internal override int EncodeUtf8(Rune value, Span <byte> destination)
{
if (value.Value == '<')
{
if (!SpanUtility.TryWriteBytes(destination, (byte)'&', (byte)'l', (byte)'t', (byte)';'))
{
goto OutOfSpace;
}
return(4);
}
else if (value.Value == '>')
{
if (!SpanUtility.TryWriteBytes(destination, (byte)'&', (byte)'g', (byte)'t', (byte)';'))
{
goto OutOfSpace;
}
return(4);
}
else if (value.Value == '&')
{
if (!SpanUtility.TryWriteBytes(destination, (byte)'&', (byte)'a', (byte)'m', (byte)'p', (byte)';'))
{
goto OutOfSpace;
}
return(5);
}
else if (value.Value == '\"')
{
if (!SpanUtility.TryWriteBytes(destination, (byte)'&', (byte)'q', (byte)'u', (byte)'o', (byte)'t', (byte)';'))
{
goto OutOfSpace;
}
return(6);
}
else
{
return(TryEncodeScalarAsHex(this, (uint)value.Value, destination));
}
OutOfSpace:
return(-1);
#pragma warning disable IDE0060 // 'this' taken explicitly to avoid argument shuffling by caller
static int TryEncodeScalarAsHex(object @this, uint scalarValue, Span <byte> destination)
#pragma warning restore IDE0060
{
UnicodeDebug.AssertIsValidScalar(scalarValue);
// See comments in the UTF-16 equivalent method later in this file.
int idxOfSemicolon = (int)((uint)BitOperations.Log2(scalarValue) / 4) + 4;
Debug.Assert(4 <= idxOfSemicolon && idxOfSemicolon <= 9, "Expected '�'..''.");
if (!SpanUtility.IsValidIndex(destination, idxOfSemicolon))
{
goto OutOfSpaceInner;
}
destination[idxOfSemicolon] = (byte)';';
if (!SpanUtility.TryWriteBytes(destination, (byte)'&', (byte)'#', (byte)'x', (byte)'0'))
{
Debug.Fail("We should've had enough room to write 4 bytes.");
}
destination = destination.Slice(3, idxOfSemicolon - 3);
for (int i = destination.Length - 1; SpanUtility.IsValidIndex(destination, i); i--)
{
char asUpperHex = HexConverter.ToCharUpper((int)scalarValue);
destination[i] = (byte)asUpperHex;
scalarValue >>= 4; // write a nibble - not a byte - at a time
}
return(destination.Length + 4);
OutOfSpaceInner:
return(-1);
}
public void TryWriteFiveBytes()
{
Span <byte> span = stackalloc byte[0];
Assert.False(SpanUtility.TryWriteBytes(span, 10, 20, 30, 40, 50));
span = stackalloc byte[4] {
100, 101, 102, 103
};
Assert.False(SpanUtility.TryWriteBytes(span, 10, 20, 30, 40, 50));
Assert.Equal(new byte[] { 100, 101, 102, 103 }, span.ToArray());
span = stackalloc byte[5] {
100, 101, 102, 103, 104
};
Assert.True(SpanUtility.TryWriteBytes(span, 10, 20, 30, 40, 50));
Assert.Equal(new byte[] { 10, 20, 30, 40, 50 }, span.ToArray());
span = stackalloc byte[6] {
100, 101, 102, 103, 104, 105
};
Assert.True(SpanUtility.TryWriteBytes(span, 10, 20, 30, 40, 50));
Assert.Equal(new byte[] { 10, 20, 30, 40, 50, 105 }, span.ToArray());
}