com.icl.saxon.expr
Class BooleanExpression

java.lang.Object
  com.icl.saxon.expr.Expression
      com.icl.saxon.expr.BinaryExpression
          com.icl.saxon.expr.BooleanExpression

 class BooleanExpression
extends BinaryExpression

Boolean expression: two booleans combined using AND or OR

Field Summary

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

operator, p1, p2

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

staticContext

Constructor Summary

BooleanExpression()

BooleanExpression(Expression p1, int operator, Expression p2)

Method Summary

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.
int	getDataType() Determine the data type of the expression
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.BinaryExpression

display, getDependencies, setDetails

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

BooleanExpression

public BooleanExpression()

BooleanExpression

public BooleanExpression(Expression p1,
                         int operator,
                         Expression p2)

Method Detail

simplify

public Expression simplify()
                    throws XPathException

Description copied from class: BinaryExpression

Simplify an expression

Overrides:

simplify in class BinaryExpression

Returns:

the simplified expression

Throws:

XPathException

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

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