Question

I have a text that is a source-code file, I need to find the first parameter of all calls of this function. That can be called in this 2 ways. I’m completely dumb in regex.

lang('FOUND') and lang('FOUND',[loremipsum])

FOUND should be anything, is this value that I’m searching.

I will execute the Regexp in delphi, but I think regular expression is language independent

EDIT

---

Using the @Ken White answer and this Video I did this code, and works fine!

Regular expression: (?:lang\s*\(\s*')(.*?)(?:'\s*\)|'\s*\,\s*\[.*\]\s*\))

Include the Unit PerlRegEx on Uses

procedure TForm1.Button1Click(Sender: TObject);
var
  Regex: TPerlRegEx;
begin

  Regex := TPerlRegEx.Create();
  Regex.RegEx := '(?:lang\s*\(\s*'')(.*?)(?:''\s*\)|''\s*,\s*\[.*\]\s*\))';
  Regex.Options := [preCaseless, preMultiLine];
  Regex.Subject := Memo1.Text;
  if Regex.Match then
  begin
    repeat

      Memo2.Lines.Add( Regex.Groups[1] );

    until not Regex.MatchAgain;
  end;

end;

Answer 1

(All of the code below was generated by Regex Buddy; I also used it to create the regex used. SubjectString is the content of your source file, loaded into a string; you can load the source file into a stringlist, for instance, and pass the Text.)

Using TPerlRegex, available from the RegEx Buddy website, you can use

var
  Regex: TPerlRegEx;
begin
  ...
  Regex := TPerlRegEx.Create(nil);
  Regex.RegEx := 'lang\((.*)\)';
  Regex.Options := [preMultiLine];
  Regex.Subject := SubjectString;
  if Regex.Match then 
  begin
    repeat
      // matched text: Regex.MatchedExpression;
      // match start: Regex.MatchedExpressionOffset;
      // match length: Regex.MatchedExpressionLength;
      // backreference n text: Regex.SubExpressions[n];
      // backreference n start: Regex.SubExpressionOffsets[n];
      // backreference n length: Regex.SubExpressionLengths[n];
    until not Regex.MatchAgain;
  end;
end;

Using Delphi XE’s regex support (use Regex), you can use

var
  Regex: TRegEx;
  MatchResults: TMatch;
begin
    ...
  try
    Regex := TRegEx.Create('lang\((.*)\)', [roMultiLine]);
    MatchResults := Regex.Match(SubjectString);
    while MatchResults.Success do begin
      MatchResults := MatchResults.NextMatch();
    end;
  except
    on E: ERegularExpressionError do 
    begin
      // Syntax error in the regular expression
    end;
  end;
end;

In both cases, the text you want (the part between the parentheses) will be in capturing group 1 of each match.

I seem to recall from other questions that you’re using Delphi 7, so the first will probably be the best option.