/*
* Kodkod -- Copyright (c) 2005-present, Emina Torlak
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package kodkod.engine.bool;
/**
* A boolean constant, true or false. The integer
* label of the true and false constants are Integer.MAX_VALUE and -Integer.MAX_VALUE, respectively.
* The two boolean constants, TRUE and FALSE, are shared among all factories.
*
* @specfield value: boolean
* @invariant this.op = Operator.CONST
* @invariant value => Integer.MAX_VALUE, -Integer.MAX_VALUE
* @author Emina Torlak
*/
public final class BooleanConstant extends BooleanValue {
final int label;
public static final BooleanConstant TRUE = new BooleanConstant(true);
public static final BooleanConstant FALSE = new BooleanConstant(false);
/**
* Constructs a BooleanConstant that represent the given boolean
* value.
* @ensures value => this.label' = Integer.MAX_VALUE, this.label' = -Integer.MAX_VALUE
*/
private BooleanConstant(boolean value) {
this.label = (value ? Integer.MAX_VALUE : -Integer.MAX_VALUE);
}
/**
* Returns the negation of this value.
* @return c: BooleanConstant | [[c]] = ![[this]]
*/
@Override
BooleanValue negation() {
return this==TRUE ? FALSE : TRUE;
}
/**
* Returns the primitive boolean representation of this label.
* @return this.label == Integer.MAX_VALUE
*/
public boolean booleanValue() { return label > 0; }
/**
* Returns the BooleanConstant that represents the given boolean value.
* @return {c: BooleanConstant | value => c.label = Integer.MAX_VALUE, c.label = -Integer.MAX_VALUE }
*/
public static BooleanConstant constant(boolean value) {
return value ? TRUE : FALSE;
}
/**
* Returns the label for this value.
* @return this.label
*/
@Override
public int label() {
return label;
}
/**
* Returns a string representation of this boolean value.
* @return a string representation of this boolean value.
*/
public String toString() {
return label>0 ? "T" : "F";
}
/**
* Returns Operator.CONST.
* @return Operator.CONST
*/
@Override
public Operator op() {
return Operator.CONST;
}
}