Re: Source to source compiling

Casper Gripenberg <casper@snakemail.hut.fi> wrote:
>The source language is a kind of state langage. 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.
>
>The destination langage is very c-like. With while loops and if-then-else
>statements.
>
>Now the problem is that I don't know how to convert these conditional goto
>statements in the source language to while/if-then-else constructs in the
>destination language. How do I check for eg. loops, and presumably some of
>the goto statements just cannot be translated into if-them-else statements.


Bo:hm & Jacopini did something similar to show any arbitrary flowchart can
be expressed without gotos:


state= 1;
while (state)
    switch (state)
    {
    case 1:
        Do something;
        if (a) state=3; else
        if (b) state=2; else
        etc...


    case 2:
        ....


    case 3:
        ....
    }


You can use state=0 to cause the code to terminate.
You could replace the switch by more nested if-then-elses if your
destination language hasn't got that construct.


I am not sure why you want to check for loops - in general this is akin to
the halting problem isn't it?
--

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