diff options
Diffstat (limited to 'lib/Utils/src/IO')
| -rw-r--r-- | lib/Utils/src/IO/VnTextReaderExtensions.cs | 120 |
1 files changed, 65 insertions, 55 deletions
diff --git a/lib/Utils/src/IO/VnTextReaderExtensions.cs b/lib/Utils/src/IO/VnTextReaderExtensions.cs index 119461b..9ca5ae5 100644 --- a/lib/Utils/src/IO/VnTextReaderExtensions.cs +++ b/lib/Utils/src/IO/VnTextReaderExtensions.cs @@ -1,5 +1,5 @@ /* -* Copyright (c) 2022 Vaughn Nugent +* Copyright (c) 2023 Vaughn Nugent * * Library: VNLib * Package: VNLib.Utils @@ -52,8 +52,9 @@ namespace VNLib.Utils.IO /// <remarks>Allows reading lines of data from the stream without allocations</remarks> public static ERRNO ReadLine<T>(this ref T reader, Span<char> charBuffer) where T:struct, IVnTextReader { - return readLine(ref reader, charBuffer); + return ReadLineInternal(ref reader, charBuffer); } + /// <summary> /// Attempts to read a line from the stream and store it in the specified buffer /// </summary> @@ -65,7 +66,7 @@ namespace VNLib.Utils.IO /// <remarks>Allows reading lines of data from the stream without allocations</remarks> public static ERRNO ReadLine<T>(this T reader, Span<char> charBuffer) where T : class, IVnTextReader { - return readLine(ref reader, charBuffer); + return ReadLineInternal(ref reader, charBuffer); } /// <summary> @@ -80,6 +81,7 @@ namespace VNLib.Utils.IO { return reader.ReadRemaining(buffer.AsSpan(offset, count)); } + /// <summary> /// Fill a buffer with reamining buffered data /// </summary> @@ -103,8 +105,9 @@ namespace VNLib.Utils.IO /// <remarks>You should use the <see cref="IVnTextReader.Available"/> property to know how much remaining data is buffered</remarks> public static int ReadRemaining<T>(this ref T reader, Span<byte> buffer) where T : struct, IVnTextReader { - return readRemaining(ref reader, buffer); + return ReadRemainingInternal(ref reader, buffer); } + /// <summary> /// Fill a buffer with reamining buffered data, up to /// the size of the supplied buffer @@ -115,10 +118,10 @@ namespace VNLib.Utils.IO /// <remarks>You should use the <see cref="IVnTextReader.Available"/> property to know how much remaining data is buffered</remarks> public static int ReadRemaining<T>(this T reader, Span<byte> buffer) where T : class, IVnTextReader { - return readRemaining(ref reader, buffer); + return ReadRemainingInternal(ref reader, buffer); } - private static ERRNO readLine<T>(ref T reader, Span<char> chars) where T: IVnTextReader + private static ERRNO ReadLineInternal<T>(ref T reader, Span<char> chars) where T: IVnTextReader { /* * I am aware of a potential bug, the line decoding process @@ -129,68 +132,32 @@ namespace VNLib.Utils.IO * I dont expect this to be an issue unless there is a bug within the specified * encoder implementation */ - ReadOnlySpan<byte> LineTermination = reader.LineTermination.Span; + + int result = 0; + //If buffered data is available, check for line termination - if (reader.Available > 0) + if (reader.Available > 0 && TryReadLine(ref reader, chars, ref result)) { - //Get current buffer window - ReadOnlySpan<byte> bytes = reader.BufferedDataWindow; - //search for line termination in current buffer - int term = bytes.IndexOf(LineTermination); - //Termination found in buffer window - if (term > -1) - { - //Capture the line from the begining of the window to the termination - ReadOnlySpan<byte> line = bytes[..term]; - //Get the number ot chars - int charCount = reader.Encoding.GetCharCount(line); - //See if the buffer is large enough - if (bytes.Length < charCount) - { - return E_BUFFER_TOO_SMALL; - } - //Use the decoder to convert the data - _ = reader.Encoding.GetChars(line, chars); - //Shift the window to the end of the line (excluding the termination, regardless of the conversion result) - reader.Advance(term + LineTermination.Length); - //Return the number of characters - return charCount; - } - //Termination not found but there may be more data waiting + return result; } + //Compact the buffer window and make sure it was compacted so there is room to fill the buffer - if (reader.CompactBufferWindow()) + if (reader.CompactBufferWindow() > 0) { //There is room, so buffer more data reader.FillBuffer(); + //Check again to see if more data is buffered if (reader.Available <= 0) { //No data avialable return 0; } - //Get current buffer window - ReadOnlySpan<byte> bytes = reader.BufferedDataWindow; - //search for line termination in current buffer - int term = bytes.IndexOf(LineTermination); - //Termination found in buffer window - if (term > -1) + + //Try to read the line again after refill + if (TryReadLine(ref reader, chars, ref result)) { - //Capture the line from the begining of the window to the termination - ReadOnlySpan<byte> line = bytes[..term]; - //Get the number ot chars - int charCount = reader.Encoding.GetCharCount(line); - //See if the buffer is large enough - if (bytes.Length < charCount) - { - return E_BUFFER_TOO_SMALL; - } - //Use the decoder to convert the data - _ = reader.Encoding.GetChars(line, chars); - //Shift the window to the end of the line (excluding the termination, regardless of the conversion result) - reader.Advance(term + LineTermination.Length); - //Return the number of characters - return charCount; + return result; } } @@ -201,20 +168,63 @@ namespace VNLib.Utils.IO throw new OutOfMemoryException("The line was not found within the current buffer, cannot continue"); #pragma warning restore CA2201 // Do not raise reserved exception types } + + private static bool TryReadLine<T>(ref T reader, Span<char> chars, ref int result) where T: IVnTextReader + { + ReadOnlySpan<byte> LineTermination = reader.LineTermination.Span; + + //Get current buffer window + ReadOnlySpan<byte> bytes = reader.BufferedDataWindow; + + //search for line termination in current buffer + int term = bytes.IndexOf(LineTermination); + + //Termination found in buffer window + if (term > -1) + { + //Capture the line from the begining of the window to the termination + ReadOnlySpan<byte> line = bytes[..term]; + + //Get the number ot chars + result = reader.Encoding.GetCharCount(line); + + //See if the buffer is large enough + if (bytes.Length < result) + { + result = E_BUFFER_TOO_SMALL; + return true; + } + + //Use the decoder to convert the data + _ = reader.Encoding.GetChars(line, chars); + + //Shift the window to the end of the line (excluding the termination, regardless of the conversion result) + reader.Advance(term + LineTermination.Length); + + //Return the number of characters + return true; + } + + return false; + } - private static int readRemaining<T>(ref T reader, Span<byte> buffer) where T: IVnTextReader + private static int ReadRemainingInternal<T>(ref T reader, Span<byte> buffer) where T: IVnTextReader { //guard for empty buffer if (buffer.Length == 0 || reader.Available == 0) { return 0; } + //get the remaining bytes in the reader Span<byte> remaining = reader.BufferedDataWindow; + //Calculate the number of bytes to copy int canCopy = Math.Min(remaining.Length, buffer.Length); + //Copy remaining bytes to buffer remaining[..canCopy].CopyTo(buffer); + //Shift the window by the number of bytes copied reader.Advance(canCopy); return canCopy; |