net.sf.saxon.expr
Class FunctionCall

java.lang.Object
  net.sf.saxon.expr.Expression
      net.sf.saxon.expr.FunctionCall

All Implemented Interfaces:

Serializable, SourceLocator, Container, EvaluableItem, SequenceIterable, InstructionInfoProvider

Direct Known Subclasses:

ExtensionFunctionCall, SystemFunction, UserFunctionCall, XPathFunctionCall

public abstract class FunctionCall
extends Expression

Abstract superclass for calls to system-defined and user-defined functions

See Also:

Serialized Form

Field Summary

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

EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD

Constructor Summary

FunctionCall()

Method Summary

void	display(int level, PrintStream out, Configuration config) Diagnostic print of expression structure.
Expression[]	getArguments() Get the expressions supplied as actual arguments to the function
String	getDisplayName(NamePool pool) Diagnostic print of expression structure
int	getFunctionNameCode() Get the name code of the function being called
int	getNumberOfArguments() Determine the number of actual arguments supplied in the function call
Iterator	iterateSubExpressions() Get the immediate subexpressions of this expression
Expression	optimize(Optimizer opt, StaticContext env, ItemType contextItemType) Perform optimisation of an expression and its subexpressions.
Expression	preEvaluate(StaticContext env) Pre-evaluate a function at compile time.
Expression	promote(PromotionOffer offer) Promote this expression if possible
boolean	replaceSubExpression(Expression original, Expression replacement) Replace one subexpression by a replacement subexpression
void	setArguments(Expression[] args) Method called by the expression parser when all arguments have been supplied
void	setFunctionNameCode(int nc) Set the name code of the function being called
Expression	simplify(StaticContext env) Simplify the function call.
Expression	typeCheck(StaticContext env, ItemType contextItemType) Type-check the expression.

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

adoptChildExpression, checkPermittedContents, computeDependencies, computeSpecialProperties, computeStaticProperties, doPromotion, effectiveBooleanValue, evaluateAsString, evaluateItem, getCardinality, getColumnNumber, getContainingProcedure, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getIntrinsicDependencies, getItemType, getLineNumber, getLocationId, getLocationProvider, getParentExpression, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasBadParentPointer, iterate, markTailFunctionCalls, process, resetStaticProperties, setLocationId, setParentExpression, setParentExpression, suppressValidation

Methods inherited from class java.lang.Object

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

Constructor Detail

FunctionCall

public FunctionCall()

Method Detail

setFunctionNameCode

public final void setFunctionNameCode(int nc)

Set the name code of the function being called

getFunctionNameCode

public final int getFunctionNameCode()

Get the name code of the function being called

Returns:

the name code as recorded in the name pool

getNumberOfArguments

public final int getNumberOfArguments()

Determine the number of actual arguments supplied in the function call

setArguments

public void setArguments(Expression[] args)

Method called by the expression parser when all arguments have been supplied

getArguments

public Expression[] getArguments()

Get the expressions supplied as actual arguments to the function

simplify

public Expression simplify(StaticContext env)
                    throws XPathException

Simplify the function call. Default method is to simplify each of the supplied arguments and evaluate the function if all are now known.

Overrides:

simplify in class Expression

Returns:

the simplified expression

Throws:

XPathException - if an error is discovered during expression rewriting

typeCheck

public Expression typeCheck(StaticContext env,
                            ItemType contextItemType)
                     throws XPathException

Type-check the expression. This also calls preEvaluate() to evaluate the function if all the arguments are constant; functions that do not require this behavior can override the preEvaluate method.

Overrides:

typeCheck in class Expression

Parameters:

env - the static context of the expression

contextItemType - the static type of "." at the point where this expression is invoked. The parameter is set to null if it is known statically that the context item will be undefined. If the type of the context item is not known statically, the argument is set to Type.ITEM_TYPE

Returns:

the original expression, rewritten to perform necessary run-time type checks, and to perform other type-related optimizations

Throws:

StaticError - if an error is discovered during this phase (typically a type error)

XPathException

optimize

public Expression optimize(Optimizer opt,
                           StaticContext env,
                           ItemType contextItemType)
                    throws XPathException

Perform optimisation of an expression and its subexpressions.

This method is called after all references to functions and variables have been resolved to the declaration of the function or variable, and after all type checking has been done.

Overrides:

optimize in class Expression

Parameters:

opt - the optimizer in use. This provides access to supporting functions; it also allows different optimization strategies to be used in different circumstances.

env - the static context of the expression

contextItemType - the static type of "." at the point where this expression is invoked. The parameter is set to null if it is known statically that the context item will be undefined. If the type of the context item is not known statically, the argument is set to Type.ITEM_TYPE

Returns:

the original expression, rewritten if appropriate to optimize execution

Throws:

StaticError - if an error is discovered during this phase (typically a type error)

XPathException

preEvaluate

public Expression preEvaluate(StaticContext env)
                       throws XPathException

Pre-evaluate a function at compile time. Functions that do not allow pre-evaluation, or that need access to context information, can override this method.

Throws:

XPathException

promote

public Expression promote(PromotionOffer offer)
                   throws XPathException

Promote this expression if possible

Overrides:

promote in class Expression

Parameters:

offer - details of the offer, for example the offer to move expressions that don't depend on the context to an outer level in the containing expression

Returns:

if the offer is not accepted, return this expression unchanged. Otherwise return the result of rewriting the expression to promote this subexpression

Throws:

XPathException - if any error is detected

iterateSubExpressions

public Iterator iterateSubExpressions()

Get the immediate subexpressions of this expression

Overrides:

iterateSubExpressions in class Expression

Returns:

an iterator containing the sub-expressions of this expression

replaceSubExpression

public boolean replaceSubExpression(Expression original,
                                    Expression replacement)

Replace one subexpression by a replacement subexpression

Specified by:

replaceSubExpression in interface Container

Overrides:

replaceSubExpression in class Expression

Parameters:

original - the original subexpression

replacement - the replacement subexpression

Returns:

true if the original subexpression is found

getDisplayName

public final String getDisplayName(NamePool pool)

Diagnostic print of expression structure

display

public void display(int level,
                    PrintStream out,
                    Configuration config)

Description copied from class: Expression

Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.

Specified by:

display in class Expression

Parameters:

level - indentation level for this expression

out - Output destination