Added hex numbers support - Githubissues

nreco / lambdaparser

Runtime parser for string expressions (formulas, method calls). Builds dynamic LINQ expression tree and compiles it to lambda delegate.

http://www.nrecosite.com/

MIT License

309 stars 55 forks source link

Added hex numbers support #28

Open michalf1 opened 4 years ago

VitaliyMF commented 4 years ago

This PR cannot be accepted:

existing tests are not passed, no tests for expressions with hex-numbers
this code can lead to 'index-out-of-range': if (s[lexem.End] == '0' && s[lexem.End + 1] == 'x') {
motivation to have hex-numbers in expressions is not explained. Hex constants are not typical, and when they are needed it is easier to provide custom function in the evaluation context to parse them, something like this:

varContext["ParseInt32"] = (Func<string,int>)((s) => {
  int numConst;
  if (!Int32.TryParse(lexem.GetValue(), NumberStyles.HexNumber, CultureInfo.InvariantCulture, out numConst)) {
    throw new Exception(String.Format("Invalid number: {0}", lexem.GetValue()));
  }
});
Console.WriteLine(lambdaParser.Eval("ParseInt(\"0xFF\")", varContext));

michalf1 commented 4 years ago

Hello Vitaliy, I don't agree that hex constants are not typical (I use them quite often). In my opinion the parser is incomplete without that functionality. Anyway I made some fixes and tests - now it's passing all tests. Br, Michał