将番石榴范围转换为不同类型(Transform a Guava Range to a Different Type)

 如何将一种类型的给定Guava Range转换为另一种类型的范围。 
 
 我期待一种类似于Predicates.compose的compose方法。 以Integer和Long为例： 
 
Range<Integer> intRange = Range.compose(Range.atLeast(10l),integerFromLongFunction);
 
 我写了撰写方法： 
 
    public static <F extends Comparable<F>, T extends Comparable<T>> Range<T> compose(Range<F> range,
        Function<F, T> function) {
    Range<T> result;
    if (range.hasUpperBound() && range.hasLowerBound()) {
        T upperEndpoint = function.apply(range.upperEndpoint());
        T lowerEndpoint = function.apply(range.lowerEndpoint());
        result = Range.range(lowerEndpoint, range.lowerBoundType(), upperEndpoint, range.upperBoundType());
    } else if (range.hasUpperBound()) {
        result = Range.upTo(function.apply(range.upperEndpoint()), range.upperBoundType());
    } else if (range.hasLowerBound()) {
        result = Range.downTo(function.apply(range.lowerEndpoint()), range.lowerBoundType());
    } else {
        result = Range.all();
    }
    return result;
}
 
 单元测试： 
 
@Test
public void testLongRangeToInteger() {
    Integer inRange = 6;
    Integer outOfRange = 3;
    Range<Long> longRange = Range.atLeast(5l);
    assertTrue(longRange.apply(inRange.longValue()));
    assertFalse(longRange.apply(outOfRange.longValue()));

    Function<Long, Integer> function = integerFromLongFunction();
    Range<Integer> intRange = RangeExtended.compose(longRange, function);
    assertTrue(intRange.apply(inRange));
    assertFalse(intRange.apply(outOfRange));
}

public static Function<Long, Integer> integerFromLongFunction() {
    return new Function<Long, Integer>() {

        @Override
        public Integer apply(Long input) {
            return (input == null) ? null : input.intValue();
        }
    };
}
 
 我目前的愿望实际上是将Joda Duration转换为相应的millis，但为了简单起见，我在Long / Integer中编写了这个例子。 
 
 似乎Guava会有这个，但我找不到任何地方。 我正在使用v14，但是查看最新的v17 javadoc没有暴露任何东西。 

How do I transform a given Guava Range of one type to a range of another type. 
 
I expect a compose method similar to Predicates.compose. Take Integer and Long for example:
 
Range<Integer> intRange = Range.compose(Range.atLeast(10l),integerFromLongFunction);
 
I wrote the compose method:
 
    public static <F extends Comparable<F>, T extends Comparable<T>> Range<T> compose(Range<F> range,
        Function<F, T> function) {
    Range<T> result;
    if (range.hasUpperBound() && range.hasLowerBound()) {
        T upperEndpoint = function.apply(range.upperEndpoint());
        T lowerEndpoint = function.apply(range.lowerEndpoint());
        result = Range.range(lowerEndpoint, range.lowerBoundType(), upperEndpoint, range.upperBoundType());
    } else if (range.hasUpperBound()) {
        result = Range.upTo(function.apply(range.upperEndpoint()), range.upperBoundType());
    } else if (range.hasLowerBound()) {
        result = Range.downTo(function.apply(range.lowerEndpoint()), range.lowerBoundType());
    } else {
        result = Range.all();
    }
    return result;
}
 
with the Unit Test:
 
@Test
public void testLongRangeToInteger() {
    Integer inRange = 6;
    Integer outOfRange = 3;
    Range<Long> longRange = Range.atLeast(5l);
    assertTrue(longRange.apply(inRange.longValue()));
    assertFalse(longRange.apply(outOfRange.longValue()));

    Function<Long, Integer> function = integerFromLongFunction();
    Range<Integer> intRange = RangeExtended.compose(longRange, function);
    assertTrue(intRange.apply(inRange));
    assertFalse(intRange.apply(outOfRange));
}

public static Function<Long, Integer> integerFromLongFunction() {
    return new Function<Long, Integer>() {

        @Override
        public Integer apply(Long input) {
            return (input == null) ? null : input.intValue();
        }
    };
}
 
My current desire is actually to convert a Joda Duration to it's corresponding millis, but I wrote the example in Long/Integer for simplicity. 
 
It seems that Guava would have this, but I can't find anywhere. I'm using v14, but looking at the latest v17 javadoc didn't expose anything.

原文：https://stackoverflow.com/questions/24889243