src/Pure/unify.ML
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(*  Title:      Pure/unify.ML
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    Author:     Lawrence C Paulson, Cambridge University Computer Laboratory
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    Copyright   Cambridge University 1992
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Higher-Order Unification.
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Types as well as terms are unified.  The outermost functions assume
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the terms to be unified already have the same type.  In resolution,
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this is assured because both have type "prop".
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*)
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signature UNIFY =
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sig
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  val trace_bound_raw: Config.raw
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  val trace_bound: int Config.T
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  val search_bound_raw: Config.raw
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  val search_bound: int Config.T
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  val trace_simp_raw: Config.raw
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  val trace_simp: bool Config.T
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  val trace_types_raw: Config.raw
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  val trace_types: bool Config.T
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  val hounifiers: theory * Envir.env * ((term * term) list) ->
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    (Envir.env * (term * term) list) Seq.seq
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  val unifiers: theory * Envir.env * ((term * term) list) ->
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    (Envir.env * (term * term) list) Seq.seq
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  val smash_unifiers: theory -> (term * term) list -> Envir.env -> Envir.env Seq.seq
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  val matchers: theory -> (term * term) list -> Envir.env Seq.seq
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  val matches_list: theory -> term list -> term list -> bool
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end
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structure Unify : UNIFY =
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struct
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(*Unification options*)
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(*tracing starts above this depth, 0 for full*)
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val trace_bound_raw = Config.declare_global "unify_trace_bound" (K (Config.Int 50));
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val trace_bound = Config.int trace_bound_raw;
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(*unification quits above this depth*)
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val search_bound_raw = Config.declare_global "unify_search_bound" (K (Config.Int 60));
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val search_bound = Config.int search_bound_raw;
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(*print dpairs before calling SIMPL*)
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val trace_simp_raw = Config.declare_global "unify_trace_simp" (K (Config.Bool false));
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val trace_simp = Config.bool trace_simp_raw;
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(*announce potential incompleteness of type unification*)
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val trace_types_raw = Config.declare_global "unify_trace_types" (K (Config.Bool false));
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val trace_types = Config.bool trace_types_raw;
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type binderlist = (string * typ) list;
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type dpair = binderlist * term * term;
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fun fastype env (Ts, t) = Envir.fastype env (map snd Ts) t;
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(* eta normal form *)
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fun eta_norm env =
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  let
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    val tyenv = Envir.type_env env;
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    fun etif (Type ("fun", [T, U]), t) =
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          Abs ("", T, etif (U, incr_boundvars 1 t $ Bound 0))
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      | etif (TVar v, t) =
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          (case Type.lookup tyenv v of
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            NONE => t
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          | SOME T => etif (T, t))
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      | etif (_, t) = t;
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    fun eta_nm (rbinder, Abs (a, T, body)) =
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          Abs (a, T, eta_nm ((a, T) :: rbinder, body))
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      | eta_nm (rbinder, t) = etif (fastype env (rbinder, t), t);
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  in eta_nm end;
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(*OCCURS CHECK
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  Does the uvar occur in the term t?
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  two forms of search, for whether there is a rigid path to the current term.
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  "seen" is list of variables passed thru, is a memo variable for sharing.
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  This version searches for nonrigid occurrence, returns true if found.
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  Since terms may contain variables with same name and different types,
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  the occurs check must ignore the types of variables. This avoids
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  that ?x::?'a is unified with f(?x::T), which may lead to a cyclic
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  substitution when ?'a is instantiated with T later. *)
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fun occurs_terms (seen: indexname list Unsynchronized.ref,
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      env: Envir.env, v: indexname, ts: term list): bool =
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  let
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    fun occurs [] = false
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      | occurs (t :: ts) = occur t orelse occurs ts
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    and occur (Const _) = false
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      | occur (Bound _) = false
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      | occur (Free _) = false
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      | occur (Var (w, T)) =
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          if member (op =) (!seen) w then false
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          else if Term.eq_ix (v, w) then true
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            (*no need to lookup: v has no assignment*)
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          else
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            (seen := w :: !seen;
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             case Envir.lookup env (w, T) of
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               NONE => false
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             | SOME t => occur t)
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      | occur (Abs (_, _, body)) = occur body
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      | occur (f $ t) = occur t orelse occur f;
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  in occurs ts end;
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(* f a1 ... an  ---->  f  using the assignments*)
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fun head_of_in env t =
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  (case t of
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    f $ _ => head_of_in env f
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  | Var vT =>
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      (case Envir.lookup env vT of
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        SOME u => head_of_in env u
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      | NONE => t)
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  | _ => t);
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datatype occ = NoOcc | Nonrigid | Rigid;
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(* Rigid occur check
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Returns Rigid    if it finds a rigid occurrence of the variable,
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        Nonrigid if it finds a nonrigid path to the variable.
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        NoOcc    otherwise.
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  Continues searching for a rigid occurrence even if it finds a nonrigid one.
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Condition for detecting non-unifable terms: [ section 5.3 of Huet (1975) ]
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   a rigid path to the variable, appearing with no arguments.
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Here completeness is sacrificed in order to reduce danger of divergence:
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   reject ALL rigid paths to the variable.
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Could check for rigid paths to bound variables that are out of scope.
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Not necessary because the assignment test looks at variable's ENTIRE rbinder.
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Treatment of head(arg1,...,argn):
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If head is a variable then no rigid path, switch to nonrigid search
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for arg1,...,argn.
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If head is an abstraction then possibly no rigid path (head could be a
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   constant function) so again use nonrigid search.  Happens only if
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   term is not in normal form.
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Warning: finds a rigid occurrence of ?f in ?f(t).
