/**
* Copyright 2014 Netflix, Inc.
*
* 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 rx.functions;
public class Functions {
/**
* Converts a {@link Func0} to a {@link FuncN} to allow heterogeneous handling of functions with different
* arities.
*
* @param f
* the {@code Func0} to convert
* @return a {@link FuncN} representation of {@code f}
*/
public static <R> FuncN<R> fromFunc(final Func0<? extends R> f) {
return new FuncN<R>() {
@Override
public R call(Object... args) {
if (args.length != 0) {
throw new RuntimeException("Func0 expecting 0 arguments.");
}
return f.call();
}
};
}
/**
* Converts a {@link Func1} to a {@link FuncN} to allow heterogeneous handling of functions with different
* arities.
*
* @param f
* the {@code Func1} to convert
* @return a {@link FuncN} representation of {@code f}
*/
public static <T0, R> FuncN<R> fromFunc(final Func1<? super T0, ? extends R> f) {
return new FuncN<R>() {
@SuppressWarnings("unchecked")
@Override
public R call(Object... args) {
if (args.length != 1) {
throw new RuntimeException("Func1 expecting 1 argument.");
}
return f.call((T0) args[0]);
}
};
}
/**
* Converts a {@link Func2} to a {@link FuncN} to allow heterogeneous handling of functions with different
* arities.
*
* @param f
* the {@code Func2} to convert
* @return a {@link FuncN} representation of {@code f}
*/
public static <T0, T1, R> FuncN<R> fromFunc(final Func2<? super T0, ? super T1, ? extends R> f) {
return new FuncN<R>() {
@SuppressWarnings("unchecked")
@Override
public R call(Object... args) {
if (args.length != 2) {
throw new RuntimeException("Func2 expecting 2 arguments.");
}
return f.call((T0) args[0], (T1) args[1]);
}
};
}
/**
* Converts a {@link Func3} to a {@link FuncN} to allow heterogeneous handling of functions with different
* arities.
*
* @param f
* the {@code Func3} to convert
* @return a {@link FuncN} representation of {@code f}
*/
public static <T0, T1, T2, R> FuncN<R> fromFunc(final Func3<? super T0, ? super T1, ? super T2, ? extends R> f) {
return new FuncN<R>() {
@SuppressWarnings("unchecked")
@Override
public R call(Object... args) {
if (args.length != 3) {
throw new RuntimeException("Func3 expecting 3 arguments.");
}
return f.call((T0) args[0], (T1) args[1], (T2) args[2]);
}
};
}
/**
* Converts a {@link Func4} to a {@link FuncN} to allow heterogeneous handling of functions with different
* arities.
*
* @param f
* the {@code Func4} to convert
* @return a {@link FuncN} representation of {@code f}
*/
public static <T0, T1, T2, T3, R> FuncN<R> fromFunc(final Func4<? super T0, ? super T1, ? super T2, ? super T3, ? extends R> f) {
return new FuncN<R>() {
@SuppressWarnings("unchecked")
@Override
public R call(Object... args) {
if (args.length != 4) {
throw new RuntimeException("Func4 expecting 4 arguments.");
}
return f.call((T0) args[0], (T1) args[1], (T2) args[2], (T3) args[3]);
}
};
}
/**
* Converts a {@link Func5} to a {@link FuncN} to allow heterogeneous handling of functions with different
* arities.
*
* @param f
* the {@code Func5} to convert
* @return a {@link FuncN} representation of {@code f}
*/
public static <T0, T1, T2, T3, T4, R> FuncN<R> fromFunc(final Func5<? super T0, ? super T1, ? super T2, ? super T3, ? super T4, ? extends R> f) {
return new FuncN<R>() {
@SuppressWarnings("unchecked")
@Override
public R call(Object... args) {
if (args.length != 5) {
throw new RuntimeException("Func5 expecting 5 arguments.");
}
return f.call((T0) args[0], (T1) args[1], (T2) args[2], (T3) args[3], (T4) args[4]);
}
};
}
/**
* Converts a {@link Func6} to a {@link FuncN} to allow heterogeneous handling of functions with different
* arities.
*
* @param f
* the {@code Func6} to convert
* @return a {@link FuncN} representation of {@code f}
*/
public static <T0, T1, T2, T3, T4, T5, R> FuncN<R> fromFunc(final Func6<? super T0, ? super T1, ? super T2, ? super T3, ? super T4, ? super T5, ? extends R> f) {
return new FuncN<R>() {
@SuppressWarnings("unchecked")
@Override
public R call(Object... args) {
if (args.length != 6) {
throw new RuntimeException("Func6 expecting 6 arguments.");
}
return f.call((T0) args[0], (T1) args[1], (T2) args[2], (T3) args[3], (T4) args[4], (T5) args[5]);
}
};
}
/**
* Converts a {@link Func7} to a {@link FuncN} to allow heterogeneous handling of functions with different
* arities.
