[bpt/coccinelle.git] / parsing_cocci / iso_pattern.ml

(*
 * Copyright 2012, INRIA
 * Julia Lawall, Gilles Muller
 * Copyright 2010-2011, INRIA, University of Copenhagen
 * Julia Lawall, Rene Rydhof Hansen, Gilles Muller, Nicolas Palix
 * Copyright 2005-2009, Ecole des Mines de Nantes, University of Copenhagen
 * Yoann Padioleau, Julia Lawall, Rene Rydhof Hansen, Henrik Stuart, Gilles Muller, Nicolas Palix
 * This file is part of Coccinelle.
 *
 * Coccinelle is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, according to version 2 of the License.
 *
 * Coccinelle is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Coccinelle.  If not, see <http://www.gnu.org/licenses/>.
 *
 * The authors reserve the right to distribute this or future versions of
 * Coccinelle under other licenses.
 *)


# 0 "./iso_pattern.ml"
(* Potential problem: offset of mcode is not updated when an iso is
instantiated, implying that a term may end up with many mcodes with the
same offset.  On the other hand, at the moment offset only seems to be used
before this phase.  Furthermore add_dot_binding relies on the offset to
remain the same between matching an iso and instantiating it with bindings. *)

(* Consider whether ... in iso should match <... ...> in smpl? *)

(* --------------------------------------------------------------------- *)
(* match a SmPL expression against a SmPL abstract syntax tree,
either - or + *)

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

let current_rule = ref ""

(* --------------------------------------------------------------------- *)

type isomorphism =
    Ast_cocci.metavar list * Ast0_cocci.anything list list * string (* name *)

let strip_info =
  let mcode (term,_,_,_,_,_) =
    (term,Ast0.NONE,Ast0.default_info(),Ast0.PLUS Ast.ONE,
     ref [],-1) in
  let donothing r k e =
    let x = k e in
    {(Ast0.wrap (Ast0.unwrap x)) with
      Ast0.mcodekind = ref (Ast0.PLUS Ast.ONE);
      Ast0.true_if_test = x.Ast0.true_if_test} in
  V0.flat_rebuilder
    mcode mcode mcode mcode mcode mcode mcode mcode mcode mcode mcode mcode
    donothing donothing donothing donothing donothing donothing
    donothing donothing donothing donothing donothing donothing donothing
    donothing donothing donothing

let anything_equal = function
    (Ast0.DotsExprTag(d1),Ast0.DotsExprTag(d2)) ->
      failwith "not a possible variable binding" (*not sure why these are pbs*)
  | (Ast0.DotsInitTag(d1),Ast0.DotsInitTag(d2)) ->
      failwith "not a possible variable binding"
  | (Ast0.DotsParamTag(d1),Ast0.DotsParamTag(d2)) ->
      failwith "not a possible variable binding"
  | (Ast0.DotsStmtTag(d1),Ast0.DotsStmtTag(d2)) ->
      (strip_info.VT0.rebuilder_rec_statement_dots d1) =
      (strip_info.VT0.rebuilder_rec_statement_dots d2)
  | (Ast0.DotsDeclTag(d1),Ast0.DotsDeclTag(d2)) ->
      failwith "not a possible variable binding"
  | (Ast0.DotsCaseTag(d1),Ast0.DotsCaseTag(d2)) ->
      failwith "not a possible variable binding"
  | (Ast0.IdentTag(d1),Ast0.IdentTag(d2)) ->
      (strip_info.VT0.rebuilder_rec_ident d1) =
      (strip_info.VT0.rebuilder_rec_ident d2)
  | (Ast0.ExprTag(d1),Ast0.ExprTag(d2)) ->
      (strip_info.VT0.rebuilder_rec_expression d1) =
      (strip_info.VT0.rebuilder_rec_expression d2)
  | (Ast0.ArgExprTag(_),_) | (_,Ast0.ArgExprTag(_)) ->
      failwith "not possible - only in isos1"
  | (Ast0.TestExprTag(_),_) | (_,Ast0.TestExprTag(_)) ->
      failwith "not possible - only in isos1"
  | (Ast0.TypeCTag(d1),Ast0.TypeCTag(d2)) ->
      (strip_info.VT0.rebuilder_rec_typeC d1) =
      (strip_info.VT0.rebuilder_rec_typeC d2)
  | (Ast0.InitTag(d1),Ast0.InitTag(d2)) ->
      (strip_info.VT0.rebuilder_rec_initialiser d1) =
      (strip_info.VT0.rebuilder_rec_initialiser d2)
  | (Ast0.ParamTag(d1),Ast0.ParamTag(d2)) ->
      (strip_info.VT0.rebuilder_rec_parameter d1) =
      (strip_info.VT0.rebuilder_rec_parameter d2)
  | (Ast0.DeclTag(d1),Ast0.DeclTag(d2)) ->
      (strip_info.VT0.rebuilder_rec_declaration d1) =
      (strip_info.VT0.rebuilder_rec_declaration d2)
  | (Ast0.StmtTag(d1),Ast0.StmtTag(d2)) ->
      (strip_info.VT0.rebuilder_rec_statement d1) =
      (strip_info.VT0.rebuilder_rec_statement d2)
  | (Ast0.CaseLineTag(d1),Ast0.CaseLineTag(d2)) ->
      (strip_info.VT0.rebuilder_rec_case_line d1) =
      (strip_info.VT0.rebuilder_rec_case_line d2)
  | (Ast0.TopTag(d1),Ast0.TopTag(d2)) ->
      (strip_info.VT0.rebuilder_rec_top_level d1) =
      (strip_info.VT0.rebuilder_rec_top_level d2)
  | (Ast0.IsoWhenTTag(_),_) | (_,Ast0.IsoWhenTTag(_)) ->
      failwith "only for isos within iso phase"
  | (Ast0.IsoWhenFTag(_),_) | (_,Ast0.IsoWhenFTag(_)) ->
      failwith "only for isos within iso phase"
  | (Ast0.IsoWhenTag(_),_) | (_,Ast0.IsoWhenTag(_)) ->
      failwith "only for isos within iso phase"
  | _ -> false

let term (var1,_,_,_,_,_) = var1
let dot_term (var1,_,info,_,_,_) =
  ("", var1 ^ (string_of_int info.Ast0.pos_info.Ast0.offset))


type reason =
    NotPure of Ast0.pure * Ast.meta_name * Ast0.anything
  | NotPureLength of Ast.meta_name
  | ContextRequired of Ast0.anything
  | NonMatch
  | Braces of Ast0.statement
  | Nest of Ast0.statement
  | Position of Ast.meta_name
  | TypeMatch of reason list

let rec interpret_reason name line reason printer =
  Printf.printf
    "warning: iso %s does not match the code below on line %d\n" name line;
  printer(); Format.print_newline();
  match reason with
    NotPure(Ast0.Pure,(_,var),nonpure) ->
      Printf.printf
        "pure metavariable %s is matched against the following nonpure code:\n"
        var;
      Unparse_ast0.unparse_anything nonpure
  | NotPure(Ast0.Context,(_,var),nonpure) ->
      Printf.printf
        "context metavariable %s is matched against the following\nnoncontext code:\n"
        var;
      Unparse_ast0.unparse_anything nonpure
  | NotPure(Ast0.PureContext,(_,var),nonpure) ->
      Printf.printf
        "pure context metavariable %s is matched against the following\nnonpure or noncontext code:\n"
        var;
      Unparse_ast0.unparse_anything nonpure
  | NotPureLength((_,var)) ->
      Printf.printf
        "pure metavariable %s is matched against too much or too little code\n"
        var;
  | ContextRequired(term) ->
      Printf.printf
        "the following code matched is not uniformly minus or context,\nor contains a disjunction:\n";
      Unparse_ast0.unparse_anything term
  | Braces(s) ->
      Printf.printf "braces must be all minus (plus code allowed) or all\ncontext (plus code not allowed in the body) to match:\n";
      Unparse_ast0.statement "" s;
      Format.print_newline()
  | Nest(s) ->
      Printf.printf "iso with nest doesn't match whencode (TODO):\n";
      Unparse_ast0.statement "" s;
      Format.print_newline()
  | Position(rule,name) ->
      Printf.printf "position variable %s.%s conflicts with an isomorphism\n"
        rule name
   | TypeMatch reason_list ->
      List.iter (function r -> interpret_reason name line r printer)
        reason_list
  | _ -> failwith "not possible"

type 'a either = OK of 'a | Fail of reason

let add_binding var exp bindings =
  let var = term var in
  let attempt bindings =
    try
      let cur = List.assoc var bindings in
      if anything_equal(exp,cur) then [bindings] else []
    with Not_found -> [((var,exp)::bindings)] in
  match List.concat(List.map attempt bindings) with
    [] -> Fail NonMatch
  | x -> OK x

let add_dot_binding var exp bindings =
  let var = dot_term var in
  let attempt bindings =
    try
      let cur = List.assoc var bindings in
      if anything_equal(exp,cur) then [bindings] else []
    with Not_found -> [((var,exp)::bindings)] in
  match List.concat(List.map attempt bindings) with
    [] -> Fail NonMatch
  | x -> OK x

(* multi-valued *)
let add_multi_dot_binding var exp bindings =
  let var = dot_term var in
  let attempt bindings = [((var,exp)::bindings)] in
  match List.concat(List.map attempt bindings) with
    [] -> Fail NonMatch
  | x -> OK x

let rec nub ls =
  match ls with
    [] -> []
  | (x::xs) when (List.mem x xs) -> nub xs
  | (x::xs) -> x::(nub xs)

(* --------------------------------------------------------------------- *)

let init_env = [[]]

let debug str m binding =
  let res = m binding in
  (match res with
    None -> Printf.printf "%s: failed\n" str
  | Some binding ->
      List.iter
        (function binding ->
          Printf.printf "%s: %s\n" str
            (String.concat " " (List.map (function (x,_) -> x) binding)))
        binding);
  res

let conjunct_bindings
    (m1 : 'binding -> 'binding either)
    (m2 : 'binding -> 'binding either)
    (binding : 'binding) : 'binding either =
  match m1 binding with Fail(reason) -> Fail(reason) | OK binding -> m2 binding

let rec conjunct_many_bindings = function
    [] -> failwith "not possible"
  | [x] -> x
  | x::xs -> conjunct_bindings x (conjunct_many_bindings xs)

let mcode_equal (x,_,_,_,_,_) (y,_,_,_,_,_) = x = y

let return b binding = if b then OK binding else Fail NonMatch
let return_false reason binding = Fail reason

let match_option f t1 t2 =
  match (t1,t2) with
    (Some t1, Some t2) -> f t1 t2
  | (None, None) -> return true
  | _ -> return false

let bool_match_option f t1 t2 =
  match (t1,t2) with
    (Some t1, Some t2) -> f t1 t2
  | (None, None) -> true
  | _ -> false

(* context_required is for the example
   if (
+      (int * )
       x == NULL)
  where we can't change x == NULL to eg NULL == x.  So there can either be
  nothing attached to the root or the term has to be all removed.
  if would be nice if we knew more about the relationship between the - and +
  code, because in the case where the + code is a separate statement in a
  sequence, this is not a problem.  Perhaps something could be done in
  insert_plus

   The example seems strange.  Why isn't the cast attached to x?
 *)
let is_context e =
  !Flag.sgrep_mode2 or (* everything is context for sgrep *)
  (match Ast0.get_mcodekind e with
    Ast0.CONTEXT(cell) -> true
  | _ -> false)

(* needs a special case when there is a Disj or an empty DOTS
   the following stops at the statement level, and gives true if one
   statement is replaced by another *)
let rec is_pure_context s =
  !Flag.sgrep_mode2 or (* everything is context for sgrep *)
  (match Ast0.unwrap s with
    Ast0.Disj(starter,statement_dots_list,mids,ender) ->
      List.for_all
        (function x ->
          match Ast0.undots x with
            [s] -> is_pure_context s
          | _ -> false (* could we do better? *))
        statement_dots_list
  | _ ->
      (match Ast0.get_mcodekind s with
        Ast0.CONTEXT(mc) ->
          (match !mc with
            (Ast.NOTHING,_,_) -> true
          | _ -> false)
      | Ast0.MINUS(mc) ->
          (match !mc with
        (* do better for the common case of replacing a stmt by another one *)
            (Ast.REPLACEMENT([[Ast.StatementTag(s)]],_),_) ->
              (match Ast.unwrap s with
                Ast.IfThen(_,_,_) -> false (* potentially dangerous *)
              | _ -> true)
          | (_,_) -> false)
      | _ -> false))

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

let match_list matcher is_list_matcher do_list_match la lb =
  let rec loop = function
      ([],[]) -> return true
    | ([x],lb) when is_list_matcher x -> do_list_match x lb
    | (x::xs,y::ys) -> conjunct_bindings (matcher x y) (loop (xs,ys))
    | _ -> return false in
  loop (la,lb)

let all_caps = Str.regexp "^[A-Z_][A-Z_0-9]*$"

let match_maker checks_needed context_required whencode_allowed =

  let check_mcode pmc (*pattern*) cmc (*code*) binding =
    if checks_needed
    then
      match Ast0.get_pos cmc with
        [] -> OK binding (* no hidden vars in smpl code, so nothing to do *)
      | ((a::_) as hidden_code) ->
          let hidden_pattern =
            List.filter (function Ast0.HiddenVarTag _ -> true | _ -> false)
              (Ast0.get_pos pmc) in
          (match hidden_pattern with
            [Ast0.HiddenVarTag([Ast0.MetaPosTag(Ast0.MetaPos (name1,_,_))])] ->
              add_binding name1 (Ast0.HiddenVarTag(hidden_code)) binding
          | [] -> Fail(Position(Ast0.unwrap_mcode(Ast0.meta_pos_name a)))
          | _ -> failwith "badly compiled iso - multiple hidden variable")
    else OK binding in

  let match_dots matcher is_list_matcher do_list_match d1 d2 =
    match (Ast0.unwrap d1, Ast0.unwrap d2) with
      (Ast0.DOTS(la),Ast0.DOTS(lb))
    | (Ast0.CIRCLES(la),Ast0.CIRCLES(lb))
    | (Ast0.STARS(la),Ast0.STARS(lb)) ->
        match_list matcher is_list_matcher (do_list_match d2) la lb
    | _ -> return false in

  let is_elist_matcher el =
    match Ast0.unwrap el with Ast0.MetaExprList(_,_,_) -> true | _ -> false in

  let is_plist_matcher pl =
    match Ast0.unwrap pl with Ast0.MetaParamList(_,_,_) -> true | _ -> false in

  let is_slist_matcher pl =
    match Ast0.unwrap pl with Ast0.MetaStmtList(_,_) -> true | _ -> false in

  let no_list _ = false in

  let build_dots pattern data =
    match Ast0.unwrap pattern with
      Ast0.DOTS(_) -> Ast0.rewrap pattern (Ast0.DOTS(data))
    | Ast0.CIRCLES(_) -> Ast0.rewrap pattern (Ast0.CIRCLES(data))
    | Ast0.STARS(_) -> Ast0.rewrap pattern (Ast0.STARS(data)) in

  let pure_sp_code =
    let bind = Ast0.lub_pure in
    let option_default = Ast0.Context in
    let pure_mcodekind mc =
      if !Flag.sgrep_mode2
      then Ast0.PureContext
      else
        match mc with
          Ast0.CONTEXT(mc) ->
            (match !mc with
              (Ast.NOTHING,_,_) -> Ast0.PureContext
            | _ -> Ast0.Context)
        | Ast0.MINUS(mc) ->
            (match !mc with
              (Ast.NOREPLACEMENT,_) -> Ast0.Pure
            | _ ->  Ast0.Impure)
        | _ -> Ast0.Impure in
    let donothing r k e =
      bind (pure_mcodekind (Ast0.get_mcodekind e)) (k e) in

