org.apache.commons.jxpath.ri.compiler
Class CoreOperation

java.lang.Object
  org.apache.commons.jxpath.ri.compiler.Expression
      org.apache.commons.jxpath.ri.compiler.Operation
          org.apache.commons.jxpath.ri.compiler.CoreOperation

Direct Known Subclasses:

CoreOperationAdd, CoreOperationAnd, CoreOperationCompare, CoreOperationDivide, CoreOperationGreaterThan, CoreOperationGreaterThanOrEqual, CoreOperationLessThan, CoreOperationLessThanOrEqual, CoreOperationMod, CoreOperationMultiply, CoreOperationNegate, CoreOperationOr, CoreOperationSubtract, CoreOperationUnion

public abstract class CoreOperation

extends Operation

The common subclass for tree elements representing core operations like "+", "- ", "*" etc.

Version:

$Revision: 1.14 $ $Date: 2004/02/29 14:17:39 $

Author:

Dmitri Plotnikov

Nested Class Summary

Nested classes inherited from class org.apache.commons.jxpath.ri.compiler.Expression

Expression.PointerIterator, Expression.ValueIterator

Field Summary

Fields inherited from class org.apache.commons.jxpath.ri.compiler.Operation

args

Fields inherited from class org.apache.commons.jxpath.ri.compiler.Expression

NOT_A_NUMBER, ONE, ZERO

Constructor Summary

CoreOperation(Expression[] args)

Method Summary

java.lang.Object	compute(EvalContext context)
abstract java.lang.Object	computeValue(EvalContext context) Evaluates the expression.
protected abstract int	getPrecedence() Computes the precedence of the operation.
abstract java.lang.String	getSymbol() Returns the XPath symbol for this operation, e.g.
protected abstract boolean	isSymmetric() Returns true if the operation is not sensitive to the order of arguments, e.g.
private java.lang.String	parenthesize(Expression expression, boolean left)
java.lang.String	toString()

Methods inherited from class org.apache.commons.jxpath.ri.compiler.Operation

computeContextDependent, getArguments

Methods inherited from class org.apache.commons.jxpath.ri.compiler.Expression

isContextDependent, iterate, iteratePointers

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

CoreOperation

public CoreOperation(Expression[] args)

Method Detail

compute

public java.lang.Object compute(EvalContext context)

Specified by:

compute in class Expression

computeValue

public abstract java.lang.Object computeValue(EvalContext context)

Description copied from class: Expression

Evaluates the expression. If the result is a node set, returns the first element of the node set.

Specified by:

computeValue in class Expression

getSymbol

public abstract java.lang.String getSymbol()

Returns the XPath symbol for this operation, e.g. "+", "div", etc.

isSymmetric

protected abstract boolean isSymmetric()

Returns true if the operation is not sensitive to the order of arguments, e.g. "=", "and" etc, and false if it is, e.g. "<=", "div".

getPrecedence

protected abstract int getPrecedence()

Computes the precedence of the operation.

toString

public java.lang.String toString()

parenthesize

private java.lang.String parenthesize(Expression expression,
                                      boolean left)