FunctionsBoolean.java
/*
* Copyright 2016-2018 Federico Vera
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package net.objecthunter.exp4j.extras;
import net.objecthunter.exp4j.function.Function;
import net.objecthunter.exp4j.operator.Operator;
import net.objecthunter.exp4j.operator.Operators;
import java.io.Serial;
import static net.objecthunter.exp4j.operator.Operator.*;
/**
* This class contains a set of commonly used boolean functions and constants.
*
* <p>The boolean value rules are the same the we use in the operators:</p><ol>
* <li>if the absolute value is less than {@link Operator#BOOLEAN_THRESHOLD} it
* will be considered {@code false}.</li>
* <li>if the absolute value is bigger or equal than
* {@link Operator#BOOLEAN_THRESHOLD} it will be considered {@code true}</li>
* <li>the recommended approach is to use functions or operators that return
* boolean values, like the comparison operators or the
* {@link FunctionsBoolean#TRUE} and {@link FunctionsBoolean#FALSE} constants
* </li>
* <li>the {@link FunctionsBoolean#TRUE} constant will always return 1.0 and
* {@link FunctionsBoolean#FALSE} will always return 0.0
* </ol>
*
* @see Operator#BOOLEAN_THRESHOLD
* @see OperatorsComparison
* @author Federico Vera {@literal <[email protected]>}
* @since 0.6-riddler
*/
public final class FunctionsBoolean {
/**
* Logical function {@code NOT}
* <pre>
* <b>a</b> | <b>~a</b>
* --+--
* 0 | <i>1</i>
* 1 | <i>0</i>
* </pre>
* @see Operators#NOT
* @since 0.6-riddler
*/
public static final Function NOT = new Not();
/**
* Logical function {@code AND}
* <pre>
* <b>a</b> | <b>b</b> | <b>a&b</b>
* --+---+----
* 0 | 0 | <i>0</i>
* 0 | 1 | <i>0</i>
* 1 | 0 | <i>0</i>
* 1 | 1 | <i>1</i>
* </pre>
* @see Operators#AND
* @since 0.6-riddler
*/
public static final Function AND = new And();
/**
* Logical function {@code OR}
* <pre>
* <b>a</b> | <b>b</b> | <b>a|b</b>
* --+---+----
* 0 | 0 | <i>0</i>
* 0 | 1 | <i>1</i>
* 1 | 0 | <i>1</i>
* 1 | 1 | <i>1</i>
* </pre>
* @see Operators#OR
* @since 0.6-riddler
*/
public static final Function OR = new Or();
/**
* Logical function {@code XOR}
* <pre>
* <b>a</b> | <b>b</b> | <b>a^b</b>
* --+---+----
* 0 | 0 | <i>0</i>
* 0 | 1 | <i>1</i>
* 1 | 0 | <i>1</i>
* 1 | 1 | <i>0</i>
* </pre>
* @since 0.6-riddler
*/
public static final Function XOR = new Xor();
/**
* Logical function {@code NAND}
* <pre>
* <b>a</b> | <b>b</b> | <b>!(a&b)</b>
* --+---+-------
* 0 | 0 | <i>1</i>
* 0 | 1 | <i>1</i>
* 1 | 0 | <i>1</i>
* 1 | 1 | <i>0</i>
* </pre>
* @since 0.6-riddler
*/
public static final Function NAND = new Nand();
/**
* Logical function {@code NOR}
* <pre>
* <b>a</b> | <b>b</b> | <b>!(a|b)</b>
* --+---+-------
* 0 | 0 | <i>1</i>
* 0 | 1 | <i>0</i>
* 1 | 0 | <i>0</i>
* 1 | 1 | <i>1</i>
* </pre>
* @since 0.6-riddler
*/
public static final Function NOR = new Nor();
/**
* Logical function {@code XNOR}
* <pre>
* <b>a</b> | <b>b</b> | <b>!(a^b)</b>
* --+---+-------
* 0 | 0 | <i>1</i>
* 0 | 1 | <i>0</i>
* 1 | 0 | <i>0</i>
* 1 | 1 | <i>1</i>
* </pre>
* @since 0.6-riddler
*/
public static final Function XNOR = new Xnor();
/**
* Boolean value {@code false} -> {@code 0.0}.
* @since 0.6-riddler
*/
public static final Function FALSE = new False();
/**
* Boolean value {@code true} -> {@code 1.0}.
