com.saxonica.functions.extfn
Class SubsequenceTestFn

java.lang.Object
  net.sf.saxon.lib.ExtensionFunctionDefinition
      com.saxonica.functions.extfn.SubsequenceTestFn

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

SubsequenceTestFn.SubsequenceAfterFn, SubsequenceTestFn.SubsequenceBeforeFn, SubsequenceTestFn.SubsequenceFromFn, SubsequenceTestFn.SubsequenceUntilFn

public abstract class SubsequenceTestFn
extends ExtensionFunctionDefinition

Abstract class providing functionality common to functions saxon:subsequence-before, saxon:subsequence-after etc; contains the concrete implementations of these functions as inner subclasses

See Also:

Serialized Form

Nested Class Summary

static class	SubsequenceTestFn.SubsequenceAfterFn Implement saxon:subsequence-after
static class	SubsequenceTestFn.SubsequenceBeforeFn Implement saxon:subsequence-before
static class	SubsequenceTestFn.SubsequenceFromFn Implement saxon:subsequence-from
static class	SubsequenceTestFn.SubsequenceUntilFn Implement saxon:subsequence-until

Constructor Summary

SubsequenceTestFn()

Method Summary

protected abstract SequenceIterator	compute(SequenceIterator input, FunctionItem test, XPathContext context) The function that does the work, which must be implemented in subclasses
SequenceType[]	getArgumentTypes() Get the required types for the arguments of this function.
int	getMaximumNumberOfArguments() Get the maximum number of arguments allowed by the function.
int	getMinimumNumberOfArguments() Get the minimum number of arguments required by the function
SequenceType	getResultType(SequenceType[] suppliedArgumentTypes) Get the type of the result of the function
ExtensionFunctionCall	makeCallExpression() Create a call on this function.
boolean	trustResultType() Ask whether the result actually returned by the function can be trusted, or whether it should be checked against the declared type.

Methods inherited from class net.sf.saxon.lib.ExtensionFunctionDefinition

dependsOnFocus, getFunctionQName, hasSideEffects

Methods inherited from class java.lang.Object

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

Constructor Detail

SubsequenceTestFn

public SubsequenceTestFn()

Method Detail

getMinimumNumberOfArguments

public int getMinimumNumberOfArguments()

Get the minimum number of arguments required by the function

The default implementation returns the number of items in the result of calling getArgumentTypes()

Overrides:

getMinimumNumberOfArguments in class ExtensionFunctionDefinition

Returns:

the minimum number of arguments that must be supplied in a call to this function

getMaximumNumberOfArguments

public int getMaximumNumberOfArguments()

Get the maximum number of arguments allowed by the function.

The default implementation returns the value of getMinimumNumberOfArguments()

Overrides:

getMaximumNumberOfArguments in class ExtensionFunctionDefinition

Returns:

the maximum number of arguments that may be supplied in a call to this function

trustResultType

public boolean trustResultType()

Ask whether the result actually returned by the function can be trusted, or whether it should be checked against the declared type.

Overrides:

trustResultType in class ExtensionFunctionDefinition

Returns:

true if the function implementation warrants that the value it returns will be an instance of the declared result type. The default value is false, in which case the result will be checked at run-time to ensure that it conforms to the declared type. If the value true is returned, but the function returns a value of the wrong type, the consequences are unpredictable.

getArgumentTypes

public SequenceType[] getArgumentTypes()

Get the required types for the arguments of this function.

This method must be implemented in all subtypes.

Specified by:

getArgumentTypes in class ExtensionFunctionDefinition

Returns:

the required types of the arguments, as defined by the function signature. Normally this should be an array of size getMaximumNumberOfArguments(); however for functions that allow a variable number of arguments, the array can be smaller than this, with the last entry in the array providing the required type for all the remaining arguments.

getResultType

public SequenceType getResultType(SequenceType[] suppliedArgumentTypes)

Get the type of the result of the function

This method must be implemented in all subtypes.

Specified by:

getResultType in class ExtensionFunctionDefinition

Parameters:

suppliedArgumentTypes - the static types of the supplied arguments to the function. This is provided so that a more precise result type can be returned in the common case where the type of the result depends on the types of the arguments.

Returns:

the return type of the function, as defined by its function signature

compute

protected abstract SequenceIterator compute(SequenceIterator input,
                                            FunctionItem test,
                                            XPathContext context)
                                     throws XPathException

The function that does the work, which must be implemented in subclasses

Parameters:

input - the input sequence

test - the function to be applied to the items in the sequence, which takes an item in the sequence as input and produces a boolean as its result

context - the XPath dynamic context

Returns:

the result

Throws:

XPathException - if a dynamic error occurs

makeCallExpression

public ExtensionFunctionCall makeCallExpression()

Create a call on this function. This method is called by the compiler when it identifies a function call that calls this function.

Specified by:

makeCallExpression in class ExtensionFunctionDefinition

Returns:

an expression representing a call of this extension function