net.sf.saxon.functions
Class Evaluate

java.lang.Object
  |
  +--net.sf.saxon.expr.ComputedExpression
        |
        +--net.sf.saxon.expr.FunctionCall
              |
              +--net.sf.saxon.functions.SystemFunction
                    |
                    +--net.sf.saxon.functions.Evaluate
All Implemented Interfaces:
Expression, java.io.Serializable, XSLTFunction

public class Evaluate
extends SystemFunction
implements XSLTFunction

This class implements the saxon:evaluate(), saxon:expression(), and saxon:eval() extension functions, which are specially-recognized by the system because they needs access to parts of the static context

See Also:
Serialized Form

Nested Class Summary
protected static class Evaluate.PreparedExpression
          Inner class PreparedExpression represents a compiled XPath expression together with the standard variables $p1 ..
 
Field Summary
static int EVAL
           
static int EVALUATE
           
static int EXPRESSION
           
 
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
Evaluate()
           
 
Method Summary
 void checkArguments(StaticContext env)
          Method supplied by each class of function to check arguments during parsing, when all the argument expressions have been read
 Item evaluateItem(XPathContext c)
          Evaluate in a general context
 int getIntrinsicDependencies()
          Determine the dependencies
protected  SequenceType getRequiredType(int arg)
          Get the required type of the nth argument
 SequenceIterator iterate(XPathContext c)
          Iterate over the results of the function
 Expression preEvaluate(StaticContext env)
          preEvaluate: this method suppresses compile-time evaluation by doing nothing (because the value of the expression depends on the runtime context)
 
Methods inherited from class net.sf.saxon.functions.SystemFunction
addContextDocumentArgument, computeCardinality, display, getDetails, getItemType, getName, main, makeSystemFunction, useContextItemAsDefault
 
Methods inherited from class net.sf.saxon.expr.FunctionCall
analyze, checkArgumentCount, getNumberOfArguments, getSubExpressions, promote, setArguments, simplify, simplifyArguments
 
Methods inherited from class net.sf.saxon.expr.ComputedExpression
computeDependencies, computeSpecialProperties, computeStaticProperties, dynamicError, effectiveBooleanValue, evaluateAsString, getCardinality, getDependencies, getLineNumber, getSourceLocator, getSpecialProperties, markTailFunctionCalls, setLineNumber, typeError
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

EVALUATE

public static final int EVALUATE
See Also:
Constant Field Values

EXPRESSION

public static final int EXPRESSION
See Also:
Constant Field Values

EVAL

public static final int EVAL
See Also:
Constant Field Values
Constructor Detail

Evaluate

public Evaluate()
Method Detail

getRequiredType

protected SequenceType getRequiredType(int arg)
Get the required type of the nth argument

Overrides:
getRequiredType in class SystemFunction

checkArguments

public 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

Overrides:
checkArguments in class SystemFunction
XPathException

preEvaluate

public Expression preEvaluate(StaticContext env)
preEvaluate: this method suppresses compile-time evaluation by doing nothing (because the value of the expression depends on the runtime context)

Overrides:
preEvaluate in class FunctionCall

evaluateItem

public Item evaluateItem(XPathContext c)
                  throws XPathException
Evaluate in a general context

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

iterate

public SequenceIterator iterate(XPathContext c)
                         throws XPathException
Iterate over the results of the function

Specified by:
iterate in interface Expression
Overrides:
iterate in class ComputedExpression
Parameters:
c - supplies the context for evaluation
Returns:
a SequenceIterator that can be used to iterate over the result of the expression
Throws:
XPathException - if any dynamic error occurs evaluating the expression

getIntrinsicDependencies

public int getIntrinsicDependencies()
Determine the dependencies

Overrides:
getIntrinsicDependencies in class ComputedExpression
Returns:
a set of bit-significant flags identifying the "intrinsic" dependencies. The flags are documented in class net.sf.saxon.value.StaticProperty