Document Sequence::single()

Author: thekid

ChangeLog.md

@@ -3,6 +3,15 @@ Data sequences change log
 
 ## ?.?.? / ????-??-??
 
+* Introduce dedicated `util.data.NoSuchElement` exception. It's thrown
+  from `Optional::get()` if no element is present instead of the generic
+  `util.NoSuchElementException`. For BC reasons, it extends the latter.
+  (@thekid)
+* Implemented PR #54: Implement `Sequence::single()` - which is similar
+  to `first()` but raises an exception if there are more than 1 element
+  in the sequence.
+  (@thekid)
+
 ## 10.0.0 / 2021-10-21
 
 * Implemented xp-framework/rfc#341, dropping compatibility with XP 9

README.md

@@ -109,6 +109,7 @@ The following operations return a single value by consuming all of the sequence:
 * **toArray** - will return a PHP array with zero-based keys
 * **toMap** - will return a PHP associative array
 * **first** - will return the first element as an `util.data.Optional` instance. A value will be present if the sequence was not empty.
+* **single** - like `first()`, but raises an exception if more than one element is contained in the sequence.
 * **count** - will return the number of elements in the sequence
 * **min** - returns the smalles element. Compares numbers by default but may be given a comparator function or a `util.Comparator` instance.
 * **max** - same as `min()`, but returns the largest element instead.