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From Paul King <>
Subject Re: CharSequence.count(Closure)
Date Sat, 23 May 2015 10:32:43 GMT

Yes, it would be StringGroovyMethods. For better or worse, the current iterable-like
methods in SGM (dropWhile, collectReplacements, takeWhile) pass a char  into the Closure.
Here is the little experiment I did for count:

      * Counts the number of occurrences which satisfy the given closure from the chars within
this CharSequence.
      * <p/>
      * Example usage:
      * <pre class="groovyTestCase">
      * assert "hello".count{ "aeiou".contains(it as String) } == 2
      * assert "hello".count{ String s -> "aeiou".contains(s) } == 2
      * </pre>
      * @param self      the CharSequence within which we count the number of occurrences
      * @param condition a closure condition which is passed each character (or String of
size 1 if the closure takes a String argument)
      * @return the number of occurrences
      * @since 2.5.0
     public static <T> Number count(CharSequence self, @ClosureParams(value=SimpleType.class,
options="char") Closure condition) {
         int index = 0;
         int result = 0;
         boolean stringArg = condition.getMaximumNumberOfParameters() == 1 && condition.getParameterTypes()[0].equals(String.class);
         BooleanClosureWrapper bcw = new BooleanClosureWrapper(condition);
         while (index < self.length()) {
             char value = self.charAt(index);
             if ( ? Character.toString(value) : value)) {
         return result;

This passes char in as the default but also will pass a String of size 1 if the provided
closure has one String arg - see the examples in the GroovyDoc.  Actually, in hindsight,
I would have made String of size 1 the default and char the thing to optionally look for.
But for consistency, not sure whether it is good to change that decision now.  Then again,
if we want to make such a change we should do it before 2.5.0 and before we add a bunch
more methods.

Cheers, Paul.

On 23/05/2015 7:22 PM, Peter Ledbrook wrote:
>     Currently you'd need to do something like:
>     "hello".iterator().count{ "aeiou".contains(it) }
>     I think it makes sense to add a direct DGM method in this instance.
>     And yes, I suspect that CharSequence versions of most of the Iterable
>     DGM methods would be appropriate.
> Should these go in DGM or StringGroovyMethods? I'm thinking the simplest solution would
be implementations of the form:
>      static int count(CharSequence seq, Closure cl) {
>          return count(seq.iterator(), cl);
>      }
> Does that make sense?
> Peter

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