net.sf.saxon.functions

Class Count

java.lang.Object

net.sf.saxon.om.AbstractItem

net.sf.saxon.functions.AbstractFunction

net.sf.saxon.functions.SystemFunction

net.sf.saxon.functions.Count

All Implemented Interfaces:

Callable, Function, GroundedValue, Item, Sequence

public class Count
extends SystemFunction

Implementation of the fn:count function

Constructor Summary

Constructors

Constructor and Description
Count()

Method Summary

Modifier and Type	Method and Description
IntegerValue	call(XPathContext context, Sequence[] arguments) Evaluate the expression
static int	count(SequenceIterator iter) Get the number of items in a sequence identified by a SequenceIterator
java.lang.String	getCompilerName() Get the (local) name of a class that can be used to generate bytecode for this system function
IntegerValue[]	getIntegerBounds() For an expression that returns an integer or a sequence of integers, get a lower and upper bound on the values of the integers that may be returned, from static analysis.
java.lang.String	getStreamerName() Get a name that identifies the class that can be used to evaluate this function in streaming mode, that is, supplying one item or event at a time as it is delivered by the parser.
static int	steppingCount(SequenceIterator iter) Get the number of items in a sequence identified by a SequenceIterator

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

dependsOnContextItem, dynamicCall, equals, export, exportAdditionalArguments, exportAttributes, fixArguments, getArity, getCardinality, getContextNode, getDescription, getDetails, getErrorCodeForTypeErrors, getFunctionItemType, getFunctionName, getNetCost, getOperandRoles, getRequiredType, getResultItemType, getResultItemType, getRetainedStaticContext, getSpecialProperties, getStaticBaseUriString, importAttributes, isTrustedResultType, makeCall, makeFunction, makeFunctionCall, makeOptimizedFunctionCall, resultIfEmpty, setArity, setDetails, setRetainedStaticContext, supplyTypeInformation, typeCheckCaller

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

atomize, deepEquals, effectiveBooleanValue, getAnnotations, getStringValue, getStringValueCS, isArray, isMap, makeNewContext, simplify, typeCheck

Methods inherited from class net.sf.saxon.om.AbstractItem

getLength, head, isStreamed, itemAt, iterate, reduce, subsequence

Methods inherited from class java.lang.Object

clone, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface net.sf.saxon.om.Function

iterate

Methods inherited from interface net.sf.saxon.om.Item

head

Methods inherited from interface net.sf.saxon.om.GroundedValue

getLength, head, itemAt, reduce, subsequence

Constructor Detail

Count

public Count()

Method Detail

getIntegerBounds

public IntegerValue[] getIntegerBounds()

For an expression that returns an integer or a sequence of integers, get a lower and upper bound on the values of the integers that may be returned, from static analysis. The default implementation returns null, meaning "unknown" or "not applicable". Other implementations return an array of two IntegerValue objects, representing the lower and upper bounds respectively. The values UNBOUNDED_LOWER and UNBOUNDED_UPPER are used by convention to indicate that the value may be arbitrarily large. The values MAX_STRING_LENGTH and MAX_SEQUENCE_LENGTH are used to indicate values limited by the size of a string or the size of a sequence.

Overrides:

getIntegerBounds in class SystemFunction

Returns:

the lower and upper bounds of integer values in the result, or null to indicate unknown or not applicable.

count

public static int count(SequenceIterator iter)
                 throws XPathException

Get the number of items in a sequence identified by a SequenceIterator

Parameters:

iter - The SequenceIterator. This method moves the current position of the supplied iterator; if this isn't safe, make a copy of the iterator first by calling getAnother(). The supplied iterator must be positioned before the first item (there must have been no call on next()).

Returns:

the number of items in the underlying sequence

Throws:

XPathException - if a failure occurs reading the input sequence

steppingCount

public static int steppingCount(SequenceIterator iter)
                         throws XPathException

Get the number of items in a sequence identified by a SequenceIterator

Parameters:

iter - The SequenceIterator. The supplied iterator must be positioned before the first item (there must have been no call on next()). It will always be consumed

Returns:

the number of items in the underlying sequence

Throws:

XPathException - if a failure occurs reading the input sequence

call

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

Evaluate the expression

Parameters:

context - the dynamic evaluation context

arguments - the values of the arguments, supplied as Sequences

Returns:

the result of the evaluation, in the form of a Sequence

Throws:

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

getCompilerName

public java.lang.String getCompilerName()

Description copied from class: SystemFunction

Get the (local) name of a class that can be used to generate bytecode for this system function

Overrides:

getCompilerName in class SystemFunction

Returns:

the name of a bytecode generation class, or null if there is no bytecode support for this function

getStreamerName

public java.lang.String getStreamerName()

Description copied from class: SystemFunction

Get a name that identifies the class that can be used to evaluate this function in streaming mode, that is, supplying one item or event at a time as it is delivered by the parser. Special streaming support is generally available in Saxon-EE for all system functions that take a sequence as their argument.

Overrides:

getStreamerName in class SystemFunction

Returns:

a name that identifies a class that supports streamed evaluation of this system function, or null if no such class is available. The mapping of names to classes is defined in the Saxon-EE class StreamerMap. In non-streaming Saxon editions (HE and PE) the method always returns null.