    let mcode m = pure_mcodekind (Ast0.get_mcode_mcodekind m) in

    (* a case for everything that has a metavariable *)
    (* pure is supposed to match only unitary metavars, not anything that
       contains only unitary metavars *)
    let ident r k i =
      bind (bind (pure_mcodekind (Ast0.get_mcodekind i)) (k i))
        (match Ast0.unwrap i with
          Ast0.MetaId(name,_,_,pure) | Ast0.MetaFunc(name,_,pure)
        | Ast0.MetaLocalFunc(name,_,pure) -> pure
        | _ -> Ast0.Impure) in

    let expression r k e =
      bind (bind (pure_mcodekind (Ast0.get_mcodekind e)) (k e))
        (match Ast0.unwrap e with
          Ast0.MetaErr(name,_,pure)
        | Ast0.MetaExpr(name,_,_,_,pure) | Ast0.MetaExprList(name,_,pure) ->
            pure
        | _ -> Ast0.Impure) in

    let typeC r k t =
      bind (bind (pure_mcodekind (Ast0.get_mcodekind t)) (k t))
        (match Ast0.unwrap t with
          Ast0.MetaType(name,pure) -> pure
        | _ -> Ast0.Impure) in

    let init r k t =
      bind (bind (pure_mcodekind (Ast0.get_mcodekind t)) (k t))
        (match Ast0.unwrap t with
          Ast0.MetaInit(name,pure) | Ast0.MetaInitList(name,_,pure) -> pure
        | _ -> Ast0.Impure) in

    let param r k p =
      bind (bind (pure_mcodekind (Ast0.get_mcodekind p)) (k p))
        (match Ast0.unwrap p with
          Ast0.MetaParam(name,pure) | Ast0.MetaParamList(name,_,pure) -> pure
        | _ -> Ast0.Impure) in

    let decl r k d =
      bind (bind (pure_mcodekind (Ast0.get_mcodekind d)) (k d))
        (match Ast0.unwrap d with
          Ast0.MetaDecl(name,pure) | Ast0.MetaField(name,pure)
        | Ast0.MetaFieldList(name,_,pure) ->
            pure
        | _ -> Ast0.Impure) in

    let stmt r k s =
      bind (bind (pure_mcodekind (Ast0.get_mcodekind s)) (k s))
        (match Ast0.unwrap s with
          Ast0.MetaStmt(name,pure) | Ast0.MetaStmtList(name,pure) -> pure
        | _ -> Ast0.Impure) in

    V0.flat_combiner bind option_default
      mcode mcode mcode mcode mcode mcode mcode mcode mcode mcode mcode mcode
      donothing donothing donothing donothing donothing donothing
      ident expression typeC init param decl stmt donothing donothing
      donothing in

  let add_pure_list_binding name pure is_pure builder1 builder2 lst =
    match (checks_needed,pure) with
      (true,Ast0.Pure) | (true,Ast0.Context) | (true,Ast0.PureContext) ->
        (match lst with
          [x] ->
            if (Ast0.lub_pure (is_pure x) pure) = pure
            then add_binding name (builder1 lst)
            else return_false (NotPure (pure,term name,builder1 lst))
        | _ -> return_false (NotPureLength (term name)))
    | (false,_) | (_,Ast0.Impure) -> add_binding name (builder2 lst) in

  let add_pure_binding name pure is_pure builder x =
    match (checks_needed,pure) with
      (true,Ast0.Pure) | (true,Ast0.Context) | (true,Ast0.PureContext) ->
        if (Ast0.lub_pure (is_pure x) pure) = pure
        then add_binding name (builder x)
        else return_false (NotPure (pure,term name, builder x))
    | (false,_) | (_,Ast0.Impure) ->  add_binding name (builder x) in

  let do_elist_match builder el lst =
    match Ast0.unwrap el with
      Ast0.MetaExprList(name,lenname,pure) ->
        (*how to handle lenname? should it be an option type and always None?*)
        failwith "expr list pattern not supported in iso"
        (*add_pure_list_binding name pure
          pure_sp_code.V0.combiner_expression
          (function lst -> Ast0.ExprTag(List.hd lst))
          (function lst -> Ast0.DotsExprTag(build_dots builder lst))
          lst*)
    | _ -> failwith "not possible" in

  let do_plist_match builder pl lst =
    match Ast0.unwrap pl with
      Ast0.MetaParamList(name,lename,pure) ->
        failwith "param list pattern not supported in iso"
        (*add_pure_list_binding name pure
          pure_sp_code.V0.combiner_parameter
          (function lst -> Ast0.ParamTag(List.hd lst))
          (function lst -> Ast0.DotsParamTag(build_dots builder lst))
          lst*)
    | _ -> failwith "not possible" in

  let do_slist_match builder sl lst =
    match Ast0.unwrap sl with
      Ast0.MetaStmtList(name,pure) ->
        add_pure_list_binding name pure
          pure_sp_code.VT0.combiner_rec_statement
          (function lst -> Ast0.StmtTag(List.hd lst))
          (function lst -> Ast0.DotsStmtTag(build_dots builder lst))
          lst
    | _ -> failwith "not possible" in

  let do_nolist_match _ _ = failwith "not possible" in

  let rec match_ident pattern id =
    match Ast0.unwrap pattern with
      Ast0.MetaId(name,_,_,pure) ->
        (add_pure_binding name pure pure_sp_code.VT0.combiner_rec_ident
          (function id -> Ast0.IdentTag id) id)
    | Ast0.MetaFunc(name,_,pure) -> failwith "metafunc not supported"
    | Ast0.MetaLocalFunc(name,_,pure) -> failwith "metalocalfunc not supported"
    | up ->
        if not(checks_needed) or not(context_required) or is_context id
        then
          match (up,Ast0.unwrap id) with
            (Ast0.Id(namea),Ast0.Id(nameb)) ->
              if mcode_equal namea nameb
              then check_mcode namea nameb
              else return false
          | (Ast0.DisjId(_,ids,_,_),_) ->
              failwith "not allowed in the pattern of an isomorphism"
          | (Ast0.OptIdent(ida),Ast0.OptIdent(idb))
          | (Ast0.UniqueIdent(ida),Ast0.UniqueIdent(idb)) ->
              match_ident ida idb
          | (_,Ast0.OptIdent(idb))
          | (_,Ast0.UniqueIdent(idb)) -> match_ident pattern idb
          | _ -> return false
        else return_false (ContextRequired (Ast0.IdentTag id)) in

  (* should we do something about matching metavars against ...? *)
  let rec match_expr pattern expr =
    match Ast0.unwrap pattern with
      Ast0.MetaExpr(name,_,ty,form,pure) ->
        let form_ok =
          match (form,expr) with
            (Ast.ANY,_) -> true
          | (Ast.CONST,e) ->
              let rec matches e =
                match Ast0.unwrap e with
                  Ast0.Constant(c) -> true
                | Ast0.Ident(c) ->
                    (match Ast0.unwrap c with
                      Ast0.Id(nm) ->
                        let nm = Ast0.unwrap_mcode nm in
                        (* all caps is a const *)
                        Str.string_match all_caps nm 0
                    | _ -> false)
                | Ast0.Cast(lp,ty,rp,e) -> matches e
                | Ast0.SizeOfExpr(se,exp) -> true
                | Ast0.SizeOfType(se,lp,ty,rp) -> true
                | Ast0.MetaExpr(nm,_,_,Ast.CONST,p) ->
                    (Ast0.lub_pure p pure) = pure
                | _ -> false in
              matches e
          | (Ast.ID,e) | (Ast.LocalID,e) ->
              let rec matches e =
                match Ast0.unwrap e with
                  Ast0.Ident(c) -> true
                | Ast0.Cast(lp,ty,rp,e) -> matches e
                | Ast0.MetaExpr(nm,_,_,Ast.ID,p) ->
                    (Ast0.lub_pure p pure) = pure
                | _ -> false in
              matches e in
        if form_ok
        then
          match ty with
            Some ts ->
              if List.exists
                  (function Type_cocci.MetaType(_,_,_) -> true | _ -> false)
                  ts
              then
                (match ts with
                  [Type_cocci.MetaType(tyname,_,_)] ->
                    let expty =
                      match (Ast0.unwrap expr,Ast0.get_type expr) with
                  (* easier than updating type inferencer to manage multiple
                     types *)
                        (Ast0.MetaExpr(_,_,Some tts,_,_),_) -> Some tts
                      | (_,Some ty) -> Some [ty]
                      | _ -> None in
                    (match expty with
                      Some expty ->
                        let tyname = Ast0.rewrap_mcode name tyname in
                        conjunct_bindings
                          (add_pure_binding name pure
                             pure_sp_code.VT0.combiner_rec_expression
                             (function expr -> Ast0.ExprTag expr)
                             expr)
                          (function bindings ->
                            let attempts =
                              List.map
                                (function expty ->
                                  (try
                                    add_pure_binding tyname Ast0.Impure
                                      (function _ -> Ast0.Impure)
                                      (function ty -> Ast0.TypeCTag ty)
                                      (Ast0.rewrap expr
                                         (Ast0.reverse_type expty))
                                      bindings
                                  with Ast0.TyConv ->
                                    Printf.printf
                                      "warning: unconvertible type";
                                    return false bindings))
                                expty in
                            if List.exists
                                (function Fail _ -> false | OK x -> true)
                                attempts
                            then
                                (* not sure why this is ok. can there be more
                                   than one OK? *)
                              OK (List.concat
                                    (List.map
                                       (function Fail _ -> [] | OK x -> x)
                                       attempts))
                            else
                              Fail
                                (TypeMatch
                                   (List.map
                                      (function
                                          Fail r -> r
                                        | OK x -> failwith "not possible")
                                      attempts)))
                    | _ ->
                  (*Printf.printf
                     "warning: type metavar can only match one type";*)
                        return false)
                | _ ->
                    failwith
                      "mixture of metatype and other types not supported")
              else
                let expty = Ast0.get_type expr in
                if List.exists (function t -> Type_cocci.compatible t expty) ts
                then
                  add_pure_binding name pure
                    pure_sp_code.VT0.combiner_rec_expression
                    (function expr -> Ast0.ExprTag expr)
                    expr
                else return false
          | None ->
              add_pure_binding name pure
                pure_sp_code.VT0.combiner_rec_expression
                (function expr -> Ast0.ExprTag expr)
                expr
        else return false
    | Ast0.MetaErr(namea,_,pure) -> failwith "metaerr not supported"
    | Ast0.MetaExprList(_,_,_) -> failwith "metaexprlist not supported"
    | up ->
        if not(checks_needed) or not(context_required) or is_context expr
        then
          match (up,Ast0.unwrap expr) with
            (Ast0.Ident(ida),Ast0.Ident(idb)) ->
              match_ident ida idb
          | (Ast0.Constant(consta),Ast0.Constant(constb)) ->
              if mcode_equal consta constb
              then check_mcode consta constb
              else return false
          | (Ast0.FunCall(fna,lp1,argsa,rp1),Ast0.FunCall(fnb,lp,argsb,rp)) ->
              conjunct_many_bindings
                [check_mcode lp1 lp; check_mcode rp1 rp; match_expr fna fnb;
                  match_dots match_expr is_elist_matcher do_elist_match
                    argsa argsb]
          | (Ast0.Assignment(lefta,opa,righta,_),
             Ast0.Assignment(leftb,opb,rightb,_)) ->
               if mcode_equal opa opb
               then
                 conjunct_many_bindings
                   [check_mcode opa opb; match_expr lefta leftb;
                     match_expr righta rightb]
               else return false
          | (Ast0.Sequence(lefta,opa,righta),
             Ast0.Sequence(leftb,opb,rightb)) ->
               if mcode_equal opa opb
               then
                 conjunct_many_bindings
                   [check_mcode opa opb; match_expr lefta leftb;
                     match_expr righta rightb]
               else return false
          | (Ast0.CondExpr(exp1a,lp1,exp2a,rp1,exp3a),
             Ast0.CondExpr(exp1b,lp,exp2b,rp,exp3b)) ->
               conjunct_many_bindings
                 [check_mcode lp1 lp; check_mcode rp1 rp;
                   match_expr exp1a exp1b; match_option match_expr exp2a exp2b;
                   match_expr exp3a exp3b]
          | (Ast0.Postfix(expa,opa),Ast0.Postfix(expb,opb)) ->
              if mcode_equal opa opb
              then
                conjunct_bindings (check_mcode opa opb) (match_expr expa expb)
              else return false
          | (Ast0.Infix(expa,opa),Ast0.Infix(expb,opb)) ->
              if mcode_equal opa opb
              then
                conjunct_bindings (check_mcode opa opb) (match_expr expa expb)
              else return false
          | (Ast0.Unary(expa,opa),Ast0.Unary(expb,opb)) ->
              if mcode_equal opa opb
              then
                conjunct_bindings (check_mcode opa opb) (match_expr expa expb)
              else return false
          | (Ast0.Binary(lefta,opa,righta),Ast0.Binary(leftb,opb,rightb)) ->
              if mcode_equal opa opb
              then
                conjunct_many_bindings
                  [check_mcode opa opb; match_expr lefta leftb;
                    match_expr righta rightb]
              else return false
          | (Ast0.Paren(lp1,expa,rp1),Ast0.Paren(lp,expb,rp)) ->
              conjunct_many_bindings
                [check_mcode lp1 lp; check_mcode rp1 rp; match_expr expa expb]
          | (Ast0.ArrayAccess(exp1a,lb1,exp2a,rb1),
             Ast0.ArrayAccess(exp1b,lb,exp2b,rb)) ->
               conjunct_many_bindings
                 [check_mcode lb1 lb; check_mcode rb1 rb;
                   match_expr exp1a exp1b; match_expr exp2a exp2b]
          | (Ast0.RecordAccess(expa,opa,fielda),
             Ast0.RecordAccess(expb,op,fieldb))
          | (Ast0.RecordPtAccess(expa,opa,fielda),
             Ast0.RecordPtAccess(expb,op,fieldb)) ->
               conjunct_many_bindings
                 [check_mcode opa op; match_expr expa expb;
                   match_ident fielda fieldb]
          | (Ast0.Cast(lp1,tya,rp1,expa),Ast0.Cast(lp,tyb,rp,expb)) ->
              conjunct_many_bindings
                [check_mcode lp1 lp; check_mcode rp1 rp;
                  match_typeC tya tyb; match_expr expa expb]
          | (Ast0.SizeOfExpr(szf1,expa),Ast0.SizeOfExpr(szf,expb)) ->
              conjunct_bindings (check_mcode szf1 szf) (match_expr expa expb)
          | (Ast0.SizeOfType(szf1,lp1,tya,rp1),
             Ast0.SizeOfType(szf,lp,tyb,rp)) ->
               conjunct_many_bindings
                 [check_mcode lp1 lp; check_mcode rp1 rp;
                   check_mcode szf1 szf; match_typeC tya tyb]
          | (Ast0.Constructor(lp1,tya,rp1,inita),
             Ast0.Constructor(lp,tyb,rp,initb)) ->
               conjunct_many_bindings
                 [check_mcode lp1 lp; check_mcode rp1 rp;
                   match_typeC tya tyb; match_init inita initb]
          | (Ast0.TypeExp(tya),Ast0.TypeExp(tyb)) ->
              match_typeC tya tyb
          | (Ast0.EComma(cm1),Ast0.EComma(cm)) -> check_mcode cm1 cm
          | (Ast0.DisjExpr(_,expsa,_,_),_) ->
              failwith "not allowed in the pattern of an isomorphism"
          | (Ast0.NestExpr(_,exp_dotsa,_,_,_),_) ->
              failwith "not allowed in the pattern of an isomorphism"
          | (Ast0.Edots(d,None),Ast0.Edots(d1,None))
          | (Ast0.Ecircles(d,None),Ast0.Ecircles(d1,None))
          | (Ast0.Estars(d,None),Ast0.Estars(d1,None)) -> check_mcode d d1
          | (Ast0.Edots(ed,None),Ast0.Edots(ed1,Some wc))
          | (Ast0.Ecircles(ed,None),Ast0.Ecircles(ed1,Some wc))
          | (Ast0.Estars(ed,None),Ast0.Estars(ed1,Some wc)) ->
            (* hope that mcode of edots is unique somehow *)
              conjunct_bindings (check_mcode ed ed1)
                (let (edots_whencode_allowed,_,_) = whencode_allowed in
                if edots_whencode_allowed
                then add_dot_binding ed (Ast0.ExprTag wc)
                else
                  (Printf.printf
                     "warning: not applying iso because of whencode";
                   return false))
          | (Ast0.Edots(_,Some _),_) | (Ast0.Ecircles(_,Some _),_)
          | (Ast0.Estars(_,Some _),_) ->
              failwith "whencode not allowed in a pattern1"
          | (Ast0.OptExp(expa),Ast0.OptExp(expb))
          | (Ast0.UniqueExp(expa),Ast0.UniqueExp(expb)) ->
              match_expr expa expb
          | (_,Ast0.OptExp(expb))
          | (_,Ast0.UniqueExp(expb)) -> match_expr pattern expb
          | _ -> return false
        else return_false (ContextRequired (Ast0.ExprTag expr))