*
* @param f
* the {@code Func7} to convert
* @return a {@link FuncN} representation of {@code f}
*/
public static <T0, T1, T2, T3, T4, T5, T6, R> FuncN<R> fromFunc(final Func7<? super T0, ? super T1, ? super T2, ? super T3, ? super T4, ? super T5, ? super T6, ? extends R> f) {
return new FuncN<R>() {
@SuppressWarnings("unchecked")
@Override
public R call(Object... args) {
if (args.length != 7) {
throw new RuntimeException("Func7 expecting 7 arguments.");
}
return f.call((T0) args[0], (T1) args[1], (T2) args[2], (T3) args[3], (T4) args[4], (T5) args[5], (T6) args[6]);
}
};
}
/**
* Converts a {@link Func8} to a {@link FuncN} to allow heterogeneous handling of functions with different
* arities.
*
* @param f
* the {@code Func8} to convert
* @return a {@link FuncN} representation of {@code f}
*/
public static <T0, T1, T2, T3, T4, T5, T6, T7, R> FuncN<R> fromFunc(final Func8<? super T0, ? super T1, ? super T2, ? super T3, ? super T4, ? super T5, ? super T6, ? super T7, ? extends R> f) {
return new FuncN<R>() {
@SuppressWarnings("unchecked")
@Override
public R call(Object... args) {
if (args.length != 8) {
throw new RuntimeException("Func8 expecting 8 arguments.");
}
return f.call((T0) args[0], (T1) args[1], (T2) args[2], (T3) args[3], (T4) args[4], (T5) args[5], (T6) args[6], (T7) args[7]);
}
};
}
/**
* Converts a {@link Func9} to a {@link FuncN} to allow heterogeneous handling of functions with different
* arities.
*
* @param f
* the {@code Func9} to convert
* @return a {@link FuncN} representation of {@code f}
*/
public static <T0, T1, T2, T3, T4, T5, T6, T7, T8, R> FuncN<R> fromFunc(final Func9<? super T0, ? super T1, ? super T2, ? super T3, ? super T4, ? super T5, ? super T6, ? super T7, ? super T8, ? extends R> f) {
return new FuncN<R>() {
@SuppressWarnings("unchecked")
@Override
public R call(Object... args) {
if (args.length != 9) {
throw new RuntimeException("Func9 expecting 9 arguments.");
}
return f.call((T0) args[0], (T1) args[1], (T2) args[2], (T3) args[3], (T4) args[4], (T5) args[5], (T6) args[6], (T7) args[7], (T8) args[8]);
}
};
}
/**
* Converts an {@link Action0} to a {@link FuncN} to allow heterogeneous handling of functions with
* different arities.
*
* @param f
* the {@code Action0} to convert
* @return a {@link FuncN} representation of {@code f}
*/
public static FuncN<Void> fromAction(final Action0 f) {
return new FuncN<Void>() {
@Override
public Void call(Object... args) {
if (args.length != 0) {
throw new RuntimeException("Action0 expecting 0 arguments.");
}
f.call();
return null;
}
};
}
/**
* Converts an {@link Action1} to a {@link FuncN} to allow heterogeneous handling of functions with
* different arities.
*
* @param f
* the {@code Action1} to convert
* @return a {@link FuncN} representation of {@code f}
*/
public static <T0> FuncN<Void> fromAction(final Action1<? super T0> f) {
return new FuncN<Void>() {
@SuppressWarnings("unchecked")
@Override
public Void call(Object... args) {
if (args.length != 1) {
throw new RuntimeException("Action1 expecting 1 argument.");
}
f.call((T0) args[0]);
return null;
}
};
}
/**
* Converts an {@link Action2} to a {@link FuncN} to allow heterogeneous handling of functions with
* different arities.
*
* @param f
* the {@code Action2} to convert
* @return a {@link FuncN} representation of {@code f}
*/
public static <T0, T1> FuncN<Void> fromAction(final Action2<? super T0, ? super T1> f) {
return new FuncN<Void>() {
@SuppressWarnings("unchecked")
@Override
public Void call(Object... args) {
if (args.length != 2) {
throw new RuntimeException("Action3 expecting 2 arguments.");
}
f.call((T0) args[0], (T1) args[1]);
return null;
}
};
}
/**
* Converts an {@link Action3} to a {@link FuncN} to allow heterogeneous handling of functions with
* different arities.
