/// <summary>
/// This method validates the state sliding window.
/// </summary>
/// <typeparam name="TSource"></typeparam>
/// <typeparam name="TMatch"></typeparam>
/// <param name="state">The match collection state.</param>
/// <param name="deQueue"></param>
/// <returns>Returns the updated match state.</returns>
private static MatchCollectionState <TSource, TMatch> ValidateCollectionSlidingWindow <TSource, TMatch>(
MatchCollectionState <TSource, TMatch> state
, bool deQueue)
{
//Remove the first item from the collection.
if (deQueue)
{
state.SlidingWindow.Dequeue();
state.Length++;
state.Length -= state.SlidingWindow.Count;
}
#if (DEBUG)
MatchStateDebugLog(state, "Recurse");
#endif
//Ok, check whether the queue is empty. This can happen when the queue only contained
//1 item and was called recursively.
if (state.SlidingWindow.Count == 0)
{
state.Status = MatchTerminatorStatus.NotSet;
return(state);
}
Queue <TSource> window = state.SlidingWindow;
state.CurrentEnumerator.Reset();
state.CurrentEnumerator.MoveNext();
state.SlidingWindow = new Queue <TSource>();
//OK, we recursively call the window to allow the queue to
//be processed.
return(window.MatchCollection(state));
}
/// <summary>
/// This is the match method. This method maps the incoming buffer to the match parameters.
/// </summary>
/// <param name="buffer">The byte buffer.</param>
/// <param name="offset">The byte offset/</param>
/// <param name="count">The number of bytes that can be read.</param>
/// <param name="length">The length of the bytes read.</param>
/// <returns>Returns true if a match has been found.</returns>
public virtual bool Match(byte[] buffer, int offset, int count, out int length, out long?bodyLength)
{
if (!Initialized)
{
throw new NotSupportedException("Match is not supported without Initialization.");
}
//Get the current start position so that we can calculate the offset later.
int lengthStart = mState.Length;
//OK, match against the specified buffer range.
mState = buffer
.Range(offset, count)
.MatchCollection(mState);
//OK, calculate the number of bytes scanned.
length = mState.Length - lengthStart;
//OK, do we have a match?
if (mState.Status.HasValue && (mState.Status.Value & MatchTerminatorStatus.Success) > 0)
{
//Yes, so calculate the actual body length.
bodyLength = mState.MatchPosition - mState.Start;
return(true);
}
//OK, we don't have a match.
bodyLength = null;
return(false);
}
/// <summary>
/// This method matches the source enumeration against the state collection, this is to allow pattern
/// matching over multiple byte blocks.
/// </summary>
/// <typeparam name="TSource">The source type.</typeparam>
/// <typeparam name="TMatch">The match type.</typeparam>
/// <param name="source">The enumerable source.</param>
/// <param name="state">The incoming match state.</param>
/// <returns>Returns the updated match state.</returns>
public static MatchCollectionState <TSource, TMatch> MatchCollection <TSource, TMatch>(
this IEnumerable <TSource> source
, MatchCollectionState <TSource, TMatch> state)
{
IEnumerator <TSource> sourceEnum = source.GetEnumerator();
sourceEnum.MoveNext();
return(sourceEnum.MatchCollection(state));
}
private static void MatchStateDebugLog <TSource, TMatch>(MatchCollectionState <TSource, TMatch> state, string type)
{
if (state.DebugTrace)
{
state.DebugTraceCollection.Add(
string.Format("{0} <- {1} Q={2}, ({3})"
, type
, state.DebugTraceRecursion
, state.SlidingWindow == null ? "null" : state.SlidingWindow.Count.ToString()
, !state.Status.HasValue ? "null" : state.Status.Value.ToString())
);
}
state.DebugTraceRecursion--;
}
/// <summary>
/// This method matches the source enumeration against the state collection, this is to allow pattern
/// matching over multiple byte blocks.
/// </summary>
/// <typeparam name="TSource">The source type.</typeparam>
/// <typeparam name="TMatch">The match type.</typeparam>
/// <param name="sourceEnum">The source enumeration data.</param>
/// <param name="state">The incoming match state.</param>
/// <returns>Returns the updated match state.</returns>
public static MatchCollectionState <TSource, TMatch> MatchCollection <TSource, TMatch>(
this IEnumerator <TSource> sourceEnum
, MatchCollectionState <TSource, TMatch> state)
{
if (state == null)
{
throw new ArgumentNullException("state cannot be null.");
}
#if (DEBUG)
state.DebugTraceRecursion++;
#endif
try
{
#if (DEBUG)
MatchStateDebugLog(state, "Entry");
#endif
//Ok, have we already matched in which case return the current state unchanged.
if (state.Status.HasValue && ((state.Status.Value & MatchTerminatorStatus.Success) > 0))
{
return(state);
}
//Initialize the state.
if (!state.Status.HasValue)
{
state.Start = state.Length;
state.Status = MatchTerminatorStatus.NotSet;
}
//OK, get the MatchTerminator current enumerator or create a new one if it is null.
