Future <string> join(string separator = "")
{
_Future result = new _Future();
StringBuilder buffer = new StringBuilder();
StreamSubscription <T> subscription = null;
bool first = true;
subscription = listen(
(T element) => {
if (!first)
{
buffer.Append(separator);
}
first = false;
try {
buffer.Append(element);
}
catch (Exception e) {
_stream._cancelAndErrorWithReplacement(subscription, result, e);
}
},
onError: (e, _) => result._completeError((Exception)e),
onDone: () => { result._complete(buffer.ToString()); },
cancelOnError: true);
return(result.to <string>());
}
Future <S> fold <S>(S initialValue, Func <S, T, S> combine)
{
_Future result = new _Future();
S value = initialValue;
StreamSubscription <T> subscription = null;
subscription = listen(
(T element) => {
_stream._runUserCode(() => combine(value, element), (S newValue) => { value = newValue; },
e => _stream._cancelAndErrorClosure(subscription, result)(e));
},
onError: (e, s) => result._completeError((Exception)e),
onDone: () => { result._complete(FutureOr.value(value)); },
cancelOnError: true);
return(result.to <S>());
}
Future <bool> contains(object needle)
{
_Future future = new _Future();
StreamSubscription <T> subscription = null;
subscription = listen(
(T element) => {
_stream._runUserCode(() => (Equals(element, needle)), (bool isMatch) => {
if (isMatch)
{
_stream._cancelAndValue(subscription, future, true);
}
}, (e) => _stream._cancelAndErrorClosure(subscription, future)(e));
},
onError: (e, _) => future._completeError((Exception)e),
onDone: () => { future._complete(false); },
cancelOnError: true);
return(future.to <bool>());
}
Future <T> reduce(Func <T, T, T> combine)
{
_Future result = new _Future();
bool seenFirst = false;
T value = default;
StreamSubscription <T> subscription = null;
subscription = listen(
(T element) => {
if (seenFirst)
{
_stream._runUserCode(() => combine(value, element), (T newValue) => { value = newValue; },
onError: (e) => _stream._cancelAndErrorClosure(subscription, result)(e));
}
else
{
value = element;
seenFirst = true;
}
},
onError: (e, s) => result._completeError((Exception)e),
onDone: () => {
if (!seenFirst)
{
try {
// Throw and recatch, instead of just doing
// _completeWithErrorCallback, e, theError, StackTrace.current),
// to ensure that the stackTrace is set on the error.
throw new Exception("IterableElementError.noElement()");
}
catch (Exception e) {
async_._completeWithErrorCallback(result, e);
}
}
else
{
// TODO: need check
result._complete(FutureOr.value(value));
}
},
cancelOnError: true);
return(result.to <T>());
}