(* the special case for function types prevents the eg T X; -> T X = E; iso
   from applying, which doesn't seem very relevant, but it also avoids a
   mysterious bug that is obtained with eg int attach(...); *)
  and match_typeC pattern t =
    match Ast0.unwrap pattern with
      Ast0.MetaType(name,pure) ->
        (match Ast0.unwrap t with
          Ast0.FunctionType(tya,lp1a,paramsa,rp1a) -> return false
        | _ ->
            add_pure_binding name pure pure_sp_code.VT0.combiner_rec_typeC
              (function ty -> Ast0.TypeCTag ty)
              t)
    | up ->
        if not(checks_needed) or not(context_required) or is_context t
        then
          match (up,Ast0.unwrap t) with
            (Ast0.ConstVol(cva,tya),Ast0.ConstVol(cvb,tyb)) ->
              if mcode_equal cva cvb
              then
                conjunct_bindings (check_mcode cva cvb) (match_typeC tya tyb)
              else return false
          | (Ast0.BaseType(tya,stringsa),Ast0.BaseType(tyb,stringsb)) ->
              if tya = tyb
              then
                match_list check_mcode
                  (function _ -> false) (function _ -> failwith "")
                  stringsa stringsb
              else return false
          | (Ast0.Signed(signa,tya),Ast0.Signed(signb,tyb)) ->
              if mcode_equal signa signb
              then
                conjunct_bindings (check_mcode signa signb)
                  (match_option match_typeC tya tyb)
              else return false
          | (Ast0.Pointer(tya,star1),Ast0.Pointer(tyb,star)) ->
              conjunct_bindings (check_mcode star1 star) (match_typeC tya tyb)
          | (Ast0.FunctionPointer(tya,lp1a,stara,rp1a,lp2a,paramsa,rp2a),
             Ast0.FunctionPointer(tyb,lp1b,starb,rp1b,lp2b,paramsb,rp2b)) ->
               conjunct_many_bindings
                 [check_mcode stara starb; check_mcode lp1a lp1b;
                   check_mcode rp1a rp1b; check_mcode lp2a lp2b;
                   check_mcode rp2a rp2b; match_typeC tya tyb;
                   match_dots match_param is_plist_matcher
                     do_plist_match paramsa paramsb]
          | (Ast0.FunctionType(tya,lp1a,paramsa,rp1a),
             Ast0.FunctionType(tyb,lp1b,paramsb,rp1b)) ->
               conjunct_many_bindings
                 [check_mcode lp1a lp1b; check_mcode rp1a rp1b;
                   match_option match_typeC tya tyb;
                   match_dots match_param is_plist_matcher do_plist_match
                     paramsa paramsb]
          | (Ast0.Array(tya,lb1,sizea,rb1),Ast0.Array(tyb,lb,sizeb,rb)) ->
              conjunct_many_bindings
                [check_mcode lb1 lb; check_mcode rb1 rb;
                  match_typeC tya tyb; match_option match_expr sizea sizeb]
          | (Ast0.EnumName(kinda,Some namea),
             Ast0.EnumName(kindb,Some nameb)) ->
               conjunct_bindings (check_mcode kinda kindb)
                 (match_ident namea nameb)
          | (Ast0.EnumDef(tya,lb1,idsa,rb1),
             Ast0.EnumDef(tyb,lb,idsb,rb)) ->
               conjunct_many_bindings
                 [check_mcode lb1 lb; check_mcode rb1 rb;
                   match_typeC tya tyb;
                   match_dots match_expr no_list do_nolist_match idsa idsb]
          | (Ast0.StructUnionName(kinda,Some namea),
             Ast0.StructUnionName(kindb,Some nameb)) ->
               if mcode_equal kinda kindb
               then
                 conjunct_bindings (check_mcode kinda kindb)
                   (match_ident namea nameb)
               else return false
          | (Ast0.StructUnionDef(tya,lb1,declsa,rb1),
             Ast0.StructUnionDef(tyb,lb,declsb,rb)) ->
               conjunct_many_bindings
                 [check_mcode lb1 lb; check_mcode rb1 rb;
                   match_typeC tya tyb;
                   match_dots match_decl no_list do_nolist_match declsa declsb]
          | (Ast0.TypeName(namea),Ast0.TypeName(nameb)) ->
              if mcode_equal namea nameb
              then check_mcode namea nameb
              else return false
          | (Ast0.DisjType(_,typesa,_,_),_) ->
              failwith "not allowed in the pattern of an isomorphism"
          | (Ast0.OptType(tya),Ast0.OptType(tyb))
          | (Ast0.UniqueType(tya),Ast0.UniqueType(tyb)) -> match_typeC tya tyb
          | (_,Ast0.OptType(tyb))
          | (_,Ast0.UniqueType(tyb)) -> match_typeC pattern tyb
          | _ -> return false
        else return_false (ContextRequired (Ast0.TypeCTag t))

  and match_decl pattern d =
    match Ast0.unwrap pattern with
      Ast0.MetaDecl(name,pure) ->
        add_pure_binding name pure pure_sp_code.VT0.combiner_rec_declaration
          (function d -> Ast0.DeclTag d)
          d
    | Ast0.MetaField(name,pure) ->
        add_pure_binding name pure pure_sp_code.VT0.combiner_rec_declaration
          (function d -> Ast0.DeclTag d)
          d
    | Ast0.MetaFieldList(name,_,pure) -> failwith "metafieldlist not supporte"
    | up ->
        if not(checks_needed) or not(context_required) or is_context d
        then
          match (up,Ast0.unwrap d) with
            (Ast0.Init(stga,tya,ida,eq1,inia,sc1),
             Ast0.Init(stgb,tyb,idb,eq,inib,sc)) ->
               if bool_match_option mcode_equal stga stgb
               then
                 conjunct_many_bindings
                   [check_mcode eq1 eq; check_mcode sc1 sc;
                     match_option check_mcode stga stgb;
                     match_typeC tya tyb; match_ident ida idb;
                     match_init inia inib]
               else return false
          | (Ast0.UnInit(stga,tya,ida,sc1),Ast0.UnInit(stgb,tyb,idb,sc)) ->
              if bool_match_option mcode_equal stga stgb
              then
                conjunct_many_bindings
                  [check_mcode sc1 sc; match_option check_mcode stga stgb;
                    match_typeC tya tyb; match_ident ida idb]
              else return false
          | (Ast0.MacroDecl(namea,lp1,argsa,rp1,sc1),
             Ast0.MacroDecl(nameb,lp,argsb,rp,sc)) ->
               conjunct_many_bindings
                 [match_ident namea nameb;
                   check_mcode lp1 lp; check_mcode rp1 rp;
                   check_mcode sc1 sc;
                   match_dots match_expr is_elist_matcher do_elist_match
                     argsa argsb]
          | (Ast0.MacroDeclInit(namea,lp1,argsa,rp1,eq1,ini1,sc1),
             Ast0.MacroDeclInit(nameb,lp,argsb,rp,eq,ini,sc)) ->
               conjunct_many_bindings
                 [match_ident namea nameb;
                   check_mcode lp1 lp; check_mcode rp1 rp;
                   check_mcode eq1 eq;
                   check_mcode sc1 sc;
                   match_dots match_expr is_elist_matcher do_elist_match
                     argsa argsb;
                   match_init ini1 ini]
          | (Ast0.TyDecl(tya,sc1),Ast0.TyDecl(tyb,sc)) ->
              conjunct_bindings (check_mcode sc1 sc) (match_typeC tya tyb)
          | (Ast0.Typedef(stga,tya,ida,sc1),Ast0.Typedef(stgb,tyb,idb,sc)) ->
              conjunct_bindings (check_mcode sc1 sc)
                (conjunct_bindings (match_typeC tya tyb) (match_typeC ida idb))
          | (Ast0.DisjDecl(_,declsa,_,_),_) ->
              failwith "not allowed in the pattern of an isomorphism"
          | (Ast0.Ddots(d1,None),Ast0.Ddots(d,None)) -> check_mcode d1 d
          |     (Ast0.Ddots(dd,None),Ast0.Ddots(d,Some wc)) ->
              conjunct_bindings (check_mcode dd d)
            (* hope that mcode of ddots is unique somehow *)
                (let (ddots_whencode_allowed,_,_) = whencode_allowed in
                if ddots_whencode_allowed
                then add_dot_binding dd (Ast0.DeclTag wc)
                else
                  (Printf.printf "warning: not applying iso because of whencode";
                   return false))
          | (Ast0.Ddots(_,Some _),_) ->
              failwith "whencode not allowed in a pattern1"
                
          | (Ast0.OptDecl(decla),Ast0.OptDecl(declb))
          | (Ast0.UniqueDecl(decla),Ast0.UniqueDecl(declb)) ->
              match_decl decla declb
          | (_,Ast0.OptDecl(declb))
          | (_,Ast0.UniqueDecl(declb)) ->
              match_decl pattern declb
          | _ -> return false
        else return_false (ContextRequired (Ast0.DeclTag d))

  and match_init pattern i =
    match Ast0.unwrap pattern with
      Ast0.MetaInit(name,pure) ->
        add_pure_binding name pure pure_sp_code.VT0.combiner_rec_initialiser
          (function ini -> Ast0.InitTag ini)
          i
    | up ->
        if not(checks_needed) or not(context_required) or is_context i
        then
          match (up,Ast0.unwrap i) with
            (Ast0.InitExpr(expa),Ast0.InitExpr(expb)) ->
              match_expr expa expb
          | (Ast0.InitList(lb1,initlista,rb1,oa),
             Ast0.InitList(lb,initlistb,rb,ob))
            when oa = ob ->
              conjunct_many_bindings
                [check_mcode lb1 lb; check_mcode rb1 rb;
                  match_dots match_init no_list do_nolist_match
                    initlista initlistb]
          | (Ast0.InitGccExt(designators1,e1,inia),
             Ast0.InitGccExt(designators2,e2,inib)) ->
               conjunct_many_bindings
                 [match_list match_designator
                     (function _ -> false) (function _ -> failwith "")
                     designators1 designators2;
                   check_mcode e1 e2;
                   match_init inia inib]
          | (Ast0.InitGccName(namea,c1,inia),Ast0.InitGccName(nameb,c,inib)) ->
              conjunct_many_bindings
                [check_mcode c1 c; match_ident namea nameb;
                  match_init inia inib]
          | (Ast0.IComma(c1),Ast0.IComma(c)) -> check_mcode c1 c
          | (Ast0.Idots(d1,None),Ast0.Idots(d,None)) -> check_mcode d1 d
          | (Ast0.Idots(id,None),Ast0.Idots(d,Some wc)) ->
              conjunct_bindings (check_mcode id d)
          (* hope that mcode of edots is unique somehow *)
                (let (_,idots_whencode_allowed,_) = whencode_allowed in
                if idots_whencode_allowed
                then add_dot_binding id (Ast0.InitTag wc)
                else
                  (Printf.printf
                     "warning: not applying iso because of whencode";
                   return false))
          | (Ast0.Idots(_,Some _),_) ->
              failwith "whencode not allowed in a pattern2"
          | (Ast0.OptIni(ia),Ast0.OptIni(ib))
          | (Ast0.UniqueIni(ia),Ast0.UniqueIni(ib)) -> match_init ia ib
          | (_,Ast0.OptIni(ib))
          | (_,Ast0.UniqueIni(ib)) -> match_init pattern ib
          | _ -> return false
        else return_false (ContextRequired (Ast0.InitTag i))

  and match_designator pattern d =
    match (pattern,d) with
      (Ast0.DesignatorField(dota,ida),Ast0.DesignatorField(dotb,idb)) ->
        conjunct_bindings (check_mcode dota dotb) (match_ident ida idb)
    | (Ast0.DesignatorIndex(lba,expa,rba),
       Ast0.DesignatorIndex(lbb,expb,rbb)) ->
         conjunct_many_bindings
           [check_mcode lba lbb; match_expr expa expb;
             check_mcode rba rbb]
    | (Ast0.DesignatorRange(lba,mina,dotsa,maxa,rba),
       Ast0.DesignatorRange(lbb,minb,dotsb,maxb,rbb)) ->
         conjunct_many_bindings
           [check_mcode lba lbb; match_expr mina minb;
             check_mcode dotsa dotsb; match_expr maxa maxb;
             check_mcode rba rbb]
    | _ -> return false

  and match_param pattern p =
    match Ast0.unwrap pattern with
      Ast0.MetaParam(name,pure) ->
        add_pure_binding name pure pure_sp_code.VT0.combiner_rec_parameter
          (function p -> Ast0.ParamTag p)
          p
    | Ast0.MetaParamList(name,_,pure) -> failwith "metaparamlist not supported"
    | up ->
        if not(checks_needed) or not(context_required) or is_context p
        then
          match (up,Ast0.unwrap p) with
            (Ast0.VoidParam(tya),Ast0.VoidParam(tyb)) -> match_typeC tya tyb
          | (Ast0.Param(tya,ida),Ast0.Param(tyb,idb)) ->
              conjunct_bindings (match_typeC tya tyb)
                (match_option match_ident ida idb)
          | (Ast0.PComma(c1),Ast0.PComma(c)) -> check_mcode c1 c
          | (Ast0.Pdots(d1),Ast0.Pdots(d))
          | (Ast0.Pcircles(d1),Ast0.Pcircles(d)) -> check_mcode d1 d
          | (Ast0.OptParam(parama),Ast0.OptParam(paramb))
          | (Ast0.UniqueParam(parama),Ast0.UniqueParam(paramb)) ->
              match_param parama paramb
          | (_,Ast0.OptParam(paramb))
          | (_,Ast0.UniqueParam(paramb)) -> match_param pattern paramb
          | _ -> return false
        else return_false (ContextRequired (Ast0.ParamTag p))

  and match_statement pattern s =
    match Ast0.unwrap pattern with
      Ast0.MetaStmt(name,pure) ->
        (match Ast0.unwrap s with
          Ast0.Dots(_,_) | Ast0.Circles(_,_) | Ast0.Stars(_,_) ->
            return false (* ... is not a single statement *)
        | _ ->
            add_pure_binding name pure pure_sp_code.VT0.combiner_rec_statement
              (function ty -> Ast0.StmtTag ty)
              s)
    | Ast0.MetaStmtList(name,pure) -> failwith "metastmtlist not supported"
    | up ->
        if not(checks_needed) or not(context_required) or is_context s
        then
          match (up,Ast0.unwrap s) with
            (Ast0.FunDecl(_,fninfoa,namea,lp1,paramsa,rp1,lb1,bodya,rb1),
             Ast0.FunDecl(_,fninfob,nameb,lp,paramsb,rp,lb,bodyb,rb)) ->
               conjunct_many_bindings
                 [check_mcode lp1 lp; check_mcode rp1 rp;
                   check_mcode lb1 lb; check_mcode rb1 rb;
                   match_fninfo fninfoa fninfob; match_ident namea nameb;
                   match_dots match_param is_plist_matcher do_plist_match
                     paramsa paramsb;
                   match_dots match_statement is_slist_matcher do_slist_match
                     bodya bodyb]
          | (Ast0.Decl(_,decla),Ast0.Decl(_,declb)) ->
              match_decl decla declb
          | (Ast0.Seq(lb1,bodya,rb1),Ast0.Seq(lb,bodyb,rb)) ->
              (* seqs can only match if they are all minus (plus code
                 allowed) or all context (plus code not allowed in the body).
                 we could be more permissive if the expansions of the isos are
                 also all seqs, but this would be hard to check except at top
                 level, and perhaps not worth checking even in that case.
                 Overall, the issue is that braces are used where single
                 statements are required, and something not satisfying these
                 conditions can cause a single statement to become a
                 non-single statement after the transformation.

