net.sf.saxon.expr
Class FunctionCall

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

All Implemented Interfaces:

Serializable, SourceLocator, LocationProvider, SaxonLocator, EvaluableItem, SequenceIterable, InstructionInfo, Locator

Direct Known Subclasses:

IntegratedFunctionCall, JavaExtensionFunctionCall, 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

protected Expression[]

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

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

EVALUATE_METHOD, EVENT_FEED_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, PROCESS_METHOD, PUSH_SELECTION, staticProperties, WATCH_METHOD

Constructor Summary

FunctionCall()

Method Summary

PathMap.PathMapNodeSet	addExternalFunctionCallToPathMap(PathMap pathMap, PathMap.PathMapNodeSet pathMapNodes) Add a representation of this expression to a PathMap.
protected int	checkArgumentCount(int min, int max, ExpressionVisitor visitor) Check number of arguments.
protected abstract void	checkArguments(ExpressionVisitor visitor) Method supplied by each class of function to check arguments during parsing, when all the argument expressions have been read
boolean	equals(Object o) Determine whether two expressions are equivalent
void	explain(ExpressionPresenter out) Diagnostic print of expression structure.
Expression[]	getArguments() Get the expressions supplied as actual arguments to the function
String	getDisplayName() Get the name of the function for display in messages
String	getExpressionName() Get a name identifying the kind of expression, in terms meaningful to a user.
StructuredQName	getFunctionName() Get the qualified of the function being called
int	getNumberOfArguments() Determine the number of actual arguments supplied in the function call
int	hashCode() Get hashCode in support of equals() method
Iterator<Expression>	iterateSubExpressions() Get the immediate subexpressions of this expression
Expression	optimize(ExpressionVisitor visitor, ItemType contextItemType) Perform optimisation of an expression and its subexpressions.
Expression	preEvaluate(ExpressionVisitor visitor) Pre-evaluate a function at compile time.
Expression	promote(PromotionOffer offer, Expression parent) 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	setFunctionName(StructuredQName name) Set the name of the function being called
Expression	simplify(ExpressionVisitor visitor) Simplify the function call.
protected Expression	simplifyArguments(ExpressionVisitor visitor) Simplify the arguments of the function.
String	toString() The toString() method for an expression attempts to give a representation of the expression in an XPath-like form, but there is no guarantee that the syntax will actually be true XPath.
Expression	typeCheck(ExpressionVisitor visitor, ItemType contextItemType) Type-check the expression.

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

addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeCardinality, computeDependencies, computeSpecialProperties, computeStaticProperties, copy, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluateItem, evaluatePendingUpdates, explain, getCardinality, getColumnNumber, getColumnNumber, getConstructType, getContainer, getDependencies, getEvaluationMethod, getExecutable, getHostLanguage, getImplementationMethod, getIntrinsicDependencies, getItemType, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterate, iterateEvents, iterateSameFocusSubExpressions, markTailFunctionCalls, process, resetLocalStaticProperties, setContainer, setEvaluationMethod, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation, typeError

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

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

setFunctionName

public final void setFunctionName(StructuredQName name)

Set the name of the function being called

Parameters:

name - the name of the function

getFunctionName

public StructuredQName getFunctionName()

Get the qualified of the function being called

Returns:

the qualified name

getNumberOfArguments

public final int getNumberOfArguments()

Determine the number of actual arguments supplied in the function call

Returns:

the arity (the number of arguments)

setArguments

public void setArguments(Expression[] args)

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

Parameters:

args - the expressions contained in the argument list of the function call

getArguments

public Expression[] getArguments()

Get the expressions supplied as actual arguments to the function

Returns:

the array of expressions supplied in the argument list of the function call

simplify

public Expression simplify(ExpressionVisitor visitor)
                    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

Parameters:

visitor - an expression visitor

Returns:

the simplified expression

Throws:

