Re: Source to source compiling

> I am currently working on a source to source compiler. The source
> language is a kind of state langage. A program containes 1-n states.
> All states have the same kind of structure, ie. in the beginning you
> initilaze variables, then comes some code to execute and at last a
> bunch of conditional jumps to other states.


How about the following (expressed in C-like syntax)? It's simplistic
but it should work okay. If you have case/switch statements available:


state = START_STATE;
while (state != END_STATE)
{
      switch (state)
      {
            case STATE_1:
                  do_something();
                  if (a) { state = STATE_2; break; }
                  if (b) { state = STATE_3; break; }
                  if (c) { state = STATE_4; break; }
                  Error();
                  break;


            case STATE_2:
                  do_something();
                  if (a) { state = STATE_6; break; }
                  if (b) { state = STATE_1; break; }
                  if (c) { state = STATE_5; break; }
                  Error();
                  break;


            etc...


            default:
                  Error();
      }
}




If you don't have case statements but have the continue statement, use
instead:


state = START_STATE;
while (state != END_STATE)
{
      if (state == STATE_1)
      {
            do_something();
            if (a) { state = STATE_2; continue; }
            if (b) { state = STATE_3; continue; }
            if (c) { state = STATE_4; continue; }
            Error();
      }


      if (state == STATE_2)
      {
            do_something();
            if (a) { state = STATE_6; continue; }
            if (b) { state = STATE_1; continue; }
            if (c) { state = STATE_5; continue; }
            Error();
      }


      Error();
}




And finally, if you have neither case statements nor the continue statement:


state = START_STATE;
while (state != END_STATE)
{
      if (state == STATE_1)
      {
            do_something();
            if (a) { state = STATE_2; }
            else if (b) { state = STATE_3; }
            else if (c) { state = STATE_4; }
            else Error();
      }
      else if (state == STATE_2)
      {
            do_something();
            if (a) { state = STATE_6; }
            else if (b) { state = STATE_1; }
            else if (c) { state = STATE_5; }
            else Error();
      }
      else ...
      else Error();
}




> One kludgy solution would be to model every state as a function in the
> destination language. Then every goto statement in the source language
> would simply convert to a function call in the destination language.


You don't want to do that... the activation records would almost
certainly overrun the machine's stack space in a short time.


Good luck,
Chris
--
Chris Frederick
f1rederc@iia.org
--

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