com.icl.saxon.expr
Class BooleanExpression

java.lang.Object
  extended bycom.icl.saxon.expr.Expression
      extended bycom.icl.saxon.expr.BinaryExpression
          extended bycom.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
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

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