org.apache.commons.jxpath.ri.compiler

Class CoreOperationCompare

java.lang.Object

org.apache.commons.jxpath.ri.compiler.Expression

org.apache.commons.jxpath.ri.compiler.Operation

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

org.apache.commons.jxpath.ri.compiler.CoreOperationCompare

Direct Known Subclasses:

CoreOperationEqual, CoreOperationNotEqual

public abstract class CoreOperationCompare
extends CoreOperation

Common superclass for the implementations of Expression for the operations "=" and "!=".

Version:

$Revision: 652845 $ $Date: 2008-05-02 12:46:46 -0500 (Fri, 02 May 2008) $

Nested Class Summary

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

Expression.PointerIterator, Expression.ValueIterator

Field Summary

Fields

Modifier and Type	Field and Description
private boolean	invert

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

ADD_PRECEDENCE, AND_PRECEDENCE, COMPARE_PRECEDENCE, MULTIPLY_PRECEDENCE, NEGATE_PRECEDENCE, OR_PRECEDENCE, RELATIONAL_EXPR_PRECEDENCE, UNION_PRECEDENCE

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

Constructors

Modifier	Constructor and Description
	CoreOperationCompare(Expression arg1, Expression arg2) Create a new CoreOperationCompare.
protected	CoreOperationCompare(Expression arg1, Expression arg2, boolean invert) Create a new CoreOperationCompare.

Method Summary

Modifier and Type	Method and Description
java.lang.Object	computeValue(EvalContext context) Evaluates the expression.
protected boolean	contains(java.util.Iterator it, java.lang.Object value) Learn whether it contains value.
protected boolean	equal(EvalContext context, Expression left, Expression right) Compares two values.
protected boolean	equal(java.lang.Object l, java.lang.Object r) Learn whether l equals r in XPath terms.
protected boolean	findMatch(java.util.Iterator lit, java.util.Iterator rit) Learn whether lit intersects rit.
protected int	getPrecedence() Computes the precedence of the operation.
protected boolean	isSymmetric() Returns true if the operation is not sensitive to the order of arguments, e.g.

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

compute, getSymbol, 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

Field Detail

invert

private boolean invert

Constructor Detail

CoreOperationCompare

public CoreOperationCompare(Expression arg1,
                            Expression arg2)

Create a new CoreOperationCompare.

Parameters:

arg1 - left operand

arg2 - right operand

CoreOperationCompare

protected CoreOperationCompare(Expression arg1,
                               Expression arg2,
                               boolean invert)

Create a new CoreOperationCompare.

Parameters:

arg1 - left operand

arg2 - right operand

invert - whether to invert (not) the comparison

Method Detail

computeValue

public 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 CoreOperation

Parameters:

context - evaluation context

Returns:

Object

getPrecedence

protected int getPrecedence()

Description copied from class: CoreOperation

Computes the precedence of the operation.

Specified by:

getPrecedence in class CoreOperation

Returns:

int precedence

isSymmetric

protected boolean isSymmetric()

Description copied from class: CoreOperation

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".

Specified by:

isSymmetric in class CoreOperation

Returns:

boolean

equal

protected boolean equal(EvalContext context,
                        Expression left,
                        Expression right)

Compares two values.

Parameters:

context - evaluation context

left - operand

right - operand

Returns:

whether left = right in XPath terms

contains

protected boolean contains(java.util.Iterator it,
                           java.lang.Object value)

Learn whether it contains value.

Parameters:

it - Iterator to check

value - for which to look

Returns:

whether value was found

findMatch

protected boolean findMatch(java.util.Iterator lit,
                            java.util.Iterator rit)

Learn whether lit intersects rit.

Parameters:

lit - left Iterator

rit - right Iterator

Returns:

boolean

equal

protected boolean equal(java.lang.Object l,
                        java.lang.Object r)

Learn whether l equals r in XPath terms.

Parameters:

l - left operand

r - right operand

Returns:

whether l = r