Hello all,

I trying to build a very small interpreter. I can type commands like:

$ add "Luciano de Souza"

Somewhere in my code, I can have something like:

procedure parse(commandline: string; var params: array of string);

In this case, the commandline has the format: "add %s %s". So I would obtain:

parse('add "Luciano de Souza" ', params);

After this command, the parameter would have the following values:

params[0] := 'add';
params[1] := 'Luciano de Souza';
params[2] := '';

My question is: there is a way to do it easily using a standard class of Freepascal?

Luciano

SScanf from SysUtils unit.

I'd suggest that this depends on two things: the first is whether input is guaranteed to be on a single line, if it is (or if multiple lines could be merged) then you could use something like the standard regular expression unit.

The second is the complexity of your quoting and escaping, and also whether you want to handle Unicode. If you only allow (say) " and restrict it to a single depth, or if you could do an initial rewrite to change nested quotes into something innocuous such as #$ff, then things are comparatively simple.

In other cases use something like recursive descent, or investigate (p)yacc, (p)lex etc.

Use TSTringList.DelimitedText:

  params.Delimiter:=' ';
  params.StrictDelimiter:=false;
  params.QuoteChar:='"';
  params.DelimitedText:='add "Luciano de Souza" ';

results in

 params[0] := 'add';
 params[1] := 'Luciano de Souza';
 params[2] := '';

Ludo

In my 'poor-mans interpreter' I use and pass around TStringList's quite a lot; although some special treatment of the string is required, to preserve spaces within parameter strings.

L.

Or use StrictDelimiter := False like Ludo suggested :)))

L.

I have a parser function somewhere around that can do more than that... let me find it...

2012/5/14 Lukasz Sokol :

Fortunately, my case is the simplest one. There will not quotes inside quotes. Therefore, I believe TStringlists will sove the whole problem. It's really amasing what we can do with a TStringlist.

Thank you for the precious tips!

2012/5/13, luciano de souza :