiple(DocumentInfo doc, SequenceIterator keys, XPathContext context)
          Get the result when multiple idref values are supplied.
 SequenceIterator iterate(XPathContext context)
          Enumerate the results of the expression
 Expression preEvaluate(ExpressionVisitor visitor)
          preEvaluate: this method suppresses compile-time evaluation by doing nothing
 Expression simplify(ExpressionVisitor visitor)
          Simplify: add a second implicit argument, the context document
 Expression typeCheck(ExpressionVisitor visitor, ItemType contextItemType)
          Type-check the expression.
 
Methods inherited from class net.sf.saxon.functions.SystemFunction
addDocToPathMap, computeCardinality, copy, getDetails, getErrorCodeForTypeErrors, getItemType, makeSystemFunction, optimize, setDetails
 
Methods inherited from class net.sf.saxon.expr.FunctionCall
addExternalFunctionCallToPathMap, equals, explain, getArguments, getDisplayName, getFunctionName, getNumberOfArguments, hashCode, iterateSubExpressions, promote, replaceSubExpression, setArguments, setFunctionName, toString
 
Methods inherited from class net.sf.saxon.expr.Expression
adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, display, doPromotion, effectiveBooleanValue, evaluateAsString, evaluateItem, explain, findParentOf, getCardinality, getColumnNumber, getContainer, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getIntrinsicDependencies, getLineNumber, getLocationId, getLocationProvider, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, iterateEvents, markTailFunctionCalls, process, setContainer, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation
 
Methods inherited from class java.lang.Object
getClass, notify, notifyAll, wait, wait, wait
 

Constructor Detail

Idref

public Idref()
Method Detail

simplify

public Expression simplify(ExpressionVisitor visitor)
                    throws XPathException
Simplify: add a second implicit argument, the context document

Overrides:
simplify in class FunctionCall
Parameters:
visitor - an expression visitor
Returns:
the simplified expression
Throws:
XPathException - if an error is discovered during expression rewriting

typeCheck

public Expression typeCheck(ExpressionVisitor visitor,
                            ItemType contextItemType)
                     throws XPathException
Type-check the expression. This also calls preEvaluate() to evaluate the function if all the arguments are constant; functions that do not require this behavior can override the preEvaluate method.

Overrides:
typeCheck in class FunctionCall
Parameters:
visitor - an expression visitor
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 Type.ITEM_TYPE
Returns:
the original expression, rewritten to perform necessary run-time type checks, and to perform other type-related optimizations
Throws:
XPathException - if an error is discovered during this phase (typically a type error)

checkArguments

public void checkArguments(ExpressionVisitor visitor)
                    throws XPathException
Description copied from class: SystemFunction
Method called during static type checking

Overrides:
checkArguments in class SystemFunction
Parameters:
visitor - the expression visitor
Throws:
XPathException

computeSpecialProperties

public int computeSpecialProperties()
Get the static properties of this expression (other than its type). The result is bit-signficant. These properties are used for optimizations. In general, if property bit is set, it is true, but if it is unset, the value is unknown.

Overrides:
computeSpecialProperties in class SystemFunction
Returns:
the special properties, as a bit-significant integer

preEvaluate

public Expression preEvaluate(ExpressionVisitor visitor)
preEvaluate: this method suppresses compile-time evaluation by doing nothing

Overrides:
preEvaluate in class FunctionCall
Parameters:
visitor - an expression visitor
Returns:
the result of the early evaluation, or the original expression, or potentially a simplified expression

addToPathMap

public PathMap.PathMapNodeSet addToPathMap(PathMap pathMap,
                                           PathMap.PathMapNodeSet pathMapNodeSet)
Add a representation of a doc() call or similar function to a PathMap. This is a convenience method called by the addToPathMap() methods for doc(), document(), collection() and similar functions. These all create a new root expression in the path map.

Overrides:
addToPathMap in class Expression
Parameters:
pathMap - the PathMap to which the expression should be added
pathMapNodeSet -
Returns:
the pathMapNode representing the focus established by this expression, in the case where this expression is the first operand of a path expression or filter expression

iterate

public SequenceIterator iterate(XPathContext context)
                         throws XPathException
Enumerate the results of the expression

Specified by:
iterate in interface SequenceIterable
Overrides:
iterate in class Expression
Parameters:
context - supplies the context for evaluation
Returns:
a SequenceIterator that can be used to iterate over the result of the expression
Throws:
XPathException - if any dynamic error occurs evaluating the expression

getIdrefMultiple

public static SequenceIterator getIdrefMultiple(DocumentInfo doc,
                                                SequenceIterator keys,
                                                XPathContext context)
                                         throws XPathException
Get the result when multiple idref values are supplied. Note this is also called from compiled XQuery code.

Parameters:
doc - the document to be searched
keys - the idref values supplied
context - the dynamic execution context
Returns:
iterator over the result of the function
Throws:
XPathException


Copyright (C) Michael H. Kay. All rights reserved.