com.icl.saxon.expr
Class RelationalExpression

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

final class RelationalExpression
extends BinaryExpression

Relational Expression: a boolean expression that compares two expressions for equals, not-equals, greater-than or less-than.


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
RelationalExpression()
          Default constructor
RelationalExpression(Expression p1, int op, Expression p2)
          Create a relational expression identifying the two operands and the operator
 
Method Summary
 Value evaluate(Context c)
          Evaluate the expression in a given context
 boolean evaluateAsBoolean(Context c)
          Evaluate the expression in a given context
 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

RelationalExpression

public RelationalExpression()
Default constructor


RelationalExpression

public RelationalExpression(Expression p1,
                            int op,
                            Expression p2)
Create a relational expression identifying the two operands and the operator

Parameters:
p1 - the left-hand operand
op - the operator, as a token returned by the Tokenizer (e.g. Tokenizer.LT)
p2 - the right-hand operand
Method Detail

simplify

public Expression simplify()
                    throws XPathException
Simplify an expression

Overrides:
simplify in class BinaryExpression
Returns:
the simplified expression
Throws:
XPathException

evaluate

public Value evaluate(Context c)
               throws XPathException
Evaluate the expression in a given context

Specified by:
evaluate in class Expression
Parameters:
c - the given context for evaluation
Returns:
a BooleanValue representing the result of the numeric comparison of the two operands
Throws:
XPathException

evaluateAsBoolean

public boolean evaluateAsBoolean(Context c)
                          throws XPathException
Evaluate the expression in a given context

Overrides:
evaluateAsBoolean in class Expression
Parameters:
c - the given context for evaluation
Returns:
a boolean representing the result of the numeric comparison of the two operands
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