IEnumerator <MatchTerminator <TSource, TMatch> > currentEnum = state.ActualEnumerator;
//Check whether there is any data from the sliding window and if so process it first.
if (state.SlidingWindow.Count > 0 && state.Status == MatchTerminatorStatus.NotSet)
{
state = ValidateCollectionSlidingWindow(state, false);
}
//If the sliding window data has completed the match, then exit
if ((state.Status & MatchTerminatorStatus.Success) > 0)
{
return(state);
}
//Ok, let's start the match.
MatchTerminatorResult result;
bool reset = false;
do
{
MatchTerminator <TSource, TMatch> term = currentEnum.Current;
result = term.Match(sourceEnum, state.SlidingWindow, state.Length - state.Start);
reset = (result.Status & MatchTerminatorStatus.Reset) > 0;
#if (DEBUG)
if (state.DebugTrace)
{
state.DebugTraceCollection.Add(
string.Format("Match ({0})={1} [{2:X}]", term.GetType().Name, result.Status, state.Length));
}
#endif
state.IsTerminator |= result.IsTerminator;
switch (result.Status)
{
case MatchTerminatorStatus.Fail:
term.Reset();
state.Length += result.Length - 1; // +state.SlidingWindow.Count - 1;
if (state.SlidingWindow.Count > 0)
{
int oldLength = state.Length;
//Dispose of the first item, and process the queue.
state = ValidateCollectionSlidingWindow <TSource, TMatch>(state, true);
//Ok, we need to check whether we have a partial match in the enqueued bytes.
currentEnum = state.CurrentEnumerator;
}
if (state.Status != MatchTerminatorStatus.SuccessPartial)
{
currentEnum.Reset();
}
break;
case MatchTerminatorStatus.SuccessPartial:
//Ok, we have a partial match but have reached the end of sourceEnum, so return
//and wait for the next piece.
state.Status = MatchTerminatorStatus.SuccessPartial;
state.Length += result.Length;
if (state.MatchPosition == -1)
{
state.MatchPosition = state.Length - state.SlidingWindow.Count;
}
return(state);
case MatchTerminatorStatus.NotSet:
//Ok, we have scanned to the end of the array and not found a match.
state.MatchPosition = -1;
state.Length += result.Length;
return(state);
case MatchTerminatorStatus.SuccessNoLength:
case MatchTerminatorStatus.SuccessNoLengthReset:
term.Reset();
state.Length += result.Length;
if (state.MatchPosition == -1)
{
state.MatchPosition = state.Length - state.SlidingWindow.Count;
}
if (reset)
{
currentEnum.Reset();
currentEnum.MoveNext();
}
break;
case MatchTerminatorStatus.Success:
case MatchTerminatorStatus.SuccessReset:
term.Reset();
state.Length += result.Length;
if (state.MatchPosition == -1)
{
state.MatchPosition = state.Length - state.SlidingWindow.Count;
}
if (reset)
{
currentEnum.Reset();
currentEnum.MoveNext();
}
//Ok, we are successful, so we need to move on to the next step.
if (!result.CanContinue || reset)
{
//We have reached the end of the byte stream so we need to check whether we have
//actually terminated.
bool moreTerminatorParts = reset ? false : currentEnum.MoveNext();
if (!state.IsTerminator && moreTerminatorParts)
{
//OK, we only have a partial match as the terminator flag is not set and we have more parts
//of the terminator to process.
state.Status = MatchTerminatorStatus.SuccessPartial;
}
else
{
//Ok, either the termination flag is set, meaning the terminator chars match a specific character
//or there are no more parts of the terminator to match.
state.Status = MatchTerminatorStatus.Success;
state.SlidingWindow.Clear();
}
return(state);
}
break;
default:
throw new ArgumentOutOfRangeException("Unknown MatchTerminatorStatus value.");
}
}while (result.CanContinue && currentEnum.MoveNext() && !reset);
//OK, we have completed. Either we have failed or succeeded
state.Status = result.Status;
//OK, time to do some tidy up.
if ((result.Status & MatchTerminatorStatus.Success) > 0)
{
int extra = state.Length - state.MatchPosition;
state.SlidingWindow.DequeueRemove(extra);
state.CurrentEnumerator = null;
}
return(state);
}
finally
{
#if (DEBUG)
MatchStateDebugLog(state, "Exit");
#endif
}
}