count method
Returns the number of entries matching the given predicate
or the number
of entries when predicate = null
.
Implementation
int count([bool Function(MapEntry<K, V>)? predicate]) {
if (predicate == null) {
return length;
}
var count = 0;
final i = entries.iterator;
while (i.moveNext()) {
if (predicate(i.current)) {
count++;
}
}
return count;
}