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-rw-r--r-- | NEWS | 7 | ||||
-rw-r--r-- | enumerator.c | 15 |
2 files changed, 22 insertions, 0 deletions
@@ -248,6 +248,13 @@ Enumerator:: New methods:: + * Added Enumerator.produce to generate Enumerator from any custom + data-transformation. [Feature #14781] + + require 'date' + dates = Enumerator.produce(Date.today, &:succ) #=> infinite sequence of dates + dates.detect(&:tuesday?) #=> next tuesday + * Added Enumerator::Lazy#eager that generates a non-lazy enumerator from a lazy enumerator. [Feature #15901] diff --git a/enumerator.c b/enumerator.c index eee3a34e6b..06e2a9e6a7 100644 --- a/enumerator.c +++ b/enumerator.c @@ -2923,6 +2923,21 @@ producer_size(VALUE obj, VALUE args, VALUE eobj) * * ancestors = Enumerator.produce(node) { |prev| node = prev.parent or raise StopIteration } * enclosing_section = ancestors.find { |n| n.type == :section } + * + * Using ::produce together with Enumerable methods like Enumerable#detect, + * Enumerable#slice, Enumerable#take_while can provide Enumerator-based alternative + * for +while+ and +until+ cycles: + * + * # Find next Tuesday + * require 'date' + * Enumerator.produce(Date.today, &:succ).detect(&:tuesday?) + * + * # Simple lexer: + * require 'strscan' + * scanner = StringScanner.new('7+38/6') + * PATTERN = %r{\d+|[-/+*]} + * p Enumerator.produce { scanner.scan(PATTERN) }.slice_after { scanner.eos? }.first + * # => ["7", "+", "38", "/", "6"] */ static VALUE enumerator_s_produce(int argc, VALUE *argv, VALUE klass) |