void ReadStringSegmentCore(out byte[] resultBytes, out int resultOffset, out int resultLength)
{
// SkipWhiteSpace is already called from IsNull
byte[] builder = null;
var builderOffset = 0;
char[] codePointStringBuffer = null;
var codePointStringOffet = 0;
if (bytes[offset] != '\"')
{
throw CreateParsingException("String Begin Token");
}
offset++;
var from = offset;
// eliminate array-bound check
for (int i = offset; i < bytes.Length; i++)
{
byte escapeCharacter = 0;
switch (bytes[i])
{
case (byte)'\\': // escape character
switch ((char)bytes[i + 1])
{
case '"':
case '\\':
case '/':
escapeCharacter = bytes[i + 1];
goto COPY;
case 'b':
escapeCharacter = (byte)'\b';
goto COPY;
case 'f':
escapeCharacter = (byte)'\f';
goto COPY;
case 'n':
escapeCharacter = (byte)'\n';
goto COPY;
case 'r':
escapeCharacter = (byte)'\r';
goto COPY;
case 't':
escapeCharacter = (byte)'\t';
goto COPY;
case 'u':
if (codePointStringBuffer == null)
{
codePointStringBuffer = StringBuilderCache.GetCodePointStringBuffer();
}
if (codePointStringOffet == 0)
{
if (builder == null)
{
builder = StringBuilderCache.GetBuffer();
}
var copyCount = i - from;
BinaryUtil.EnsureCapacity(ref builder, builderOffset, copyCount + 1); // require + 1
Buffer.BlockCopy(bytes, from, builder, builderOffset, copyCount);
builderOffset += copyCount;
}
if (codePointStringBuffer.Length == codePointStringOffet)
{
Array.Resize(ref codePointStringBuffer, codePointStringBuffer.Length * 2);
}
var a = (char)bytes[i + 2];
var b = (char)bytes[i + 3];
var c = (char)bytes[i + 4];
var d = (char)bytes[i + 5];
var codepoint = GetCodePoint(a, b, c, d);
codePointStringBuffer[codePointStringOffet++] = (char)codepoint;
i += 5;
offset += 6;
from = offset;
continue;
default:
throw CreateParsingExceptionMessage("Bad JSON escape.");
}
case (byte)'"': // endtoken
offset++;
goto END;
default: // string
if (codePointStringOffet != 0)
{
if (builder == null)
{
builder = StringBuilderCache.GetBuffer();
}
BinaryUtil.EnsureCapacity(ref builder, builderOffset, StringEncoding.UTF8.GetMaxByteCount(codePointStringOffet));
builderOffset += StringEncoding.UTF8.GetBytes(codePointStringBuffer, 0, codePointStringOffet, builder, builderOffset);
codePointStringOffet = 0;
}
offset++;
continue;
}
COPY:
{
if (builder == null)
{
builder = StringBuilderCache.GetBuffer();
}
if (codePointStringOffet != 0)
{
BinaryUtil.EnsureCapacity(ref builder, builderOffset, StringEncoding.UTF8.GetMaxByteCount(codePointStringOffet));
builderOffset += StringEncoding.UTF8.GetBytes(codePointStringBuffer, 0, codePointStringOffet, builder, builderOffset);
codePointStringOffet = 0;
}
var copyCount = i - from;
BinaryUtil.EnsureCapacity(ref builder, builderOffset, copyCount + 1); // require + 1!
Buffer.BlockCopy(bytes, from, builder, builderOffset, copyCount);
builderOffset += copyCount;
builder[builderOffset++] = escapeCharacter;
i += 1;
offset += 2;
from = offset;
}
}
resultLength = 0;
resultBytes = null;
resultOffset = 0;
throw CreateParsingException("String End Token");
END:
if (builderOffset == 0 && codePointStringOffet == 0) // no escape
{
resultBytes = bytes;
resultOffset = from;
resultLength = offset - 1 - from; // skip last quote
}
else
{
if (builder == null)
{
builder = StringBuilderCache.GetBuffer();
}
if (codePointStringOffet != 0)
{
BinaryUtil.EnsureCapacity(ref builder, builderOffset, StringEncoding.UTF8.GetMaxByteCount(codePointStringOffet));
builderOffset += StringEncoding.UTF8.GetBytes(codePointStringBuffer, 0, codePointStringOffet, builder, builderOffset);
codePointStringOffet = 0;
}
var copyCount = offset - from - 1;
BinaryUtil.EnsureCapacity(ref builder, builderOffset, copyCount);
Buffer.BlockCopy(bytes, from, builder, builderOffset, copyCount);
builderOffset += copyCount;
resultBytes = builder;
resultOffset = 0;
resultLength = builderOffset;
}
}