com.saxonica.xslt3.instruct

Class AccumulatorManagerPE

java.lang.Object

com.saxonica.xslt3.instruct.AccumulatorManagerPE

All Implemented Interfaces:

Serializable, FunctionLibrary, IAccumulatorManager

Direct Known Subclasses:

AccumulatorManagerEE

public class AccumulatorManagerPE
extends Object
implements IAccumulatorManager, FunctionLibrary

Manager for accumulator functions (XSLT 3.0). Like the KeyManager, this is able to maintain data for the same accumulator in multiple executions of a stylesheet: the accumulator data is designed to be available for garbage collection if either the document or the stylesheet is no longer needed. This class also performs the role of a function library, handling requests to bind the two accumulator functions.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected Map<StructuredQName,Accumulator>	map

Constructor Summary

Constructors

Constructor and Description
AccumulatorManagerPE()

Method Summary

Methods

Modifier and Type	Method and Description
void	addAccumulator(Accumulator acc) Register an accumulator with the manager
Expression	bind(StructuredQName functionName, int arity, Expression[] staticArgs, StaticContext env, Container container) Bind a function call to a function in this library
FunctionLibrary	copy() Copy this function library
AccumulatorData	getAccumulatorData(DocumentInfo doc, Accumulator acc, XPathContext context) Get the data relating to a particular accumulator for a particular unstreamed document tree
FunctionLibrary	getAccumulatorFunctionLibrary() Get the library of accumulator functions
FunctionItem	getFunctionItem(StructuredQName functionName, int arity, StaticContext staticContext) Test whether a function with a given name and arity is available; if so, return a function item that can be dynamically called.
boolean	isAvailable(StructuredQName functionName, int arity) Test whether a function with a given name and arity is available
boolean	isEmpty() Ask whether any accumulators exist
protected AccumulatorFunctionCallPE	newAccumulatorFunctionCall(Accumulator acc, boolean isPostDescent)

Methods inherited from class java.lang.Object

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

Field Detail

map

protected Map<StructuredQName,Accumulator> map

Constructor Detail

AccumulatorManagerPE

public AccumulatorManagerPE()

Method Detail

getAccumulatorFunctionLibrary

public FunctionLibrary getAccumulatorFunctionLibrary()

Get the library of accumulator functions

Specified by:

getAccumulatorFunctionLibrary in interface IAccumulatorManager

Returns:

this object, which itself implements the function library

addAccumulator

public void addAccumulator(Accumulator acc)

Register an accumulator with the manager

Parameters:

acc - the accumulator to be registered

bind

public Expression bind(StructuredQName functionName,
              int arity,
              Expression[] staticArgs,
              StaticContext env,
              Container container)
                throws XPathException

Bind a function call to a function in this library

Specified by:

bind in interface FunctionLibrary

Parameters:

functionName - the QName of the function being called

arity -

staticArgs - The expressions supplied statically in arguments to the function call. The length of this array represents the arity of the function. The intention is that the static type of the arguments (obtainable via getItemType() and getCardinality()) may be used as part of the binding algorithm. In some cases it may be possible for the function to be pre-evaluated at compile time, for example if these expressions are all constant values.

The conventions of the XPath language demand that the results of a function depend only on the values of the expressions supplied as arguments, and not on the form of those expressions. For example, the result of f(4) is expected to be the same as f(2+2). The actual expression is supplied here to enable the binding mechanism to select the most efficient possible implementation (including compile-time pre-evaluation where appropriate).

env - The static context of the function call

container - The container for the newly created Expression

Returns:

a function call expression, which in this case will be an AccumulatorFunctionCallPE object

Throws:

XPathException

newAccumulatorFunctionCall

protected AccumulatorFunctionCallPE newAccumulatorFunctionCall(Accumulator acc,
                                                   boolean isPostDescent)

getFunctionItem

public FunctionItem getFunctionItem(StructuredQName functionName,
                           int arity,
                           StaticContext staticContext)
                             throws XPathException

Test whether a function with a given name and arity is available; if so, return a function item that can be dynamically called.

This supports the function-lookup() function in XPath 3.0.

Specified by:

getFunctionItem in interface FunctionLibrary

Parameters:

functionName - the qualified name of the function being called

arity - The number of arguments.

staticContext - the static context to be used by the function, in the event that it is a system function with dependencies on the static context

Returns:

if a function of this name and arity is available for calling, then a corresponding function item; or null if the function does not exist

Throws:

XPathException - in the event of certain errors, for example attempting to get a function that is private

isAvailable

public boolean isAvailable(StructuredQName functionName,
                  int arity)

Test whether a function with a given name and arity is available

This supports the function-available() function in XSLT.

Specified by:

isAvailable in interface FunctionLibrary

Parameters:

functionName - the qualified name of the function being called

arity - The number of arguments.

Returns:

true if a function of this name and arity is available for calling

copy

public FunctionLibrary copy()

Copy this function library

Specified by:

copy in interface FunctionLibrary

Returns:

a copy

isEmpty

public boolean isEmpty()

Ask whether any accumulators exist

Returns:

true if no accumulators have been registered

getAccumulatorData

public AccumulatorData getAccumulatorData(DocumentInfo doc,
                                 Accumulator acc,
                                 XPathContext context)
                                   throws XPathException

Get the data relating to a particular accumulator for a particular unstreamed document tree

Parameters:

doc - the source document tree in question

acc - the required accumulator

context - the XPath dynamic evaluation context

Returns:

a data structure holding the evaluated values of the accumulator for this source document

Throws:

XPathException - if any dynamic error occurs