IMPLEMENTATION MODULE CommandLineInterface;

FROM SYSTEM IMPORT ADR, TSIZE;

FROM Args IMPORT GetArg, Narg;
FROM FIO IMPORT WriteString, WriteChar, WriteLine, StdErr;
FROM Storage IMPORT ALLOCATE;
FROM Strings IMPORT CompareStr, Length;
FROM MemUtils IMPORT MemZero;

FROM Common IMPORT ShortString;

PROCEDURE parse_command_line(): PCommandLine;
VAR
  parameter: ShortString;
  i: CARDINAL;
  result: PCommandLine;
  parsed: BOOLEAN;
BEGIN
  i := 1;
  ALLOCATE(result, TSIZE(CommandLine));
  result^.lex := FALSE;
  result^.parse := FALSE;
  MemZero(ADR(result^.input), 256);

  WHILE (i < Narg()) AND (result <> NIL) DO
    parsed := GetArg(parameter, i);
    parsed := FALSE;

    IF CompareStr(parameter, '--lex') = 0 THEN
      parsed := TRUE;
      result^.lex := TRUE
    END;
    IF CompareStr(parameter, '--parse') = 0 THEN
      parsed := TRUE;
      result^.parse := TRUE
    END;
    IF parameter[1] <> '-' THEN
      parsed := TRUE;

      IF Length(result^.input) > 0 THEN
        WriteString(StdErr, 'Fatal error: only one source file can be compiled at once. First given "');
        WriteString(StdErr, result^.input);
        WriteString(StdErr, '", then "');
        WriteString(StdErr, parameter);
        WriteString(StdErr, '".');
        WriteLine(StdErr);
        result := NIL
      END;
      IF result <> NIL THEN
        result^.input := parameter
      END
    END;
    IF parsed = FALSE THEN
      WriteString(StdErr, 'Fatal error: unknown command line options: ');

      WriteString(StdErr, parameter);
      WriteChar(StdErr, '.');
      WriteLine(StdErr);

      result := NIL
    END;

    i := i + 1
  END;
  IF (result <> NIL) AND (Length(result^.input) = 0) THEN
    WriteString(StdErr, 'Fatal error: no input files.');
    WriteLine(StdErr);
    result := NIL
  END;

  RETURN result
END parse_command_line;
END CommandLineInterface.