net.sf.saxon.expr
Class FunctionCall

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

All Implemented Interfaces:

Container, Expression, InstructionInfoProvider, java.io.Serializable, javax.xml.transform.SourceLocator

Direct Known Subclasses:

ExtensionFunctionCall, SystemFunction, UserFunctionCall, XPathFunctionCall

public abstract class FunctionCall

extends ComputedExpression

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

See Also:

Serialized Form

Field Summary

protected Expression[]

argument The array of expressions representing the actual parameters to the function call

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

locationId, staticProperties

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

EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD

Constructor Summary

FunctionCall()

Method Summary

protected int	checkArgumentCount(int min, int max, StaticContext env) Check number of arguments.
protected abstract void	checkArguments(StaticContext env) Method supplied by each class of function to check arguments during parsing, when all the argument expressions have been read
void	display(int level, NamePool pool, java.io.PrintStream out) Diagnostic print of expression structure.
java.lang.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
java.util.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
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.
protected Expression	simplifyArguments(StaticContext env) Simplify the arguments of the function.
Expression	typeCheck(StaticContext env, ItemType contextItemType) Type-check the expression.

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

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

Methods inherited from class java.lang.Object

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

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

getItemType

Field Detail

argument

protected Expression[] argument

The array of expressions representing the actual parameters to the function call

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

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.

Specified by:

simplify in interface Expression

Overrides:

simplify in class ComputedExpression

Returns:

the simplified expression

Throws:

XPathException - if an error is discovered during expression rewriting

simplifyArguments

protected final Expression simplifyArguments(StaticContext env)
                                      throws XPathException

Simplify the arguments of the function. Called from the simplify() method of each function.

Returns:

the result of simplifying the arguments of the expression

Throws:

XPathException

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.

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:

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.

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

Specified by:

promote in interface Expression

Overrides:

promote in class ComputedExpression

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

checkArguments

protected abstract void checkArguments(StaticContext env)
                                throws XPathException

Method supplied by each class of function to check arguments during parsing, when all the argument expressions have been read

Throws:

XPathException

checkArgumentCount

protected int checkArgumentCount(int min,
                                 int max,
                                 StaticContext env)
                          throws XPathException

Check number of arguments.
A convenience routine for use in subclasses.

Parameters:

min - the minimum number of arguments allowed

max - the maximum number of arguments allowed

Returns:

the actual number of arguments

Throws:

XPathException - if the number of arguments is out of range

iterateSubExpressions

public java.util.Iterator iterateSubExpressions()

Get the immediate subexpressions of this expression

Specified by:

iterateSubExpressions in interface Expression

Overrides:

iterateSubExpressions in class ComputedExpression

Returns:

an iterator containing the sub-expressions of this expression

getDisplayName

public final java.lang.String getDisplayName(NamePool pool)

Diagnostic print of expression structure

display

public void display(int level,
                    NamePool pool,
                    java.io.PrintStream out)

Description copied from interface: Expression

Diagnostic print of expression structure. The expression is written to the System.err output stream

Parameters:

level - indentation level for this expression

pool - NamePool used to expand any names appearing in the expression

out - Output destination