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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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subexpressions, 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 inplace.

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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 sideeffects *)

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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 subterms).

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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_var_desc fvar e.dim_desc }

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and expr_replace_var_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)

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let rec expr_replace_expr fvar e =

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{ e with dim_desc = expr_replace_expr_desc fvar e.dim_desc }

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and expr_replace_expr_desc fvar e =

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let re = expr_replace_expr 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 > (fvar v).dim_desc

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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)
