public static String Unescape(this String s)
{
var sb = new System.Text.StringBuilder();
UnescapeState state = UnescapeState.Unescaped;
foreach (var ch in s)
{
switch (state)
{
case UnescapeState.Escaped:
switch (ch)
{
case 't':
sb.Append('\t');
break;
case 'n':
sb.Append('\n');
break;
case 'r':
sb.Append('\r');
break;
case '\\':
case '\"':
sb.Append(ch);
break;
default:
throw new Exception("Unrecognized escape sequence '\\" + ch + "'");
}
state = UnescapeState.Unescaped;
break;
case UnescapeState.Unescaped:
if (ch == '\\')
{
state = UnescapeState.Escaped;
}
else
{
sb.Append(ch);
}
break;
}
}
if (state == UnescapeState.Escaped)
{
throw new Exception("Unterminated escape sequence");
}
return(sb.ToString());
}
public static String Unescape(this String s)
{
var sb = new System.Text.StringBuilder();
UnescapeState state = UnescapeState.Unescaped;
foreach (var ch in s)
{
switch (state)
{
case UnescapeState.Escaped:
switch (ch)
{
case 't':
sb.Append('\t');
break;
case 'n':
sb.Append('\n');
break;
case 'r':
sb.Append('\r');
break;
case '\\':
case '\"':
sb.Append(ch);
break;
default:
throw new Exception("Unrecognized escape sequence '\\" + ch + "'");
// Finally, what about stuff like '\x0a'? That's a much more
// complicated state machine. When you see 'x' in Escaped state,
// you transition to UnescapeState.HexDigit0, then either
// UnescapeState.HexDigit1 or throw an exception, etc.
// Wicked fun to write.
}
state = UnescapeState.Unescaped;
break;
case UnescapeState.Unescaped:
if (ch == '\\')
{
state = UnescapeState.Escaped;
}
else
{
sb.Append(ch);
}
break;
}
}
if (state == UnescapeState.Escaped)
{
throw new Exception("Unterminated escape sequence");
}
return(sb.ToString());
}