XPathException - if an error is discovered during expression rewriting

simplifyArguments

protected final Expression simplifyArguments(ExpressionVisitor visitor)
                                      throws XPathException

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

Parameters:

visitor - an expression visitor

Returns:

the result of simplifying the arguments of the expression

Throws:

XPathException

typeCheck

public Expression typeCheck(ExpressionVisitor visitor,
                            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:

visitor - an expression visitor

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

optimize

public Expression optimize(ExpressionVisitor visitor,
                           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:

visitor - an expression visitor

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:

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

preEvaluate

public Expression preEvaluate(ExpressionVisitor visitor)
                       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.

Parameters:

visitor - an expression visitor

Returns:

the result of the early evaluation, or the original expression, or potentially a simplified expression

Throws:

XPathException

promote

public Expression promote(PromotionOffer offer,
                          Expression parent)
                   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

checkArguments

protected abstract void checkArguments(ExpressionVisitor visitor)
                                throws XPathException

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

Parameters:

visitor - the expression visitor

Throws:

XPathException

checkArgumentCount

protected int checkArgumentCount(int min,
                                 int max,
                                 ExpressionVisitor visitor)
                          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

visitor - an expression visitor

Returns:

the actual number of arguments

Throws:

XPathException - if the number of arguments is out of range

iterateSubExpressions

public Iterator<Expression> 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

Overrides:

replaceSubExpression in class Expression

Parameters:

original - the original subexpression

replacement - the replacement subexpression

Returns:

true if the original subexpression is found

addExternalFunctionCallToPathMap

public PathMap.PathMapNodeSet addExternalFunctionCallToPathMap(PathMap pathMap,
                                                               PathMap.PathMapNodeSet pathMapNodes)

Add a representation of this expression to a PathMap. The PathMap captures a map of the nodes visited by an expression in a source tree.

The default implementation of this method assumes that an expression does no navigation other than the navigation done by evaluating its subexpressions, and that the subexpressions are evaluated in the same context as the containing expression. The method must be overridden for any expression where these assumptions do not hold. For example, implementations exist for AxisExpression, ParentExpression, and RootExpression (because they perform navigation), and for the doc(), document(), and collection() functions because they create a new navigation root. Implementations also exist for PathExpression and FilterExpression because they have subexpressions that are evaluated in a different context from the calling expression.

Parameters:

pathMap - the PathMap to which the expression should be added

pathMapNodes - the node in the PathMap representing the focus at the point where this expression is called. Set to null if this expression appears at the top level, in which case the expression, if it is registered in the path map at all, must create a new path map root.

Returns:

the pathMapNode representing the focus established by this expression, in the case where this expression is the first operand of a path expression or filter expression. For an expression that does navigation, it represents the end of the arc in the path map that describes the navigation route. For other expressions, it is the same as the input pathMapNode.

getExpressionName

public final String getExpressionName()

Get a name identifying the kind of expression, in terms meaningful to a user.

Overrides:

getExpressionName in class Expression

Returns:

a name identifying the kind of expression, in terms meaningful to a user. The name will always be in the form of a lexical XML QName, and should match the name used in explain() output displaying the expression.

getDisplayName

public final String getDisplayName()

Get the name of the function for display in messages

Returns:

the name of the function as a lexical QName

toString

public String toString()

The toString() method for an expression attempts to give a representation of the expression in an XPath-like form, but there is no guarantee that the syntax will actually be true XPath. In the case of XSLT instructions, the toString() method gives an abstracted view of the syntax

Overrides:

toString in class Expression

Returns:

a representation of the expression as a string

explain

public void explain(ExpressionPresenter out)

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

Specified by:

explain in class Expression

Parameters:

out - the expression presenter used to display the structure

equals

public boolean equals(Object o)

Determine whether two expressions are equivalent

Overrides:

equals in class Object

hashCode

public int hashCode()

Get hashCode in support of equals() method

Overrides:

hashCode in class Object