src/Tools/eqsubst.ML
author wenzelm
Sat Feb 28 14:02:12 2009 +0100 (2009-02-28)
changeset 30160 5f7b17941730
parent 29269 src/Provers/eqsubst.ML@5c25a2012975
child 30318 3d03190d2864
permissions -rw-r--r--
moved some generic tools to src/Tools/ -- src/Provers is essentially obsolete;
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(*  Title:      Tools/eqsubst.ML
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    Author:     Lucas Dixon, University of Edinburgh
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A proof method to perform a substiution using an equation.
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*)
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signature EQSUBST =
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sig
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  (* a type abbreviation for match information *)
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  type match =
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       ((indexname * (sort * typ)) list (* type instantiations *)
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        * (indexname * (typ * term)) list) (* term instantiations *)
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       * (string * typ) list (* fake named type abs env *)
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       * (string * typ) list (* type abs env *)
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       * term (* outer term *)
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  type searchinfo =
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       theory
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       * int (* maxidx *)
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       * Zipper.T (* focusterm to search under *)
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    exception eqsubst_occL_exp of
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       string * int list * Thm.thm list * int * Thm.thm
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    (* low level substitution functions *)
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    val apply_subst_in_asm :
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       int ->
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       Thm.thm ->
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       Thm.thm ->
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       (Thm.cterm list * int * 'a * Thm.thm) * match -> Thm.thm Seq.seq
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    val apply_subst_in_concl :
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       int ->
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       Thm.thm ->
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       Thm.cterm list * Thm.thm ->
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       Thm.thm -> match -> Thm.thm Seq.seq
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    (* matching/unification within zippers *)
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    val clean_match_z :
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       Context.theory -> Term.term -> Zipper.T -> match option
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    val clean_unify_z :
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       Context.theory -> int -> Term.term -> Zipper.T -> match Seq.seq
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    (* skipping things in seq seq's *)
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   (* skipping non-empty sub-sequences but when we reach the end
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      of the seq, remembering how much we have left to skip. *)
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    datatype 'a skipseq = SkipMore of int
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      | SkipSeq of 'a Seq.seq Seq.seq;
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    val skip_first_asm_occs_search :
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       ('a -> 'b -> 'c Seq.seq Seq.seq) ->
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       'a -> int -> 'b -> 'c skipseq
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    val skip_first_occs_search :
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       int -> ('a -> 'b -> 'c Seq.seq Seq.seq) -> 'a -> 'b -> 'c Seq.seq
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    val skipto_skipseq : int -> 'a Seq.seq Seq.seq -> 'a skipseq
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    (* tactics *)
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    val eqsubst_asm_tac :
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       Proof.context ->
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       int list -> Thm.thm list -> int -> Thm.thm -> Thm.thm Seq.seq
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    val eqsubst_asm_tac' :
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       Proof.context ->
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       (searchinfo -> int -> Term.term -> match skipseq) ->
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       int -> Thm.thm -> int -> Thm.thm -> Thm.thm Seq.seq
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    val eqsubst_tac :
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       Proof.context ->
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       int list -> (* list of occurences to rewrite, use [0] for any *)
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       Thm.thm list -> int -> Thm.thm -> Thm.thm Seq.seq
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    val eqsubst_tac' :
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       Proof.context -> (* proof context *)
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       (searchinfo -> Term.term -> match Seq.seq) (* search function *)
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       -> Thm.thm (* equation theorem to rewrite with *)
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       -> int (* subgoal number in goal theorem *)
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       -> Thm.thm (* goal theorem *)
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       -> Thm.thm Seq.seq (* rewritten goal theorem *)
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    val fakefree_badbounds :
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       (string * Term.typ) list ->
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       Term.term ->
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       (string * Term.typ) list * (string * Term.typ) list * Term.term
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    val mk_foo_match :
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       (Term.term -> Term.term) ->
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       ('a * Term.typ) list -> Term.term -> Term.term
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    (* preparing substitution *)
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    val prep_meta_eq : Proof.context -> Thm.thm -> Thm.thm list
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    val prep_concl_subst :
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       int -> Thm.thm -> (Thm.cterm list * Thm.thm) * searchinfo
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    val prep_subst_in_asm :
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       int -> Thm.thm -> int ->
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       (Thm.cterm list * int * int * Thm.thm) * searchinfo
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    val prep_subst_in_asms :
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       int -> Thm.thm ->
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       ((Thm.cterm list * int * int * Thm.thm) * searchinfo) list
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    val prep_zipper_match :
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       Zipper.T -> Term.term * ((string * Term.typ) list * (string * Term.typ) list * Term.term)
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    (* search for substitutions *)
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    val valid_match_start : Zipper.T -> bool
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    val search_lr_all : Zipper.T -> Zipper.T Seq.seq
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    val search_lr_valid : (Zipper.T -> bool) -> Zipper.T -> Zipper.T Seq.seq
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    val searchf_lr_unify_all :
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       searchinfo -> Term.term -> match Seq.seq Seq.seq
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    val searchf_lr_unify_valid :
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       searchinfo -> Term.term -> match Seq.seq Seq.seq
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    val searchf_bt_unify_valid :
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       searchinfo -> Term.term -> match Seq.seq Seq.seq
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    (* syntax tools *)
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    val ith_syntax : Args.T list -> int list * Args.T list
