net.sf.saxon.functions
Class Available
java.lang.Object
net.sf.saxon.expr.ComputedExpression
net.sf.saxon.expr.FunctionCall
net.sf.saxon.functions.SystemFunction
net.sf.saxon.functions.Available
- All Implemented Interfaces:
- Expression, Serializable, XSLTFunction
- public class Available
- extends SystemFunction
- implements XSLTFunction
This class supports the XSLT element-available and function-available functions.
- See Also:
- Serialized Form
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 |
ELEMENT_AVAILABLE
public static final int ELEMENT_AVAILABLE
- See Also:
- Constant Field Values
FUNCTION_AVAILABLE
public static final int FUNCTION_AVAILABLE
- See Also:
- Constant Field Values
Available
public Available()
checkArguments
public void checkArguments(StaticContext env)
throws XPathException
- Description copied from class:
SystemFunction
- Method called during static type checking
- Overrides:
checkArguments
in class SystemFunction
- Throws:
XPathException
preEvaluate
public Expression preEvaluate(StaticContext env)
throws XPathException
- preEvaluate: this method uses the static context to do early evaluation of the function
if the argument is known
- Overrides:
preEvaluate
in class FunctionCall
- Throws:
XPathException
evaluateItem
public Item evaluateItem(XPathContext context)
throws XPathException
- Run-time evaluation. This is tricky: we don't keep all the information
necessary at run time. Fortunately, this case is rarely used. The function
currently returns true only for XSLT and Saxon instructions, and for
core functions and Java extensions (not stylesheet functions).
- Specified by:
evaluateItem
in interface Expression
- Overrides:
evaluateItem
in class ComputedExpression
- Parameters:
context
- 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