Predicates.forFunction(Function<T, Boolean>) about google-collections

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It does seem like a gap that we don't have that.

And do we not have a method that composes a Function and a Predicate into a
Predicate?  I'm surprised, I thought we had that.

Original comment by [email protected] on 23 Oct 2007 at 7:15

• Added labels: Type-Enhancement
• Removed labels: Type-Defect

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Original comment by [email protected] on 27 May 2008 at 6:29

• Added labels: 1.0

[GoogleCodeExporter]

I built an implementation that mirrors the Functions.forPredicate method:

    public static <T> Predicate<T> forFunction(Function<T, Boolean> function) {
        return new FunctionPredicate<T>(function);
    }

    private static class FunctionPredicate<T> implements Predicate<T>, Serializable {
        private final Function<T, Boolean> function;

        private FunctionPredicate(Function<T, Boolean> function) {
            this.function = checkNotNull(function);
        }

        @Override
        public boolean apply(T t) {
            return function.apply(t);
        }

        @Override
        public boolean equals(Object obj) {
            if (obj instanceof FunctionPredicate) {
                FunctionPredicate<?> that = (FunctionPredicate<?>) obj;
                return function.equals(that.function);
            }
            return false;
        }

        @Override
        public int hashCode() {
            return function.hashCode();
        }

        @Override
        public String toString() {
            return "forFunction(" + function + ")";
        }

        private static final long serialVersionUID = 0;
    }

Original comment by seantparsons on 12 Mar 2009 at 10:24

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Original comment by [email protected] on 18 Mar 2009 at 2:20

• Removed labels: 1.0

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Original comment by [email protected] on 17 Sep 2009 at 6:02

• Added labels: Milestone-Post1.0

[GoogleCodeExporter]

This issue has been moved to the Guava project (keeping the same id number). 
Simply replace 'google-collections' with 'guava-libraries' in your address 
bar and it should take you there.

Original comment by [email protected] on 5 Jan 2010 at 11:09

• Changed state: Moved