Question

I’m trying to parse instructions passed in. I want to use regex to validate each substring.
How can I make sure a string ends with a comma? My regex for memory(mips) is also not working.

public static OperandType GetRegisterType(this string source)
        {
            if (Regex.IsMatch(source, @"\$t[0-9]"))
                return OperandType.Temporary; // $t0 - $t9
            if (Regex.IsMatch(source, @"\$s[0-9]"))
                return OperandType.Store; // $s0 - $s9
            if (Regex.IsMatch(source, @"\$k[0-1]"))
                return OperandType.OSReserved; // $k0 - $k1
            if (Regex.IsMatch(source, @"[-+]?\b\d+\b"))
                return OperandType.Constant;
            if (Regex.IsMatch(source, @"\$zero"))
                return OperandType.Special;
            if (Regex.IsMatch(source, @"[a-zA-Z0-9]+\b\:"))
                return OperandType.Label;
            if (Regex.IsMatch(source, @"\d+\b\(\$[s-t]\b[0-9])"))
                return OperandType.Memory;
            return OperandType.Invalid;

        }

example of how to load from memory

lw $t7,248($t2) 

Answer 1

I am not sure what you mean about a string ending with a comma. As far as I can tell you can just write @"\$t[0-9],".

Your memory regex doesn’t match because you have [s-t]\b[0-9]. Since s and t and 0 through 9 are all word characters there cannot be a word boundary between them. Also you have an unescaped closing parenthesis. This @"\d+\(\$[st][0-9]\)" will work.

If your operand list is simply delimited by commas, then split the string on commas and verify each one

string command = "$t7,248($t2)";

string [] operands = command.Split(new Char [] {','});

and your regexes need to be anchored at the beginning and end, like this

if (Regex.IsMatch(source, @"^\$t[0-9]$"))
    return OperandType.Temporary;
if (Regex.IsMatch(source, @"^\$s[0-9]$"))
    return OperandType.Store;

and so on.