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  Should NOT be called in this case: there is a flex-flex unifier
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*)
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fun rigid_occurs_term (seen: indexname list Unsynchronized.ref, env, v: indexname, t) =
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  let
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    fun nonrigid t =
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      if occurs_terms (seen, env, v, [t]) then Nonrigid
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      else NoOcc
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    fun occurs [] = NoOcc
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      | occurs (t :: ts) =
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          (case occur t of
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            Rigid => Rigid
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          | oc => (case occurs ts of NoOcc => oc | oc2 => oc2))
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    and occomb (f $ t) =
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        (case occur t of
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          Rigid => Rigid
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        | oc => (case occomb f of NoOcc => oc | oc2 => oc2))
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      | occomb t = occur t
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    and occur (Const _) = NoOcc
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      | occur (Bound _) = NoOcc
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      | occur (Free _) = NoOcc
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      | occur (Var (w, T)) =
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          if member (op =) (!seen) w then NoOcc
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          else if Term.eq_ix (v, w) then Rigid
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          else
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            (seen := w :: !seen;
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             case Envir.lookup env (w, T) of
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               NONE => NoOcc
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             | SOME t => occur t)
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      | occur (Abs (_, _, body)) = occur body
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      | occur (t as f $ _) =  (*switch to nonrigid search?*)
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          (case head_of_in env f of
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            Var (w,_) => (*w is not assigned*)
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              if Term.eq_ix (v, w) then Rigid
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              else nonrigid t
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          | Abs _ => nonrigid t (*not in normal form*)
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          | _ => occomb t)
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  in occur t end;
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exception CANTUNIFY;  (*Signals non-unifiability.  Does not signal errors!*)
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exception ASSIGN;  (*Raised if not an assignment*)
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fun unify_types thy TU env =
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  Pattern.unify_types thy TU env handle Pattern.Unif => raise CANTUNIFY;
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fun test_unify_types thy (T, U) env =
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  let
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    val str_of = Syntax.string_of_typ_global thy;
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    fun warn () =
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      if Context_Position.is_visible_global thy then
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        tracing ("Potential loss of completeness: " ^ str_of U ^ " = " ^ str_of T)
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      else ();
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    val env' = unify_types thy (T, U) env;
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  in if is_TVar T orelse is_TVar U then warn () else (); env' end;
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(*Is the term eta-convertible to a single variable with the given rbinder?
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  Examples: ?a   ?f(B.0)   ?g(B.1,B.0)
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  Result is var a for use in SIMPL. *)
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fun get_eta_var ([], _, Var vT) = vT
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  | get_eta_var (_::rbinder, n, f $ Bound i) =
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      if n = i then get_eta_var (rbinder, n + 1, f)
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      else raise ASSIGN
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  | get_eta_var _ = raise ASSIGN;
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(*Solve v=u by assignment -- "fixedpoint" to Huet -- if v not in u.
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  If v occurs rigidly then nonunifiable.
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  If v occurs nonrigidly then must use full algorithm. *)
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fun assignment thy (rbinder, t, u) env =
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  let val vT as (v,T) = get_eta_var (rbinder, 0, t) in
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    (case rigid_occurs_term (Unsynchronized.ref [], env, v, u) of
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      NoOcc =>
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        let val env = unify_types thy (Envir.body_type env T, fastype env (rbinder, u)) env
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        in Envir.update (vT, Logic.rlist_abs (rbinder, u)) env end
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    | Nonrigid => raise ASSIGN
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    | Rigid => raise CANTUNIFY)
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  end;
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(*Extends an rbinder with a new disagreement pair, if both are abstractions.
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  Tries to unify types of the bound variables!
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  Checks that binders have same length, since terms should be eta-normal;
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    if not, raises TERM, probably indicating type mismatch.
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  Uses variable a (unless the null string) to preserve user's naming.*)
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fun new_dpair thy (rbinder, Abs (a, T, body1), Abs (b, U, body2)) env =
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      let
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        val env' = unify_types thy (T, U) env;
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        val c = if a = "" then b else a;
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      in new_dpair thy ((c,T) :: rbinder, body1, body2) env' end
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  | new_dpair _ (_, Abs _, _) _ = raise TERM ("new_dpair", [])
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  | new_dpair _ (_, _, Abs _) _ = raise TERM ("new_dpair", [])
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  | new_dpair _ (rbinder, t1, t2) env = ((rbinder, t1, t2), env);
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fun head_norm_dpair thy (env, (rbinder, t, u)) : dpair * Envir.env =
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  new_dpair thy (rbinder,
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    eta_norm env (rbinder, Envir.head_norm env t),
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    eta_norm env (rbinder, Envir.head_norm env u)) env;
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(*flexflex: the flex-flex pairs,  flexrigid: the flex-rigid pairs
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  Does not perform assignments for flex-flex pairs:
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    may create nonrigid paths, which prevent other assignments.
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  Does not even identify Vars in dpairs such as ?a =?= ?b; an attempt to
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    do so caused numerous problems with no compensating advantage.
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*)
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fun SIMPL0 thy dp0 (env,flexflex,flexrigid) : Envir.env * dpair list * dpair list =
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  let
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    val (dp as (rbinder, t, u), env) = head_norm_dpair thy (env, dp0);
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    fun SIMRANDS (f $ t, g $ u, env) =
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          SIMPL0 thy (rbinder, t, u) (SIMRANDS (f, g, env))
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      | SIMRANDS (t as _$_, _, _) =
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          raise TERM ("SIMPL: operands mismatch", [t, u])
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      | SIMRANDS (t, u as _ $ _, _) =
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          raise TERM ("SIMPL: operands mismatch", [t, u])
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      | SIMRANDS (_, _, env) = (env, flexflex, flexrigid);
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  in
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    (case (head_of t, head_of u) of
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      (Var (_, T), Var (_, U)) =>
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        let
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          val T' = Envir.body_type env T and U' = Envir.body_type env U;
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          val env = unify_types thy (T', U') env;
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        in (env, dp :: flexflex, flexrigid) end
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    | (Var _, _) =>
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        ((assignment thy (rbinder,t,u) env, flexflex, flexrigid)
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          handle ASSIGN => (env, flexflex, dp :: flexrigid))
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    | (_, Var _) =>
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        ((assignment thy (rbinder, u, t) env, flexflex, flexrigid)
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          handle ASSIGN => (env, flexflex, (rbinder, u, t) :: flexrigid))
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    | (Const (a, T), Const (b, U)) =>
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        if a = b then SIMRANDS (t, u, unify_types thy (T, U) env)
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        else raise CANTUNIFY
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    | (Bound i, Bound j) =>
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        if i = j then SIMRANDS (t, u, env) else raise CANTUNIFY
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    | (Free (a, T), Free (b, U)) =>
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        if a = b then SIMRANDS (t, u, unify_types thy (T, U) env)
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        else raise CANTUNIFY
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    | _ => raise CANTUNIFY)
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  end;
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(* changed(env,t) checks whether the head of t is a variable assigned in env*)
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fun changed env (f $ _) = changed env f
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  | changed env (Var v) = (case Envir.lookup env v of NONE => false | _ => true)
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  | changed _ _ = false;
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(*Recursion needed if any of the 'head variables' have been updated
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  Clever would be to re-do just the affected dpairs*)
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fun SIMPL thy (env,dpairs) : Envir.env * dpair list * dpair list =
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  let
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    val all as (env', flexflex, flexrigid) = fold_rev (SIMPL0 thy) dpairs (env, [], []);
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    val dps = flexrigid @ flexflex;
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  in
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    if exists (fn (_, t, u) => changed env' t orelse changed env' u) dps
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    then SIMPL thy (env', dps) else all
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  end;
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(*Makes the terms E1,...,Em,    where Ts = [T...Tm].
