net.sf.saxon.functions

Class ItemAt

public class ItemAt extends ExtensionFunctionDefinition

Implements the saxon:item-at() function. This is handled specially because it is generated by the optimizer.

The function takes two arguments: the first is an arbitrary sequence, the second is optional numeric. The function returns the same result as let $N := NUMBER return SEQUENCE[$N], including cases where the numeric argument is not a whole number.

Method Summary
SequenceType[]getArgumentTypes()
Get the required types for the arguments of this function, counting from zero
ObjectgetCompilerForJava()
Return an object capable of compiling this IntegratedFunction call to Java source code.
StructuredQNamegetFunctionQName()
Get the function name, as a QName
intgetMaximumNumberOfArguments()
Get the maximum number of arguments allowed by the function
intgetMinimumNumberOfArguments()
Get the minimum number of arguments required by the function
SequenceTypegetResultType(SequenceType[] suppliedArgumentTypes)
Get the type of the result of the function
ExtensionFunctionCallmakeCallExpression()
Create a call on this function.

Method Detail

getArgumentTypes

public SequenceType[] getArgumentTypes()
Get the required types for the arguments of this function, counting from zero

Returns: the required types of the argument, 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.

getCompilerForJava

public Object getCompilerForJava()
Return an object capable of compiling this IntegratedFunction call to Java source code. The returned object may be null, in which case Java code generation is not supported for this IntegratedFunction. If the returned object is not null, it must implement the interface com.saxonica.codegen.IntegratedFunctionCompiler. The default implementation returns null

Returns: an instance of com.saxonica.codegen.IntegratedFunctionCompiler that generates Java code to implement the call on this extension function

getFunctionQName

public StructuredQName getFunctionQName()
Get the function name, as a QName

Returns: the QName of the function

getMaximumNumberOfArguments

public int getMaximumNumberOfArguments()
Get the maximum number of arguments allowed by the function

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

getMinimumNumberOfArguments

public int getMinimumNumberOfArguments()
Get the minimum number of arguments required by the function

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

getResultType

public SequenceType getResultType(SequenceType[] suppliedArgumentTypes)
Get the type of the result of the function

Parameters: suppliedArgumentTypes the static types of the 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 type of the first argument. The value will be null if the function call has no arguments.

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

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.