net.sf.saxon.expr

Class FunctionCall

public abstract class FunctionCall extends ComputedExpression

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
Method Summary
protected intcheckArgumentCount(int min, int max, StaticContext env)
Check number of arguments.
protected abstract voidcheckArguments(StaticContext env)
Method supplied by each class of function to check arguments during parsing, when all the argument expressions have been read
voiddisplay(int level, NamePool pool, PrintStream out)
StringgetDisplayName(NamePool pool)
Diagnostic print of expression structure
intgetFunctionNameCode()
Get the name code of the function being called
intgetNumberOfArguments()
Determine the number of actual arguments supplied in the function call
IteratoriterateSubExpressions()
Get the immediate subexpressions of this expression
Expressionoptimize(Optimizer opt, StaticContext env, ItemType contextItemType)
Perform optimisation of an expression and its subexpressions.
ExpressionpreEvaluate(StaticContext env)
Pre-evaluate a function at compile time.
Expressionpromote(PromotionOffer offer)
Promote this expression if possible
voidsetArguments(Expression[] args)
Method called by the expression parser when all arguments have been supplied
voidsetFunctionNameCode(int nc)
Set the name code of the function being called
Expressionsimplify(StaticContext env)
Simplify the function call.
protected ExpressionsimplifyArguments(StaticContext env)
Simplify the arguments of the function.
ExpressiontypeCheck(StaticContext env, ItemType contextItemType)
Type-check the expression.

Field Detail

argument

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

Method Detail

checkArgumentCount

protected int checkArgumentCount(int min, int max, StaticContext env)
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: net.sf.saxon.trans.XPathException if the number of arguments is out of range

checkArguments

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

display

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

getDisplayName

public final String getDisplayName(NamePool pool)
Diagnostic print of expression structure

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

iterateSubExpressions

public Iterator iterateSubExpressions()
Get the immediate subexpressions of this expression

optimize

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

Returns: the original expression, rewritten if appropriate to optimize execution

Throws: net.sf.saxon.trans.StaticError if an error is discovered during this phase (typically a type error)

preEvaluate

public Expression preEvaluate(StaticContext env)
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.

promote

public Expression promote(PromotionOffer offer)
Promote this expression if possible

setArguments

public void setArguments(Expression[] args)
Method called by the expression parser when all arguments have been supplied

setFunctionNameCode

public final void setFunctionNameCode(int nc)
Set the name code of the function being called

simplify

public Expression simplify(StaticContext env)
Simplify the function call. Default method is to simplify each of the supplied arguments and evaluate the function if all are now known.

simplifyArguments

protected final Expression simplifyArguments(StaticContext env)
Simplify the arguments of the function. Called from the simplify() method of each function.

Returns: the result of simplifying the arguments of the expression

typeCheck

public Expression typeCheck(StaticContext env, ItemType contextItemType)
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.