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  Each Ei is   ?Gi(B.(n-1),...,B.0), and has type Ti
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  The B.j are bound vars of binder.
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  The terms are not made in eta-normal-form, SIMPL does that later.
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  If done here, eta-expansion must be recursive in the arguments! *)
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fun make_args _ (_, env, []) = (env, [])   (*frequent case*)
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  | make_args name (binder: typ list, env, Ts) : Envir.env * term list =
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      let
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        fun funtype T = binder ---> T;
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        val (env', vars) = Envir.genvars name (env, map funtype Ts);
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      in (env', map (fn var => Logic.combound (var, 0, length binder)) vars) end;
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(*Abstraction over a list of types*)
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fun types_abs ([], u) = u
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  | types_abs (T :: Ts, u) = Abs ("", T, types_abs (Ts, u));
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(*Abstraction over the binder of a type*)
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fun type_abs (env, T, t) = types_abs (Envir.binder_types env T, t);
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(*MATCH taking "big steps".
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  Copies u into the Var v, using projection on targs or imitation.
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  A projection is allowed unless SIMPL raises an exception.
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  Allocates new variables in projection on a higher-order argument,
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    or if u is a variable (flex-flex dpair).
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  Returns long sequence of every way of copying u, for backtracking
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  For example, projection in ?b'(?a) may be wrong if other dpairs constrain ?a.
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  The order for trying projections is crucial in ?b'(?a)
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  NB "vname" is only used in the call to make_args!!   *)
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fun matchcopy thy vname =
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  let
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    fun mc (rbinder, targs, u, ed as (env, dpairs)) : (term * (Envir.env * dpair list)) Seq.seq =
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      let
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        val trace_types = Config.get_global thy trace_types;
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        (*Produce copies of uarg and cons them in front of uargs*)
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        fun copycons uarg (uargs, (env, dpairs)) =
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          Seq.map (fn (uarg', ed') => (uarg' :: uargs, ed'))
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            (mc (rbinder, targs,eta_norm env (rbinder, Envir.head_norm env uarg),
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              (env, dpairs)));
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        (*Produce sequence of all possible ways of copying the arg list*)
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        fun copyargs [] = Seq.cons ([], ed) Seq.empty
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          | copyargs (uarg :: uargs) = Seq.maps (copycons uarg) (copyargs uargs);
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        val (uhead, uargs) = strip_comb u;
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        val base = Envir.body_type env (fastype env (rbinder, uhead));
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        fun joinargs (uargs', ed') = (list_comb (uhead, uargs'), ed');
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        (*attempt projection on argument with given typ*)
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        val Ts = map (curry (fastype env) rbinder) targs;
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        fun projenv (head, (Us, bary), targ, tail) =
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          let
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            val env =
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              if trace_types then test_unify_types thy (base, bary) env
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              else unify_types thy (base, bary) env
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          in
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            Seq.make (fn () =>
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              let
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                val (env', args) = make_args vname (Ts, env, Us);
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                (*higher-order projection: plug in targs for bound vars*)
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                fun plugin arg = list_comb (head_of arg, targs);
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                val dp = (rbinder, list_comb (targ, map plugin args), u);
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                val (env2, frigid, fflex) = SIMPL thy (env', dp :: dpairs);
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                (*may raise exception CANTUNIFY*)
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              in
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                SOME ((list_comb (head, args), (env2, frigid @ fflex)), tail)
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              end handle CANTUNIFY => Seq.pull tail)
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          end handle CANTUNIFY => tail;
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        (*make a list of projections*)
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        fun make_projs (T::Ts, targ::targs) =
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            (Bound(length Ts), T, targ) :: make_projs (Ts,targs)
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          | make_projs ([],[]) = []
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          | make_projs _ = raise TERM ("make_projs", u::targs);
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        (*try projections and imitation*)
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        fun matchfun ((bvar,T,targ)::projs) =
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             (projenv(bvar, Envir.strip_type env T, targ, matchfun projs))
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          | matchfun [] = (*imitation last of all*)
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            (case uhead of
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         Const _ => Seq.map joinargs (copyargs uargs)
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             | Free _  => Seq.map joinargs (copyargs uargs)
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             | _ => Seq.empty)  (*if Var, would be a loop!*)
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    in
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      (case uhead of
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        Abs (a, T, body) =>
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   386
          Seq.map (fn (body', ed') => (Abs (a, T, body'), ed'))
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            (mc ((a, T) :: rbinder, (map (incr_boundvars 1) targs) @ [Bound 0], body, ed))
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      | Var (w, _) =>
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          (*a flex-flex dpair: make variable for t*)
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   390
          let
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            val (env', newhd) = Envir.genvar (#1 w) (env, Ts ---> base);
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            val tabs = Logic.combound (newhd, 0, length Ts);
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            val tsub = list_comb (newhd, targs);
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          in Seq.single (tabs, (env', (rbinder, tsub, u) :: dpairs)) end
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      | _ => matchfun (rev (make_projs (Ts, targs))))
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   396
    end;
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   397
  in mc end;
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   399
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(*Call matchcopy to produce assignments to the variable in the dpair*)
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   401
fun MATCH thy (env, (rbinder, t, u), dpairs) : (Envir.env * dpair list) Seq.seq =
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   402
  let
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   403
    val (Var (vT as (v, T)), targs) = strip_comb t;
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   404
    val Ts = Envir.binder_types env T;
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   405
    fun new_dset (u', (env', dpairs')) =
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   406
      (*if v was updated to s, must unify s with u' *)
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   407
      (case Envir.lookup env' vT of
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   408
        NONE => (Envir.update (vT, types_abs (Ts, u')) env', dpairs')
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   409
      | SOME s => (env', ([], s, types_abs (Ts, u')) :: dpairs'));
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   410
  in
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   411
    Seq.map new_dset (matchcopy thy (#1 v) (rbinder, targs, u, (env, dpairs)))
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   412
  end;
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   414
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   415
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   416
(**** Flex-flex processing ****)
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   417
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   418
(*At end of unification, do flex-flex assignments like ?a -> ?f(?b)
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   419
  Attempts to update t with u, raising ASSIGN if impossible*)
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   420
fun ff_assign thy (env, rbinder, t, u) : Envir.env =
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   421
  let val vT as (v, T) = get_eta_var (rbinder, 0, t) in
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   422
    if occurs_terms (Unsynchronized.ref [], env, v, [u]) then raise ASSIGN
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   423
    else
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   424
      let val env = unify_types thy (Envir.body_type env T, fastype env (rbinder, u)) env
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wenzelm
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   425
      in Envir.vupdate (vT, Logic.rlist_abs (rbinder, u)) env end
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   426
  end;
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   427
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   428
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50a9e2fa4f6b Unification (flexflex) bug fix; making "auto" deterministic
paulson
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   429
(*If an argument contains a banned Bound, then it should be deleted.
