net.sf.mmm.util.query.base.expression

Class ConstantExpression

java.lang.Object

net.sf.mmm.util.query.base.expression.ConstantExpression

All Implemented Interfaces:

Expression

public class ConstantExpression
extends Object
implements Expression

This is an implementation of Expression that is constant and will always evaluate to a static (fixed) value.

Since:

8.0.0

Author:

hohwille

See Also:

TRUE, FALSE, valueOf(boolean)

Field Summary

Fields

Modifier and Type	Field and Description
static ConstantExpression	FALSE ConstantExpression that always evaluates to false.
static ConstantExpression	TRUE ConstantExpression that always evaluates to true.

Constructor Summary

Constructors

Modifier	Constructor and Description
private	ConstantExpression() The constructor.

Method Summary

Modifier and Type	Method and Description
Expression	combine(Conjunction conjunction, Collection<Expression> expressions)
boolean	evaluate()
void	format(ExpressionFormatter formatter, Bracketing bracketing)
boolean	isConstant()
Expression	negate()
static ConstantExpression	valueOf(boolean value)

Methods inherited from class java.lang.Object

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

Methods inherited from interface net.sf.mmm.util.query.api.expression.Expression

and, combine, or

Field Detail

TRUE

public static final ConstantExpression TRUE

ConstantExpression that always evaluates to true.

FALSE

public static final ConstantExpression FALSE

ConstantExpression that always evaluates to false.

Constructor Detail

ConstantExpression

private ConstantExpression()

The constructor.

Method Detail

evaluate

public boolean evaluate()

Specified by:

evaluate in interface Expression

Returns:

true if the expression is fulfilled, false otherwise.

See Also:

Predicate.test(Object)

negate

public Expression negate()

Specified by:

negate in interface Expression

Returns:

the negation of this Expression.

combine

public Expression combine(Conjunction conjunction,
                          Collection<Expression> expressions)

Specified by:

combine in interface Expression

Parameters:

conjunction - the Conjunction.

expressions - the Collection of the Expressions to combine with this one.

Returns:

a new Expression combining this Expression with the given Expressions using the given Conjunction.

isConstant

public boolean isConstant()

Specified by:

isConstant in interface Expression

Returns:

true if this is a constant expression that evaluates to a fixed result, false otherwise.

valueOf

public static ConstantExpression valueOf(boolean value)

Parameters:

value - the boolean value the requested ConstantExpression should evaluate to.

Returns:

TRUE if value is true, FALSE otherwise.

format

public void format(ExpressionFormatter formatter,
                   Bracketing bracketing)

Specified by:

format in interface Expression

Parameters:

formatter - the ExpressionFormatter where to append this Expression.

bracketing - the Bracketing.