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com.strobel.core.Predicates Maven / Gradle / Ivy
/*
* Predicates.java
*
* Copyright (c) 2013 Mike Strobel
*
* This source code is subject to terms and conditions of the Apache License, Version 2.0.
* A copy of the license can be found in the License.html file at the root of this distribution.
* By using this source code in any fashion, you are agreeing to be bound by the terms of the
* Apache License, Version 2.0.
*
* You must not remove this notice, or any other, from this software.
*/
package com.strobel.core;
import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.Objects;
/**
* Static utility methods pertaining to {@code Predicate} instances.
*
* All of the returned predicates are serializable if given serializable
* parameters.
*/
@SuppressWarnings("unchecked")
public final class Predicates {
/**
* a predicate that evaluates to {@code true} if the reference
* being tested is {@code null}.
*/
public static final Predicate IS_NULL = new Predicate() {
@Override
public boolean test(final Object o) {
return o == null;
}
};
/**
* a predicate that evaluates to {@code true} if the reference
* being tested is not {@code null}.
*/
public static final Predicate NON_NULL = new Predicate() {
@Override
public boolean test(final Object o) {
return o != null;
}
};
/**
* a predicate who's result is always {@code false}.
*/
public static final Predicate FALSE = new Predicate() {
@Override
public boolean test(final Object o) {
return false;
}
};
/**
* a predicate who's result is always {@code true}.
*/
public static final Predicate TRUE = new Predicate() {
@Override
public boolean test(final Object o) {
return true;
}
};
/**
* singleton utils
*/
private Predicates() {
throw new AssertionError("No instances!");
}
/**
* Returns a predicate that evaluates to {@code true} if the reference
* being tested is {@code null}.
*
* @return a predicate that evaluates to {@code true} if the reference
* being tested is {@code null}
*/
public static Predicate isNull() {
return (Predicate) IS_NULL;
}
/**
* Returns a predicate that evaluates to {@code true} if the reference
* being tested is non-{@code null}.
*
* @return a predicate that evaluates to {@code true} if the reference
* being tested is is non-{@code null}
*/
public static Predicate nonNull() {
return (Predicate) NON_NULL;
}
/**
* Returns a predicate who's result is always {@code false}.
*
* @return a predicate who's result is always {@code false}.
*/
public static Predicate alwaysFalse() {
return (Predicate) FALSE;
}
/**
* Returns a predicate who's result is always {@code true}.
*
* @return a predicate who's result is always {@code true}.
*/
public static Predicate alwaysTrue() {
return (Predicate) TRUE;
}
/**
* Returns a predicate that evaluates to {@code true} if the object being
* tested is an instance of the provided class. If the object being tested
* is {@code null} this predicate evaluates to {@code false}.
*
* @param clazz The target class to be matched by the predicate.
* @return a predicate that evaluates to {@code true} if the object being
* tested is an instance of the provided class
*/
public static Predicate instanceOf(final Class clazz) {
return new Predicate() {
@Override
public boolean test(final T o) {
return clazz.isInstance(o);
}
};
}
/**
* Returns a predicate that who's result is {@code target == object}.
*
* @param the type of predicate values.
* @param target The target value to be compared for identity equality.
* @return a predicate that who's result is {@code target == object}
*/
public static Predicate isSame(final T target) {
return new Predicate() {
@Override
public boolean test(final T t) {
return t == target;
}
};
}
/**
* Returns a predicate who's result matches
* {@code Objects.equals(target, t)}.
*
* @param the type of predicate values.
* @param target The target value to be compared for equality.
* @return a predicate who's result matches {@code Objects.equals(target, t)}
*/
public static Predicate isEqual(final T target) {
if (null == target)
return Predicates.isNull();
return new Predicate() {
@Override
public boolean test(final T t) {
return target.equals(t);
}
};
}
/**
* Creates a predicate that evaluates to {@code true} if the tested object
* is a member of the provided collection. The collection is not defensively
* copied, so changes to it will alter the behavior of the predicate.
*
* @param Type of predicate values.
* @param target the collection against which objects will be tested.
* @return a predicate that evaluates to {@code true} if the tested object
* is a member of the provided collection. The collection is not defensively
* copied, so changes to it will alter the behavior of the predicate.
*/
public static Predicate contains(final Collection target) {
return new Predicate() {
@Override
public boolean test(final T t) {
return target.contains(t);
}
};
}
/**
* Creates a predicate that evaluates to {@code true} if the tested object
* is a key in the provided map. The map is not defensively copied, so changes
* to it will alter the behavior of the predicate.
*
* @param Type of predicate values.