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paulson
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   430
  But if the only path is flexible, this is difficult; the code gives up!
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paulson
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   431
  In  %x y.?a(x) =?= %x y.?b(?c(y)) should we instantiate ?b or ?c *)
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   432
exception CHANGE_FAIL;   (*flexible occurrence of banned variable, or other reason to quit*)
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   433
50a9e2fa4f6b Unification (flexflex) bug fix; making "auto" deterministic
paulson
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   434
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   435
(*Flex argument: a term, its type, and the index that refers to it.*)
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   436
type flarg = {t: term, T: typ, j: int};
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   437
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   438
(*Form the arguments into records for deletion/sorting.*)
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   439
fun flexargs ([], [], []) = [] : flarg list
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   440
  | flexargs (j :: js, t :: ts, T :: Ts) = {j = j, t = t, T = T} :: flexargs (js, ts, Ts)
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   441
  | flexargs _ = raise CHANGE_FAIL;
41422
8a765db7e0f8 uniform treatment of type vs. term environment (cf. b654fa27fbc4);
wenzelm
parents: 39997
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   442
(*We give up if we see a variable of function type not applied to a full list of
8a765db7e0f8 uniform treatment of type vs. term environment (cf. b654fa27fbc4);
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   443
  arguments (remember, this code assumes that terms are fully eta-expanded).  This situation
37720
50a9e2fa4f6b Unification (flexflex) bug fix; making "auto" deterministic
paulson
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diff changeset
   444
  can occur if a type variable is instantiated with a function type.
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paulson
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   445
*)
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   446
651
4b0455fbcc49 Pure/Unify/IMPROVING "CLEANING" OF FLEX-FLEX PAIRS: Old code would refuse
lcp
parents: 646
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   447
(*Check whether the 'banned' bound var indices occur rigidly in t*)
19864
227a01b8db80 added matchers, matches_list;
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   448
fun rigid_bound (lev, banned) t =
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   449
  let val (head,args) = strip_comb t in
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   450
    (case head of
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   451
      Bound i =>
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   452
        member (op =) banned (i - lev) orelse exists (rigid_bound (lev, banned)) args
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   453
    | Var _ => false  (*no rigid occurrences here!*)
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   454
    | Abs (_, _, u) =>
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diff changeset
   455
        rigid_bound (lev + 1, banned) u orelse
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   456
        exists (rigid_bound (lev, banned)) args
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   457
    | _ => exists (rigid_bound (lev, banned)) args)
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clasohm
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diff changeset
   458
  end;
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clasohm
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   459
651
4b0455fbcc49 Pure/Unify/IMPROVING "CLEANING" OF FLEX-FLEX PAIRS: Old code would refuse
lcp
parents: 646
diff changeset
   460
(*Squash down indices at level >=lev to delete the banned from a term.*)
4b0455fbcc49 Pure/Unify/IMPROVING "CLEANING" OF FLEX-FLEX PAIRS: Old code would refuse
lcp
parents: 646
diff changeset
   461
fun change_bnos banned =
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   462
  let
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diff changeset
   463
    fun change lev (Bound i) =
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   464
          if i < lev then Bound i
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   465
          else if member (op =) banned (i - lev) then
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   466
            raise CHANGE_FAIL (**flexible occurrence: give up**)
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   467
          else Bound (i - length (filter (fn j => j < i - lev) banned))
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   468
      | change lev (Abs (a, T, t)) = Abs (a, T, change(lev + 1) t)
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   469
      | change lev (t $ u) = change lev t $ change lev u
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   470
      | change lev t = t;
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   471
  in change 0 end;
0
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   472
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   473
(*Change indices, delete the argument if it contains a banned Bound*)
48263
94a7dc2276e4 prefer canonical fold_rev;
wenzelm
parents: 48262
diff changeset
   474
fun change_arg banned {j, t, T} args : flarg list =
37635
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   475
  if rigid_bound (0, banned) t then args  (*delete argument!*)
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   476
  else {j = j, t = change_bnos banned t, T = T} :: args;
0
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   477
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   478
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   479
(*Sort the arguments to create assignments if possible:
48262
a0d8abca8d7a back to naive insertion sort before 1997 to accommodate peculiar less_arg relation -- NB: make_ord arg_less was not a quasi-order and thus inappropriate for generic sort (cf. de74b549f976, ecfeff48bf0c);
wenzelm
parents: 46219
diff changeset
   480
  create eta-terms like ?g B.1 B.0*)
a0d8abca8d7a back to naive insertion sort before 1997 to accommodate peculiar less_arg relation -- NB: make_ord arg_less was not a quasi-order and thus inappropriate for generic sort (cf. de74b549f976, ecfeff48bf0c);
wenzelm
parents: 46219
diff changeset
   481
local
a0d8abca8d7a back to naive insertion sort before 1997 to accommodate peculiar less_arg relation -- NB: make_ord arg_less was not a quasi-order and thus inappropriate for generic sort (cf. de74b549f976, ecfeff48bf0c);