*
* @param f
* the {@code Action3} to convert
* @return a {@link FuncN} representation of {@code f}
*/
public static <T0, T1, T2> FuncN<Void> fromAction(final Action3<? super T0, ? super T1, ? super T2> f) {
return new FuncN<Void>() {
@SuppressWarnings("unchecked")
@Override
public Void call(Object... args) {
if (args.length != 3) {
throw new RuntimeException("Action3 expecting 3 arguments.");
}
f.call((T0) args[0], (T1) args[1], (T2) args[2]);
return null;
}
};
}
/**
* Constructs a predicate that returns true for each input for which the source predicate returns false, and
* vice versa.
*
* @param predicate
* the source predicate to negate
* @return a function that returns a Boolean that represents an inversion of the logical effect of
* {@code predicate}
*/
public static <T> Func1<T, Boolean> not(Func1<? super T, Boolean> predicate) {
return new Not<T>(predicate);
}
/**
* Returns a function that always returns {@code true}.
*
* @return a {@link Func1} that accepts an Object and returns the Boolean {@code true}
*/
public static <T> Func1<? super T, Boolean> alwaysTrue() {
return AlwaysTrue.INSTANCE;
}
/**
* Returns a function that always returns {@code false}.
*
* @return a {@link Func1} that accepts an Object and returns the Boolean {@code false}
*/
public static <T> Func1<? super T, Boolean> alwaysFalse() {
return AlwaysFalse.INSTANCE;
}
/**
* Returns a function that always returns the Object it is passed.
*
* @return a {@link Func1} that accepts an Object and returns the same Object
*/
public static <T> Func1<T, T> identity() {
return new Func1<T, T>() {
@Override
public T call(T o) {
return o;
}
};
}
private enum AlwaysTrue implements Func1<Object, Boolean> {
INSTANCE;
@Override
public Boolean call(Object o) {
return true;
}
}
private enum AlwaysFalse implements Func1<Object, Boolean> {
INSTANCE;
@Override
public Boolean call(Object o) {
return false;
}
}
/**
* Returns a function that merely returns {@code null}, without side effects.
*
* @return a function that returns {@code null}
*/
@SuppressWarnings("unchecked")
public static <T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, R> NullFunction<T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, R> returnNull() {
return (NullFunction<T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, R>) NULL_FUNCTION;
}
@SuppressWarnings("rawtypes")
private static final NullFunction NULL_FUNCTION = new NullFunction();
private static final class NullFunction<T0, T1, T2, T3, T4, T5, T6, T7, T8, T9, R> implements
Func0<R>,
Func1<T0, R>,
Func2<T0, T1, R>,
Func3<T0, T1, T2, R>,
Func4<T0, T1, T2, T3, R>,
Func5<T0, T1, T2, T3, T4, R>,
Func6<T0, T1, T2, T3, T4, T5, R>,
Func7<T0, T1, T2, T3, T4, T5, T6, R>,
Func8<T0, T1, T2, T3, T4, T5, T6, T7, R>,
Func9<T0, T1, T2, T3, T4, T5, T6, T7, T8, R>,
FuncN<R> {
@Override
public R call() {
return null;
}
@Override
public R call(T0 t1) {
return null;
}
@Override
public R call(T0 t1, T1 t2) {
return null;
}
@Override
public R call(T0 t1, T1 t2, T2 t3) {
return null;
}
@Override
public R call(T0 t1, T1 t2, T2 t3, T3 t4) {
return null;
}
@Override
public R call(T0 t1, T1 t2, T2 t3, T3 t4, T4 t5) {
return null;
}
@Override
public R call(T0 t1, T1 t2, T2 t3, T3 t4, T4 t5, T5 t6) {
return null;
}
@Override
public R call(T0 t1, T1 t2, T2 t3, T3 t4, T4 t5, T5 t6, T6 t7) {
return null;
}
@Override
public R call(T0 t1, T1 t2, T2 t3, T3 t4, T4 t5, T5 t6, T6 t7, T7 t8) {
return null;
}
@Override
public R call(T0 t1, T1 t2, T2 t3, T3 t4, T4 t5, T5 t6, T6 t7, T7 t8, T8 t9) {
return null;
}
@Override
public R call(Object... args) {
return null;
}
}
}