* @param target the map against which objects will be tested.
* @return a predicate that evaluates to {@code true} if the tested object
* is a key in the provided map. The map is not defensively copied, so changes
* to it will alter the behavior of the predicate.
*/
public static Predicate containsKey(final Map target) {
return new Predicate() {
@Override
public boolean test(final T t) {
return target.containsKey(t);
}
};
}
/**
* Returns a predicate that evaluates to {@code true} if the provided
* predicate evaluates to {@code false}
*
* @param the type of values evaluated by the predicate.
* @param predicate The predicate to be evaluated.
* @return A predicate who's result is the logical inverse of the provided
* predicate.
*/
public static > Predicate negate(final P predicate) {
return new Predicate() {
@Override
public boolean test(final T t) {
return !predicate.test(t);
}
};
}
/**
* Returns a predicate that evaluates to {@code true} if all of the
* component predicates evaluate to {@code true}. The components are
* evaluated in order, and evaluation will terminate upon the first
* {@code false} predicate.
*
* @param the type of values evaluated by the predicates.
* @param first initial component predicate to be evaluated.
* @param second additional component predicate to be evaluated.
* @return A predicate who's result is {@code true} iff all component
* predicates are {@code true}.
*/
public static > Predicate and(final Predicate first, final P second) {
if(first != null && first == second) {
return first;
}
Objects.requireNonNull(first);
Objects.requireNonNull(second);
return new Predicate() {
@Override
public boolean test(final T t) {
//noinspection ConstantConditions
return first.test(t) && second.test(t);
}
};
}
/**
* Returns a predicate that evaluates to {@code true} if all of the
* component predicates evaluate to {@code true}. The components are
* evaluated in order, and evaluation will end upon the first
* {@code false} predicate.
*
* @param the type of values evaluated by the predicates.
* @param components The predicates to be evaluated.
* @return A predicate who's result is {@code true} iff all component
* predicates are {@code true}.
*/
public static > Predicate and(final Iterable components) {
final List
predicates = safeCopyOf(components);
if(predicates.isEmpty()) {
throw new IllegalArgumentException("no predicates");
}
return new Predicate() {
@Override
public boolean test(final T t) {
for (final P predicate : predicates) {
if (!predicate.test(t)) {
return false;
}
}
return true;
}
};
}
/**
* Returns a predicate that evaluates to {@code true} if all of the
* component predicates evaluate to {@code true}. The components are
* evaluated in order, and evaluation will end upon the first
* {@code false} predicate.
*
* @param the type of values evaluated by the predicates.
* @param components The predicates to be evaluated.
* @return A predicate who's result is {@code true} iff all component
* predicates are {@code true}.
*/
static > Predicate and(final P first, final Iterable components) {
final List
predicates = safeCopyOf(first, components);
return new Predicate() {
@Override
public boolean test(final T t) {
for (final P predicate : predicates) {
if (!predicate.test(t)) {
return false;
}
}
return true;
}
};
}
/**
* Returns a predicate that evaluates to {@code true} if all of the
* component predicates evaluate to {@code true}. The components are
* evaluated in order, and evaluation will end upon the first
* {@code false} predicate.
*
* @param the type of values evaluated by the predicates.
* @param components The predicates to be evaluated. A copy is made of the
* components.
* @return A predicate who's result is {@code true} iff all component
* predicates are {@code true}.
*/
@SafeVarargs
public static > Predicate and(final P... components) {
final P[] predicates = safeCopyOf(components);
if(0 == predicates.length) {
throw new IllegalArgumentException("no predicates");
}
return new Predicate() {
@Override
public boolean test(final T t) {
for (final P predicate : predicates) {
if (!predicate.test(t)) {
return false;
}
}
return true;
}
};
}
/**
* Returns a predicate that evaluates to {@code true} if all of the
* component predicates evaluate to {@code true}. The components are
* evaluated in order, and evaluation will end upon the first
* {@code false} predicate.
*
* @param the type of values evaluated by the predicates.
* @param first first predicate to be evaluated.
* @param components The predicates to be evaluated. A copy is made of the
* components.
* @return A predicate who's result is {@code true} iff all component
* predicates are {@code true}.
*/
@SafeVarargs
static > Predicate and(final P first, final P... components) {
final P[] predicates = safeCopyOf(first, components);
if(0 == predicates.length) {
throw new IllegalArgumentException("no predicates");
}
return new Predicate() {
@Override
public boolean test(final T t) {
for (final P predicate : predicates) {
if (!predicate.test(t)) {
return false;
}
}
return true;
}
};
}
/**
* Returns a predicate that evaluates to {@code true} if any of the
* component predicates evaluate to {@code true}. The components are
* evaluated in order, and evaluation will end upon the first
* {@code true} predicate.
