net.sf.saxon.functions

Class Collection

java.lang.Object

net.sf.saxon.expr.Expression

net.sf.saxon.expr.FunctionCall

net.sf.saxon.functions.SystemFunctionCall

net.sf.saxon.functions.Collection

All Implemented Interfaces:

SourceLocator, Callable, IdentityComparable, InstructionInfo

public class Collection
extends SystemFunctionCall
implements Callable

Implement the fn:collection() function. This is responsible for calling the registered CollectionURIResolver. For the effect of the default system-supplied CollectionURIResolver, see StandardCollectionURIResolver

Field Summary

Fields

Modifier and Type	Field and Description
static String	EMPTY_COLLECTION URI representing a collection that is always empty, regardless of any collection URI resolver

Fields inherited from class net.sf.saxon.functions.SystemFunctionCall

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, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, WATCH_METHOD

Constructor Summary

Constructors

Constructor and Description
Collection()

Method Summary

Methods

Modifier and Type	Method and Description
PathMap.PathMapNodeSet	addToPathMap(PathMap pathMap, PathMap.PathMapNodeSet pathMapNodeSet) Add a representation of this expression to a PathMap.
Sequence	call(XPathContext context, Sequence[] arguments) Call the Callable.
void	checkArguments(ExpressionVisitor visitor) Method called during static type checking
int	computeSpecialProperties() Determine the special properties of this expression.
Expression	copy() Copy an expression.
static SequenceIterator	getResolverResults(SequenceIterator iter, String baseURI, XPathContext context, SourceLocator locator) Return the results of iterating over the results returned by the CollectionURIResolver.
SequenceIterator	iterate(XPathContext context) Iterate over the contents of the collection
Expression	preEvaluate(ExpressionVisitor visitor) preEvaluate: this method suppresses compile-time evaluation by doing nothing

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

addContextDocumentArgument, addDocToPathMap, bindStaticContext, computeCardinality, equalOrNull, equals, getContextNode, getConvertingCallable, getDefaultArgumentNode, getDetails, getErrorCodeForTypeErrors, getFunctionItemType, getImplementationMethod, getItemType, getOperation, getRequiredType, makeSystemFunction, operands, optimize, setDetails, toShortString, useContextItemAsDefault

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

addExternalFunctionCallToPathMap, checkArgumentCount, explain, getArguments, getDisplayName, getExpressionName, getFunctionName, getNumberOfArguments, hashCode, promote, replaceOperand, setArguments, setFunctionName, simplifyArguments, toString, typeCheck

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

adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, clearStreamabilityData, computeDependencies, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluateItem, evaluatePendingUpdates, explain, getCardinality, getColumnNumber, getConfiguration, getConstructType, getContainer, getDependencies, getEvaluationMethod, getExpressionCompiler, getHostLanguage, getIntegerBounds, getIntrinsicDependencies, getLineNumber, getLocationId, getObjectName, getPosture, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getStreamability, getStreamingAdjunct, getSweep, getSystemId, hasVariableBinding, identityHashCode, implementsStaticTypeCheck, isIdentical, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterateEvents, makeStreamingAdjunct, markTailFunctionCalls, operandList, process, resetLocalStaticProperties, setContainer, setEvaluationMethod, setFiltered, setFlattened, setLocationId, setPostureAndSweep, simplify, staticTypeCheck, suppressValidation, toPattern, toStreamingPattern, typeError, unordered

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

EMPTY_COLLECTION

public static String EMPTY_COLLECTION

URI representing a collection that is always empty, regardless of any collection URI resolver

Constructor Detail

Collection

public Collection()

Method Detail

checkArguments

public void checkArguments(ExpressionVisitor visitor)
                    throws XPathException

Description copied from class: SystemFunctionCall

Method called during static type checking

Overrides:

checkArguments in class SystemFunctionCall

Parameters:

visitor - the expression visitor

Throws:

XPathException - if the arguments are incorrect

computeSpecialProperties

public int computeSpecialProperties()

Description copied from class: SystemFunctionCall

Determine the special properties of this expression. The general rule is that a system function call is non-creative if its return type is atomic, or if all its arguments are non-creative. This is overridden for the generate-id() function, which is considered creative if its operand is creative (because the result depends on the identity of the operand)

Overrides:

computeSpecialProperties in class SystemFunctionCall

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 this expression to a PathMap. The PathMap captures a map of the nodes visited by an expression in a source tree.

Overrides:

addToPathMap in class Expression

Parameters:

pathMap - the PathMap to which the expression should be added

pathMapNodeSet - the PathMapNodeSet to which the paths embodied in this expression should be added

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

copy

public Expression copy()

Description copied from class: SystemFunctionCall

Copy an expression. This makes a deep copy.

Overrides:

copy in class SystemFunctionCall

Returns:

the copy of the original expression

iterate

public SequenceIterator iterate(XPathContext context)
                         throws XPathException

Iterate over the contents of the collection

Overrides:

iterate in class Expression

Parameters:

context - the dynamic context

Returns:

an iterator, whose items will always be nodes (typically but not necessarily document nodes)

Throws:

XPathException

getResolverResults

public static SequenceIterator getResolverResults(SequenceIterator iter,
                                  String baseURI,
                                  XPathContext context,
                                  SourceLocator locator)

Return the results of iterating over the results returned by the CollectionURIResolver.

Note, this method is called by generated code

Parameters:

iter - iterator over the results of the CollectionURIResolver

baseURI - the base URI

context - the dynamic context

locator - location of the instruction

Returns:

an iterator over the documents in the collection.

call

public Sequence call(XPathContext context,
            Sequence[] arguments)
              throws XPathException

Description copied from interface: Callable

Call the Callable.

Specified by:

call in interface Callable

Parameters:

context - the dynamic evaluation context

arguments - the values of the arguments, supplied as Sequences.

Generally it is advisable, if calling iterate() to process a supplied sequence, to call it only once; if the value is required more than once, it should first be converted to a GroundedValue by calling the utility methd SequenceTool.toGroundedValue().

If the expected value is a single item, the item should be obtained by calling Sequence.head(): it cannot be assumed that the item will be passed as an instance of Item or AtomicValue.

It is the caller's responsibility to perform any type conversions required to convert arguments to the type expected by the callee. An exception is where this Callable is explicitly an argument-converting wrapper around the original Callable.

Returns:

the result of the evaluation, in the form of a Sequence. It is the responsibility of the callee to ensure that the type of result conforms to the expected result type.

Throws:

XPathException - if a dynamic error occurs during the evaluation of the expression