wenzelm
parents: 46219
diff changeset
   482
  fun less_arg ({t = Bound i1, ...}, {t = Bound i2, ...}) = (i2 < i1)
a0d8abca8d7a back to naive insertion sort before 1997 to accommodate peculiar less_arg relation -- NB: make_ord arg_less was not a quasi-order and thus inappropriate for generic sort (cf. de74b549f976, ecfeff48bf0c);
wenzelm
parents: 46219
diff changeset
   483
    | less_arg (_: flarg, _: flarg) = false;
a0d8abca8d7a back to naive insertion sort before 1997 to accommodate peculiar less_arg relation -- NB: make_ord arg_less was not a quasi-order and thus inappropriate for generic sort (cf. de74b549f976, ecfeff48bf0c);
wenzelm
parents: 46219
diff changeset
   484
a0d8abca8d7a back to naive insertion sort before 1997 to accommodate peculiar less_arg relation -- NB: make_ord arg_less was not a quasi-order and thus inappropriate for generic sort (cf. de74b549f976, ecfeff48bf0c);
wenzelm
parents: 46219
diff changeset
   485
  fun ins_arg x [] = [x]
a0d8abca8d7a back to naive insertion sort before 1997 to accommodate peculiar less_arg relation -- NB: make_ord arg_less was not a quasi-order and thus inappropriate for generic sort (cf. de74b549f976, ecfeff48bf0c);
wenzelm
parents: 46219
diff changeset
   486
    | ins_arg x (y :: ys) =
a0d8abca8d7a back to naive insertion sort before 1997 to accommodate peculiar less_arg relation -- NB: make_ord arg_less was not a quasi-order and thus inappropriate for generic sort (cf. de74b549f976, ecfeff48bf0c);
wenzelm
parents: 46219
diff changeset
   487
        if less_arg (y, x) then y :: ins_arg x ys else x :: y :: ys;
a0d8abca8d7a back to naive insertion sort before 1997 to accommodate peculiar less_arg relation -- NB: make_ord arg_less was not a quasi-order and thus inappropriate for generic sort (cf. de74b549f976, ecfeff48bf0c);
wenzelm
parents: 46219
diff changeset
   488
in
a0d8abca8d7a back to naive insertion sort before 1997 to accommodate peculiar less_arg relation -- NB: make_ord arg_less was not a quasi-order and thus inappropriate for generic sort (cf. de74b549f976, ecfeff48bf0c);
wenzelm
parents: 46219
diff changeset
   489
  fun sort_args [] = []
a0d8abca8d7a back to naive insertion sort before 1997 to accommodate peculiar less_arg relation -- NB: make_ord arg_less was not a quasi-order and thus inappropriate for generic sort (cf. de74b549f976, ecfeff48bf0c);
wenzelm
parents: 46219
diff changeset
   490
    | sort_args (x :: xs) = ins_arg x (sort_args xs);
a0d8abca8d7a back to naive insertion sort before 1997 to accommodate peculiar less_arg relation -- NB: make_ord arg_less was not a quasi-order and thus inappropriate for generic sort (cf. de74b549f976, ecfeff48bf0c);
wenzelm
parents: 46219
diff changeset
   491
end;
0
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   492
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   493
(*Test whether the new term would be eta-equivalent to a variable --
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   494
  if so then there is no point in creating a new variable*)
37635
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   495
fun decreasing n ([]: flarg list) = (n = 0)
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   496
  | decreasing n ({j, ...} :: args) = j = n - 1 andalso decreasing (n - 1) args;
0
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   497
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   498
(*Delete banned indices in the term, simplifying it.
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   499
  Force an assignment, if possible, by sorting the arguments.
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   500
  Update its head; squash indices in arguments. *)
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   501
fun clean_term banned (env,t) =
37635
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   502
  let
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   503
    val (Var (v, T), ts) = strip_comb t;
52221
4ffe819a9b11 tuned signature;
wenzelm
parents: 52220
diff changeset
   504
    val (Ts, U) = Envir.strip_type env T
37635
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   505
    and js = length ts - 1  downto 0;
48263
94a7dc2276e4 prefer canonical fold_rev;
wenzelm
parents: 48262
diff changeset
   506
    val args = sort_args (fold_rev (change_arg banned) (flexargs (js, ts, Ts)) [])
37635
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   507
    val ts' = map #t args;
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   508
  in
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   509
    if decreasing (length Ts) args then (env, (list_comb (Var (v, T), ts')))
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   510
    else
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   511
      let
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   512
        val (env', v') = Envir.genvar (#1 v) (env, map #T args ---> U);
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   513
        val body = list_comb (v', map (Bound o #j) args);
51700
c8f2bad67dbb tuned signature;
wenzelm
parents: 48263
diff changeset
   514
        val env2 = Envir.vupdate ((v, T), types_abs (Ts, body)) env';
37635
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   515
        (*the vupdate affects ts' if they contain v*)
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   516
      in (env2, Envir.norm_term env2 (list_comb (v', ts'))) end
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   517
  end;
0
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   518
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   519
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   520
(*Add tpair if not trivial or already there.
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   521
  Should check for swapped pairs??*)
37635
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   522
fun add_tpair (rbinder, (t0, u0), tpairs) : (term * term) list =
19864
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   523
  if t0 aconv u0 then tpairs
0
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   524
  else
37635
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   525
    let
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   526
      val t = Logic.rlist_abs (rbinder, t0)
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   527
      and u = Logic.rlist_abs (rbinder, u0);
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   528
      fun same (t', u') = (t aconv t') andalso (u aconv u')
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   529
    in if exists same tpairs then tpairs else (t, u) :: tpairs end;
0
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   530
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   531
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   532
(*Simplify both terms and check for assignments.
