public static bool IsIdentifier(Token token)
{
string value = token.Value;
for (int i = value.Length - 1; i >= 0; --i)
{
char c = value[i];
if (i == 0)
{
if (c >= '0' && c <= '9') return false;
}
if (!IDENTIFIER_CHARS.Contains(c))
{
return false;
}
}
return true;
}
private static string GetTokenInfo(Token token)
{
if (token == null) return "[No token info] ";
return token.File + ", Line " + (token.Line + 1) + ", Col " + (token.Col + 1) + " ";
}
public ParserException(Token token, string message)
: base(GetTokenInfo(token) + message)
{
}
public static string RemoveEscapeSequences(Token token, string value)
{
StringBuilder sb = new StringBuilder();
char c;
for (int i = 0; i < value.Length; ++i)
{
c = value[i];
if (c == '\\')
{
if (i + 1 < value.Length)
{
switch (value[i + 1])
{
case 'n': c = '\n'; break;
case 'r': c = '\r'; break;
case 't': c = '\t'; break;
case '\\': c = '\\'; break;
case '0': c = '\0'; break;
case '"': c = '"'; break;
case '\'': c = '\''; break;
default: throw new ParserException(token, "Invalid escape sequence in string.");
}
++i;
}
else
{
throw new ParserException(token, "Backslash at the end.");
}
}
sb.Append(c);
}
return sb.ToString();
}
public static int ParseNumber(Token token, string value, int radix)
{
value = value.ToLowerInvariant();
int output = 0;
for (int i = 0; i < value.Length; ++i)
{
int digitValue = NUMBER_DIGITS.IndexOf(value[i]);
if (digitValue == -1)
{
throw new ParserException(token, "Invalid base " + radix + " constant.");
}
output = output * radix + digitValue;
}
return output;
}
public static double ParseDouble(Token token)
{
string[] parts = token.Value.ToLowerInvariant().Split('e');
if (parts.Length > 2) throw new ParserException(token, "Invalid float constant.");
string value = parts[0];
string exponent = parts.Length == 1 ? "1" : parts[1];
double rootValue;
if (!double.TryParse(value, out rootValue)) throw new ParserException(token, "Invalid float constant.");
int exponentValue;
if (!int.TryParse(exponent, out exponentValue)) throw new ParserException(token, "Invalid float constant.");
if (rootValue == 0 && exponentValue == 0) return 0.0;
return System.Math.Pow(rootValue, exponentValue);
}
