Intermediate Trees

Well, I have Intermediate Tree (IT) output from my tiger compiler. I received some help with the IT generation, but the text output is just not readable. So, what I did was generated a graphical representation using graphviz.

The most difficult thing about IT generation is following static links. I am going to show you the tree and the code that generates it.

/* define a recursive function */
let

/* calculate n! */
function nfactor(n: int): int =
  if  n = 0 
   then 1
   else n * nfactor(n-1)

in
 nfactor(10)
end

and here is the tree

The tree on the right shows the main code

Can you guess what tree the following code will generate

let 

 type any = {any : int}
 var buffer := getchar()

function readint(any: any) : int =
 let var i := 0
     function isdigit(s : string) : int = 
    ord(buffer)>=ord("0") & 
         ord(buffer)<=ord("9")
     function skipto() =
       while buffer=" " | buffer="\n"
         do buffer := getchar()
  in skipto();
     any.any := isdigit(buffer);
     while isdigit(buffer)
       do (i := i*10+ord(buffer)-ord("0"); 
            buffer := getchar());
     i
 end

 type list = {first: int, rest: list}

 function readlist() : list =
    let var any := any{any=0}
        var i := readint(any)
     in if any.any
         then list{first=i,rest=readlist()}
         else nil
    end

 function merge(a: list, b: list) : list =
   if a=nil then b
   else if b=nil then a
   else if a.first < b.first 
      then 
       list{first=a.first,rest=merge(a.rest,b)}
      else 
       list{first=b.first,rest=merge(a,b.rest)}

 function printint(i: int) =
  let function f(i:int) = if i>0 
      then (f(i/10); 
        print(chr(i-i/10*10+ord("0"))))
   in if i<0 then (print("-"); f(-i))
      else if i>0 then f(i)
      else print("0")
  end

 function printlist(l: list) =
   if l=nil then print("\n")
   else (printint(l.first); print(" "); 
       printlist(l.rest))

   var list1 := readlist()
   var list2 := (buffer:=getchar(); 
                   readlist())


  /* BODY OF MAIN PROGRAM */
 in printlist(merge(list1,list2))
end

Well, the tree could take up a whole room, so here is the
condensed version


If you find too many long left/right subtrees, well they are due to static links. The language is tiger, see Andrew Appel's Home Page for more details

WARNING: The IT have not been checked for correctness, I can only hope they are correct.