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   533
  Bound vars in the binder are "banned" unless used in both t AND u *)
37635
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   534
fun clean_ffpair thy ((rbinder, t, u), (env, tpairs)) =
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   535
  let
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   536
    val loot = loose_bnos t and loou = loose_bnos u
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   537
    fun add_index (j, (a, T)) (bnos, newbinder) =
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   538
      if member (op =) loot j andalso member (op =) loou j
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   539
      then (bnos, (a, T) :: newbinder)  (*needed by both: keep*)
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   540
      else (j :: bnos, newbinder);   (*remove*)
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   541
    val (banned, rbin') = fold_rev add_index ((0 upto (length rbinder - 1)) ~~ rbinder) ([], []);
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   542
    val (env', t') = clean_term banned (env, t);
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   543
    val (env'',u') = clean_term banned (env',u);
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   544
  in
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   545
    (ff_assign thy (env'', rbin', t', u'), tpairs)
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   546
      handle ASSIGN =>
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   547
        (ff_assign thy (env'', rbin', u', t'), tpairs)
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   548
          handle ASSIGN => (env'', add_tpair (rbin', (t', u'), tpairs))
0
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   549
  end
37635
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   550
  handle CHANGE_FAIL => (env, add_tpair (rbinder, (t, u), tpairs));
0
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   551
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   552
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   553
(*IF the flex-flex dpair is an assignment THEN do it  ELSE  put in tpairs
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   554
  eliminates trivial tpairs like t=t, as well as repeated ones
19864
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   555
  trivial tpairs can easily escape SIMPL:  ?A=t, ?A=?B, ?B=t gives t=t
0
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   556
  Resulting tpairs MAY NOT be in normal form:  assignments may occur here.*)
48263
94a7dc2276e4 prefer canonical fold_rev;
wenzelm
parents: 48262
diff changeset
   557
fun add_ffpair thy (rbinder,t0,u0) (env,tpairs) : Envir.env * (term * term) list =
37635
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   558
  let
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   559
    val t = Envir.norm_term env t0
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   560
    and u = Envir.norm_term env u0;
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   561
  in
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   562
    (case (head_of t, head_of u) of
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   563
      (Var (v, T), Var (w, U)) =>  (*Check for identical variables...*)
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   564
        if Term.eq_ix (v, w) then     (*...occur check would falsely return true!*)
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   565
          if T = U then (env, add_tpair (rbinder, (t, u), tpairs))
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   566
          else raise TERM ("add_ffpair: Var name confusion", [t, u])
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   567
        else if Term_Ord.indexname_ord (v, w) = LESS then (*prefer to update the LARGER variable*)
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   568
          clean_ffpair thy ((rbinder, u, t), (env, tpairs))
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   569
        else clean_ffpair thy ((rbinder, t, u), (env, tpairs))
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   570
    | _ => raise TERM ("add_ffpair: Vars expected", [t, u]))
0
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   571
  end;
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   572
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   573
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   574
(*Print a tracing message + list of dpairs.
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   575
  In t==u print u first because it may be rigid or flexible --
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   576
    t is always flexible.*)
37635
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   577
fun print_dpairs thy msg (env, dpairs) =
52701
51dfdcd88e84 guard unify tracing via visible status of global theory;
wenzelm
parents: 52698
diff changeset
   578
  if Context_Position.is_visible_global thy then
51dfdcd88e84 guard unify tracing via visible status of global theory;
wenzelm
parents: 52698
diff changeset
   579
    let
51dfdcd88e84 guard unify tracing via visible status of global theory;
wenzelm
parents: 52698
diff changeset
   580
      fun pdp (rbinder, t, u) =
51dfdcd88e84 guard unify tracing via visible status of global theory;
wenzelm
parents: 52698
diff changeset
   581
        let
51dfdcd88e84 guard unify tracing via visible status of global theory;
wenzelm
parents: 52698
diff changeset
   582
          fun termT t =
51dfdcd88e84 guard unify tracing via visible status of global theory;
wenzelm
parents: 52698
diff changeset
   583
            Syntax.pretty_term_global thy (Envir.norm_term env (Logic.rlist_abs (rbinder, t)));
51dfdcd88e84 guard unify tracing via visible status of global theory;
wenzelm
parents: 52698
diff changeset
   584
          val bsymbs = [termT u, Pretty.str " =?=", Pretty.brk 1, termT t];
51dfdcd88e84 guard unify tracing via visible status of global theory;
wenzelm
parents: 52698
diff changeset
   585
        in tracing (Pretty.string_of (Pretty.blk (0, bsymbs))) end;
51dfdcd88e84 guard unify tracing via visible status of global theory;
wenzelm
parents: 52698
diff changeset
   586
    in tracing msg; List.app pdp dpairs end
51dfdcd88e84 guard unify tracing via visible status of global theory;
wenzelm
parents: 52698
diff changeset
   587
  else ();
0
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   588
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   589
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   590
(*Unify the dpairs in the environment.
19864
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   591
  Returns flex-flex disagreement pairs NOT IN normal form.
