singleWhere method
- bool test(
- E value
- {E orElse(
override
Returns the single element that satisfies test
.
Checks elements to see if test(element)
returns true.
If exactly one element satisfies test
, that element is returned.
If more than one matching element is found, throws StateError.
If no matching element is found, returns the result of orElse
.
If orElse
is omitted, it defaults to throwing a StateError.
Implementation
E singleWhere(bool test(E value), {E orElse()}) {
E result;
bool foundMatching = false;
for (E element in this) {
if (test(element)) {
if (foundMatching) {
throw IterableElementError.tooMany();
}
result = element;
foundMatching = true;
}
}
if (foundMatching) return result;
if (orElse != null) return orElse();
throw IterableElementError.noElement();
}