*
* @param the type of values evaluated by the predicates.
* @param first initial component predicate to be evaluated.
* @param second additional component predicate to be evaluated.
* @return A predicate who's result is {@code true} if any component
* predicate's result is {@code true}.
*/
public static > Predicate or(final Predicate first, final P second) {
if(first != null && first == second) {
return first;
}
Objects.requireNonNull(first);
Objects.requireNonNull(second);
return new Predicate() {
@Override
public boolean test(final T t) {
//noinspection ConstantConditions
return first.test(t) || second.test(t);
}
};
}
/**
* Returns a predicate that evaluates to {@code true} if any of the
* component predicates evaluate to {@code true}. The components are
* evaluated in order, and evaluation will end upon the first
* {@code true} predicate.
*
* @param the type of values evaluated by the predicates.
* @param components The predicates to be evaluated. A copy is made of the
* components.
* @return A predicate who's result is {@code true} if any component
* predicate's result is {@code true}.
*/
public static > Predicate or(final Iterable components) {
final List
predicates = safeCopyOf(components);
if(predicates.isEmpty()) {
throw new IllegalArgumentException("no predicates");
}
return new Predicate() {
@Override
public boolean test(final T t) {
for (final P predicate : predicates) {
if (predicate.test(t)) {
return true;
}
}
return false;
}
};
}
/**
* Returns a predicate that evaluates to {@code true} if any of the
* component predicates evaluate to {@code true}. The components are
* evaluated in order, and evaluation will end upon the first
* {@code true} predicate.
*
* @param the type of values evaluated by the predicates.
* @param components The predicates to be evaluated. A copy is made of the
* components.
* @return A predicate who's result is {@code true} if any component
* predicate's result is {@code true}.
*/
static > Predicate or(final P first, final Iterable components) {
final List
predicates = safeCopyOf(first, components);
return new Predicate() {
@Override
public boolean test(final T t) {
for (final P predicate : predicates) {
if (predicate.test(t)) {
return true;
}
}
return false;
}
};
}
/**
* Returns a predicate that evaluates to {@code true} if any of the
* component predicates evaluate to {@code true}. The components are
* evaluated in order, and evaluation will terminate upon the first
* {@code true} predicate.
*
* @param the type of values evaluated by the predicates.
* @param components The predicates to be evaluated. A copy is made of the
* components.
* @return A predicate who's result is {@code true} if any component
* predicate's result is {@code true}.
*/
@SafeVarargs
public static > Predicate or(final P... components) {
final P[] predicates = safeCopyOf(components);
if(0 == predicates.length) {
throw new IllegalArgumentException("no predicates");
}
return new Predicate() {
@Override
public boolean test(final T t) {
for (final P predicate : predicates) {
if (predicate.test(t)) {
return true;
}
}
return false;
}
};
}
/**
* Returns a predicate that evaluates to {@code true} if any of the
* component predicates evaluate to {@code true}. The components are
* evaluated in order, and evaluation will terminate upon the first
* {@code true} predicate.
*
* @param the type of values evaluated by the predicates.
* @param components The predicates to be evaluated. A copy is made of the
* components.
* @return A predicate who's result is {@code true} if any component
* predicate's result is {@code true}.
*/
@SafeVarargs
static > Predicate or(final Predicate first, final P... components) {
final P[] predicates = safeCopyOf((P) first, components);
return new Predicate() {
@Override
public boolean test(final T t) {
for (final P predicate : predicates) {
if (predicate.test(t)) {
return true;
}
}
return false;
}
};
}
/**
* Returns a predicate that evaluates to {@code true} if all or none of the
* component predicates evaluate to {@code true}. The components are
* evaluated in order, and evaluation will end if a predicate result
* fails to match the first predicate's result.
*
* @param the type of values evaluated by the predicates.
* @param first initial component predicate to be evaluated.
* @param second additional component predicate to be evaluated.
* @return a predicate that evaluates to {@code true} if all or none of the
* component predicates evaluate to {@code true}
*/
public static > Predicate xor(final Predicate first, final P second) {
if(null != first && first == second) {
return alwaysFalse();
}
Objects.requireNonNull(first);
Objects.requireNonNull(second);
return new Predicate() {
@Override
public boolean test(final T t) {
//noinspection ConstantConditions
return first.test(t) ^ second.test(t);
}
};
}
/**
* Returns a predicate that evaluates to {@code false} if all or none of the
* component predicates evaluate to {@code true}. The components are
* evaluated in order, and evaluation will end if a predicate result
* fails to match the first predicate's result.