0
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   592
  SIMPL may raise exception CANTUNIFY. *)
37635
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   593
fun hounifiers (thy, env, tus : (term * term) list) : (Envir.env * (term * term) list) Seq.seq =
24178
4ff1dc2aa18d turned Unify flags into configuration options (global only);
wenzelm
parents: 23178
diff changeset
   594
  let
52698
wenzelm
parents: 52221
diff changeset
   595
    val trace_bound = Config.get_global thy trace_bound;
wenzelm
parents: 52221
diff changeset
   596
    val search_bound = Config.get_global thy search_bound;
wenzelm
parents: 52221
diff changeset
   597
    val trace_simp = Config.get_global thy trace_simp;
37635
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   598
    fun add_unify tdepth ((env, dpairs), reseq) =
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   599
      Seq.make (fn () =>
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   600
        let
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   601
          val (env', flexflex, flexrigid) =
52698
wenzelm
parents: 52221
diff changeset
   602
           (if tdepth > trace_bound andalso trace_simp
37635
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   603
            then print_dpairs thy "Enter SIMPL" (env, dpairs) else ();
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   604
            SIMPL thy (env, dpairs));
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   605
        in
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   606
          (case flexrigid of
48263
94a7dc2276e4 prefer canonical fold_rev;
wenzelm
parents: 48262
diff changeset
   607
            [] => SOME (fold_rev (add_ffpair thy) flexflex (env', []), reseq)
37635
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   608
          | dp :: frigid' =>
52698
wenzelm
parents: 52221
diff changeset
   609
              if tdepth > search_bound then
52701
51dfdcd88e84 guard unify tracing via visible status of global theory;
wenzelm
parents: 52698
diff changeset
   610
                (Context_Position.if_visible_global thy warning "Unification bound exceeded";
51dfdcd88e84 guard unify tracing via visible status of global theory;
wenzelm
parents: 52698
diff changeset
   611
                 Seq.pull reseq)
37635
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   612
              else
52698
wenzelm
parents: 52221
diff changeset
   613
               (if tdepth > trace_bound then
37635
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   614
                  print_dpairs thy "Enter MATCH" (env',flexrigid@flexflex)
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   615
                else ();
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   616
                Seq.pull (Seq.it_right
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   617
                    (add_unify (tdepth + 1)) (MATCH thy (env',dp, frigid'@flexflex), reseq))))
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   618
        end
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   619
        handle CANTUNIFY =>
52701
51dfdcd88e84 guard unify tracing via visible status of global theory;
wenzelm
parents: 52698
diff changeset
   620
         (if tdepth > trace_bound then Context_Position.if_visible_global thy tracing "Failure node"
51dfdcd88e84 guard unify tracing via visible status of global theory;
wenzelm
parents: 52698
diff changeset
   621
          else (); Seq.pull reseq));
37635
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   622
    val dps = map (fn (t, u) => ([], t, u)) tus;
16425
2427be27cc60 accomodate identification of type Sign.sg and theory;
wenzelm
parents: 15797
diff changeset
   623
  in add_unify 1 ((env, dps), Seq.empty) end;
0
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   624
18184
43c4589a9a78 tuned Pattern.match/unify;
wenzelm
parents: 17344
diff changeset
   625
fun unifiers (params as (thy, env, tus)) =
19473
wenzelm
parents: 18945
diff changeset
   626
  Seq.cons (fold (Pattern.unify thy) tus env, []) Seq.empty
16425
2427be27cc60 accomodate identification of type Sign.sg and theory;
wenzelm
parents: 15797
diff changeset
   627
    handle Pattern.Unif => Seq.empty
37635
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   628
      | Pattern.Pattern => hounifiers params;
0
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   629
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   630
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   631
(*For smash_flexflex1*)
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   632
fun var_head_of (env,t) : indexname * typ =
37635
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   633
  (case head_of (strip_abs_body (Envir.norm_term env t)) of
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   634
    Var (v, T) => (v, T)
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   635
  | _ => raise CANTUNIFY);  (*not flexible, cannot use trivial substitution*)
0
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   636
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   637
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   638
(*Eliminate a flex-flex pair by the trivial substitution, see Huet (1975)
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   639
  Unifies ?f(t1...rm) with ?g(u1...un) by ?f -> %x1...xm.?a, ?g -> %x1...xn.?a
19864
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   640
  Unfortunately, unifies ?f(t,u) with ?g(t,u) by ?f, ?g -> %(x,y)?a,
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   641
  though just ?g->?f is a more general unifier.
0
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   642
  Unlike Huet (1975), does not smash together all variables of same type --
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   643
    requires more work yet gives a less general unifier (fewer variables).
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   644
  Handles ?f(t1...rm) with ?f(u1...um) to avoid multiple updates. *)
48263
94a7dc2276e4 prefer canonical fold_rev;
wenzelm
parents: 48262
diff changeset
   645
fun smash_flexflex1 (t, u) env : Envir.env =
37635
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   646
  let
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   647
    val vT as (v, T) = var_head_of (env, t)
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   648
    and wU as (w, U) = var_head_of (env, u);
52221
4ffe819a9b11 tuned signature;
wenzelm
parents: 52220
diff changeset
   649
    val (env', var) = Envir.genvar (#1 v) (env, Envir.body_type env T);
51700
c8f2bad67dbb tuned signature;
wenzelm
parents: 48263
diff changeset
   650
    val env'' = Envir.vupdate (wU, type_abs (env', U, var)) env';
37635
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   651
  in
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   652
    if vT = wU then env''  (*the other update would be identical*)
51700
c8f2bad67dbb tuned signature;
wenzelm
parents: 48263
diff changeset
   653
    else Envir.vupdate (vT, type_abs (env', T, var)) env''
0
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   654
  end;
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   655
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   656
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   657
(*Smash all flex-flexpairs.  Should allow selection of pairs by a predicate?*)
37636
ab50854da897 eliminated some unused bindings;
wenzelm
parents: 37635
diff changeset
   658
fun smash_flexflex (env, tpairs) : Envir.env =
48263
94a7dc2276e4 prefer canonical fold_rev;
wenzelm
parents: 48262
diff changeset
   659
  fold_rev smash_flexflex1 tpairs env;
0
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   660
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   661
(*Returns unifiers with no remaining disagreement pairs*)
19864
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   662
fun smash_unifiers thy tus env =
37635
484efa650907 recovered some indentation from the depths of time;