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    val options_syntax : Args.T list -> bool * Args.T list
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    (* Isar level hooks *)
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    val eqsubst_asm_meth : Proof.context -> int list -> Thm.thm list -> Proof.method
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    val eqsubst_meth : Proof.context -> int list -> Thm.thm list -> Proof.method
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    val subst_meth : Method.src -> Proof.context -> Proof.method
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    val setup : theory -> theory
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end;
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structure EqSubst
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: EQSUBST
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= struct
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structure Z = Zipper;
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(* changes object "=" to meta "==" which prepares a given rewrite rule *)
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fun prep_meta_eq ctxt =
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  let val (_, {mk_rews = {mk, ...}, ...}) = Simplifier.rep_ss (Simplifier.local_simpset_of ctxt)
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  in mk #> map Drule.zero_var_indexes end;
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  (* a type abriviation for match information *)
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  type match =
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       ((indexname * (sort * typ)) list (* type instantiations *)
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        * (indexname * (typ * term)) list) (* term instantiations *)
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       * (string * typ) list (* fake named type abs env *)
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       * (string * typ) list (* type abs env *)
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       * term (* outer term *)
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  type searchinfo =
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       theory
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       * int (* maxidx *)
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       * Zipper.T (* focusterm to search under *)
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(* skipping non-empty sub-sequences but when we reach the end
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   of the seq, remembering how much we have left to skip. *)
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datatype 'a skipseq = SkipMore of int
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  | SkipSeq of 'a Seq.seq Seq.seq;
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(* given a seqseq, skip the first m non-empty seq's, note deficit *)
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fun skipto_skipseq m s = 
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    let 
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      fun skip_occs n sq = 
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          case Seq.pull sq of 
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            NONE => SkipMore n
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          | SOME (h,t) => 
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            (case Seq.pull h of NONE => skip_occs n t
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             | SOME _ => if n <= 1 then SkipSeq (Seq.cons h t)
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                         else skip_occs (n - 1) t)
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    in (skip_occs m s) end;
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(* note: outerterm is the taget with the match replaced by a bound 
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         variable : ie: "P lhs" beocmes "%x. P x" 
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         insts is the types of instantiations of vars in lhs
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         and typinsts is the type instantiations of types in the lhs
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         Note: Final rule is the rule lifted into the ontext of the 
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         taget thm. *)
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fun mk_foo_match mkuptermfunc Ts t = 
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    let 
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      val ty = Term.type_of t
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      val bigtype = (rev (map snd Ts)) ---> ty
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      fun mk_foo 0 t = t
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        | mk_foo i t = mk_foo (i - 1) (t $ (Bound (i - 1)))
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      val num_of_bnds = (length Ts)
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      (* foo_term = "fooabs y0 ... yn" where y's are local bounds *)
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      val foo_term = mk_foo num_of_bnds (Bound num_of_bnds)
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    in Abs("fooabs", bigtype, mkuptermfunc foo_term) end;
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(* T is outer bound vars, n is number of locally bound vars *)
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(* THINK: is order of Ts correct...? or reversed? *)
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fun fakefree_badbounds Ts t = 
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    let val (FakeTs,Ts,newnames) = 
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            List.foldr (fn ((n,ty),(FakeTs,Ts,usednames)) => 
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                           let val newname = Name.variant usednames n
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                           in ((RWTools.mk_fake_bound_name newname,ty)::FakeTs,
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                               (newname,ty)::Ts, 
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                               newname::usednames) end)
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                       ([],[],[])
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                       Ts
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    in (FakeTs, Ts, Term.subst_bounds (map Free FakeTs, t)) end;
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(* before matching we need to fake the bound vars that are missing an
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abstraction. In this function we additionally construct the
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abstraction environment, and an outer context term (with the focus
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abstracted out) for use in rewriting with RWInst.rw *)
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fun prep_zipper_match z = 
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    let 
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      val t = Z.trm z  
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      val c = Z.ctxt z
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      val Ts = Z.C.nty_ctxt c
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      val (FakeTs', Ts', t') = fakefree_badbounds Ts t
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      val absterm = mk_foo_match (Z.C.apply c) Ts' t'
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    in
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      (t', (FakeTs', Ts', absterm))
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    end;
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(* Matching and Unification with exception handled *)
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fun clean_match thy (a as (pat, t)) =
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  let val (tyenv, tenv) = Pattern.match thy a (Vartab.empty, Vartab.empty)
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  in SOME (Vartab.dest tyenv, Vartab.dest tenv)
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  end handle Pattern.MATCH => NONE;
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(* given theory, max var index, pat, tgt; returns Seq of instantiations *)
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fun clean_unify thry ix (a as (pat, tgt)) =
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    let
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      (* type info will be re-derived, maybe this can be cached
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         for efficiency? *)
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      val pat_ty = Term.type_of pat;
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      val tgt_ty = Term.type_of tgt;
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      (* is it OK to ignore the type instantiation info?
