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, 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()
Method Detail

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

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