net.sf.saxon.functions
Class StringFn

java.lang.Object
  |
  +--net.sf.saxon.expr.ComputedExpression
        |
        +--net.sf.saxon.expr.FunctionCall
              |
              +--net.sf.saxon.functions.SystemFunction
                    |
                    +--net.sf.saxon.functions.StringFn

All Implemented Interfaces:

Expression, java.io.Serializable

public class StringFn

extends SystemFunction

Implement XPath function string()

See Also:

Serialized Form

Field Summary

 

Fields inherited from class net.sf.saxon.functions.SystemFunction

operation

 

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

argument

 

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

lineNumber, NO_ARGUMENTS, staticProperties

 

Constructor Summary

StringFn()

 

Method Summary
Expression	analyze(StaticContext env)           Type check.
Item	evaluateItem(XPathContext c)           Evaluate the function
Expression	simplify()           Simplify and validate.

 

Methods inherited from class net.sf.saxon.functions.SystemFunction

addContextDocumentArgument, checkArguments, computeCardinality, display, getDetails, getItemType, getName, getRequiredType, main, makeSystemFunction, useContextItemAsDefault

 

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

checkArgumentCount, getNumberOfArguments, getSubExpressions, preEvaluate, promote, setArguments, simplifyArguments

 

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

computeDependencies, computeSpecialProperties, computeStaticProperties, dynamicError, effectiveBooleanValue, evaluateAsString, getCardinality, getDependencies, getIntrinsicDependencies, getLineNumber, getSourceLocator, getSpecialProperties, iterate, markTailFunctionCalls, setLineNumber, typeError

 

Methods inherited from class java.lang.Object

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

 

Constructor Detail

StringFn

public StringFn()

simplify

public Expression simplify()
                    throws XPathException

Simplify and validate. This is a pure function so it can be simplified in advance if the arguments are known

Specified by:

simplify in interface Expression

Overrides:

simplify in class FunctionCall

Returns:

the simplified expression

Throws:

XPathException - if an error is discovered during expression rewriting

analyze

public Expression analyze(StaticContext env)
                   throws XPathException

Type check. This refinement of the method removes the function call wrapper if the argument is already of type single string

Specified by:

analyze in interface Expression

Overrides:

analyze in class FunctionCall

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

XPathException

evaluateItem

public Item evaluateItem(XPathContext c)
                  throws XPathException

Evaluate the function

Specified by:

evaluateItem in interface Expression

Overrides:

evaluateItem in class ComputedExpression

Parameters:

c - The context in which the expression is to be evaluated

Returns:

the node or atomic value that results from evaluating the expression; or null to indicate that the result is an empty sequence

Throws:

XPathException - if any dynamic error occurs evaluating the expression