net.sf.saxon.expr
Class FunctionCall

java.lang.Object
  |
  +--net.sf.saxon.expr.ComputedExpression
        |
        +--net.sf.saxon.expr.FunctionCall
All Implemented Interfaces:
Expression, java.io.Serializable
Direct Known Subclasses:
FunctionProxy, SystemFunction, UserFunctionCall

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
lineNumber, NO_ARGUMENTS, staticProperties
 
Constructor Summary
FunctionCall()
           
 
Method Summary
 Expression analyze(StaticContext env)
          Type-check the expression.
protected  int checkArgumentCount(int min, int max)
          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)
          Diagnostic print of expression structure.
abstract  java.lang.String getName()
          Diagnostic print of expression structure
 int getNumberOfArguments()
          Determine the number of actual arguments supplied in the function call
 Expression[] getSubExpressions()
          Get the immediate subexpressions of this expression
 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
 Expression simplify()
          Simplify the function call.
protected  Expression simplifyArguments()
          Simplify the arguments of the function.
 
Methods inherited from class net.sf.saxon.expr.ComputedExpression
computeCardinality, computeDependencies, computeSpecialProperties, computeStaticProperties, dynamicError, effectiveBooleanValue, evaluateAsString, evaluateItem, getCardinality, getDependencies, getIntrinsicDependencies, getLineNumber, getSpecialProperties, iterate, markTailFunctionCalls, setLineNumber, 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

getNumberOfArguments

public final int getNumberOfArguments()
Determine the number of actual arguments supplied in the function call


setArguments

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

XPathException

simplify

public Expression simplify()
                    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()
                                      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
XPathException

analyze

public Expression analyze(StaticContext env)
                   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
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)

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.

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

XPathException

checkArgumentCount

protected int checkArgumentCount(int min,
                                 int max)
                          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

getSubExpressions

public Expression[] getSubExpressions()
Get the immediate subexpressions of this expression

Specified by:
getSubExpressions in interface Expression
Overrides:
getSubExpressions in class ComputedExpression
Returns:
an array containing the sub-expressions of this expression

getName

public abstract java.lang.String getName()
Diagnostic print of expression structure


display

public void display(int level,
                    NamePool pool)
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