(* searches for E op ..., for any commutative and associative binary
operator.  When this satisfies the isomorphism conditions (ie all minus, or
context for the op and ...), then this is converted to Nested(E,op).
Nested is not used before this phase. *)

module Ast = Ast_cocci
module Ast0 = Ast0_cocci
module V0 = Visitor_ast0
module VT0 = Visitor_ast0_types

let comm_assoc =
  [Ast.Arith(Ast.Plus);Ast.Arith(Ast.Mul);Ast.Arith(Ast.And);Ast.Arith(Ast.Or);
    Ast.Logical(Ast.AndLog);Ast.Logical(Ast.OrLog)]

let is_minus e =
  match Ast0.get_mcodekind e with Ast0.MINUS(cell) -> true | _ -> false

let is_context e =
  !Flag.sgrep_mode2 or (* everything is context for sgrep *)
  (match Ast0.get_mcodekind e with
    Ast0.CONTEXT(cell) -> true
  | _ -> false)

let nopos mc =
  match Ast0.get_pos mc with Ast0.MetaPos _ -> false | Ast0.NoMetaPos -> true

let process_binops rule_name =
  let expr r k e1 =
    let e = k e1 in
    match Ast0.unwrap e with
      Ast0.Binary(left,op,right)
      when List.mem (Ast0.unwrap_mcode op) comm_assoc ->
	(match Ast0.unwrap right with
	  Ast0.Edots(d,None) ->
	    if (is_minus e || (is_context e && is_context right))
		&& nopos op && nopos d
	    (* keep dots to record required modif *)
	    then Ast0.rewrap e (Ast0.Nested(left,op,right))
	    else
	      (Printf.printf
		 "%s: position variables or mixed modifs interfere with comm_assoc iso" rule_name;
	       Unparse_ast0.expression e1;
	       Format.print_newline();
	       e)
	| Ast0.Edots(d,_) ->
	    (Printf.printf
	       "%s: whencode interferes with comm_assoc iso" rule_name;
	     Unparse_ast0.expression e1;
	     Format.print_newline();
	     e)
	| _ -> e)
    | _ -> e in
  V0.rebuilder {V0.rebuilder_functions with VT0.rebuilder_exprfn = expr}

let comm_assoc rule rule_name dropped_isos =
  if List.mem "comm_assoc" dropped_isos
  then rule
  else List.map (process_binops rule_name).VT0.rebuilder_rec_top_level rule