*
* @param the type of values evaluated by the predicates.
* @param components The predicates to be evaluated. A copy is made of the
* components.
* @return a predicate that evaluates to {@code false} if all or none of the
* component predicates evaluate to {@code true}
*/
public static > Predicate xor(final Iterable components) {
final List
predicates = safeCopyOf(components);
if(predicates.isEmpty()) {
throw new IllegalArgumentException("no predicates");
}
return new Predicate() {
@Override
public boolean test(final T t) {
Boolean initial = null;
for (final P predicate : predicates) {
if (null == initial) {
initial = predicate.test(t);
}
else {
if (!(initial ^ predicate.test(t))) {
return true;
}
}
}
return false;
}
};
}
/**
* Returns a predicate that evaluates to {@code false} if all or none of the
* component predicates evaluate to {@code true}. The components are
* evaluated in order, and evaluation will terminate if a predicate result
* fails to match the first predicate's result.
*
* @param the type of values evaluated by the predicates.
* @param components The predicates to be evaluated. A copy is made of the
* components.
* @return a predicate that evaluates to {@code false} if all or none of the
* component predicates evaluate to {@code true}
*/
@SafeVarargs
public static > Predicate xor(final P... components) {
final P[] predicates = safeCopyOf(components);
if(0 == predicates.length) {
throw new IllegalArgumentException("no predicates");
}
return new Predicate() {
@Override
public boolean test(final T t) {
Boolean initial = null;
for (final P predicate : predicates) {
if (null == initial) {
initial = predicate.test(t);
}
else {
if (!(initial ^ predicate.test(t))) {
return true;
}
}
}
return false;
}
};
}
/**
* Returns a predicate that evaluates to {@code false} if all or none of the
* component predicates evaluate to {@code true}. The components are
* evaluated in order, and evaluation will end if a predicate result
* fails to match the first predicate's result.
*
* @param the type of values evaluated by the predicates.
* @param components The predicates to be evaluated. A copy is made of the
* components.
* @return a predicate that evaluates to {@code false} if all or none of the
* component predicates evaluate to {@code true}
*/
@SafeVarargs
static > Predicate xor(final Predicate first, final P... components) {
final P[] predicates = safeCopyOf((P) first, components);
return new Predicate() {
@Override
public boolean test(final T t) {
Boolean initial = null;
for (final P predicate : predicates) {
if (null == initial) {
initial = predicate.test(t);
}
else {
if (!(initial ^ predicate.test(t))) {
return true;
}
}
}
return false;
}
};
}
/**
* Returns a predicate that evaluates to {@code false} if all or none of the
* component predicates evaluate to {@code true}. The components are
* evaluated in order, and evaluation will end if a predicate result
* fails to match the first predicate's result.
*
* @param the type of values evaluated by the predicates.
* @param components The predicates to be evaluated. A copy is made of the
* components.
* @return a predicate that evaluates to {@code false} if all or none of the
* component predicates evaluate to {@code true}
*/
static > Predicate xor(final Predicate first, final Iterable components) {
final List
predicates = safeCopyOf((P) first, components);
return new Predicate() {
@Override
public boolean test(final T t) {
Boolean initial = null;
for (final P predicate : predicates) {
if (null == initial) {
initial = predicate.test(t);
}
else {
if (!(initial ^ predicate.test(t))) {
return true;
}
}
}
return false;
}
};
}
@SafeVarargs
private static T[] safeCopyOf(final T... array) {
final T[] copy = Arrays.copyOf(array, array.length);
for(final T each : copy) {
Objects.requireNonNull(each);
}
return copy;
}
@SafeVarargs
private static T[] safeCopyOf(final T first, final T... array) {
final T[] copy = (T[]) Array.newInstance(array.getClass().getComponentType(), array.length + 1);
copy[0] = Objects.requireNonNull(first);
System.arraycopy(array, 0, copy, 1, array.length);
for(final T each : copy) {
Objects.requireNonNull(each);
}
return copy;
}
private static List safeCopyOf(final T first, final Iterable iterable) {
final ArrayList list = new ArrayList<>();
list.add(Objects.requireNonNull(first));
for (final T element : iterable) {
list.add(Objects.requireNonNull(element));
}
return list;
}
private static List safeCopyOf(final Iterable iterable) {
final ArrayList list = new ArrayList<>();
for (final T element : iterable) {
list.add(Objects.requireNonNull(element));
}
return list;
}
}
