com.icl.saxon.expr
Class BooleanExpression

java.lang.Object
  extended by com.icl.saxon.expr.Expression
      extended by com.icl.saxon.expr.BinaryExpression
          extended by 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