private static unsafe int IndexOfHtmlEncodingChars(string s, int startPos)
{
Debug.Assert(0 <= startPos && startPos <= s.Length, "0 <= startPos && startPos <= s.Length");
UnicodeEncodingConformance encodeConformance = HtmlEncodeConformance;
int cch = s.Length - startPos;
fixed(char *str = s)
{
for (char *pch = &str[startPos]; cch > 0; pch++, cch--)
{
char ch = *pch;
if (ch <= '>')
{
switch (ch)
{
case '<':
case '>':
case '"':
case '\'':
case '&':
return(s.Length - cch);
}
}
#if ENTITY_ENCODE_HIGH_ASCII_CHARS
else if (ch >= 160 && ch < 256)
{
return(s.Length - cch);
}
#endif // ENTITY_ENCODE_HIGH_ASCII_CHARS
else if (encodeConformance == UnicodeEncodingConformance.Strict && Char.IsSurrogate(ch))
{
return(s.Length - cch);
}
}
}
return(-1);
}
static WebUtility()
{
s_htmlDecodeConformance = UnicodeDecodingConformance.Strict;
s_htmlEncodeConformance = UnicodeEncodingConformance.Strict;
}
public static unsafe void HtmlEncode(string value, TextWriter output)
{
if (value == null)
{
return;
}
if (output == null)
{
throw new ArgumentNullException("output");
}
int index = IndexOfHtmlEncodingChars(value, 0);
if (index == -1)
{
output.Write(value);
return;
}
Debug.Assert(0 <= index && index <= value.Length, "0 <= index && index <= value.Length");
UnicodeEncodingConformance encodeConformance = HtmlEncodeConformance;
int cch = value.Length - index;
fixed(char *str = value)
{
char *pch = str;
while (index-- > 0)
{
output.Write(*pch++);
}
for (; cch > 0; cch--, pch++)
{
char ch = *pch;
if (ch <= '>')
{
switch (ch)
{
case '<':
output.Write("<");
break;
case '>':
output.Write(">");
break;
case '"':
output.Write(""");
break;
case '\'':
output.Write("'");
break;
case '&':
output.Write("&");
break;
default:
output.Write(ch);
break;
}
}
else
{
int valueToEncode = -1; // set to >= 0 if needs to be encoded
#if ENTITY_ENCODE_HIGH_ASCII_CHARS
if (ch >= 160 && ch < 256)
{
// The seemingly arbitrary 160 comes from RFC
valueToEncode = ch;
}
else
#endif // ENTITY_ENCODE_HIGH_ASCII_CHARS
if (encodeConformance == UnicodeEncodingConformance.Strict && Char.IsSurrogate(ch))
{
int scalarValue = GetNextUnicodeScalarValueFromUtf16Surrogate(ref pch, ref cch);
if (scalarValue >= UNICODE_PLANE01_START)
{
valueToEncode = scalarValue;
}
else
{
// Don't encode BMP characters (like U+FFFD) since they wouldn't have
// been encoded if explicitly present in the string anyway.
ch = (char)scalarValue;
}
}
if (valueToEncode >= 0)
{
// value needs to be encoded
output.Write("&#");
output.Write(valueToEncode.ToString(NumberFormatInfo.InvariantInfo));
output.Write(';');
}
else
{
// write out the character directly
output.Write(ch);
}
}
}
}
}
static WebUtility()
{
s_htmlDecodeConformance = UnicodeDecodingConformance.Strict;
s_htmlEncodeConformance = UnicodeEncodingConformance.Strict;
}