com.icl.saxon.expr
Class IsLastExpression

java.lang.Object
  com.icl.saxon.expr.Expression
      com.icl.saxon.expr.IsLastExpression

public final class IsLastExpression

extends Expression

position()=last() expression

Field Summary

Fields inherited from class com.icl.saxon.expr.Expression

staticContext

Constructor Summary

IsLastExpression(boolean condition)
Construct a condition that tests position()=last (if condition is true) or position()!=last() (if condition is false).

Method Summary

void	display(int level) Diagnostic print of expression structure
Value	evaluate(Context c) Evaluate an expression.
boolean	evaluateAsBoolean(Context c) Evaluate an expression as a Boolean. The result of x.evaluateAsBoolean(c) must be equivalent to x.evaluate(c).asBoolean(); but optimisations are possible when it is known that a boolean result is required, especially in the case of a NodeSet.
boolean	getCondition()
int	getDataType() Determine the data type of the expression
int	getDependencies() Get the dependencies of this expression on the context
Expression	reduce(int dependencies, Context context) Perform a partial evaluation of the expression, by eliminating specified dependencies on the context.
Expression	simplify() Simplify an expression.

Methods inherited from class com.icl.saxon.expr.Expression

containsReferences, enumerate, evaluateAsNodeSet, evaluateAsNumber, evaluateAsString, getStaticContext, indent, isContextDocumentNodeSet, make, outputStringValue, setStaticContext, usesCurrent

Methods inherited from class java.lang.Object

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

Constructor Detail

IsLastExpression

public IsLastExpression(boolean condition)

Construct a condition that tests position()=last (if condition is true) or position()!=last() (if condition is false).

Method Detail

getCondition

public boolean getCondition()

simplify

public Expression simplify()

Description copied from class: Expression

Simplify an expression. Default implementation does nothing.

Overrides:

simplify in class Expression

Returns:

the simplified expression

evaluate

public Value evaluate(Context c)
               throws XPathException

Description copied from class: Expression

Evaluate an expression.

Specified by:

evaluate in class Expression

Parameters:

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

Returns:

the value of the expression, evaluated in the current context

Throws:

XPathException

evaluateAsBoolean

public boolean evaluateAsBoolean(Context c)
                          throws XPathException

Description copied from class: Expression

Evaluate an expression as a Boolean.
The result of x.evaluateAsBoolean(c) must be equivalent to x.evaluate(c).asBoolean(); but optimisations are possible when it is known that a boolean result is required, especially in the case of a NodeSet.

Overrides:

evaluateAsBoolean in class Expression

Parameters:

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

Returns:

the value of the expression, evaluated in the current context

Throws:

XPathException

getDataType

public int getDataType()

Determine the data type of the expression

Specified by:

getDataType in class Expression

Returns:

Value.BOOLEAN

getDependencies

public int getDependencies()

Get the dependencies of this expression on the context

Specified by:

getDependencies in class Expression

reduce

public Expression reduce(int dependencies,
                         Context context)
                  throws XPathException

Perform a partial evaluation of the expression, by eliminating specified dependencies on the context.

Specified by:

reduce in class Expression

Parameters:

dependencies - The dependencies to be removed

context - The context to be used for the partial evaluation

Returns:

a new expression that does not have any of the specified dependencies

Throws:

XPathException

display

public void display(int level)

Diagnostic print of expression structure

Specified by:

display in class Expression