net.sf.saxon.functions
Class Id

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.Id
All Implemented Interfaces:
Serializable, SourceLocator, LocationProvider, SaxonLocator, CallableExpression, InstructionInfo, Locator

public class Id
extends SystemFunction
implements CallableExpression

The XPath id() or element-with-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
static int ELEMENT_WITH_ID
           
static int ID
           
 
Fields inherited from class net.sf.saxon.functions.SystemFunction
operation
 
Fields inherited from class net.sf.saxon.expr.FunctionCall
argument
 
Fields inherited from class net.sf.saxon.expr.Expression
EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, EVENT_FEED_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, PUSH_SELECTION, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, WATCH_METHOD
 
Constructor Summary
Id()
           
 
Method Summary
 PathMap.PathMapNodeSet addToPathMap(PathMap pathMap, PathMap.PathMapNodeSet pathMapNodeSet)
          Add a representation of a doc() call or similar function to a PathMap.
 SequenceIterator call(SequenceIterator[] arguments, XPathContext context)
          Evaluate the expression
 void checkArguments(ExpressionVisitor visitor)
          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, int operation)
          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, int operation)
          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(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, ExpressionVisitor.ContextItemType contextItemType)
          Type-check the expression.
 
Methods inherited from class net.sf.saxon.functions.SystemFunction
addContextDocumentArgument, addDocToPathMap, computeCardinality, copy, equals, getDetails, getErrorCodeForTypeErrors, getImplementationMethod, getItemType, getOperation, getRequiredType, makeSystemFunction, optimize, setDetails, useContextItemAsDefault
 
Methods inherited from class net.sf.saxon.expr.FunctionCall
addExternalFunctionCallToPathMap, checkArgumentCount, explain, getArguments, getDisplayName, getExpressionName, getFunctionName, getNumberOfArguments, hashCode, iterateSubExpressions, promote, replaceSubExpression, setArguments, setFunctionName, simplifyArguments, toString
 
Methods inherited from class net.sf.saxon.expr.Expression
adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluateItem, evaluatePendingUpdates, explain, getCardinality, getColumnNumber, getColumnNumber, getConstructType, getContainer, getDependencies, getEvaluationMethod, getExecutable, getHostLanguage, getIntegerBounds, getIntrinsicDependencies, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, hasLoopingSubexpression, hasVariableBinding, implementsStaticTypeCheck, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterateEvents, iterateSameFocusSubExpressions, markTailFunctionCalls, process, resetLocalStaticProperties, setContainer, setEvaluationMethod, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation, typeError
 
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface net.sf.saxon.expr.CallableExpression
getArguments
 

Field Detail

ID

public static final int ID
See Also:
Constant Field Values

ELEMENT_WITH_ID

public static final int ELEMENT_WITH_ID
See Also:
Constant Field Values
Constructor Detail

Id

public Id()
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,
                            ExpressionVisitor.ContextItemType 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
Static analysis: prevent sorting of the argument

Overrides:
checkArguments in class SystemFunction
Parameters:
visitor - the expression visitor
Throws:
XPathException - if the arguments are incorrect

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

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

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
Evaluate the function to return an iteration of selected nodes.

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,
                                           int operation)
                                    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
operation - either ID or ELEMENT_WITH_ID
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,
                                             int operation)
                                      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

call

public SequenceIterator call(SequenceIterator[] arguments,
                             XPathContext context)
                      throws XPathException
Evaluate the expression

Specified by:
call in interface CallableExpression
Parameters:
arguments - the values of the arguments, supplied as SequenceIterators
context - the dynamic evaluation context
Returns:
the result of the evaluation, in the form of a SequenceIterator
Throws:
XPathException - if a dynamic error occurs during the evaluation of the expression


Copyright (c) 2004-2011 Saxonica Limited. All rights reserved.