Equivalent of Maps.uniqueIndex?

[Brian Goetz]

Stuff is in flux, apologies.

In the current tip, Tabulators became Accumulators, and we have these 
versions which take a T->U, plus optionally a Supplier<Map> and a merge 
function (the default throws on duplicates.)

     public static <T, U> Accumulator<T, Map<T,U>> mappedTo(Function<? 
super T, ? extends U> mapper) {
         return mappedTo(mapper, (BinaryOperator<U>) THROWING_MERGER);
     }

     public static <T, U> Accumulator<T, Map<T,U>> mappedTo(Function<? 
super T, ? extends U> mapper,
 
BinaryOperator<U> mergeFunction) {
         return mappedTo(mapper, mergeFunction, (Supplier<Map<T,U>>) 
HashMap::new);
     }

     public static <T, U, M extends Map<T, U>> Accumulator<T, M> 
mappedTo(Function<? super T, ? extends U> mapper,
 
   Supplier<M> mapSupplier) {
         return mappedTo(mapper, (BinaryOperator<U>) THROWING_MERGER, 
mapSupplier);
     }
     public static <T, U, M extends Map<T, U>> Accumulator<T, M> 
mappedTo(Function<? super T, ? extends U> mapper,
 
   BinaryOperator<U> mergeFunction,
 
   Supplier<M> mapSupplier) {
         return new MergingMapAccumulator<T, T, U, M>(mapSupplier, 
mergeFunction) {
             @Override
             public void accumulate(M map, T value) {
                 accumulate(map, value, mapper.apply(value));
             }
         };
     }


On 1/4/2013 10:37 AM, Michael Nascimento wrote:
> There is no mapTo() in Tabulators in build 69. There is a mappedTo,
> but it takes a BinaryOperator. Which one am I supposed to use?
>
> Regards,
> Michael
>
> On Fri, Jan 4, 2013 at 1:28 PM, Brian Goetz <brian.goetz at oracle.com> wrote:
>> tabulate(Tabulators.mapTo())
>>
>>
>> On 1/4/2013 10:22 AM, Michael Nascimento wrote:
>>>
>>> Guys,
>>>
>>> What is the equivalent in Lambda to Guava's Maps.uniqueIndex:
>>>
>>>
>>> http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/com/google/common/collect/Maps.html#uniqueIndex(java.lang.Iterable,
>>> com.google.common.base.Function)
>>>
>>> I was trying the tabulate method, but couldn't find a method in
>>> Tabulators with a single function that assumes the stream has unique
>>> keys.
>>>
>>> Regards,
>>> Michael
>>>
>>