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-rw-r--r--NEWS7
-rw-r--r--enumerator.c15
2 files changed, 22 insertions, 0 deletions
diff --git a/NEWS b/NEWS
index 5379caa..acc3d0c 100644
--- a/NEWS
+++ b/NEWS
@@ -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 eee3a34..06e2a9e 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)