                 example: if { ... -foo(); ... }
                 if we let the sequence convert to just -foo();
                 then we produce invalid code.  For some reason,
                 single_statement can't deal with this case, perhaps because
                 it starts introducing too many braces?  don't remember the
                 exact problem...
              *)
              conjunct_bindings (check_mcode lb1 lb)
                (conjunct_bindings (check_mcode rb1 rb)
                   (if not(checks_needed) or is_minus s or
                     (is_context s &&
                      List.for_all is_pure_context (Ast0.undots bodyb))
                   then
                     match_dots match_statement is_slist_matcher do_slist_match
                       bodya bodyb
                   else return_false (Braces(s))))
          | (Ast0.ExprStatement(expa,sc1),Ast0.ExprStatement(expb,sc)) ->
              conjunct_bindings (check_mcode sc1 sc)
                (match_option match_expr expa expb)
          | (Ast0.IfThen(if1,lp1,expa,rp1,branch1a,_),
             Ast0.IfThen(if2,lp2,expb,rp2,branch1b,_)) ->
               conjunct_many_bindings
                 [check_mcode if1 if2; check_mcode lp1 lp2;
                   check_mcode rp1 rp2;
                   match_expr expa expb;
                   match_statement branch1a branch1b]
          | (Ast0.IfThenElse(if1,lp1,expa,rp1,branch1a,e1,branch2a,_),
             Ast0.IfThenElse(if2,lp2,expb,rp2,branch1b,e2,branch2b,_)) ->
               conjunct_many_bindings
                 [check_mcode if1 if2; check_mcode lp1 lp2;
                   check_mcode rp1 rp2; check_mcode e1 e2;
                   match_expr expa expb;
                   match_statement branch1a branch1b;
                   match_statement branch2a branch2b]
          | (Ast0.While(w1,lp1,expa,rp1,bodya,_),
             Ast0.While(w,lp,expb,rp,bodyb,_)) ->
               conjunct_many_bindings
                 [check_mcode w1 w; check_mcode lp1 lp;
                   check_mcode rp1 rp; match_expr expa expb;
                   match_statement bodya bodyb]
          | (Ast0.Do(d1,bodya,w1,lp1,expa,rp1,_),
             Ast0.Do(d,bodyb,w,lp,expb,rp,_)) ->
               conjunct_many_bindings
                 [check_mcode d1 d; check_mcode w1 w; check_mcode lp1 lp;
                   check_mcode rp1 rp; match_statement bodya bodyb;
                   match_expr expa expb]
          | (Ast0.For(f1,lp1,firsta,e2a,sc2a,e3a,rp1,bodya,_),
             Ast0.For(f,lp,firstb,e2b,sc2b,e3b,rp,bodyb,_)) ->
               let first =
                 match (Ast0.unwrap firsta,Ast0.unwrap firstb) with
                   (Ast0.ForExp(e1a,sc1a),Ast0.ForExp(e1b,sc1b)) ->
                     conjunct_bindings
                       (check_mcode sc2a sc2b)
                       (match_option match_expr e1a e1b)
                 | (Ast0.ForDecl (_,decla),Ast0.ForDecl (_,declb)) ->
                     match_decl decla declb
                 | _ -> return false in
               conjunct_many_bindings
                 [check_mcode f1 f; check_mcode lp1 lp; first;
                   check_mcode sc2a sc2b; check_mcode rp1 rp;
                   match_option match_expr e2a e2b;
                   match_option match_expr e3a e3b;
                   match_statement bodya bodyb]
          | (Ast0.Iterator(nma,lp1,argsa,rp1,bodya,_),
             Ast0.Iterator(nmb,lp,argsb,rp,bodyb,_)) ->
               conjunct_many_bindings
                 [match_ident nma nmb;
                   check_mcode lp1 lp; check_mcode rp1 rp;
                   match_dots match_expr is_elist_matcher do_elist_match
                     argsa argsb;
                   match_statement bodya bodyb]
          | (Ast0.Switch(s1,lp1,expa,rp1,lb1,declsa,casesa,rb1),
             Ast0.Switch(s,lp,expb,rp,lb,declsb,casesb,rb)) ->
               conjunct_many_bindings
                 [check_mcode s1 s; check_mcode lp1 lp; check_mcode rp1 rp;
                   check_mcode lb1 lb; check_mcode rb1 rb;
                   match_expr expa expb;
                   match_dots match_statement is_slist_matcher do_slist_match
                     declsa declsb;
                   match_dots match_case_line no_list do_nolist_match
                     casesa casesb]
          | (Ast0.Break(b1,sc1),Ast0.Break(b,sc))
          | (Ast0.Continue(b1,sc1),Ast0.Continue(b,sc)) ->
              conjunct_bindings (check_mcode b1 b) (check_mcode sc1 sc)
          | (Ast0.Label(l1,c1),Ast0.Label(l2,c)) ->
              conjunct_bindings (match_ident l1 l2) (check_mcode c1 c)
          | (Ast0.Goto(g1,l1,sc1),Ast0.Goto(g,l2,sc)) ->
              conjunct_many_bindings
                [check_mcode g1 g; check_mcode sc1 sc; match_ident l1 l2]
          | (Ast0.Return(r1,sc1),Ast0.Return(r,sc)) ->
              conjunct_bindings (check_mcode r1 r) (check_mcode sc1 sc)
          | (Ast0.ReturnExpr(r1,expa,sc1),Ast0.ReturnExpr(r,expb,sc)) ->
              conjunct_many_bindings
                [check_mcode r1 r; check_mcode sc1 sc; match_expr expa expb]
          | (Ast0.Disj(_,statement_dots_lista,_,_),_) ->
              failwith "disj not supported in patterns"
          | (Ast0.Nest(_,stmt_dotsa,_,[],multia),
             Ast0.Nest(_,stmt_dotsb,_,wc,multib)) ->
               if multia = multib
               then
                 (match wc with
                   [] ->
                   (* not sure this is correct, perhaps too restrictive *)
                     if not(checks_needed) or is_minus s or
                       (is_context s &&
                        List.for_all is_pure_context (Ast0.undots stmt_dotsb))
                     then
                       match_dots match_statement
                         is_slist_matcher do_slist_match
                         stmt_dotsa stmt_dotsb
                     else return_false (Braces(s))
                 | _ -> return_false (Nest(s)))
               else return false (* diff kind of nest *)
          | (Ast0.Nest(_,stmt_dotsa,_,_,_),_) ->
              failwith "nest with whencode not supported in patterns"
          | (Ast0.Exp(expa),Ast0.Exp(expb)) -> match_expr expa expb
          | (Ast0.TopExp(expa),Ast0.TopExp(expb)) -> match_expr expa expb
          | (Ast0.Exp(expa),Ast0.TopExp(expb)) -> match_expr expa expb
          | (Ast0.TopInit(inita),Ast0.TopInit(initb)) -> match_init inita initb
          | (Ast0.Ty(tya),Ast0.Ty(tyb)) -> match_typeC tya tyb
          | (Ast0.Dots(d,[]),Ast0.Dots(d1,wc))
          | (Ast0.Circles(d,[]),Ast0.Circles(d1,wc))
          | (Ast0.Stars(d,[]),Ast0.Stars(d1,wc)) ->
              (match wc with
                [] -> check_mcode d d1
              | _ ->
                  let (_,_,dots_whencode_allowed) = whencode_allowed in
                  if dots_whencode_allowed
                  then
                    conjunct_bindings (check_mcode d d1)
                      (List.fold_left
                         (function prev ->
                           function
                             | Ast0.WhenNot wc ->
                                 conjunct_bindings prev
                                   (add_multi_dot_binding d
                                      (Ast0.DotsStmtTag wc))
                             | Ast0.WhenAlways wc ->
                                 conjunct_bindings prev
                                   (add_multi_dot_binding d (Ast0.StmtTag wc))
                             | Ast0.WhenNotTrue wc ->
                                 conjunct_bindings prev
                                   (add_multi_dot_binding d
                                      (Ast0.IsoWhenTTag wc))
                             | Ast0.WhenNotFalse wc ->
                                 conjunct_bindings prev
                                   (add_multi_dot_binding d
                                      (Ast0.IsoWhenFTag wc))
                             | Ast0.WhenModifier(x) ->
                                 conjunct_bindings prev
                                   (add_multi_dot_binding d
                                      (Ast0.IsoWhenTag x)))
                         (return true) wc)
                  else
                    (Printf.printf
                       "warning: not applying iso because of whencode";
                     return false))
          | (Ast0.Dots(_,_::_),_) | (Ast0.Circles(_,_::_),_)
          | (Ast0.Stars(_,_::_),_) ->
              failwith "whencode not allowed in a pattern3"
          | (Ast0.OptStm(rea),Ast0.OptStm(reb))
          | (Ast0.UniqueStm(rea),Ast0.UniqueStm(reb)) ->
              match_statement rea reb
          | (_,Ast0.OptStm(reb))
          | (_,Ast0.UniqueStm(reb)) -> match_statement pattern reb
          |     _ -> return false
        else return_false (ContextRequired (Ast0.StmtTag s))

  (* first should provide a subset of the information in the second *)
  and match_fninfo patterninfo cinfo =
    let patterninfo = List.sort compare patterninfo in
    let cinfo = List.sort compare cinfo in
    let rec loop = function
        (Ast0.FStorage(sta)::resta,Ast0.FStorage(stb)::restb) ->
          if mcode_equal sta stb
          then conjunct_bindings (check_mcode sta stb) (loop (resta,restb))
          else return false
      | (Ast0.FType(tya)::resta,Ast0.FType(tyb)::restb) ->
          conjunct_bindings (match_typeC tya tyb) (loop (resta,restb))
      | (Ast0.FInline(ia)::resta,Ast0.FInline(ib)::restb) ->
          if mcode_equal ia ib
          then conjunct_bindings (check_mcode ia ib) (loop (resta,restb))
          else return false
      | (Ast0.FAttr(ia)::resta,Ast0.FAttr(ib)::restb) ->
          if mcode_equal ia ib
          then conjunct_bindings (check_mcode ia ib) (loop (resta,restb))
          else return false
      | (x::resta,((y::_) as restb)) ->
          (match compare x y with
            -1 -> return false
          | 1 -> loop (resta,restb)
          | _ -> failwith "not possible")
      | _ -> return false in
    loop (patterninfo,cinfo)

  and match_case_line pattern c =
    if not(checks_needed) or not(context_required) or is_context c
    then
      match (Ast0.unwrap pattern,Ast0.unwrap c) with
        (Ast0.Default(d1,c1,codea),Ast0.Default(d,c,codeb)) ->
          conjunct_many_bindings
            [check_mcode d1 d; check_mcode c1 c;
              match_dots match_statement is_slist_matcher do_slist_match
                codea codeb]
      | (Ast0.Case(ca1,expa,c1,codea),Ast0.Case(ca,expb,c,codeb)) ->
          conjunct_many_bindings
            [check_mcode ca1 ca; check_mcode c1 c; match_expr expa expb;
              match_dots match_statement is_slist_matcher do_slist_match
                codea codeb]
      | (Ast0.DisjCase(_,case_linesa,_,_),_) ->
          failwith "not allowed in the pattern of an isomorphism"
      | (Ast0.OptCase(ca),Ast0.OptCase(cb)) -> match_case_line ca cb
      | (_,Ast0.OptCase(cb)) -> match_case_line pattern cb
      | _ -> return false
    else return_false (ContextRequired (Ast0.CaseLineTag c)) in

  let match_statement_dots x y =
    match_dots match_statement is_slist_matcher do_slist_match x y in

  (match_expr, match_decl, match_statement, match_typeC,
   match_statement_dots)

let match_expr dochecks context_required whencode_allowed =
  let (fn,_,_,_,_) = match_maker dochecks context_required whencode_allowed in
  fn

let match_decl dochecks context_required whencode_allowed =
  let (_,fn,_,_,_) = match_maker dochecks context_required whencode_allowed in
  fn

let match_statement dochecks context_required whencode_allowed =
  let (_,_,fn,_,_) = match_maker dochecks context_required whencode_allowed in
  fn

let match_typeC dochecks context_required whencode_allowed =
  let (_,_,_,fn,_) = match_maker dochecks context_required whencode_allowed in
  fn

let match_statement_dots dochecks context_required whencode_allowed =
  let (_,_,_,_,fn) = match_maker dochecks context_required whencode_allowed in
  fn

(* --------------------------------------------------------------------- *)
(* make an entire tree MINUS *)

let make_minus =
  let mcode (term,arity,info,mcodekind,pos,adj) =
    let new_mcodekind =
     match mcodekind with
       Ast0.CONTEXT(mc) ->
         (match !mc with
           (Ast.NOTHING,_,_) ->
             Ast0.MINUS(ref(Ast.NOREPLACEMENT,Ast0.default_token_info))
         | _ -> failwith "make_minus: unexpected befaft")
     | Ast0.MINUS(mc) -> mcodekind (* in the part copied from the src term *)
     | _ -> failwith "make_minus mcode: unexpected mcodekind" in
    (term,arity,info,new_mcodekind,pos,adj) in

  let update_mc mcodekind e =
    match !mcodekind with
      Ast0.CONTEXT(mc) ->
        (match !mc with
          (Ast.NOTHING,_,_) ->
            mcodekind :=
              Ast0.MINUS(ref(Ast.NOREPLACEMENT,Ast0.default_token_info))
        | _ -> failwith "make_minus: unexpected befaft")
    | Ast0.MINUS(_mc) -> () (* in the part copied from the src term *)
    | Ast0.PLUS _ -> failwith "make_minus donothing: unexpected plus mcodekind"
    | _ -> failwith "make_minus donothing: unexpected mcodekind" in

  let donothing r k e =
    let mcodekind = Ast0.get_mcodekind_ref e in
    let e = k e in update_mc mcodekind e; e in

