PL/0 Completed?

Brave words! Can it really be completed? There are still things I would like to add but I need to move on. The current state of play is:

1. Recognises most PL/0 dialects.
2. Tolerant to redundant ";"
3. One dimensional arrays
4. Pascal strings

To do:

Would like to add an ASM instruction (pass through to the target CPU).

Rework the error messages to provide better hints.

Here is an example program:

{ Program Test String }
var Str[16],Prompt[16];

  procedure ReadStr;
  var i,test;
  { Read a Pascal string, uses Str }
  begin 
    i:=1;
    test:=1;
    while test=1 do begin
      getc Str[i];
      if Str[i]<32 then begin
        Str:=i-1; { Str == Str[0] }
        test:=0
      end else begin
        if i=16 then begin
          test:=0;
          Str:=i
        end else begin
          i:=i+1
        end
      end
    end
  end;

  procedure WriteStr;
  var i;
  { Write a string, uses Str }
  begin
    i:=1;
    while i<=Str do begin
      putc Str[i];
      i:=i+1
    end
  end;

  procedure WritePrompt;
  var i;
  { Write Prompt }
  begin
    i:=1;
    while i<=Prompt do begin
      putc Prompt[i];
      i:=i+1
    end
  end;

begin
  Prompt:="String Test";
  call WritePrompt;
  putc 10; { new line }

  Prompt:="Enter a string: ";
  call WritePrompt;
  call ReadStr;

  Prompt:="You wrote: ";
  call WritePrompt;
  call WriteStr;
  putc 10; { new line }
end.

And here is the run:

C:\AlanX\pl0>.\PLZero_Tokeniser\PLZero_Tokeniser     -i test18.pl0   -o test18.token -nl

C:\AlanX\pl0>.\PLZero_Compiler\PLZero_Compiler       -i test18.token -o test18.code  -t  test18.table

C:\AlanX\pl0>.\PLZero_Interpreter\PLZero_Interpreter -i test18.code  -o test18.run   -s  test18.stack
String Test
Enter a string: Hello World!
You wrote: Hello World!

C:\AlanX\pl0>pause
Press any key to continue . . .

I think that is pretty cool!

Next

The next task is to write a P-Code to Subleq translator.

AlanX