/// <summary>
/// Encodes the given string into the target buffer
/// </summary>
/// <param name="buf">The buffer into which the string should be serialized</param>
/// <param name="value">The value to encode</param>
/// <param name="valueByteLen">
/// The length of the string in bytes in non-huffman-encoded form.
/// This can be retrieved through the GetByteLength method.
/// </param>
/// <param name="huffman">Controls the huffman encoding</param>
/// <returns>
/// The number of bytes that were required to encode the value.
/// -1 if the value did not fit into the buffer.
/// </returns>
public static int EncodeInto(
ArraySegment <byte> buf,
string value, int valueByteLen, HuffmanStrategy huffman)
{
var offset = buf.Offset;
var free = buf.Count;
// Fast check for free space. Doesn't need to be exact
if (free < 1 + valueByteLen)
{
return(-1);
}
var encodedByteLen = valueByteLen;
var requiredHuffmanBytes = 0;
var useHuffman = huffman == HuffmanStrategy.Always;
byte[] huffmanInputBuf = null;
// Check if the string should be reencoded with huffman encoding
if (huffman == HuffmanStrategy.Always || huffman == HuffmanStrategy.IfSmaller)
{
huffmanInputBuf = Encoding.ASCII.GetBytes(value);
requiredHuffmanBytes = Huffman.EncodedLength(
new ArraySegment <byte>(huffmanInputBuf));
if (huffman == HuffmanStrategy.IfSmaller && requiredHuffmanBytes < encodedByteLen)
{
useHuffman = true;
}
}
if (useHuffman)
{
encodedByteLen = requiredHuffmanBytes;
}
// Write the required length to the target buffer
var prefixContent = useHuffman ? (byte)0x80 : (byte)0;
var used = IntEncoder.EncodeInto(
new ArraySegment <byte>(buf.Array, offset, free),
encodedByteLen, prefixContent, 7);
if (used == -1)
{
return(-1); // Couldn't write length
}
offset += used;
free -= used;
if (useHuffman)
{
if (free < requiredHuffmanBytes)
{
return(-1);
}
// Use the huffman encoder to write bytes to target buffer
used = Huffman.EncodeInto(
new ArraySegment <byte>(buf.Array, offset, free),
new ArraySegment <byte>(huffmanInputBuf));
if (used == -1)
{
return(-1); // Couldn't write length
}
offset += used;
}
else
{
if (free < valueByteLen)
{
return(-1);
}
// Use ASCII encoder to write bytes to target buffer
used = Encoding.ASCII.GetBytes(
value, 0, value.Length, buf.Array, offset);
offset += used;
}
// Return the number amount of used bytes
return(offset - buf.Offset);
}
