org.osgl

Class Lang.Predicate<T>

java.lang.Object

org.osgl.Lang.FuncBase

org.osgl.Lang.F1<T,Boolean>

org.osgl.Lang.Predicate<T>

All Implemented Interfaces:

Lang.Bijection<T,Boolean>, Lang.Func1<T,Boolean>, Lang.Function<T,Boolean>, Lang.MultiplicableFunction<T,Boolean>

Enclosing class:

Lang

public abstract static class Lang.Predicate<T>
extends Lang.F1<T,Boolean>

Predicate is a predefined Function<Boolean, T> typed function with a set of utilities dealing with boolean operations. This is often known as Predicate

Note in user application, it should NOT assume an argument is of Predicate typed function, instead the argument should always be declared as Function<Boolean T>:

  // bad way  void foo(Predicate<MyData> predicate) {  …  }  // good way  void foo(Function<Boolean, MyData> predicate) {  Predicate<MyData> p = predicate(predicate);  …  } 

Since:

0.2

Constructor Summary

Constructors

Constructor and Description
Predicate()

Method Summary

Modifier and Type	Method and Description
Lang.Predicate<T>	and(Lang.Function<? super T,Boolean>... predicates) Return an Predicate predicate from a list of Function<Boolean, T> with AND operation.
Boolean	apply(T t) Apply this function to <T> type parameter.
<R> Lang.F1<T,Lang.Option<R>>	elseThen(Lang.Function<? super T,R> func)
<R> Lang.F1<T,Lang.Option<R>>	ifThen(Lang.Function<? super T,R> func)
Lang.Predicate<T>	negate() Returns a negate function of this
static <T> Lang.Predicate<T>	negate(Lang.Function<T,Boolean> predicate)
Lang.Predicate<T>	or(Lang.Function<? super T,Boolean>... predicates) Return an Predicate predicate from a list of Function<Boolean, T> with OR operation.
abstract boolean	test(T t) Sub class to implement this method to test on the supplied elements

Methods inherited from class org.osgl.Lang.F1

andThen, andThen, applyOrElse, compose, compose, compose, compose, compose, compose, curry, invert, lift, orElse, times

Methods inherited from class org.osgl.Lang.FuncBase

breakOut

Methods inherited from class java.lang.Object

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

Constructor Detail

Predicate

public Predicate()

Method Detail

apply

public final Boolean apply(T t)

Description copied from interface: Lang.Function

Apply this function to <T> type parameter.

In case implementing a partial function, it can throw out an NotAppliedException if the function is not defined for the given parameter(s)

Parameters:

t - the argument

Returns:

U type result

test

public abstract boolean test(T t)

Sub class to implement this method to test on the supplied elements

Parameters:

t - the element to be test

Returns:

true or false depends on the implementation

negate

public Lang.Predicate<T> negate()

Returns a negate function of this

Returns:

the negate function

and

public Lang.Predicate<T> and(Lang.Function<? super T,Boolean>... predicates)

Return an Predicate predicate from a list of Function<Boolean, T> with AND operation. For any T t to be tested, if any specified predicates must returns false on it, the resulting predicate will return false.

Parameters:

predicates - the predicate function array

Returns:

a function that returns true only when all functions in predicates returns true on a given argument

Since:

0.2

or

public Lang.Predicate<T> or(Lang.Function<? super T,Boolean>... predicates)

Return an Predicate predicate from a list of Function<Boolean, T> with OR operation. For any T t to be tested, if any specified predicates must returns true on it, the resulting predicate will return true.

Parameters:

predicates - the predicate functions

Returns:

a function returns true if any one of the predicate functions returns true on a given argument

Since:

0.2

ifThen

public <R> Lang.F1<T,Lang.Option<R>> ifThen(Lang.Function<? super T,R> func)

elseThen

public <R> Lang.F1<T,Lang.Option<R>> elseThen(Lang.Function<? super T,R> func)

negate

public static <T> Lang.Predicate<T> negate(Lang.Function<T,Boolean> predicate)