net.sf.saxon.expr

Class FunctionCall

Implemented Interfaces:
EvaluableItem, InstructionInfoProvider, SequenceIterable, Serializable, SourceLocator
Known Direct Subclasses:
DotNetExtensionFunctionCall, ExtensionFunctionCall, SystemFunction, UserFunctionCall, XPathFunctionCall

public abstract class FunctionCall
extends Expression

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

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, ITERATE_METHOD, PROCESS_METHOD, locationId, staticProperties

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
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
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)
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, checkPermittedContents, computeCardinality, computeDependencies, computeSpecialProperties, computeStaticProperties, copy, display, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluateItem, explain, explain, findParentOf, getCardinality, getColumnNumber, getConstructType, getContainer, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getInstructionInfo, getIntrinsicDependencies, getItemType, getLineNumber, getLocationId, getLocationProvider, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, iterate, iterateEvents, iterateSubExpressions, markTailFunctionCalls, optimize, process, promote, replaceSubExpression, resetLocalStaticProperties, setContainer, setFiltered, setFlattened, setLocationId, simplify, staticTypeCheck, suppressValidation, toString, typeCheck, typeError

Field Details

argument

protected Expression[] argument
The array of expressions representing the actual parameters to the function call

Method Details

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.

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

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

equals

public boolean equals(Object o)
Determine whether two expressions are equivalent

explain

public void explain(ExpressionPresenter out)
Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.
Overrides:
explain in interface Expression

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

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

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)

hashCode

public int hashCode()
Get hashCode in support of equals() method

iterateSubExpressions

public Iterator iterateSubExpressions()
Get the immediate subexpressions of this expression
Overrides:
iterateSubExpressions in interface Expression

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 interface 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

promote

public Expression promote(PromotionOffer offer)
            throws XPathException
Promote this expression if possible
Overrides:
promote in interface Expression

replaceSubExpression

public boolean replaceSubExpression(Expression original,
                                    Expression replacement)
Replace one subexpression by a replacement subexpression
Overrides:
replaceSubExpression in interface Expression
Parameters:
original - the original subexpression
replacement - the replacement subexpression
Returns:
true if the original subexpression is found

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

setFunctionName

public final void setFunctionName(StructuredQName name)
Set the name of the function being called
Parameters:
name - the name of the function

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 interface Expression
Parameters:
visitor - an expression visitor

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

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 interface Expression

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 interface Expression