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lustrec / src / dimension.ml @ ed81df06

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(********************************************************************)
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(*                                                                  *)
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(*  The LustreC compiler toolset   /  The LustreC Development Team  *)
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(*  Copyright 2012 -    --   ONERA - CNRS - INPT                    *)
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(*                                                                  *)
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(*  LustreC is free software, distributed WITHOUT ANY WARRANTY      *)
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(*  under the terms of the GNU Lesser General Public License        *)
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(*  version 2.1.                                                    *)
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(*                                                                  *)
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(********************************************************************)
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open Format
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type dim_expr =
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  {mutable dim_desc: dim_desc;
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   dim_loc: Location.t;
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   dim_id: int}
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and dim_desc =
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| Dbool of bool
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| Dint  of int
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| Dident of Utils.ident
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| Dappl of Utils.ident * dim_expr list
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| Dite of dim_expr * dim_expr * dim_expr
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| Dlink of dim_expr
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| Dvar
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| Dunivar
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exception Unify of dim_expr * dim_expr
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exception InvalidDimension
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let new_id = ref (-1)
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let mkdim loc dim =
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  incr new_id;
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  { dim_loc = loc;
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    dim_id = !new_id;
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    dim_desc = dim;}
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let mkdim_var () =
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  incr new_id;
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  { dim_loc = Location.dummy_loc;
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    dim_id = !new_id;
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    dim_desc = Dvar;}
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let mkdim_ident loc id =
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  incr new_id;
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  { dim_loc = loc;
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    dim_id = !new_id;
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    dim_desc = Dident id;}
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let mkdim_bool loc b =
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  incr new_id;
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  { dim_loc = loc;
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    dim_id = !new_id;
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    dim_desc = Dbool b;}
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let mkdim_int loc i =
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  incr new_id;
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  { dim_loc = loc;
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    dim_id = !new_id;
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    dim_desc = Dint i;}
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let mkdim_appl loc f args =
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  incr new_id;
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  { dim_loc = loc;
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    dim_id = !new_id;
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    dim_desc = Dappl (f, args);}
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let mkdim_ite loc i t e =
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  incr new_id;
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  { dim_loc = loc;
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    dim_id = !new_id;
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    dim_desc = Dite (i, t, e);}
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let rec pp_dimension fmt dim =
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(*fprintf fmt "<%d>" (Obj.magic dim: int);*)
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 match dim.dim_desc with
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 | Dident id       ->
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     fprintf fmt "%s" id
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 | Dint i          ->
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     fprintf fmt "%d" i
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 | Dbool b         ->
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     fprintf fmt "%B" b
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 | Dite (i, t, e)  ->
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     fprintf fmt "if %a then %a else %a"
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       pp_dimension i pp_dimension t pp_dimension e
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 | Dappl (f, [arg]) ->
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     fprintf fmt "(%s%a)" f pp_dimension arg
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 | Dappl (f, [arg1; arg2]) ->
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     fprintf fmt "(%a%s%a)" pp_dimension arg1 f pp_dimension arg2
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 | Dappl (_, _) -> assert false
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 | Dlink dim' -> fprintf fmt "%a" pp_dimension dim'
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 | Dvar       -> fprintf fmt "_%s" (Utils.name_of_dimension dim.dim_id)
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 | Dunivar    -> fprintf fmt "'%s" (Utils.name_of_dimension dim.dim_id)
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let rec multi_dimension_product loc dim_list =
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 match dim_list with
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 | []   -> mkdim_int loc 1
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 | [d]  -> d
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 | d::q -> mkdim_appl loc "*" [d; multi_dimension_product loc q]
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(* Builds a dimension expr representing 0<=d *)
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let check_bound loc d =
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 mkdim_appl loc "<=" [mkdim_int loc 0; d]
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(* Builds a dimension expr representing 0<=i<d *)
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let check_access loc d i =
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 mkdim_appl loc "&&"
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   [mkdim_appl loc "<=" [mkdim_int loc 0; i];
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    mkdim_appl loc "<"  [i; d]]
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let rec repr dim =
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 match dim.dim_desc with
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 | Dlink dim' -> repr dim'
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 | _          -> dim
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let rec is_eq_dimension d1 d2 =
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  let d1 = repr d1 in
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  let d2 = repr d2 in
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  d1.dim_id = d2.dim_id ||
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  match d1.dim_desc, d2.dim_desc with
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  | Dappl (f1, args1), Dappl (f2, args2) ->
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    f1 = f2 && List.length args1 = List.length args2 && List.for_all2 is_eq_dimension args1 args2
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  | Dite (c1, t1, e1), Dite (c2, t2, e2) ->
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    is_eq_dimension c1 c2 && is_eq_dimension t1 t2 && is_eq_dimension e1 e2
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  | Dint i1   , Dint i2    -> i1 = i2
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  | Dbool b1  , Dbool b2   -> b1 = b2
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  | Dident id1, Dident id2 -> id1 = id2
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  | _                      -> false
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let is_dimension_const dim =
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 match (repr dim).dim_desc with
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 | Dint _
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 | Dbool _ -> true
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 | _       -> false
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let size_const_dimension dim =
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  match (repr dim).dim_desc with
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 | Dint i  -> i
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 | Dbool b -> if b then 1 else 0
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 | _       -> (Format.eprintf "internal error: size_const_dimension %a@." pp_dimension dim; assert false)
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let rec is_polymorphic dim =
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  match dim.dim_desc with
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  | Dident _
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  | Dint _
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  | Dbool _
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  | Dvar             -> false
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  | Dite (i, t, e)   ->
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      is_polymorphic i || is_polymorphic t || is_polymorphic e
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  | Dappl (_, args) -> List.exists is_polymorphic args
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  | Dlink dim' -> is_polymorphic dim'
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  | Dunivar    -> true
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(* Normalizes a dimension expression, i.e. canonicalize all polynomial
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   sub-expressions, where unsupported operations (eg. '/') are treated
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   as variables.