  (* special case for whencode, because it isn't processed by contextneg,
     since it doesn't appear in the + code *)
  (* cases for dots and nests *)
  let expression r k e =
    let mcodekind = Ast0.get_mcodekind_ref e in
    match Ast0.unwrap e with
      Ast0.Edots(d,whencode) ->
       (*don't recurse because whencode hasn't been processed by context_neg*)
        update_mc mcodekind e; Ast0.rewrap e (Ast0.Edots(mcode d,whencode))
    | Ast0.Ecircles(d,whencode) ->
       (*don't recurse because whencode hasn't been processed by context_neg*)
        update_mc mcodekind e; Ast0.rewrap e (Ast0.Ecircles(mcode d,whencode))
    | Ast0.Estars(d,whencode) ->
       (*don't recurse because whencode hasn't been processed by context_neg*)
        update_mc mcodekind e; Ast0.rewrap e (Ast0.Estars(mcode d,whencode))
    | Ast0.NestExpr(starter,expr_dots,ender,whencode,multi) ->
        update_mc mcodekind e;
        Ast0.rewrap e
          (Ast0.NestExpr(mcode starter,
                         r.VT0.rebuilder_rec_expression_dots expr_dots,
                         mcode ender,whencode,multi))
    | _ -> donothing r k e in

  let declaration r k e =
    let mcodekind = Ast0.get_mcodekind_ref e in
    match Ast0.unwrap e with
      Ast0.Ddots(d,whencode) ->
       (*don't recurse because whencode hasn't been processed by context_neg*)
        update_mc mcodekind e; Ast0.rewrap e (Ast0.Ddots(mcode d,whencode))
    | _ -> donothing r k e in

  let statement r k e =
    let mcodekind = Ast0.get_mcodekind_ref e in
    match Ast0.unwrap e with
      Ast0.Dots(d,whencode) ->
       (*don't recurse because whencode hasn't been processed by context_neg*)
        update_mc mcodekind e; Ast0.rewrap e (Ast0.Dots(mcode d,whencode))
    | Ast0.Circles(d,whencode) ->
        update_mc mcodekind e; Ast0.rewrap e (Ast0.Circles(mcode d,whencode))
    | Ast0.Stars(d,whencode) ->
        update_mc mcodekind e; Ast0.rewrap e (Ast0.Stars(mcode d,whencode))
    | Ast0.Nest(starter,stmt_dots,ender,whencode,multi) ->
        update_mc mcodekind e;
        Ast0.rewrap e
          (Ast0.Nest
             (mcode starter,r.VT0.rebuilder_rec_statement_dots stmt_dots,
              mcode ender,whencode,multi))
    | _ -> donothing r k e in

  let initialiser r k e =
    let mcodekind = Ast0.get_mcodekind_ref e in
    match Ast0.unwrap e with
      Ast0.Idots(d,whencode) ->
       (*don't recurse because whencode hasn't been processed by context_neg*)
        update_mc mcodekind e; Ast0.rewrap e (Ast0.Idots(mcode d,whencode))
    | _ -> donothing r k e in

  let dots r k e =
    let info = Ast0.get_info e in
    let mcodekind = Ast0.get_mcodekind_ref e in
    match Ast0.unwrap e with
      Ast0.DOTS([]) ->
        (* if context is - this should be - as well.  There are no tokens
           here though, so the bottom-up minusifier in context_neg leaves it
           as mixed (or context for sgrep2).  It would be better to fix
           context_neg, but that would
           require a special case for each term with a dots subterm. *)
        (match !mcodekind with
          Ast0.MIXED(mc) | Ast0.CONTEXT(mc) ->
            (match !mc with
              (Ast.NOTHING,_,_) ->
                mcodekind :=
                  Ast0.MINUS(ref(Ast.NOREPLACEMENT,Ast0.default_token_info));
                e
            | _ -> failwith "make_minus: unexpected befaft")
          (* code already processed by an enclosing iso *)
        | Ast0.MINUS(mc) -> e
        | _ ->
            failwith
              (Printf.sprintf
                 "%d: make_minus donothingxxx: unexpected mcodekind: %s"
                 info.Ast0.pos_info.Ast0.line_start (Dumper.dump e)))
    | _ -> donothing r k e in

  V0.flat_rebuilder
    mcode mcode mcode mcode mcode mcode mcode mcode mcode mcode mcode mcode
    dots dots dots dots dots dots
    donothing expression donothing initialiser donothing declaration
    statement donothing donothing donothing

(* --------------------------------------------------------------------- *)
(* rebuild mcode cells in an instantiated alt *)

(* mcodes will be side effected later with plus code, so we have to copy
   them on instantiating an isomorphism.  One could wonder whether it would
   be better not to use side-effects, but they are convenient for insert_plus
   where is it useful to manipulate a list of the mcodes but side-effect a
   tree *)
(* hmm... Insert_plus is called before Iso_pattern... *)
let rebuild_mcode start_line =
  let copy_mcodekind = function
      Ast0.CONTEXT(mc) -> Ast0.CONTEXT(ref (!mc))
    | Ast0.MINUS(mc) ->   Ast0.MINUS(ref (!mc))
    | Ast0.MIXED(mc) ->   Ast0.MIXED(ref (!mc))
    | Ast0.PLUS count ->
        (* this function is used elsewhere where we need to rebuild the
           indices, and so we allow PLUS code as well *)
        Ast0.PLUS count in

  let mcode (term,arity,info,mcodekind,pos,adj) =
    let info =
      match start_line with
        Some x ->
          let new_pos_info =
            {info.Ast0.pos_info with
              Ast0.line_start = x;
              Ast0.line_end = x; } in
          {info with Ast0.pos_info = new_pos_info}
      | None -> info in
    (term,arity,info,copy_mcodekind mcodekind,pos,adj) in

  let copy_one x =
    let old_info = Ast0.get_info x in
    let info =
      match start_line with
        Some x ->
          let new_pos_info =
            {old_info.Ast0.pos_info with
              Ast0.line_start = x;
              Ast0.line_end = x; } in
          {old_info with Ast0.pos_info = new_pos_info}
      | None -> old_info in
    {x with Ast0.info = info; Ast0.index = ref(Ast0.get_index x);
      Ast0.mcodekind = ref (copy_mcodekind (Ast0.get_mcodekind x))} in

  let donothing r k e = copy_one (k e) in

  (* case for control operators (if, etc) *)
  let statement r k e =
    let s = k e in
    let res =
      copy_one
        (Ast0.rewrap s
           (match Ast0.unwrap s with
             Ast0.Decl((info,mc),decl) ->
               Ast0.Decl((info,copy_mcodekind mc),decl)
           | Ast0.IfThen(iff,lp,tst,rp,branch,(info,mc)) ->
               Ast0.IfThen(iff,lp,tst,rp,branch,(info,copy_mcodekind mc))
           | Ast0.IfThenElse(iff,lp,tst,rp,branch1,els,branch2,(info,mc)) ->
               Ast0.IfThenElse(iff,lp,tst,rp,branch1,els,branch2,
                 (info,copy_mcodekind mc))
           | Ast0.While(whl,lp,exp,rp,body,(info,mc)) ->
               Ast0.While(whl,lp,exp,rp,body,(info,copy_mcodekind mc))
           | Ast0.For(fr,lp,first,e2,sem2,e3,rp,body,(info,mc)) ->
               Ast0.For(fr,lp,first,e2,sem2,e3,rp,body,
                        (info,copy_mcodekind mc))
           | Ast0.Iterator(nm,lp,args,rp,body,(info,mc)) ->
               Ast0.Iterator(nm,lp,args,rp,body,(info,copy_mcodekind mc))
           | Ast0.FunDecl
               ((info,mc),fninfo,name,lp,params,rp,lbrace,body,rbrace) ->
                 Ast0.FunDecl
                   ((info,copy_mcodekind mc),
                    fninfo,name,lp,params,rp,lbrace,body,rbrace)
           | s -> s)) in
    Ast0.set_dots_bef_aft res
      (match Ast0.get_dots_bef_aft res with
        Ast0.NoDots -> Ast0.NoDots
      | Ast0.AddingBetweenDots s ->
          Ast0.AddingBetweenDots(r.VT0.rebuilder_rec_statement s)
      | Ast0.DroppingBetweenDots s ->
          Ast0.DroppingBetweenDots(r.VT0.rebuilder_rec_statement s)) in

  V0.flat_rebuilder
    mcode mcode mcode mcode mcode mcode mcode mcode mcode mcode mcode mcode
    donothing donothing donothing donothing donothing donothing
    donothing donothing donothing donothing donothing
    donothing statement donothing donothing donothing

(* --------------------------------------------------------------------- *)
(* The problem of whencode.  If an isomorphism contains dots in multiple
   rules, then the code that is matched cannot contain whencode, because we
   won't know which dots it goes with. Should worry about nests, but they
   aren't allowed in isomorphisms for the moment. *)

let count_edots =
  let option_default = 0 in
  let bind x y = x + y in
  let exprfn r k e =
    match Ast0.unwrap e with
      Ast0.Edots(_,_) | Ast0.Ecircles(_,_) | Ast0.Estars(_,_) -> 1
    | _ -> 0 in

  V0.combiner bind option_default
    {V0.combiner_functions with VT0.combiner_exprfn = exprfn}

let count_idots =
  let option_default = 0 in
  let bind x y = x + y in
  let initfn r k e =
    match Ast0.unwrap e with Ast0.Idots(_,_) -> 1 | _ -> 0 in

  V0.combiner bind option_default
    {V0.combiner_functions with VT0.combiner_initfn = initfn}

let count_dots =
  let option_default = 0 in
  let bind x y = x + y in
  let stmtfn r k e =
    match Ast0.unwrap e with
      Ast0.Dots(_,_) | Ast0.Circles(_,_) | Ast0.Stars(_,_) -> 1
    | _ -> 0 in

  V0.combiner bind option_default
    {V0.combiner_functions with VT0.combiner_stmtfn = stmtfn}

(* --------------------------------------------------------------------- *)

let lookup name bindings mv_bindings =
  try Common.Left (List.assoc (term name) bindings)
  with
    Not_found ->
      (* failure is not possible anymore *)
      Common.Right (List.assoc (term name) mv_bindings)

(* mv_bindings is for the fresh metavariables that are introduced by the
   isomorphism *)
let instantiate bindings mv_bindings =
  let mcode x =
    let (hidden,others) =
      List.partition
        (function Ast0.HiddenVarTag _ -> true | _ -> false)
        (Ast0.get_pos x) in
    let new_names =
      match hidden with
        [Ast0.HiddenVarTag([Ast0.MetaPosTag(Ast0.MetaPos (name,_,_))])] ->
          (try
          (* not at all sure that this is good enough *)
            match lookup name bindings mv_bindings with
              Common.Left(Ast0.HiddenVarTag(ids)) -> ids
            | _ -> failwith "not possible"
          with Not_found ->
             (*can't fail because checks_needed could be false?*)
            [])
      | [] -> [] (* no hidden metavars allowed *)
      | _ -> failwith "badly compiled mcode" in
    Ast0.set_pos (new_names@others) x in
  let donothing r k e = k e in

  (* cases where metavariables can occur *)
  let identfn r k e =
    let e = k e in
    match Ast0.unwrap e with
      Ast0.MetaId(name,constraints,seed,pure) ->
        (rebuild_mcode None).VT0.rebuilder_rec_ident
          (match lookup name bindings mv_bindings with
            Common.Left(Ast0.IdentTag(id)) -> id
          | Common.Left(_) -> failwith "not possible 1"
          | Common.Right(new_mv) ->
              Ast0.rewrap e
                (Ast0.MetaId
                   (Ast0.set_mcode_data new_mv name,constraints,seed,pure)))
    | Ast0.MetaFunc(name,_,pure) -> failwith "metafunc not supported"
    | Ast0.MetaLocalFunc(name,_,pure) -> failwith "metalocalfunc not supported"
    | _ -> e in

  (* case for list metavariables *)
  let rec elist r same_dots = function
      [] -> []
    | [x] ->
        (match Ast0.unwrap x with
          Ast0.MetaExprList(name,lenname,pure) ->
            failwith "meta_expr_list in iso not supported"
            (*match lookup name bindings mv_bindings with
              Common.Left(Ast0.DotsExprTag(exp)) ->
                (match same_dots exp with
                  Some l -> l
                | None -> failwith "dots put in incompatible context")
            | Common.Left(Ast0.ExprTag(exp)) -> [exp]
            | Common.Left(_) -> failwith "not possible 1"
            | Common.Right(new_mv) ->
                failwith "MetaExprList in SP not supported"*)
        | _ -> [r.VT0.rebuilder_rec_expression x])
    | x::xs -> (r.VT0.rebuilder_rec_expression x)::(elist r same_dots xs) in

  let rec plist r same_dots = function
      [] -> []
    | [x] ->
        (match Ast0.unwrap x with
          Ast0.MetaParamList(name,lenname,pure) ->
            failwith "meta_param_list in iso not supported"
            (*match lookup name bindings mv_bindings with
                Common.Left(Ast0.DotsParamTag(param)) ->
                (match same_dots param with
                Some l -> l
                | None -> failwith "dots put in incompatible context")
                | Common.Left(Ast0.ParamTag(param)) -> [param]
                | Common.Left(_) -> failwith "not possible 1"
                | Common.Right(new_mv) ->
                failwith "MetaExprList in SP not supported"*)
        | _ -> [r.VT0.rebuilder_rec_parameter x])
    | x::xs -> (r.VT0.rebuilder_rec_parameter x)::(plist r same_dots xs) in

  let rec slist r same_dots = function
      [] -> []
    | [x] ->
        (match Ast0.unwrap x with
          Ast0.MetaStmtList(name,pure) ->
            (match lookup name bindings mv_bindings with
              Common.Left(Ast0.DotsStmtTag(stm)) ->
                (match same_dots stm with
                  Some l -> l
                | None -> failwith "dots put in incompatible context")
            | Common.Left(Ast0.StmtTag(stm)) -> [stm]
            | Common.Left(_) -> failwith "not possible 1"
            | Common.Right(new_mv) ->
                failwith "MetaExprList in SP not supported")
        | _ -> [r.VT0.rebuilder_rec_statement x])
    | x::xs -> (r.VT0.rebuilder_rec_statement x)::(slist r same_dots xs) in

  let same_dots d =
    match Ast0.unwrap d with Ast0.DOTS(l) -> Some l |_ -> None in
  let same_circles d =
    match Ast0.unwrap d with Ast0.CIRCLES(l) -> Some l |_ -> None in
  let same_stars d =
    match Ast0.unwrap d with Ast0.STARS(l) -> Some l |_ -> None in

  let dots list_fn r k d =
    Ast0.rewrap d
      (match Ast0.unwrap d with
        Ast0.DOTS(l) -> Ast0.DOTS(list_fn r same_dots l)
      | Ast0.CIRCLES(l) -> Ast0.CIRCLES(list_fn r same_circles l)
      | Ast0.STARS(l) -> Ast0.STARS(list_fn r same_stars l)) in