wenzelm
parents: 36787
diff changeset
   663
  Seq.map smash_flexflex (unifiers (thy, env, tus));
0
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   664
19864
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   665
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   666
(*Pattern matching*)
32032
a6a6e8031c14 tuned/modernized Envir operations;
wenzelm
parents: 29269
diff changeset
   667
fun first_order_matchers thy pairs (Envir.Envir {maxidx, tenv, tyenv}) =
20020
9e7d3d06c643 matchers: fall back on plain first_order_matchers, not pattern;
wenzelm
parents: 19920
diff changeset
   668
  let val (tyenv', tenv') = fold (Pattern.first_order_match thy) pairs (tyenv, tenv)
32032
a6a6e8031c14 tuned/modernized Envir operations;
wenzelm
parents: 29269
diff changeset
   669
  in Seq.single (Envir.Envir {maxidx = maxidx, tenv = tenv', tyenv = tyenv'}) end
19864
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   670
  handle Pattern.MATCH => Seq.empty;
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   671
41422
8a765db7e0f8 uniform treatment of type vs. term environment (cf. b654fa27fbc4);
wenzelm
parents: 39997
diff changeset
   672
(*General matching -- keep variables disjoint*)
19864
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   673
fun matchers _ [] = Seq.single (Envir.empty ~1)
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   674
  | matchers thy pairs =
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   675
      let
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   676
        val maxidx = fold (Term.maxidx_term o #2) pairs ~1;
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   677
        val offset = maxidx + 1;
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   678
        val pairs' = map (apfst (Logic.incr_indexes ([], offset))) pairs;
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   679
        val maxidx' = fold (fn (t, u) => Term.maxidx_term t #> Term.maxidx_term u) pairs' ~1;
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   680
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   681
        val pat_tvars = fold (Term.add_tvars o #1) pairs' [];
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   682
        val pat_vars = fold (Term.add_vars o #1) pairs' [];
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   683
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   684
        val decr_indexesT =
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   685
          Term.map_atyps (fn T as TVar ((x, i), S) =>
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   686
            if i > maxidx then TVar ((x, i - offset), S) else T | T => T);
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   687
        val decr_indexes =
20548
8ef25fe585a8 renamed Term.map_term_types to Term.map_types (cf. Term.fold_types);
wenzelm
parents: 20098
diff changeset
   688
          Term.map_types decr_indexesT #>
19864
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   689
          Term.map_aterms (fn t as Var ((x, i), T) =>
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   690
            if i > maxidx then Var ((x, i - offset), T) else t | t => t);
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   691
32032
a6a6e8031c14 tuned/modernized Envir operations;
wenzelm
parents: 29269
diff changeset
   692
        fun norm_tvar env ((x, i), S) =
41422
8a765db7e0f8 uniform treatment of type vs. term environment (cf. b654fa27fbc4);
wenzelm
parents: 39997
diff changeset
   693
          let
8a765db7e0f8 uniform treatment of type vs. term environment (cf. b654fa27fbc4);
wenzelm
parents: 39997
diff changeset
   694
            val tyenv = Envir.type_env env;
8a765db7e0f8 uniform treatment of type vs. term environment (cf. b654fa27fbc4);
wenzelm
parents: 39997
diff changeset
   695
            val T' = Envir.norm_type tyenv (TVar ((x, i), S));
8a765db7e0f8 uniform treatment of type vs. term environment (cf. b654fa27fbc4);
wenzelm
parents: 39997
diff changeset
   696
          in
8a765db7e0f8 uniform treatment of type vs. term environment (cf. b654fa27fbc4);
wenzelm
parents: 39997
diff changeset
   697
            if (case T' of TVar (v, _) => v = (x, i) | _ => false) then NONE
8a765db7e0f8 uniform treatment of type vs. term environment (cf. b654fa27fbc4);
wenzelm
parents: 39997
diff changeset
   698
            else SOME ((x, i - offset), (S, decr_indexesT T'))
8a765db7e0f8 uniform treatment of type vs. term environment (cf. b654fa27fbc4);
wenzelm
parents: 39997
diff changeset
   699
          end;
8a765db7e0f8 uniform treatment of type vs. term environment (cf. b654fa27fbc4);
wenzelm
parents: 39997
diff changeset
   700
32032
a6a6e8031c14 tuned/modernized Envir operations;
wenzelm
parents: 29269
diff changeset
   701
        fun norm_var env ((x, i), T) =
19864
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   702
          let
32032
a6a6e8031c14 tuned/modernized Envir operations;
wenzelm
parents: 29269
diff changeset
   703
            val tyenv = Envir.type_env env;
19864
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   704
            val T' = Envir.norm_type tyenv T;
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   705
            val t' = Envir.norm_term env (Var ((x, i), T'));
41422
8a765db7e0f8 uniform treatment of type vs. term environment (cf. b654fa27fbc4);
wenzelm
parents: 39997
diff changeset
   706
          in
8a765db7e0f8 uniform treatment of type vs. term environment (cf. b654fa27fbc4);
wenzelm
parents: 39997
diff changeset
   707
            if (case t' of Var (v, _) => v = (x, i) | _ => false) then NONE
8a765db7e0f8 uniform treatment of type vs. term environment (cf. b654fa27fbc4);
wenzelm
parents: 39997
diff changeset
   708
            else SOME ((x, i - offset), (decr_indexesT T', decr_indexes t'))
8a765db7e0f8 uniform treatment of type vs. term environment (cf. b654fa27fbc4);
wenzelm
parents: 39997
diff changeset
   709
          end;
19864
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   710
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   711
        fun result env =
19876
wenzelm
parents: 19866
diff changeset
   712
          if Envir.above env maxidx then   (* FIXME proper handling of generated vars!? *)
19864
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   713
            SOME (Envir.Envir {maxidx = maxidx,
41422
8a765db7e0f8 uniform treatment of type vs. term environment (cf. b654fa27fbc4);
wenzelm
parents: 39997
diff changeset
   714
              tyenv = Vartab.make (map_filter (norm_tvar env) pat_tvars),
8a765db7e0f8 uniform treatment of type vs. term environment (cf. b654fa27fbc4);
wenzelm
parents: 39997
diff changeset
   715
              tenv = Vartab.make (map_filter (norm_var env) pat_vars)})
19866
wenzelm
parents: 19864
diff changeset
   716
          else NONE;
19864
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   717
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   718
        val empty = Envir.empty maxidx';
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   719
      in
19876
wenzelm
parents: 19866
diff changeset
   720
        Seq.append
19920
8257e52164a1 matchers: try pattern_matchers only *after* general matching (The
wenzelm
parents: 19876
diff changeset
   721
          (Seq.map_filter result (smash_unifiers thy pairs' empty))
20020
9e7d3d06c643 matchers: fall back on plain first_order_matchers, not pattern;
wenzelm
parents: 19920
diff changeset
   722
          (first_order_matchers thy pairs empty)
19864
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   723
      end;
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   724
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   725
fun matches_list thy ps os =
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   726
  length ps = length os andalso is_some (Seq.pull (matchers thy (ps ~~ os)));
227a01b8db80 added matchers, matches_list;
wenzelm
parents: 19473
diff changeset
   727
0
a5a9c433f639 Initial revision
clasohm
parents:
diff changeset
   728
end;