* @since 0.6-riddler
*/
public static final Function TRUE = new True();
/**
* Array with all the available functions
*
* @return {@link Function} array
* @see FunctionsBoolean#getFunction(String)
* @see FunctionsBoolean#NOT
* @see FunctionsBoolean#AND
* @see FunctionsBoolean#OR
* @see FunctionsBoolean#XOR
* @see FunctionsBoolean#NAND
* @see FunctionsBoolean#NOR
* @see FunctionsBoolean#XNOR
* @see FunctionsBoolean#FALSE
* @see FunctionsBoolean#TRUE
*/
public static Function[] getFunctions() {
return new Function[] {NOT, AND, OR, XOR, NAND, NOR, XNOR, FALSE, TRUE};
}
/**
* Get the function for a given name
* @param name the name of the function
* @return a Function instance
* @see FunctionsBoolean#getFunctions()
* @see FunctionsBoolean#NOT
* @see FunctionsBoolean#AND
* @see FunctionsBoolean#OR
* @see FunctionsBoolean#XOR
* @see FunctionsBoolean#NAND
* @see FunctionsBoolean#NOR
* @see FunctionsBoolean#XNOR
* @see FunctionsBoolean#FALSE
* @see FunctionsBoolean#TRUE
*/
public static Function getFunction(final String name) {
return switch (name) {
case "not" -> NOT;
case "and" -> AND;
case "or" -> OR;
case "xor" -> XOR;
case "nand" -> NAND;
case "nor" -> NOR;
case "xnor" -> XNOR;
case "false" -> FALSE;
case "true" -> TRUE;
default -> null;
};
}
private FunctionsBoolean() {
// Don't let anyone initialize this class
}
private static final class Not extends Function {
@Serial
private static final long serialVersionUID = 5548754689040328198L;
Not() { super("not", 1); }
@Override
public double apply(double... args) {
return (Math.abs(args[0]) >= BOOLEAN_THRESHOLD) ? 0 : 1;
}
}
private static final class And extends Function {
@Serial
private static final long serialVersionUID = 610825426695578129L;
And() { super("and", 2); }
@Override
public double apply(double... args) {
final boolean a = Math.abs(args[0]) >= BOOLEAN_THRESHOLD;
final boolean b = Math.abs(args[1]) >= BOOLEAN_THRESHOLD;
return (a & b) ? 1 : 0;
}
}
private static final class Or extends Function {
@Serial
private static final long serialVersionUID = -6688682627798315082L;
Or() { super("or", 2); }
@Override
public double apply(double... args) {
final boolean a = Math.abs(args[0]) >= BOOLEAN_THRESHOLD;
final boolean b = Math.abs(args[1]) >= BOOLEAN_THRESHOLD;
return (a | b) ? 1 : 0;
}
}
private static final class Xor extends Function {
@Serial
private static final long serialVersionUID = 9162299011098408477L;
Xor() { super("xor", 2); }
@Override
public double apply(double... args) {
final boolean a = Math.abs(args[0]) >= BOOLEAN_THRESHOLD;
final boolean b = Math.abs(args[1]) >= BOOLEAN_THRESHOLD;
return (a ^ b) ? 1 : 0;
}
}
private static final class Nand extends Function {
@Serial
private static final long serialVersionUID = -5696690796736889084L;
Nand() { super("nand", 2); }
@Override
public double apply(double... args) {
final boolean a = Math.abs(args[0]) >= BOOLEAN_THRESHOLD;
final boolean b = Math.abs(args[1]) >= BOOLEAN_THRESHOLD;
return (a & b) ? 0 : 1;
}
}
private static final class Nor extends Function {
@Serial
private static final long serialVersionUID = 7443039549525626711L;
Nor() { super("nor", 2); }
@Override
public double apply(double... args) {
final boolean a = Math.abs(args[0]) >= BOOLEAN_THRESHOLD;
final boolean b = Math.abs(args[1]) >= BOOLEAN_THRESHOLD;
return (a | b) ? 0 : 1;
}
}
private static final class Xnor extends Function {
@Serial
private static final long serialVersionUID = -7602049045810375102L;
Xnor() { super("xnor", 2); }
@Override
public double apply(double... args) {
final boolean a = Math.abs(args[0]) >= BOOLEAN_THRESHOLD;
final boolean b = Math.abs(args[1]) >= BOOLEAN_THRESHOLD;
return (a ^ b) ? 0 : 1;
}
}
private static final class False extends Function {
@Serial
private static final long serialVersionUID = 8888653636237556280L;
False() { super("false", 0); }
@Override
public double apply(double... args) {
return 0;
}
}
private static final class True extends Function {
@Serial
private static final long serialVersionUID = -5934349523714582684L;
True() { super("true", 0); }
@Override
public double apply(double... args) {
return 1;
}
}
}