/// <summary>
/// Creates a <see cref="NmeaLineToAisStreamAdapter"/>.
/// </summary>
/// <param name="messageProcessor">
/// The message process to which complete AIS messages are to be passed.
/// </param>
/// <param name="options">Configures parser behaviour.</param>
public NmeaLineToAisStreamAdapter(
INmeaAisMessageStreamProcessor messageProcessor,
NmeaParserOptions options)
{
this.messageProcessor = messageProcessor;
this.options = options;
}
/// <summary>
/// Process the contents of a file one AIS message at a time.
/// </summary>
/// <param name="path">Path of the file to process.</param>
/// <param name="processor">Handler for the AIS messages.</param>
/// <param name="options">Configures parser behaviour.</param>
/// <returns>A task that completes when the stream has been processed.</returns>
/// <remarks>
/// This reassembles AIS messages that have been split over multiple NMEA lines.
/// </remarks>
public static async Task ParseFileAsync(
string path,
INmeaAisMessageStreamProcessor processor,
NmeaParserOptions options)
{
using var adapter = new NmeaLineToAisStreamAdapter(processor, options);
await ParseFileAsync(path, adapter, options).ConfigureAwait(false);
}
/// <summary>
/// Process the contents of a file.
/// </summary>
/// <param name="path">Path of the file to process.</param>
/// <param name="processor">Handler for the parsed lines.</param>
/// <param name="options">Configures parser behaviour.</param>
/// <returns>A task that completes when the stream has been processed.</returns>
public static async Task ParseFileAsync(
string path,
INmeaLineStreamProcessor processor,
NmeaParserOptions options)
{
// This turns off internal file stream buffering
using var file = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.ReadWrite, bufferSize: 1, useAsync: true);
await ParseStreamAsync(file, processor, options).ConfigureAwait(false);
}
/// <summary>
/// Process the contents of a stream.
/// </summary>
/// <param name="stream">The stream to process.</param>
/// <param name="processor">Handler for the parsed lines.</param>
/// <param name="options">Configures parser behaviour.</param>
/// <returns>A task that completes when the stream has been processed.</returns>
public static async Task ParseStreamAsync(
Stream stream,
INmeaLineStreamProcessor processor,
NmeaParserOptions options)
{
int lines = 0;
int ticksAtStart = Environment.TickCount;
int ticksAtLastLineCount = ticksAtStart;
try
{
PipeReader reader = CreateFileReader(stream);
byte[] splitLineBuffer = new byte[1000];
while (true)
{
ReadResult result = await reader.ReadAsync().ConfigureAwait(false);
ReadOnlySequence <byte> remainingSequence = ProcessBuffer(result);
reader.AdvanceTo(remainingSequence.Start, remainingSequence.End);
if (result.IsCompleted)
{
break;
}
}
const int LineCountInterval = 100000;
int finalTicks = Environment.TickCount;
int totalTicks = finalTicks - ticksAtStart;
processor.Progress(
true,
lines,
totalTicks,
lines % LineCountInterval,
finalTicks - ticksAtLastLineCount);
ReadOnlySequence <byte> ProcessBuffer(
in ReadResult result)
{
ReadOnlySpan <byte> lineSpan;
SequencePosition? position = null;
ReadOnlySequence <byte> remainingSequence = result.Buffer;
while ((position = remainingSequence.PositionOf((byte)'\n') ?? (remainingSequence.IsEmpty || !result.IsCompleted ? default(SequencePosition?) : remainingSequence.End)) != null)
{
ReadOnlySequence <byte> line = remainingSequence.Slice(remainingSequence.Start, position.Value);
if (line.IsSingleSegment)
{
lineSpan = line.First.Span;
}
else
{
Span <byte> reassemblySpan = splitLineBuffer;
line.CopyTo(reassemblySpan);
lineSpan = reassemblySpan.Slice(0, (int)line.Length);
}
if (lineSpan.Length > 0 && lineSpan[lineSpan.Length - 1] == (byte)'\r')
{
lineSpan = lineSpan.Slice(0, lineSpan.Length - 1);
}
if (lineSpan.Length > 0)
{
try
{
var parsedLine = new NmeaLineParser(lineSpan, options.ThrowWhenTagBlockContainsUnknownFields);
processor.OnNext(parsedLine, lines + 1);
}
catch (Exception x)
{
processor.OnError(lineSpan, x, lines + 1);
}
}
remainingSequence = position.Value.Equals(remainingSequence.End)
? remainingSequence.Slice(remainingSequence.End)
: remainingSequence.Slice(remainingSequence.GetPosition(1, position.Value));
if (++lines % LineCountInterval == 0)
{
int currentTicks = Environment.TickCount;
int ticksSinceLastLineCount = currentTicks - ticksAtLastLineCount;
processor.Progress(
false,
lines,
currentTicks - ticksAtStart,
LineCountInterval,
ticksSinceLastLineCount);
ticksAtLastLineCount = currentTicks;
}
}
return(remainingSequence);
}
}
finally
{
processor.OnCompleted();
}
}