  let exprfn r k old_e = (* need to keep the original code for ! optim *)
    let e = k old_e in
    let e1 =
    match Ast0.unwrap e with
      Ast0.MetaExpr(name,constraints,x,form,pure) ->
        (rebuild_mcode None).VT0.rebuilder_rec_expression
          (match lookup name bindings mv_bindings with
            Common.Left(Ast0.ExprTag(exp)) -> exp
          | Common.Left(_) -> failwith "not possible 1"
          | Common.Right(new_mv) ->
              let new_types =
                match x with
                  None -> None
                | Some types ->
                    let rec renamer = function
                        Type_cocci.MetaType(name,keep,inherited) ->
                          (match
                            lookup (name,(),(),(),None,-1)
                              bindings mv_bindings
                          with
                            Common.Left(Ast0.TypeCTag(t)) ->
                              Ast0.ast0_type_to_type t
                          | Common.Left(_) ->
                              failwith "iso pattern: unexpected type"
                          | Common.Right(new_mv) ->
                              Type_cocci.MetaType(new_mv,keep,inherited))
                      | Type_cocci.ConstVol(cv,ty) ->
                          Type_cocci.ConstVol(cv,renamer ty)
                      | Type_cocci.Pointer(ty) ->
                          Type_cocci.Pointer(renamer ty)
                      | Type_cocci.FunctionPointer(ty) ->
                          Type_cocci.FunctionPointer(renamer ty)
                      | Type_cocci.Array(ty) ->
                          Type_cocci.Array(renamer ty)
                      | t -> t in
                    Some(List.map renamer types) in
              Ast0.rewrap e
                (Ast0.MetaExpr
                   (Ast0.set_mcode_data new_mv name,constraints,
                    new_types,form,pure)))
    | Ast0.MetaErr(namea,_,pure) -> failwith "metaerr not supported"
    | Ast0.MetaExprList(namea,lenname,pure) ->
        failwith "metaexprlist not supported"
    | Ast0.Unary(exp,unop) ->
        (match Ast0.unwrap_mcode unop with
          (* propagate negation only when the propagated and the encountered
             negation have the same transformation, when there is nothing
             added to the original one, and when there is nothing added to
             the expression into which we are doing the propagation.  This
             may be too conservative. *)
          Ast.Not ->
            let was_meta =
              (* k e doesn't change the outer structure of the term,
                 only the metavars *)
              match Ast0.unwrap old_e with
                Ast0.Unary(exp,_) ->
                  (match Ast0.unwrap exp with
                    Ast0.MetaExpr(name,constraints,x,form,pure) -> true
                  | _ -> false)
              | _ -> failwith "not possible" in
            let nomodif = function
                Ast0.MINUS(x) ->
                  (match !x with
                    (Ast.NOREPLACEMENT,_) -> true
                  | _ -> false)
              | Ast0.CONTEXT(x) | Ast0.MIXED(x) ->
                  (match !x with
                    (Ast.NOTHING,_,_) -> true
                  | _ -> false)
              | _ -> failwith "plus not possible" in
            let same_modif newop oldop =
              (* only propagate ! is they have the same modification
                 and no + code on the old one (the new one from the iso
                 surely has no + code) *)
              match (newop,oldop) with
                (Ast0.MINUS(x1),Ast0.MINUS(x2)) -> nomodif oldop
              | (Ast0.CONTEXT(x1),Ast0.CONTEXT(x2)) -> nomodif oldop
              | (Ast0.MIXED(x1),Ast0.MIXED(x2)) -> nomodif oldop
              | _ -> false in
            if was_meta
            then
              let idcont x = x in
              let rec negate e (*for rewrapping*) res (*code to process*) k =
                (* k accumulates parens, to keep negation outside if no
                   propagation is possible *)
                if nomodif (Ast0.get_mcodekind e)
                then
                  match Ast0.unwrap res with
                    Ast0.Unary(e1,op) when Ast0.unwrap_mcode op = Ast.Not &&
                      same_modif
                        (Ast0.get_mcode_mcodekind unop)
                        (Ast0.get_mcode_mcodekind op) ->
                          k e1
                  | Ast0.Edots(_,_) -> k (Ast0.rewrap e (Ast0.unwrap res))
                  | Ast0.Paren(lp,e1,rp) ->
                      negate e e1
                        (function x ->
                          k (Ast0.rewrap res (Ast0.Paren(lp,x,rp))))
                  | Ast0.Binary(e1,op,e2) when
                      same_modif
                        (Ast0.get_mcode_mcodekind unop)
                        (Ast0.get_mcode_mcodekind op) ->
                          let reb nop =
                            Ast0.rewrap_mcode op (Ast.Logical(nop)) in
                          let k1 x = k (Ast0.rewrap e x) in
                          (match Ast0.unwrap_mcode op with
                            Ast.Logical(Ast.Inf) ->
                              k1 (Ast0.Binary(e1,reb Ast.SupEq,e2))
                          | Ast.Logical(Ast.Sup) ->
                              k1 (Ast0.Binary(e1,reb Ast.InfEq,e2))
                          | Ast.Logical(Ast.InfEq) ->
                              k1 (Ast0.Binary(e1,reb Ast.Sup,e2))
                          | Ast.Logical(Ast.SupEq) ->
                              k1 (Ast0.Binary(e1,reb Ast.Inf,e2))
                          | Ast.Logical(Ast.Eq) ->
                              k1 (Ast0.Binary(e1,reb Ast.NotEq,e2))
                          | Ast.Logical(Ast.NotEq) ->
                              k1 (Ast0.Binary(e1,reb Ast.Eq,e2))
                          | Ast.Logical(Ast.AndLog) ->
                              k1 (Ast0.Binary(negate_reb e e1 idcont,
                                              reb Ast.OrLog,
                                              negate_reb e e2 idcont))
                          | Ast.Logical(Ast.OrLog) ->
                              k1 (Ast0.Binary(negate_reb e e1 idcont,
                                              reb Ast.AndLog,
                                              negate_reb e e2 idcont))
                          | _ ->
                              Ast0.rewrap e
                                (Ast0.Unary(k res,
                                            Ast0.rewrap_mcode op Ast.Not)))
                  | Ast0.DisjExpr(lp,exps,mids,rp) ->
                      (* use res because it is the transformed argument *)
                      let exps =
                        List.map (function e1 -> negate_reb e e1 k) exps in
                      Ast0.rewrap res (Ast0.DisjExpr(lp,exps,mids,rp))
                  | _ ->
                      (*use e, because this might be the toplevel expression*)
                      Ast0.rewrap e
                        (Ast0.Unary(k res,Ast0.rewrap_mcode unop Ast.Not))
                else
                  Ast0.rewrap e
                    (Ast0.Unary(k res,Ast0.rewrap_mcode unop Ast.Not))
              and negate_reb e e1 k =
                (* used when ! is propagated to multiple places, to avoid
                   duplicating mcode cells *)
                let start_line =
                  Some ((Ast0.get_info e).Ast0.pos_info.Ast0.line_start) in
                (rebuild_mcode start_line).VT0.rebuilder_rec_expression
                  (negate e e1 k) in
              negate e exp idcont
            else e
        | _ -> e)
    | Ast0.Edots(d,_) ->
        (try
          (match List.assoc (dot_term d) bindings with
            Ast0.ExprTag(exp) -> Ast0.rewrap e (Ast0.Edots(d,Some exp))
          | _ -> failwith "unexpected binding")
        with Not_found -> e)
    | Ast0.Ecircles(d,_) ->
        (try
          (match List.assoc (dot_term d) bindings with
            Ast0.ExprTag(exp) -> Ast0.rewrap e (Ast0.Ecircles(d,Some exp))
          | _ -> failwith "unexpected binding")
        with Not_found -> e)
    | Ast0.Estars(d,_) ->
        (try
          (match List.assoc (dot_term d) bindings with
            Ast0.ExprTag(exp) -> Ast0.rewrap e (Ast0.Estars(d,Some exp))
          | _ -> failwith "unexpected binding")
        with Not_found -> e)
    | _ -> e in
    if Ast0.get_test_exp old_e then Ast0.set_test_exp e1 else e1 in

  let tyfn r k e =
    let e = k e in
    match Ast0.unwrap e with
      Ast0.MetaType(name,pure) ->
        (rebuild_mcode None).VT0.rebuilder_rec_typeC
          (match lookup name bindings mv_bindings with
            Common.Left(Ast0.TypeCTag(ty)) -> ty
          | Common.Left(_) -> failwith "not possible 1"
          | Common.Right(new_mv) ->
              Ast0.rewrap e
                (Ast0.MetaType(Ast0.set_mcode_data new_mv name,pure)))
    | _ -> e in

  let initfn r k e =
    let e = k e in
    match Ast0.unwrap e with
      Ast0.MetaInit(name,pure) ->
        (rebuild_mcode None).VT0.rebuilder_rec_initialiser
          (match lookup name bindings mv_bindings with
            Common.Left(Ast0.InitTag(ty)) -> ty
          | Common.Left(_) -> failwith "not possible 1"
          | Common.Right(new_mv) ->
              Ast0.rewrap e
                (Ast0.MetaInit(Ast0.set_mcode_data new_mv name,pure)))
    | _ -> e in

  let declfn r k e =
    let e = k e in
    match Ast0.unwrap e with
      Ast0.MetaDecl(name,pure) ->
        (rebuild_mcode None).VT0.rebuilder_rec_declaration
          (match lookup name bindings mv_bindings with
            Common.Left(Ast0.DeclTag(d)) -> d
          | Common.Left(_) -> failwith "not possible 1"
          | Common.Right(new_mv) ->
              Ast0.rewrap e
                (Ast0.MetaDecl(Ast0.set_mcode_data new_mv name, pure)))
    | Ast0.MetaField(name,pure) ->
        (rebuild_mcode None).VT0.rebuilder_rec_declaration
          (match lookup name bindings mv_bindings with
            Common.Left(Ast0.DeclTag(d)) -> d
          | Common.Left(_) -> failwith "not possible 1"
          | Common.Right(new_mv) ->
              Ast0.rewrap e
                (Ast0.MetaField(Ast0.set_mcode_data new_mv name, pure)))
    | Ast0.MetaFieldList(name,lenname,pure) ->
        failwith "metafieldlist not supported"
    | Ast0.Ddots(d,_) ->
        (try
          (match List.assoc (dot_term d) bindings with
            Ast0.DeclTag(exp) -> Ast0.rewrap e (Ast0.Ddots(d,Some exp))
          | _ -> failwith "unexpected binding")
        with Not_found -> e)
    | _ -> e in

  let paramfn r k e =
    let e = k e in
    match Ast0.unwrap e with
      Ast0.MetaParam(name,pure) ->
        (rebuild_mcode None).VT0.rebuilder_rec_parameter
          (match lookup name bindings mv_bindings with
            Common.Left(Ast0.ParamTag(param)) -> param
          | Common.Left(_) -> failwith "not possible 1"
          | Common.Right(new_mv) ->
              Ast0.rewrap e
                (Ast0.MetaParam(Ast0.set_mcode_data new_mv name, pure)))
    | Ast0.MetaParamList(name,lenname,pure) ->
        failwith "metaparamlist not supported"
    | _ -> e in

  let whenfn (_,v) =
    match v with
      Ast0.DotsStmtTag(stms) -> Ast0.WhenNot stms
    | Ast0.StmtTag(stm) -> Ast0.WhenAlways stm
    | Ast0.IsoWhenTTag(stm) -> Ast0.WhenNotTrue stm
    | Ast0.IsoWhenFTag(stm) -> Ast0.WhenNotFalse stm
    | Ast0.IsoWhenTag(x) -> Ast0.WhenModifier(x)
    | _ -> failwith "unexpected binding" in

  let stmtfn r k e =
    let e = k e in
    match Ast0.unwrap e with
      Ast0.MetaStmt(name,pure) ->
        (rebuild_mcode None).VT0.rebuilder_rec_statement
          (match lookup name bindings mv_bindings with
            Common.Left(Ast0.StmtTag(stm)) -> stm
          | Common.Left(_) -> failwith "not possible 1"
          | Common.Right(new_mv) ->
              Ast0.rewrap e
                (Ast0.MetaStmt(Ast0.set_mcode_data new_mv name,pure)))
    | Ast0.MetaStmtList(name,pure) -> failwith "metastmtlist not supported"
    | Ast0.Dots(d,_) ->
        Ast0.rewrap e
          (Ast0.Dots
             (d,
              List.map whenfn
                (List.filter (function (x,v) -> x = (dot_term d)) bindings)))
    | Ast0.Circles(d,_) ->
        Ast0.rewrap e
          (Ast0.Circles
             (d,
              List.map whenfn
                (List.filter (function (x,v) -> x = (dot_term d)) bindings)))
    | Ast0.Stars(d,_) ->
        Ast0.rewrap e
          (Ast0.Stars
             (d,
              List.map whenfn
                (List.filter (function (x,v) -> x = (dot_term d)) bindings)))
    | _ -> e in

  V0.flat_rebuilder
    mcode mcode mcode mcode mcode mcode mcode mcode mcode mcode mcode mcode
    (dots elist) donothing (dots plist) (dots slist) donothing donothing
    identfn exprfn tyfn initfn paramfn declfn stmtfn donothing donothing
    donothing

(* --------------------------------------------------------------------- *)

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

let context_required e = not(is_minus e) && not !Flag.sgrep_mode2

let disj_fail bindings e =
  match bindings with
    Some x -> Printf.fprintf stderr "no disj available at this type"; e
  | None -> e

