public static bool SkipUnicodeEscape(CharacterStream cs)
{
// Skip: \012345
if (AtUnicodeEscape(cs))
{
cs.Advance(2); // Skip "\X"
// Skip up to six hex characters
for (int count = 1; count < 6; count++, cs.Advance(1))
{
if (!TextHelper.IsHexDigit(cs.CurrentChar))
{
break;
}
}
// Eat a single space or line after the unicode character
if (TextHelper.IsNewLine(cs.CurrentChar))
{
SkipNewLine(cs);
}
else if (TextHelper.IsWhiteSpace(cs.CurrentChar))
{
cs.Advance(1);
}
return(true);
}
return(false);
}
/// <summary>
/// This is similar to string.Substring, but it deals with encoded unicode chars and escaped chars.
/// Escaped line breaks are only valid within strings, so set "forStringToken" to true for strings.
/// </summary>
public static string DecodeText(ITextProvider textProvider, int start, int length, bool forStringToken)
{
if (RangeCouldContainEncodedChars(textProvider, start, length))
{
// Need to carefully investigate every character and decode it
System.Text.StringBuilder sb = new System.Text.StringBuilder(length);
CharacterStream cs = new CharacterStream(textProvider);
for (cs.Position = start; cs.Position < start + length && !cs.IsAtEnd;)
{
if (forStringToken && AtEscapedNewLine(cs))
{
// Ignore this line break within a string
cs.Advance(1);
SkipNewLine(cs);
}
else
{
DecodedChar decodedChar = TextHelpers.DecodeCurrentChar(cs);
if (decodedChar.RequiresUtf32)
{
// http://www.w3.org/TR/CSS21/syndata.html#characters
//
// If the number is outside the range allowed by Unicode (e.g., "\110000" is above the maximum 10FFFF
// allowed in current Unicode), the UA may replace the escape with the "replacement character" (U+FFFD).
int utf32 = decodedChar.CharUtf32;
if ((utf32 < 0) || (utf32 > 0x10FFFF))
{
utf32 = 0xFFFD;
}
sb.Append(char.ConvertFromUtf32(utf32));
}
else
{
sb.Append(decodedChar.Char);
}
cs.Advance(decodedChar.EncodedLength);
}
}
return(sb.ToString());
}
else
{
// Nothing can possibly be encoded, so return the plain string
return(textProvider.GetText(start, length));
}
}
public static void SkipToEOL(CharacterStream cs)
{
while (!(cs.IsAtEnd || TextHelper.IsNewLine(cs.CurrentChar)))
{
cs.Advance(1);
}
}
public static bool SkipWhitespaceReverse(CharacterStream cs)
{
int start = cs.Position;
while (TextHelper.IsWhiteSpace(cs.Peek(-1)))
{
cs.Advance(-1);
}
return(start != cs.Position);
}
public static bool SkipWhitespace(CharacterStream cs)
{
int start = cs.Position;
while (TextHelper.IsWhiteSpace(cs.CurrentChar))
{
cs.Advance(1);
}
return(start != cs.Position);
}
public static bool SkipNewLine(CharacterStream cs)
{
switch (cs.CurrentChar)
{
case '\r':
cs.Advance(1);
if (cs.CurrentChar == '\n')
{
// A "\r\n" pair is always treated as a single line break
cs.Advance(1);
}
return(true);
case '\n':
case '\f':
cs.Advance(1);
return(true);
default:
return(false);
}
}
public static bool SkipEscape(CharacterStream cs)
{
// Skips:
// "\abc " - Unicode escape (notice that the trailing space is included)
// "\X" - Any other character escape (except line breaks)
if (AtUnicodeEscape(cs))
{
return(SkipUnicodeEscape(cs));
}
else if (AtEscape(cs))
{
cs.Advance(2);
return(true);
}
return(false);
}