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*)
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let rec factors dim =
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  match dim.dim_desc with
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  | Dappl (f, args) when f = "*" -> List.flatten (List.map factors args)
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  | _                            -> [dim]
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let rec factors_constant fs =
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  match fs with
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  | []   -> 1
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  | f::q ->
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    match f.dim_desc with
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    | Dint i -> i * (factors_constant q)
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    | _      -> factors_constant q
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let norm_factors fs =
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  let k = factors_constant fs in
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  let nk = List.filter (fun d -> not (is_dimension_const d)) fs in
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  (k, List.sort Pervasives.compare nk)
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let rec terms dim =
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 match dim.dim_desc with
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 | Dappl (f, args) when f = "+" -> List.flatten (List.map terms args)
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 | _                            -> [dim]
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let rec normalize dim =
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 dim
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(*
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let rec unnormalize loc l =
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  let l = List.sort (fun (k, l) (k', l') -> compare l l') (List.map (fun (k, l) -> (k, List.sort compare l)) l) in
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  match l with
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  | []   -> mkdim_int loc 0
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  | t::q -> 
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 List.fold_left (fun res (k, l) -> mkdim_appl loc "+" res (mkdim_appl loc "*" (mkdim_int loc k) l)) t q
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*)
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let copy copy_dim_vars dim =
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  let rec cp dim =
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  match dim.dim_desc with
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  | Dbool _
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  | Dint _    -> dim
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  | Dident id -> mkdim_ident dim.dim_loc id
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  | Dite (c, t, e) -> mkdim_ite dim.dim_loc (cp c) (cp t) (cp e)
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  | Dappl (id, args) -> mkdim_appl dim.dim_loc id (List.map cp args)
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  | Dlink dim' -> cp dim'
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  | Dunivar -> assert false
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  | Dvar      ->
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    try
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      List.assoc dim.dim_id !copy_dim_vars
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    with Not_found ->
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      let var = mkdim dim.dim_loc Dvar in
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      copy_dim_vars := (dim.dim_id, var)::!copy_dim_vars;
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      var
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  in cp dim
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(* Partially evaluates a 'simple' dimension expr [dim], i.e. an expr containing only int and bool 
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   constructs, with conditionals. [eval_const] is a typing environment for static values. [eval_op] is an evaluation env for basic operators. The argument [dim] is modified in-place. 
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*)
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let rec eval eval_op eval_const dim =
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  match dim.dim_desc with
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  | Dbool _
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  | Dint _    -> ()
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  | Dident id ->
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    (match eval_const id with
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    | Some val_dim -> dim.dim_desc <- Dlink val_dim
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    | None         -> raise InvalidDimension)
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  | Dite (c, t, e) ->
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    begin
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      eval eval_op eval_const c;
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      eval eval_op eval_const t;
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      eval eval_op eval_const e;
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      match (repr c).dim_desc with
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      | Dbool b -> dim.dim_desc <- Dlink (if b then t else e)
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      | _       -> ()
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       end
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  | Dappl (id, args) ->
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    begin
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      List.iter (eval eval_op eval_const) args;
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      if List.for_all is_dimension_const args
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      then dim.dim_desc <- Env.lookup_value eval_op id (List.map (fun d -> (repr d).dim_desc) args)
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    end
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  | Dlink dim' ->
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    begin
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      eval eval_op eval_const dim';
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      dim.dim_desc <- Dlink (repr dim')
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    end
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  | Dvar -> ()
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  | Dunivar -> assert false
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let uneval const univar =
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  let univar = repr univar in
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  match univar.dim_desc with
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  | Dunivar -> univar.dim_desc <- Dident const
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  | _       -> assert false
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(** [occurs dvar dim] returns true if the dimension variable [dvar] occurs in
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    dimension expression [dim]. False otherwise. *)
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let rec occurs dvar dim =
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  let dim = repr dim in
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  match dim.dim_desc with
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  | Dvar  -> dim.dim_id = dvar.dim_id
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  | Dident _
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  | Dint _
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  | Dbool _
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  | Dunivar          -> false
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  | Dite (i, t, e)   ->
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      occurs dvar i || occurs dvar t || occurs dvar e
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  | Dappl (_, args) -> List.exists (occurs dvar) args
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  | Dlink _ -> assert false
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(* Promote monomorphic dimension variables to polymorphic variables.