(* isomorphism code is by default CONTEXT *)
let merge_plus model_mcode e_mcode =
  match model_mcode with
    Ast0.MINUS(mc) ->
      (* add the replacement information at the root *)
      (match e_mcode with
        Ast0.MINUS(emc) ->
          emc :=
            (match (!mc,!emc) with
              ((Ast.NOREPLACEMENT,_),(x,t))
            | ((x,_),(Ast.NOREPLACEMENT,t)) -> (x,t)
            | _ -> failwith "how can we combine minuses?")
      | _ -> failwith "not possible 6")
  | Ast0.CONTEXT(mc) ->
      (match e_mcode with
        Ast0.CONTEXT(emc) ->
          (* keep the logical line info as in the model *)
          let (mba,tb,ta) = !mc in
          let (eba,_,_) = !emc in
          (* merging may be required when a term is replaced by a subterm *)
          let merged =
            match (mba,eba) with
              (x,Ast.NOTHING) | (Ast.NOTHING,x) -> x
            | (Ast.BEFORE(b1,it1),Ast.BEFORE(b2,it2)) ->
                Ast.BEFORE(b1@b2,Ast.lub_count it1 it2)
            | (Ast.BEFORE(b,it1),Ast.AFTER(a,it2)) ->
                Ast.BEFOREAFTER(b,a,Ast.lub_count it1 it2)
            | (Ast.BEFORE(b1,it1),Ast.BEFOREAFTER(b2,a,it2)) ->
                Ast.BEFOREAFTER(b1@b2,a,Ast.lub_count it1 it2)
            | (Ast.AFTER(a,it1),Ast.BEFORE(b,it2)) ->
                Ast.BEFOREAFTER(b,a,Ast.lub_count it1 it2)
            | (Ast.AFTER(a1,it1),Ast.AFTER(a2,it2)) ->
                Ast.AFTER(a2@a1,Ast.lub_count it1 it2)
            | (Ast.AFTER(a1,it1),Ast.BEFOREAFTER(b,a2,it2)) ->
                Ast.BEFOREAFTER(b,a2@a1,Ast.lub_count it1 it2)
            | (Ast.BEFOREAFTER(b1,a,it1),Ast.BEFORE(b2,it2)) ->
                Ast.BEFOREAFTER(b1@b2,a,Ast.lub_count it1 it2)
            | (Ast.BEFOREAFTER(b,a1,it1),Ast.AFTER(a2,it2)) ->
                Ast.BEFOREAFTER(b,a2@a1,Ast.lub_count it1 it2)
            | (Ast.BEFOREAFTER(b1,a1,it1),Ast.BEFOREAFTER(b2,a2,it2)) ->
                Ast.BEFOREAFTER(b1@b2,a2@a1,Ast.lub_count it1 it2) in
          emc := (merged,tb,ta)
      | Ast0.MINUS(emc) ->
          let (anything_bef_aft,_,_) = !mc in
          let (anythings,t) = !emc in
          (match (anything_bef_aft,anythings) with
            (Ast.BEFORE(b1,it1),Ast.NOREPLACEMENT) ->
              emc := (Ast.REPLACEMENT(b1,it1),t)
          | (Ast.AFTER(a1,it1),Ast.NOREPLACEMENT) ->
              emc := (Ast.REPLACEMENT(a1,it1),t)
          | (Ast.BEFOREAFTER(b1,a1,it1),Ast.NOREPLACEMENT) ->
              emc := (Ast.REPLACEMENT(b1@a1,it1),t)
          | (Ast.NOTHING,Ast.NOREPLACEMENT) ->
              emc := (Ast.NOREPLACEMENT,t)
          | (Ast.BEFORE(b1,it1),Ast.REPLACEMENT(a2,it2)) ->
              emc := (Ast.REPLACEMENT(b1@a2,Ast.lub_count it1 it2),t)
          | (Ast.AFTER(a1,it1),Ast.REPLACEMENT(a2,it2)) ->
              emc := (Ast.REPLACEMENT(a2@a1,Ast.lub_count it1 it2),t)
          | (Ast.BEFOREAFTER(b1,a1,it1),Ast.REPLACEMENT(a2,it2)) ->
              emc := (Ast.REPLACEMENT(b1@a2@a1,Ast.lub_count it1 it2),t)
          | (Ast.NOTHING,Ast.REPLACEMENT(a2,it2)) -> ()) (* no change *)
      | Ast0.MIXED(_) -> failwith "how did this become mixed?"
      | _ -> failwith "not possible 7")
  | Ast0.MIXED(_) -> failwith "not possible 8"
  | Ast0.PLUS _ -> failwith "not possible 9"

let copy_plus printer minusify model e =
  if !Flag.sgrep_mode2
  then e (* no plus code, can cause a "not possible" error, so just avoid it *)
  else
    begin
      let e =
        match Ast0.get_mcodekind model with
          Ast0.MINUS(mc) -> minusify e
        | Ast0.CONTEXT(mc) -> e
        | _ -> failwith "not possible: copy_plus\n" in
      merge_plus (Ast0.get_mcodekind model) (Ast0.get_mcodekind e);
      e
    end

let copy_minus printer minusify model e =
  match Ast0.get_mcodekind model with
    Ast0.MINUS(mc) -> minusify e
  | Ast0.CONTEXT(mc) -> e
  | Ast0.MIXED(_) ->
      if !Flag.sgrep_mode2
      then e
      else failwith "not possible 8"
  | Ast0.PLUS _ -> failwith "not possible 9"

let whencode_allowed prev_ecount prev_icount prev_dcount
    ecount icount dcount rest =
  (* actually, if ecount or dcount is 0, the flag doesn't matter, because it
     won't be tested *)
  let other_ecount = (* number of edots *)
    List.fold_left (function rest -> function (_,ec,ic,dc) -> ec + rest)
      prev_ecount rest in
  let other_icount = (* number of dots *)
    List.fold_left (function rest -> function (_,ec,ic,dc) -> ic + rest)
      prev_icount rest in
  let other_dcount = (* number of dots *)
    List.fold_left (function rest -> function (_,ec,ic,dc) -> dc + rest)
      prev_dcount rest in
  (ecount = 0 or other_ecount = 0, icount = 0 or other_icount = 0,
   dcount = 0 or other_dcount = 0)

(* copy the befores and afters to the instantiated code *)
let extra_copy_stmt_plus model e =
  (if not !Flag.sgrep_mode2 (* sgrep has no plus code, so nothing to do *)
  then
    (match Ast0.unwrap model with
      Ast0.FunDecl((info,bef),_,_,_,_,_,_,_,_)
    | Ast0.Decl((info,bef),_) ->
        (match Ast0.unwrap e with
          Ast0.FunDecl((info,bef1),_,_,_,_,_,_,_,_)
        | Ast0.Decl((info,bef1),_) ->
            merge_plus bef bef1
        | _ ->  merge_plus bef (Ast0.get_mcodekind e))
    | Ast0.IfThen(_,_,_,_,_,(info,aft))
    | Ast0.IfThenElse(_,_,_,_,_,_,_,(info,aft))
    | Ast0.While(_,_,_,_,_,(info,aft))
    | Ast0.For(_,_,_,_,_,_,_,_,(info,aft))
    | Ast0.Iterator(_,_,_,_,_,(info,aft)) ->
        (match Ast0.unwrap e with
          Ast0.IfThen(_,_,_,_,_,(info,aft1))
        | Ast0.IfThenElse(_,_,_,_,_,_,_,(info,aft1))
        | Ast0.While(_,_,_,_,_,(info,aft1))
        | Ast0.For(_,_,_,_,_,_,_,_,(info,aft1))
        | Ast0.Iterator(_,_,_,_,_,(info,aft1)) ->
            merge_plus aft aft1
        | _ -> merge_plus aft (Ast0.get_mcodekind e))
    | _ -> ()));
  e

let extra_copy_other_plus model e = e

(* --------------------------------------------------------------------- *)

let mv_count = ref 0
let new_mv (_,s) =
  let ct = !mv_count in
  mv_count := !mv_count + 1;
  "_"^s^"_"^(string_of_int ct)

let get_name = function
    Ast.MetaMetaDecl(ar,nm) ->
      (nm,function nm -> Ast.MetaMetaDecl(ar,nm))
  | Ast.MetaIdDecl(ar,nm) ->
      (nm,function nm -> Ast.MetaIdDecl(ar,nm))
  | Ast.MetaFreshIdDecl(nm,seed) ->
      (nm,function nm -> Ast.MetaFreshIdDecl(nm,seed))
  | Ast.MetaTypeDecl(ar,nm) ->
      (nm,function nm -> Ast.MetaTypeDecl(ar,nm))
  | Ast.MetaInitDecl(ar,nm) ->
      (nm,function nm -> Ast.MetaInitDecl(ar,nm))
  | Ast.MetaInitListDecl(ar,nm,nm1) ->
      (nm,function nm -> Ast.MetaInitListDecl(ar,nm,nm1))
  | Ast.MetaListlenDecl(nm) ->
      failwith "should not be rebuilt"
  | Ast.MetaParamDecl(ar,nm) ->
      (nm,function nm -> Ast.MetaParamDecl(ar,nm))
  | Ast.MetaParamListDecl(ar,nm,nm1) ->
      (nm,function nm -> Ast.MetaParamListDecl(ar,nm,nm1))
  | Ast.MetaConstDecl(ar,nm,ty) ->
      (nm,function nm -> Ast.MetaConstDecl(ar,nm,ty))
  | Ast.MetaErrDecl(ar,nm) ->
      (nm,function nm -> Ast.MetaErrDecl(ar,nm))
  | Ast.MetaExpDecl(ar,nm,ty) ->
      (nm,function nm -> Ast.MetaExpDecl(ar,nm,ty))
  | Ast.MetaIdExpDecl(ar,nm,ty) ->
      (nm,function nm -> Ast.MetaIdExpDecl(ar,nm,ty))
  | Ast.MetaLocalIdExpDecl(ar,nm,ty) ->
      (nm,function nm -> Ast.MetaLocalIdExpDecl(ar,nm,ty))
  | Ast.MetaExpListDecl(ar,nm,nm1) ->
      (nm,function nm -> Ast.MetaExpListDecl(ar,nm,nm1))
  | Ast.MetaDeclDecl(ar,nm) ->
      (nm,function nm -> Ast.MetaDeclDecl(ar,nm))
  | Ast.MetaFieldListDecl(ar,nm,nm1) ->
      (nm,function nm -> Ast.MetaFieldListDecl(ar,nm,nm1))
  | Ast.MetaFieldDecl(ar,nm) ->
      (nm,function nm -> Ast.MetaFieldDecl(ar,nm))
  | Ast.MetaStmDecl(ar,nm) ->
      (nm,function nm -> Ast.MetaStmDecl(ar,nm))
  | Ast.MetaStmListDecl(ar,nm) ->
      (nm,function nm -> Ast.MetaStmListDecl(ar,nm))
  | Ast.MetaFuncDecl(ar,nm) ->
      (nm,function nm -> Ast.MetaFuncDecl(ar,nm))
  | Ast.MetaLocalFuncDecl(ar,nm) ->
      (nm,function nm -> Ast.MetaLocalFuncDecl(ar,nm))
  | Ast.MetaPosDecl(ar,nm) ->
      (nm,function nm -> Ast.MetaPosDecl(ar,nm))
  | Ast.MetaDeclarerDecl(ar,nm) ->
      (nm,function nm -> Ast.MetaDeclarerDecl(ar,nm))
  | Ast.MetaIteratorDecl(ar,nm) ->
      (nm,function nm -> Ast.MetaIteratorDecl(ar,nm))

let make_new_metavars metavars bindings =
  let new_metavars =
    List.filter
      (function mv ->
        let (s,_) = get_name mv in
        try let _ = List.assoc s bindings in false with Not_found -> true)
      metavars in
  List.split
    (List.map
       (function mv ->
         let (s,rebuild) = get_name mv in
         let new_s = (!current_rule,new_mv s) in
         (rebuild new_s, (s,new_s)))
       new_metavars)

(* --------------------------------------------------------------------- *)

let do_nothing x = x

let mkdisj matcher metavars alts e instantiater mkiso disj_maker minusify
    rebuild_mcodes name printer extra_plus update_others has_context =
  let call_instantiate bindings mv_bindings alts pattern has_context =
    List.concat
      (List.map
         (function (a,_,_,_) ->
           nub
           (* no need to create duplicates when the bindings have no effect *)
             (List.map
                (function bindings ->
                  let instantiated =
                    instantiater bindings mv_bindings (rebuild_mcodes a) in
                  let plus_added =
                    if has_context (* ie if pat is not just a metavara *)
                    then
                      copy_plus printer minusify e (extra_plus e instantiated)
                    else instantiated in
                  if pattern = a
                  then plus_added
                  else (* iso tracking *)
                  Ast0.set_iso plus_added
                    ((name,mkiso a)::(Ast0.get_iso e))) (* keep count, not U *)
                bindings))
         alts) in
  let rec inner_loop all_alts prev_ecount prev_icount prev_dcount = function
      [] -> Common.Left (prev_ecount, prev_icount, prev_dcount)
    | ((pattern,ecount,icount,dcount)::rest) ->
        let wc =
          whencode_allowed prev_ecount prev_icount prev_dcount
            ecount dcount icount rest in
        (match matcher true (context_required e) wc pattern e init_env with
          Fail(reason) ->
            if reason = NonMatch || not !Flag_parsing_cocci.show_iso_failures
            then ()
            else
              (match matcher false false wc pattern e init_env with
                OK _ ->
                  interpret_reason name (Ast0.get_line e) reason
                    (function () -> printer e)
              | _ -> ());
            inner_loop all_alts (prev_ecount + ecount) (prev_icount + icount)
              (prev_dcount + dcount) rest
        | OK (bindings : ((Ast.meta_name * 'a) list list)) ->
            let all_alts =
              (* apply update_others to all patterns other than the matched
                 one.  This is used to desigate the others as test
                 expressions in the TestExpression case *)
              (List.map
                 (function (x,e,i,d) as all ->
                   if x = pattern
                   then all
                   else (update_others x,e,i,d))
                 (List.hd all_alts)) ::
              (List.map
                 (List.map (function (x,e,i,d) -> (update_others x,e,i,d)))
                 (List.tl all_alts)) in
            (match List.concat all_alts with
              [x] -> Common.Left (prev_ecount, prev_icount, prev_dcount)
            | all_alts ->
                let (new_metavars,mv_bindings) =
                  make_new_metavars metavars (nub(List.concat bindings)) in
                Common.Right
                  (new_metavars,
                   call_instantiate bindings mv_bindings all_alts pattern
                     (has_context pattern)))) in
  let rec outer_loop prev_ecount prev_icount prev_dcount = function
      [] | [[_]] (*only one alternative*)  -> (0,[],e) (* nothing matched *)
    | (alts::rest) as all_alts ->
        match inner_loop all_alts prev_ecount prev_icount prev_dcount alts with
          Common.Left(prev_ecount, prev_icount, prev_dcount) ->
            outer_loop prev_ecount prev_icount prev_dcount rest
        | Common.Right (new_metavars,res) ->
            (1,new_metavars,
             copy_minus printer minusify e (disj_maker res)) in
  let (count,metavars,e) = outer_loop 0 0 0 alts in
  (count, metavars, e)

(* no one should ever look at the information stored in these mcodes *)
let disj_starter lst =
  let old_info = Ast0.get_info(List.hd lst) in
  let new_pos_info =
    { old_info.Ast0.pos_info with
      Ast0.line_end = old_info.Ast0.pos_info.Ast0.line_start;
      Ast0.logical_end = old_info.Ast0.pos_info.Ast0.logical_start; } in
  let info =
    { Ast0.pos_info = new_pos_info;
      Ast0.attachable_start = false; Ast0.attachable_end = false;
      Ast0.mcode_start = []; Ast0.mcode_end = [];
      Ast0.strings_before = []; Ast0.strings_after = [];
      Ast0.isSymbolIdent = false; } in
  Ast0.make_mcode_info "(" info

let disj_ender lst =
  let old_info = Ast0.get_info(List.hd lst) in
  let new_pos_info =
    { old_info.Ast0.pos_info with
      Ast0.line_start = old_info.Ast0.pos_info.Ast0.line_end;
      Ast0.logical_start = old_info.Ast0.pos_info.Ast0.logical_end; } in
  let info =
    { Ast0.pos_info = new_pos_info;
      Ast0.attachable_start = false; Ast0.attachable_end = false;
      Ast0.mcode_start = []; Ast0.mcode_end = [];
      Ast0.strings_before = []; Ast0.strings_after = [];
      Ast0.isSymbolIdent = false; } in
  Ast0.make_mcode_info ")" info

let disj_mid _ = Ast0.make_mcode "|"

let make_disj_type tl =
  let mids =
    match tl with
      [] -> failwith "bad disjunction"
    | x::xs -> List.map disj_mid xs in
  Ast0.context_wrap (Ast0.DisjType(disj_starter tl,tl,mids,disj_ender tl))
let make_disj_stmt_list tl =
  let mids =
    match tl with
      [] -> failwith "bad disjunction"
    | x::xs -> List.map disj_mid xs in
  Ast0.context_wrap (Ast0.Disj(disj_starter tl,tl,mids,disj_ender tl))
let make_disj_expr model el =
  let mids =
    match el with
      [] -> failwith "bad disjunction"
    | x::xs -> List.map disj_mid xs in
  let update_arg x =
    if Ast0.get_arg_exp model then Ast0.set_arg_exp x else x in
  let update_test x =
    let x = if Ast0.get_test_pos model then Ast0.set_test_pos x else x in
    if Ast0.get_test_exp model then Ast0.set_test_exp x else x in
  let el = List.map update_arg (List.map update_test el) in
  Ast0.context_wrap (Ast0.DisjExpr(disj_starter el,el,mids,disj_ender el))
let make_disj_decl dl =
  let mids =
    match dl with
      [] -> failwith "bad disjunction"
    | x::xs -> List.map disj_mid xs in
  Ast0.context_wrap (Ast0.DisjDecl(disj_starter dl,dl,mids,disj_ender dl))
let make_disj_stmt sl =
  let dotify x = Ast0.context_wrap (Ast0.DOTS[x]) in
  let mids =
    match sl with
      [] -> failwith "bad disjunction"
    | x::xs -> List.map disj_mid xs in
  Ast0.context_wrap
    (Ast0.Disj(disj_starter sl,List.map dotify sl,mids,disj_ender sl))

