public IObservable <IParseResult <IObservable <TResult> > > Parse(IObservableCursor <TSource> source)
{
return(Observable.Defer(() =>
{
firstParser = null;
bool first = true;
var any = new AnyObservableParser <TSource, TResult>(parsers);
var except = new List <IObservableParser <TSource, TResult> >();
// See the AllObservableParser.Parse method for an explanation of the optimization that is provided by SelectMany's TContext argument
var root = source.Branch();
var rootDisposable = new RefCountDisposable(root);
return ObservableParseResult.ReturnSuccessMany <TResult>(0)
.SelectMany(
Tuple.Create(root, rootDisposable),
parsers.Select(
parser => (Func <Tuple <IObservableCursor <TSource>, RefCountDisposable>, Tuple <IParseResult <IObservable <TResult> >, bool>, Tuple <Tuple <IObservableCursor <TSource>, RefCountDisposable>, IObservable <IParseResult <IObservable <TResult> > > > >)
((context, value) =>
{
if (first)
{
first = false;
firstParser = parser;
}
var branch = context.Item1;
var disposable = context.Item2;
var refDisposable = disposable.GetDisposable();
IObservable <IParseResult <IObservable <TResult> > > results;
// Item2 is only true when value.Item1 is the last element of its sequence.
if (value.Item2)
{
branch.Move(value.Item1.Length);
results = any.Parse(except, branch)
.Select(result => result.YieldMany())
.Finally(refDisposable.Dispose);
}
else
{
branch = branch.Remainder(value.Item1.Length);
disposable = new RefCountDisposable(new CompositeDisposable(branch, refDisposable));
results = any.Parse(except, branch)
.Select(result => result.YieldMany())
.Finally(disposable.Dispose);
}
return Tuple.Create(Tuple.Create(branch, disposable), results);
})),
(firstResult, otherResults) => firstResult.Concat(otherResults))
.Finally(rootDisposable.Dispose);
}));
}
public IObservable <IParseResult <IObservable <TResult> > > Parse(IObservableCursor <TSource> source)
{
return(Observable.Defer(() =>
{
firstParser = null;
bool first = true;
/* The TContext of branches allows for an optimization on top of the previous implementation, which used to create a new
* branch for every parse result in every parse result sequence. This new implementation changes that behavior slightly
* by not creating a new branch for the last result in each sequence. All parser rules (at the time of writing) in Rxx
* generate zero or one result only; therefore, the current branch can be moved forward and reused by child sequences
* without affecting the parent result sequence, because it's already completed. This optimization has proven to be
* slightly beneficial across normal parser queries that use And, All and Exactly operators. It should also be beneficial
* for multi-result queries since most of the individual parser rules in these queries will only generate a single result.
* A new branch would only be created for each result in the multi-result sequence. Scalar-result parsers that follow
* sequentially in the All query would simply move their shared parent branch instead of creating new branches.
*/
var root = source.Branch();
var rootDisposable = new RefCountDisposable(root);
return ObservableParseResult.ReturnSuccessMany <TResult>(0)
.SelectMany(
Tuple.Create(root, rootDisposable),
parsers.Select(
parser => (Func <Tuple <IObservableCursor <TSource>, RefCountDisposable>, Tuple <IParseResult <IObservable <TResult> >, bool>, Tuple <Tuple <IObservableCursor <TSource>, RefCountDisposable>, IObservable <IParseResult <IObservable <TResult> > > > >)
((context, value) =>
{
if (first)
{
first = false;
firstParser = parser;
}
var branch = context.Item1;
var disposable = context.Item2;
var refDisposable = disposable.GetDisposable();
IObservable <IParseResult <IObservable <TResult> > > results;
// Item2 is only true when value.Item1 is the last element of its sequence.
if (value.Item2)
{
branch.Move(value.Item1.Length);
results = parser.Parse(branch)
.Select(result => result.YieldMany())
.Finally(refDisposable.Dispose);
}
else
{
branch = branch.Remainder(value.Item1.Length);
disposable = new RefCountDisposable(new CompositeDisposable(branch, refDisposable));
results = parser.Parse(branch)
.Select(result => result.YieldMany())
.Finally(disposable.Dispose);
}
return Tuple.Create(Tuple.Create(branch, disposable), results);
})),
(firstResult, otherResults) => firstResult.Concat(otherResults))
.Finally(rootDisposable.Dispose);
}));
}
public IObservable <IParseResult <IObservable <TResult> > > Parse(IObservableCursor <TSource> source)
{
return(Observable.Create <IParseResult <IObservable <TResult> > >(
observer =>
{
int matchCount = 0;
int remainingLength = 0;
Action <Action> iterate = moveNext =>
{
bool hasResult = false;
int length = 0;
var branch = source.Branch();
var values = parser.Parse(branch)
.Finally(branch.Dispose)
.Select(result =>
{
if (!hasResult)
{
matchCount++;
hasResult = true;
}
length = Math.Max(length, result.Length);
return result.Value;
})
.Do(
__ => { },
() =>
{
/* We must respect the greediness of the results unless the length is zero since the
* cursor would have already moved to the following element. It is acceptable to ignore
* zero-length results because marking an entirely non-greedy parser as ambiguous would
* otherwise cause the parser to continously parse the first element indefinitely.
*/
if (length > 0)
{
remainingLength = length - 1;
}
else if (remainingLength > 0)
{
remainingLength--;
}
moveNext();
});
observer.OnNext(ParseResult.Create(values, length: 1));
};
Action complete = () =>
{
if (remainingLength > 0)
{
observer.OnNext(ObservableParseResult.SuccessMany <TResult>(remainingLength));
}
observer.OnCompleted();
};
var untilSubscription = new SerialDisposable();
var schedule = Scheduler.Immediate.Schedule(
self =>
{
if (!source.AtEndOfSequence &&
(untilCount == unlimitedCount || matchCount < untilCount))
{
if (untilParser == null)
{
iterate(self);
}
else
{
untilSubscription.SetDisposableIndirectly(() =>
untilParser.Parse(source).Any().Subscribe(
any =>
{
if (!any)
{
iterate(self);
}
else
{
complete();
}
},
observer.OnError));
}
}
else
{
complete();
}
});
return new CompositeDisposable(schedule, untilSubscription);
}));
}
private IObservableParser <byte, int> Yield(int value)
{
Contract.Ensures(Contract.Result <IObservableParser <byte, int> >() != null);
return(this.Yield(_ => ObservableParseResult.Return(value, 0)));
}