com.icl.saxon.expr

Class 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, display, enumerate, evaluate, evaluateAsBoolean, evaluateAsNodeSet, evaluateAsNumber, evaluateAsString, getDataType, getDependencies, getStaticContext, indent, isContextDocumentNodeSet, make, outputStringValue, reduce, setStaticContext, simplify, usesCurrent

Constructor Details

IsLastExpression

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

Method Details

display

public void display(int level)
Diagnostic print of expression structure
Overrides:
display in interface Expression

evaluate

public Value evaluate(Context c)
            throws XPathException
Evaluate an expression.
Overrides:
evaluate in interface Expression
Parameters:
Returns:
the value of the expression, evaluated in the current context

evaluateAsBoolean

public boolean evaluateAsBoolean(Context c)
            throws XPathException
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 interface Expression
Parameters:
Returns:
the value of the expression, evaluated in the current context

getCondition

public boolean getCondition()

getDataType

public int getDataType()
Determine the data type of the expression
Overrides:
getDataType in interface Expression
Returns:
Value.BOOLEAN

getDependencies

public int getDependencies()
Get the dependencies of this expression on the context
Overrides:
getDependencies in interface 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.
Overrides:
reduce in interface 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

simplify

public Expression simplify()
Simplify an expression. Default implementation does nothing.
Overrides:
simplify in interface Expression
Returns:
the simplified expression