let transform_type (metavars,alts,name) e =
  match alts with
    (Ast0.TypeCTag(_)::_)::_ ->
      (* start line is given to any leaves in the iso code *)
      let start_line =
        Some ((Ast0.get_info e).Ast0.pos_info.Ast0.line_start) in
      let alts =
        List.map
          (List.map
             (function
                 Ast0.TypeCTag(p) ->
                   (p,count_edots.VT0.combiner_rec_typeC p,
                    count_idots.VT0.combiner_rec_typeC p,
                    count_dots.VT0.combiner_rec_typeC p)
               | _ -> failwith "invalid alt"))
          alts in
      mkdisj match_typeC metavars alts e
        (function b -> function mv_b ->
          (instantiate b mv_b).VT0.rebuilder_rec_typeC)
        (function t -> Ast0.TypeCTag t)
        make_disj_type make_minus.VT0.rebuilder_rec_typeC
        (rebuild_mcode start_line).VT0.rebuilder_rec_typeC
        name Unparse_ast0.typeC extra_copy_other_plus do_nothing
        (function x ->
          match Ast0.unwrap x with Ast0.MetaType _ -> false | _ -> true)
  | _ -> (0,[],e)


let transform_expr (metavars,alts,name) e =
  let process update_others =
      (* start line is given to any leaves in the iso code *)
    let start_line =
      Some ((Ast0.get_info e).Ast0.pos_info.Ast0.line_start) in
    let alts =
      List.map
        (List.map
           (function
               Ast0.ExprTag(p) | Ast0.ArgExprTag(p) | Ast0.TestExprTag(p) ->
                 (p,count_edots.VT0.combiner_rec_expression p,
                  count_idots.VT0.combiner_rec_expression p,
                  count_dots.VT0.combiner_rec_expression p)
             | _ -> failwith "invalid alt"))
        alts in
    mkdisj match_expr metavars alts e
      (function b -> function mv_b ->
        (instantiate b mv_b).VT0.rebuilder_rec_expression)
      (function e -> Ast0.ExprTag e)
      (make_disj_expr e)
      make_minus.VT0.rebuilder_rec_expression
      (rebuild_mcode start_line).VT0.rebuilder_rec_expression
      name Unparse_ast0.expression extra_copy_other_plus update_others
      (function x ->
         match Ast0.unwrap x with
           Ast0.MetaExpr _ | Ast0.MetaExprList _ | Ast0.MetaErr _ -> false
         | _ -> true)
  in
  match alts with
    (Ast0.ExprTag(_)::r)::rs ->
      (* hack to accomodate ToTestExpression case, where the first pattern is
         a normal expression, but the others are test expressions *)
      let others = r @ (List.concat rs) in
      let is_test = function Ast0.TestExprTag(_) -> true | _ -> false in
      if List.for_all is_test others then process Ast0.set_test_exp
      else if List.exists is_test others then failwith "inconsistent iso"
      else process do_nothing
  | (Ast0.ArgExprTag(_)::_)::_ when Ast0.get_arg_exp e -> process do_nothing
  | (Ast0.TestExprTag(_)::_)::_ when Ast0.get_test_pos e ->
      process Ast0.set_test_exp
  | _ -> (0,[],e)

let transform_decl (metavars,alts,name) e =
  match alts with
    (Ast0.DeclTag(_)::_)::_ ->
      (* start line is given to any leaves in the iso code *)
      let start_line =
        Some (Ast0.get_info e).Ast0.pos_info.Ast0.line_start in
      let alts =
        List.map
          (List.map
             (function
                 Ast0.DeclTag(p) ->
                   (p,count_edots.VT0.combiner_rec_declaration p,
                    count_idots.VT0.combiner_rec_declaration p,
                    count_dots.VT0.combiner_rec_declaration p)
               | _ -> failwith "invalid alt"))
          alts in
      mkdisj match_decl metavars alts e
        (function b -> function mv_b ->
          (instantiate b mv_b).VT0.rebuilder_rec_declaration)
        (function d -> Ast0.DeclTag d)
        make_disj_decl
        make_minus.VT0.rebuilder_rec_declaration
        (rebuild_mcode start_line).VT0.rebuilder_rec_declaration
        name Unparse_ast0.declaration extra_copy_other_plus do_nothing
        (function _ -> true (* no metavars *))
  | _ -> (0,[],e)

let transform_stmt (metavars,alts,name) e =
  match alts with
    (Ast0.StmtTag(_)::_)::_ ->
      (* start line is given to any leaves in the iso code *)
      let start_line =
        Some (Ast0.get_info e).Ast0.pos_info.Ast0.line_start in
      let alts =
        List.map
          (List.map
             (function
                 Ast0.StmtTag(p) ->
                   (p,count_edots.VT0.combiner_rec_statement p,
                    count_idots.VT0.combiner_rec_statement p,
                    count_dots.VT0.combiner_rec_statement p)
               | _ -> failwith "invalid alt"))
          alts in
      mkdisj match_statement metavars alts e
        (function b -> function mv_b ->
          (instantiate b mv_b).VT0.rebuilder_rec_statement)
        (function s -> Ast0.StmtTag s)
        make_disj_stmt make_minus.VT0.rebuilder_rec_statement
        (rebuild_mcode start_line).VT0.rebuilder_rec_statement
        name (Unparse_ast0.statement "") extra_copy_stmt_plus do_nothing
        (function x ->
          match Ast0.unwrap x with
            Ast0.MetaStmt _ | Ast0.MetaStmtList _ -> false
          | _ -> true)
  | _ -> (0,[],e)

(* sort of a hack, because there is no disj at top level *)
let transform_top (metavars,alts,name) e =
  match Ast0.unwrap e with
    Ast0.NONDECL(declstm) ->
      (try
        let strip alts =
          List.map
            (List.map
               (function
                   Ast0.DotsStmtTag(d) ->
                     (match Ast0.unwrap d with
                       Ast0.DOTS([s]) -> Ast0.StmtTag(s)
                     | _ -> raise (Failure ""))
                 | _ -> raise (Failure "")))
            alts in
        let (count,mv,s) = transform_stmt (metavars,strip alts,name) declstm in
        (count,mv,Ast0.rewrap e (Ast0.NONDECL(s)))
      with Failure _ -> (0,[],e))
  | Ast0.CODE(stmts) ->
      let (count,mv,res) =
        match alts with
          (Ast0.DotsStmtTag(_)::_)::_ ->
              (* start line is given to any leaves in the iso code *)
            let start_line =
              Some ((Ast0.get_info e).Ast0.pos_info.Ast0.line_start) in
            let alts =
              List.map
                (List.map
                   (function
                       Ast0.DotsStmtTag(p) ->
                         (p,count_edots.VT0.combiner_rec_statement_dots p,
                          count_idots.VT0.combiner_rec_statement_dots p,
                          count_dots.VT0.combiner_rec_statement_dots p)
                     | _ -> failwith "invalid alt"))
                alts in
            mkdisj match_statement_dots metavars alts stmts
              (function b -> function mv_b ->
                (instantiate b mv_b).VT0.rebuilder_rec_statement_dots)
              (function s -> Ast0.DotsStmtTag s)
              (function x ->
                Ast0.rewrap e (Ast0.DOTS([make_disj_stmt_list x])))
              (function x ->
                make_minus.VT0.rebuilder_rec_statement_dots x)
              (rebuild_mcode start_line).VT0.rebuilder_rec_statement_dots
              name Unparse_ast0.statement_dots extra_copy_other_plus do_nothing
              (function _ -> true)
        | _ -> (0,[],stmts) in
      (count,mv,Ast0.rewrap e (Ast0.CODE res))
  | _ -> (0,[],e)

(* --------------------------------------------------------------------- *)

let transform (alts : isomorphism) t =
  (* the following ugliness is because rebuilder only returns a new term *)
  let extra_meta_decls = ref ([] : Ast_cocci.metavar list) in
  let in_limit n = function
      None -> true
    | Some n1 ->
        n < n1 or
        ((if !Flag_parsing_cocci.show_iso_failures
        then Common.pr2_once "execeeded iso threshold, see -iso_limit option");
         false) in
  let bind x y = x + y in
  let option_default = 0 in
  let exprfn r k e =
    let (e_count,e) = k e in
    if in_limit e_count !Flag_parsing_cocci.iso_limit
    then
      let (count,extra_meta,exp) = transform_expr alts e in
      extra_meta_decls := extra_meta @ !extra_meta_decls;
      (bind count e_count,exp)
    else (e_count,e) in

  let declfn r k e =
    let (e_count,e) = k e in
    if in_limit e_count !Flag_parsing_cocci.iso_limit
    then
      let (count,extra_meta,dec) = transform_decl alts e in
      extra_meta_decls := extra_meta @ !extra_meta_decls;
      (bind count e_count,dec)
    else (e_count,e) in

  let stmtfn r k e =
    let (e_count,e) = k e in
    if in_limit e_count !Flag_parsing_cocci.iso_limit
    then
      let (count,extra_meta,stm) = transform_stmt alts e in
      extra_meta_decls := extra_meta @ !extra_meta_decls;
      (bind count e_count,stm)
    else (e_count,e) in

  let typefn r k e =
    let (continue,e_count,e) =
      match Ast0.unwrap e with
        Ast0.Signed(signb,tyb) ->
       (* Hack!  How else to prevent iso from applying under an
          unsigned??? *)
          (true,0,e)
      | _ ->
          let (e_count,e) = k e in
          if in_limit e_count !Flag_parsing_cocci.iso_limit
          then (true,e_count,e)
          else (false,e_count,e) in
    if continue
    then
      let (count,extra_meta,ty) = transform_type alts e in
      extra_meta_decls := extra_meta @ !extra_meta_decls;
      (bind count e_count,ty)
    else (e_count,e) in

  let topfn r k e =
    let (e_count,e) = k e in
    if in_limit e_count !Flag_parsing_cocci.iso_limit
    then
      let (count,extra_meta,ty) = transform_top alts e in
      extra_meta_decls := extra_meta @ !extra_meta_decls;
      (bind count e_count,ty)
    else (e_count,e) in

  let res =
    V0.combiner_rebuilder bind option_default
      {V0.combiner_rebuilder_functions with
        VT0.combiner_rebuilder_exprfn = exprfn;
        VT0.combiner_rebuilder_tyfn = typefn;
        VT0.combiner_rebuilder_declfn = declfn;
        VT0.combiner_rebuilder_stmtfn = stmtfn;
        VT0.combiner_rebuilder_topfn = topfn} in
  let (_,res) = res.VT0.top_level t in
  (!extra_meta_decls,res)

(* --------------------------------------------------------------------- *)

(* should be done by functorizing the parser to use wrap or context_wrap *)
let rewrap =
  let mcode (x,a,i,mc,pos,adj) = (x,a,i,Ast0.context_befaft(),pos,adj) in
  let donothing r k e = Ast0.context_wrap(Ast0.unwrap(k e)) in
  V0.flat_rebuilder
    mcode mcode mcode mcode mcode mcode mcode mcode mcode mcode mcode mcode
    donothing donothing donothing donothing donothing donothing
    donothing donothing donothing donothing donothing donothing donothing
    donothing donothing donothing

let rewrap_anything = function
    Ast0.DotsExprTag(d) ->
      Ast0.DotsExprTag(rewrap.VT0.rebuilder_rec_expression_dots d)
  | Ast0.DotsInitTag(d) ->
      Ast0.DotsInitTag(rewrap.VT0.rebuilder_rec_initialiser_list d)
  | Ast0.DotsParamTag(d) ->
      Ast0.DotsParamTag(rewrap.VT0.rebuilder_rec_parameter_list d)
  | Ast0.DotsStmtTag(d) ->
      Ast0.DotsStmtTag(rewrap.VT0.rebuilder_rec_statement_dots d)
  | Ast0.DotsDeclTag(d) ->
      Ast0.DotsDeclTag(rewrap.VT0.rebuilder_rec_declaration_dots d)
  | Ast0.DotsCaseTag(d) ->
      Ast0.DotsCaseTag(rewrap.VT0.rebuilder_rec_case_line_dots d)
  | Ast0.IdentTag(d) -> Ast0.IdentTag(rewrap.VT0.rebuilder_rec_ident d)
  | Ast0.ExprTag(d) -> Ast0.ExprTag(rewrap.VT0.rebuilder_rec_expression d)
  | Ast0.ArgExprTag(d) ->
      Ast0.ArgExprTag(rewrap.VT0.rebuilder_rec_expression d)
  | Ast0.TestExprTag(d) ->
      Ast0.TestExprTag(rewrap.VT0.rebuilder_rec_expression d)
  | Ast0.TypeCTag(d) -> Ast0.TypeCTag(rewrap.VT0.rebuilder_rec_typeC d)
  | Ast0.InitTag(d) -> Ast0.InitTag(rewrap.VT0.rebuilder_rec_initialiser d)
  | Ast0.ParamTag(d) -> Ast0.ParamTag(rewrap.VT0.rebuilder_rec_parameter d)
  | Ast0.DeclTag(d) -> Ast0.DeclTag(rewrap.VT0.rebuilder_rec_declaration d)
  | Ast0.StmtTag(d) -> Ast0.StmtTag(rewrap.VT0.rebuilder_rec_statement d)
  | Ast0.ForInfoTag(d) -> Ast0.ForInfoTag(rewrap.VT0.rebuilder_rec_forinfo d)
  | Ast0.CaseLineTag(d) ->
      Ast0.CaseLineTag(rewrap.VT0.rebuilder_rec_case_line d)
  | Ast0.TopTag(d) -> Ast0.TopTag(rewrap.VT0.rebuilder_rec_top_level d)
  | Ast0.IsoWhenTag(_) | Ast0.IsoWhenTTag(_) | Ast0.IsoWhenFTag(_) ->
      failwith "only for isos within iso phase"
  | Ast0.MetaPosTag(p) -> Ast0.MetaPosTag(p)
  | Ast0.HiddenVarTag(p) -> Ast0.HiddenVarTag(p) (* not sure it is possible *)

(* --------------------------------------------------------------------- *)

let apply_isos isos rule rule_name =
  if isos = []
  then ([],rule)
  else
    begin
      current_rule := rule_name;
      let isos =
        List.map
          (function (metavars,iso,name) ->
            (metavars,List.map (List.map rewrap_anything) iso,name))
          isos in
      let (extra_meta,rule) =
        List.split
          (List.map
             (function t ->
               List.fold_left
                 (function (extra_meta,t) -> function iso ->
                   let (new_extra_meta,t) = transform iso t in
                   (new_extra_meta@extra_meta,t))
                 ([],t) isos)
             rule) in
      (List.concat extra_meta, (Compute_lines.compute_lines true) rule)
    end