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         or should I be using it? *)
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      val typs_unify =
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          SOME (Sign.typ_unify thry (pat_ty, tgt_ty) (Vartab.empty, ix))
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            handle Type.TUNIFY => NONE;
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    in
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      case typs_unify of
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        SOME (typinsttab, ix2) =>
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        let
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      (* is it right to throw away the flexes?
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         or should I be using them somehow? *)
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          fun mk_insts env =
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            (Vartab.dest (Envir.type_env env),
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             Envir.alist_of env);
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          val initenv = Envir.Envir {asol = Vartab.empty,
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                                     iTs = typinsttab, maxidx = ix2};
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          val useq = Unify.smash_unifiers thry [a] initenv
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	            handle UnequalLengths => Seq.empty
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		               | Term.TERM _ => Seq.empty;
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          fun clean_unify' useq () =
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              (case (Seq.pull useq) of
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                 NONE => NONE
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               | SOME (h,t) => SOME (mk_insts h, Seq.make (clean_unify' t)))
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	            handle UnequalLengths => NONE
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                   | Term.TERM _ => NONE
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        in
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          (Seq.make (clean_unify' useq))
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        end
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      | NONE => Seq.empty
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    end;
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(* Matching and Unification for zippers *)
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(* Note: Ts is a modified version of the original names of the outer
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bound variables. New names have been introduced to make sure they are
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unique w.r.t all names in the term and each other. usednames' is
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oldnames + new names. *)
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fun clean_match_z thy pat z = 
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    let val (t, (FakeTs,Ts,absterm)) = prep_zipper_match z in
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      case clean_match thy (pat, t) of 
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        NONE => NONE 
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      | SOME insts => SOME (insts, FakeTs, Ts, absterm) end;
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(* ix = max var index *)
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fun clean_unify_z sgn ix pat z = 
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    let val (t, (FakeTs, Ts,absterm)) = prep_zipper_match z in
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    Seq.map (fn insts => (insts, FakeTs, Ts, absterm)) 
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            (clean_unify sgn ix (t, pat)) end;
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(* FOR DEBUGGING...
