[antlr-interest] Question about PL/0 grammar

sunao furukawa sadie at kind.ocn.ne.jp
Tue Jun 21 22:29:02 PDT 2011


Hello,Everybody.
I wrote grammar file from PL/0 ebnf.
But Antlrworks emitted "Break on Enter subrule",then at event "Enter subrule 
2".
I want to proceed parsing grammar file.
Please give me advice,or where to read "The Definitive ANTLR Reference".

Thanks.


<Debug INPUT Script>
const
  m =  7,
  n = 85;

var
  x, y, z, q, r;

procedure multiply;
var a, b;

begin
  a := x;
  b := y;
  z := 0;
  while b > 0 do begin
    if odd b then z := z + a;
    a := 2 * a;
    b := b / 2;
  end
end;

procedure divide;
var w;
begin
  r := x;
  q := 0;
  w := y;
  while w <= r do w := 2 * w;
  while w > y do begin
    q := 2 * q;
    w := w / 2;
    if w <= r then begin
      r := r - w;
      q := q + 1
    end
  end
end;

procedure gcd;
var f, g;
begin
  f := x;
  g := y;
  while f # g do begin
    if f < g then g := g - f;
    if g < f then f := f - g;
  end;
  z := f
end;

begin
  x := m;
  y := n;
  call multiply;
  x := 25;
  y :=  3;
  call divide;
  x := 84;
  y := 36;
  call gcd;
end.
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