p6i Example: Bounded Buffer: Implementation

• Implementaiton --- inst. vars, method bodies.

  bbuf_basei = class implements bbuf
    slot arr:aint, size, cnt, ipt, opt:int
    new = method(n:int) replies(bbuf{empty})                             
      return(bbuf$[arr:aint!new(n),
                   size:n, cnt:0, ipt:0, opt:0]!{empty})
    end new
    put = method({empty,mid}b:bbuf{mid,full}, val:int)
      b.ipt := (b.ipt+1) // b.size; b.cnt := b.cnt + 1
      b.arr[b.ipt] := val
      if b.cnt = b.size then b!{full} else b!{mid} end
    end put
    get = method({full,mid}b:bbuf{mid,empty}) replies(int)
      b.opt := (b.opt + 1) // b.size; b.cnt := b.cnt - 1
      v:int := b.arr[b.opt]
      if b.c = 0 then b!{empty} else b!{mid} end
      return(v)                                 
    end get
  end bbuf_basei