net.sf.saxon.functions
Class Id

java.lang.Object
  net.sf.saxon.expr.Expression
      net.sf.saxon.expr.FunctionCall
          net.sf.saxon.functions.SystemFunction
              net.sf.saxon.functions.Id

All Implemented Interfaces:

Serializable, SourceLocator, Container, EvaluableItem, SequenceIterable, InstructionInfoProvider

public class Id
extends SystemFunction

The XPath id() function XPath 2.0 version: accepts any sequence as the first parameter; each item in the sequence is taken as an IDREFS value, that is, a space-separated list of ID values. Also accepts an optional second argument to identify the target document, this defaults to the context node.

See Also:

Serialized Form

Field Summary

Fields inherited from class net.sf.saxon.expr.Expression

EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD

Constructor Summary

Id()

Method Summary

void	checkArguments(StaticContext env) Static analysis: prevent sorting of the argument
int	computeSpecialProperties() Get the static properties of this expression (other than its type).
static SequenceIterator	getIdMultiple(DocumentInfo doc, SequenceIterator idrefs) Get an iterator over the nodes that have an id equal to one of the values is a set of whitespace separated strings
static SequenceIterator	getIdSingle(DocumentInfo doc, String idrefs) Get an iterator over the nodes that have an id equal to one of the values is a whitespace separated string
SequenceIterator	iterate(XPathContext context) Evaluate the function to return an iteration of selected nodes.
Expression	preEvaluate(StaticContext env) preEvaluate: this method suppresses compile-time evaluation by doing nothing
Expression	simplify(StaticContext env) Simplify: add a second implicit argument, the context document

Methods inherited from class net.sf.saxon.functions.SystemFunction

computeCardinality, display, getDetails, getErrorCodeForTypeErrors, getItemType, main, makeSystemFunction, optimize, setDetails

Methods inherited from class net.sf.saxon.expr.FunctionCall

getArguments, getDisplayName, getFunctionNameCode, getNumberOfArguments, iterateSubExpressions, promote, replaceSubExpression, setArguments, setFunctionNameCode, typeCheck

Methods inherited from class net.sf.saxon.expr.Expression

adoptChildExpression, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, effectiveBooleanValue, evaluateAsString, evaluateItem, getCardinality, getColumnNumber, getContainingProcedure, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getIntrinsicDependencies, getLineNumber, getLocationId, getLocationProvider, getParentExpression, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasBadParentPointer, markTailFunctionCalls, process, resetStaticProperties, setLocationId, setParentExpression, setParentExpression, suppressValidation

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Id

public Id()

Method Detail

simplify

public Expression simplify(StaticContext env)
                    throws XPathException

Simplify: add a second implicit argument, the context document

Overrides:

simplify in class FunctionCall

Returns:

the simplified expression

Throws:

XPathException - if an error is discovered during expression rewriting

checkArguments

public void checkArguments(StaticContext env)
                    throws XPathException

Static analysis: prevent sorting of the argument

Overrides:

checkArguments in class SystemFunction

Throws:

XPathException

preEvaluate

public Expression preEvaluate(StaticContext env)

preEvaluate: this method suppresses compile-time evaluation by doing nothing

Overrides:

preEvaluate in class FunctionCall

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

iterate

public SequenceIterator iterate(XPathContext context)
                         throws XPathException

Evaluate the function to return an iteration of selected nodes.

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

getIdSingle

public static SequenceIterator getIdSingle(DocumentInfo doc,
                                           String idrefs)
                                    throws XPathException

Get an iterator over the nodes that have an id equal to one of the values is a whitespace separated string

Parameters:

doc - The document to be searched

idrefs - a string containing zero or more whitespace-separated ID values to be found in the document

Returns:

an iterator over the nodes whose ID is one of the specified values

Throws:

XPathException

getIdMultiple

public static SequenceIterator getIdMultiple(DocumentInfo doc,
                                             SequenceIterator idrefs)
                                      throws XPathException

Get an iterator over the nodes that have an id equal to one of the values is a set of whitespace separated strings

Parameters:

doc - The document to be searched

idrefs - an iterator over a set of strings each of which is a string containing zero or more whitespace-separated ID values to be found in the document

Returns:

an iterator over the nodes whose ID is one of the specified values

Throws:

XPathException