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

protected int	operator
protected Expression	p1
protected Expression	p2

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

staticContext

Constructor Summary

BooleanExpression()

BooleanExpression(Expression p1, int operator, Expression p2)

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.
int	getDataType() Determine the data type of the expression
int	getDependencies() Determine which aspects of the context the expression depends on.
Expression	reduce(int dependencies, Context context) Perform a partial evaluation of the expression, by eliminating specified dependencies on the context.
void	setDetails(Expression p1, int op, Expression p2) Identify the two operands and the operator (for use when the default constructor was used)
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

Field Detail

p1

protected Expression p1

p2

protected Expression p2

operator

protected int operator

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

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

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

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

XPathException

setDetails

public void setDetails(Expression p1,
                       int op,
                       Expression p2)

Identify the two operands and the operator (for use when the default constructor was used)

Parameters:

p1 - the left-hand operand

op - the operator, as a token returned by the Tokenizer (e.g. Tokenizer.AND)

p2 - the right-hand operand

getDependencies

public int getDependencies()

Determine which aspects of the context the expression depends on. The result is a bitwise-or'ed value composed from constants such as Context.VARIABLES and Context.CURRENT_NODE

Specified by:

getDependencies in class Expression

display

public void display(int level)

Diagnostic print of expression structure

Specified by:

display in class Expression