/// <summary>
/// Escape characters inside a text literal
/// </summary>
private string PELEscape(TextPortion SourcePosition, char EscapeChar)
{
StringBuilder sb = new StringBuilder(SourcePosition.Length);
//Last position in the string
var old_pos = SourcePosition.Begin;
//Caret for finding \
var crt = new Caret();
crt.Source = SourcePosition.Text;
string esc_char = EscapeChar.ToString(), esc_chars = esc_char + esc_char;
for (var pos = SourcePosition.Text.IndexOf('\\', SourcePosition.Begin, SourcePosition.Length); pos >= 0; pos = SourcePosition.Text.IndexOf('\\', pos, SourcePosition.End - pos))
{
//Append in-between text
if (pos != old_pos)
sb.Append(SourcePosition.Text.Substring(old_pos, pos - old_pos).Replace(esc_chars, esc_char));
if (pos == SourcePosition.End)
{
ThrowParseError("Expected a character to escape", new TextPortion(pos, 1));
break;
}
pos++;
//End of file
if (pos >= SourcePosition.End)
break;
switch (SourcePosition.Text[pos])
{
case '\\':
sb.Append('\\');
pos++;
break;
case 'r':
case 'R':
sb.Append('\r');
pos++;
break;
case 'n':
case 'N':
sb.Append('\n');
pos++;
break;
case 't':
case 'T':
sb.Append('\t');
pos++;
break;
case 'x':
case 'X':
pos++;
crt.Position = pos;
if (!crt.Match(@"(?<cap>([0-9a-fA-F]{2})+)\\"))
ThrowParseError(
"Expected one or more consecutive 2-digit hexadecimal values, followed by a \\ (eg \\x2A\\, or \\x02A5F2\\)",
new TextPortion(pos, 1));
else
{
var cap = crt.LastMatch.Groups["cap"].Value;
for (int i = 0; i < cap.Length; i += 2)
sb.Append((char) Int16.Parse(cap.Substring(i, 2), NumberStyles.HexNumber));
pos = crt.Position;
}
break;
case 'u':
case 'U':
pos++;
crt.Position = pos;
if (!crt.Match(@"(?<cap>([0-9a-fA-F]{4})+)\\"))
ThrowParseError(
"Expected one or more consecutive 4-digit hexadecimal values, followed by a \\ (eg \\u002A\\, or \\u000200A510F2\\)",
new TextPortion(pos, 1));
else
{
var cap = crt.LastMatch.Groups["cap"].Value;
for (int i = 0; i < cap.Length; i += 4)
sb.Append((char) Int16.Parse(cap.Substring(i, 4), NumberStyles.HexNumber));
pos = crt.Position;
}
break;
default:
ThrowParseError("Unexpected escape character", new TextPortion(pos, 1));
break;
}
old_pos = pos;
}
//Append remaining text
if (old_pos != SourcePosition.End)
sb.Append(SourcePosition.Text, old_pos, SourcePosition.End - old_pos);
return sb.ToString();
}