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   Generalize by side-effects *)
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let rec generalize dim =
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  match dim.dim_desc with
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  | Dvar -> dim.dim_desc <- Dunivar
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  | Dident _
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  | Dint _
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  | Dbool _
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  | Dunivar          -> ()
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  | Dite (i, t, e)   ->
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      generalize i; generalize t; generalize e
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  | Dappl (_, args) -> List.iter generalize args
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  | Dlink dim' -> generalize dim'
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(* Instantiate polymorphic dimension variables to monomorphic variables.
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   Also duplicates the whole term structure (but the constant sub-terms).
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*)
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let rec instantiate inst_dim_vars dim =
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  let dim = repr dim in
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  match dim.dim_desc with
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  | Dvar
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  | Dident _
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  | Dint _
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  | Dbool _ -> dim
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  | Dite (i, t, e)   ->
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      mkdim_ite dim.dim_loc
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	(instantiate inst_dim_vars i)
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	(instantiate inst_dim_vars t)
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	(instantiate inst_dim_vars e)
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  | Dappl (f, args) -> mkdim_appl dim.dim_loc f (List.map (instantiate inst_dim_vars) args)
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  | Dlink dim' -> assert false (*mkdim dim.dim_loc (Dlink (instantiate inst_dim_vars dim'))*)
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  | Dunivar ->
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      try
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        List.assoc dim.dim_id !inst_dim_vars
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      with Not_found ->
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        let var = mkdim dim.dim_loc Dvar in
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	inst_dim_vars := (dim.dim_id, var)::!inst_dim_vars;
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	var
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(** destructive unification of [dim1] and [dim2].
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   Raises [Unify (t1,t2)] if the types are not unifiable.
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   if [semi] unification is required,
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   [dim1] should furthermore be an instance of [dim2] *)
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let unify ?(semi=false) dim1 dim2 =
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  let rec unif dim1 dim2 =
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    let dim1 = repr dim1 in
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    let dim2 = repr dim2 in
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    if dim1.dim_id = dim2.dim_id then () else
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      match dim1.dim_desc, dim2.dim_desc with
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      | Dunivar, _
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      | _      , Dunivar -> assert false
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      | Dvar   , Dvar    ->
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	if dim1.dim_id < dim2.dim_id
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	then dim2.dim_desc <- Dlink dim1
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	else dim1.dim_desc <- Dlink dim2
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      | Dvar   , _ when (not semi) && not (occurs dim1 dim2) ->
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	dim1.dim_desc <- Dlink dim2
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      | _      , Dvar when not (occurs dim2 dim1) ->
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	dim2.dim_desc <- Dlink dim1
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      | Dite(i1, t1, e1), Dite(i2, t2, e2) ->
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	begin
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          unif i1 i2;
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	  unif t1 t2;
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	  unif e1 e2
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	end
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      | Dappl(f1, args1), Dappl(f2, args2) when f1 = f2 && List.length args1 = List.length args2 ->
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	List.iter2 unif args1 args2
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      | Dbool b1, Dbool b2 when b1 = b2 -> ()
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      | Dint i1 , Dint i2 when i1 = i2 -> ()
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      | Dident id1, Dident id2 when id1 = id2 -> ()
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      | _ -> raise (Unify (dim1, dim2))
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  in unif dim1 dim2
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let rec expr_replace_var fvar e = 
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 { e with dim_desc = expr_replace_desc fvar e.dim_desc }
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and expr_replace_desc fvar e =
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  let re = expr_replace_var fvar in
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  match e with
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  | Dvar
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  | Dunivar
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  | Dbool _
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  | Dint _ -> e
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  | Dident v -> Dident (fvar v)
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  | Dappl (id, el) -> Dappl (id, List.map re el)
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  | Dite (g,t,e) -> Dite (re g, re t, re e)
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  | Dlink e -> Dlink (re e)