opendap.servers

Class RelOpClause

java.lang.Object

opendap.servers.AbstractClause

opendap.servers.RelOpClause

All Implemented Interfaces:

Clause, TopLevelClause

public class RelOpClause
extends AbstractClause
implements TopLevelClause

Represents a clause which compares subclauses, using one of the relative operators supported by the Operator class.

Author:

joew

See Also:

Operator, ClauseFactory

Field Summary

Fields

Modifier and Type	Field and Description
protected SubClause	lhs
protected int	operator
protected List	rhs
protected boolean	value

Fields inherited from class opendap.servers.AbstractClause

children, constant, defined

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	RelOpClause(int operator, SubClause lhs, List rhs) Creates a new RelOpClause.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	evaluate() Evaluates the clause, first calling evaluate() on any sub-clauses it contains.
SubClause	getLHS() Returns a SubClause representing the right-hand side of the comparison.
int	getOperator() Returns the type of comparison
List	getRHS() Returns a list of SubClauses representing the right-hand side of the comparison.
boolean	getValue() Returns the current value of the clause.
void	printConstraint(PrintWriter os) Prints the original string representation of this clause.

Methods inherited from class opendap.servers.AbstractClause

getChildren, isConstant, isDefined

Methods inherited from class java.lang.Object

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

Methods inherited from interface opendap.servers.Clause

getChildren, isConstant, isDefined

Field Detail

value

protected boolean value

operator

protected int operator

lhs

protected SubClause lhs

rhs

protected List rhs

Constructor Detail

RelOpClause

protected RelOpClause(int operator,
           SubClause lhs,
           List rhs)
               throws DAP2ServerSideException

Creates a new RelOpClause. If the lhs and all the elements of the rhs are constant, the RelOpClause will be flagged as constant, and evaluated immediately.

Parameters:

operator - The operator invoked by the clause

lhs - The left-hand side of the comparison.

rhs - A list of SubClauses representing the right-hand side of the comparison.

Throws:

DAP2ServerSideException - Thrown if the clause is constant, but the attempt to evaluate it fails.

Method Detail

getValue

public boolean getValue()

Description copied from interface: TopLevelClause

Returns the current value of the clause. The value of non-constant Clauses is undefined until the evaluate() method has been called.

Specified by:

getValue in interface TopLevelClause

evaluate

public boolean evaluate()
                 throws DAP2ServerSideException

Description copied from interface: TopLevelClause

Evaluates the clause, first calling evaluate() on any sub-clauses it contains. Implementations of this method should flag the clause as "defined" if the evaluation is successful.

Specified by:

evaluate in interface TopLevelClause

Throws:

DAP2ServerSideException - Thrown if the evaluation fails for any reason.

getLHS

public SubClause getLHS()

Returns a SubClause representing the right-hand side of the comparison.

getRHS

public List getRHS()

Returns a list of SubClauses representing the right-hand side of the comparison.

getOperator

public int getOperator()

Returns the type of comparison

See Also:

ExprParserConstants

printConstraint

public void printConstraint(PrintWriter os)

Prints the original string representation of this clause. For use in debugging.

Specified by:

printConstraint in interface Clause