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type trace_subst_errT = int (* subgoal *)
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        * thm (* thm with all goals *)
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        * (Thm.cterm list (* certified free var placeholders for vars *)
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           * thm)  (* trivial thm of goal concl *)
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            (* possible matches/unifiers *)
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        * thm (* rule *)
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        * (((indexname * typ) list (* type instantiations *)
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              * (indexname * term) list ) (* term instantiations *)
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             * (string * typ) list (* Type abs env *)
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             * term) (* outer term *);
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val trace_subst_err = (ref NONE : trace_subst_errT option ref);
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val trace_subst_search = ref false;
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exception trace_subst_exp of trace_subst_errT;
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*)
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fun bot_left_leaf_of (l $ r) = bot_left_leaf_of l
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  | bot_left_leaf_of (Abs(s,ty,t)) = bot_left_leaf_of t
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  | bot_left_leaf_of x = x;
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(* Avoid considering replacing terms which have a var at the head as
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   they always succeed trivially, and uninterestingly. *)
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fun valid_match_start z =
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    (case bot_left_leaf_of (Z.trm z) of 
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      Var _ => false 
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      | _ => true);
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(* search from top, left to right, then down *)
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val search_lr_all = ZipperSearch.all_bl_ur;
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(* search from top, left to right, then down *)
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fun search_lr_valid validf =
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    let 
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      fun sf_valid_td_lr z = 
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          let val here = if validf z then [Z.Here z] else [] in
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            case Z.trm z 
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             of _ $ _ => [Z.LookIn (Z.move_down_left z)] 
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                         @ here 
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                         @ [Z.LookIn (Z.move_down_right z)]
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              | Abs _ => here @ [Z.LookIn (Z.move_down_abs z)]
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              | _ => here
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          end;
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    in Z.lzy_search sf_valid_td_lr end;
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(* search from bottom to top, left to right *)
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fun search_bt_valid validf =
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    let 
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      fun sf_valid_td_lr z = 
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          let val here = if validf z then [Z.Here z] else [] in
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            case Z.trm z 
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             of _ $ _ => [Z.LookIn (Z.move_down_left z), 
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                          Z.LookIn (Z.move_down_right z)] @ here
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              | Abs _ => [Z.LookIn (Z.move_down_abs z)] @ here
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              | _ => here
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          end;
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    in Z.lzy_search sf_valid_td_lr end;
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fun searchf_unify_gen f (sgn, maxidx, z) lhs =
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    Seq.map (clean_unify_z sgn maxidx lhs) 
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            (Z.limit_apply f z);
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(* search all unifications *)
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val searchf_lr_unify_all =
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    searchf_unify_gen search_lr_all;
paulson@15481
   338
dixon@15814
   339
(* search only for 'valid' unifiers (non abs subterms and non vars) *)
narboux@23064
   340
val searchf_lr_unify_valid = 
narboux@23064
   341
    searchf_unify_gen (search_lr_valid valid_match_start);
dixon@15929
   342
narboux@23064
   343
val searchf_bt_unify_valid =
narboux@23064
   344
    searchf_unify_gen (search_bt_valid valid_match_start);
dixon@15814
   345
dixon@15538
   346
(* apply a substitution in the conclusion of the theorem th *)
dixon@15538
   347
(* cfvs are certified free var placeholders for goal params *)
dixon@15538
   348
(* conclthm is a theorem of for just the conclusion *)
dixon@15538
   349
(* m is instantiation/match information *)
dixon@15538
   350
(* rule is the equation for substitution *)
wenzelm@16978
   351
fun apply_subst_in_concl i th (cfvs, conclthm) rule m =
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   352
    (RWInst.rw m rule conclthm)
dixon@15855
   353
      |> IsaND.unfix_frees cfvs
dixon@15915
   354
      |> RWInst.beta_eta_contract
dixon@15538
   355
      |> (fn r => Tactic.rtac r i th);
paulson@15481
   356
paulson@15481
   357
(* substitute within the conclusion of goal i of gth, using a meta
dixon@15538
   358
equation rule. Note that we assume rule has var indicies zero'd *)
wenzelm@16978
   359
fun prep_concl_subst i gth =
wenzelm@16978
   360
    let
paulson@15481
   361
      val th = Thm.incr_indexes 1 gth;
paulson@15481
   362
      val tgt_term = Thm.prop_of th;
paulson@15481
   363
wenzelm@22578
   364
      val sgn = Thm.theory_of_thm th;
paulson@15481
   365
      val ctermify = Thm.cterm_of sgn;
paulson@15481
   366
      val trivify = Thm.trivial o ctermify;
paulson@15481
   367
paulson@15481
   368
      val (fixedbody, fvs) = IsaND.fix_alls_term i tgt_term;
paulson@15481
   369
      val cfvs = rev (map ctermify fvs);
paulson@15481
   370
dixon@15538
   371
      val conclterm = Logic.strip_imp_concl fixedbody;
dixon@15538
   372
      val conclthm = trivify conclterm;
dixon@27033
   373
      val maxidx = Thm.maxidx_of th;
dixon@19835
   374
      val ft = ((Z.move_down_right (* ==> *)
dixon@19835
   375
                 o Z.move_down_left (* Trueprop *)
dixon@19835
   376
                 o Z.mktop
dixon@16004
   377
                 o Thm.prop_of) conclthm)
paulson@15481
   378
    in
dixon@16004
   379
      ((cfvs, conclthm), (sgn, maxidx, ft))
paulson@15481
   380
    end;
paulson@15481
   381
paulson@15481
   382
(* substitute using an object or meta level equality *)
wenzelm@18598
   383
fun eqsubst_tac' ctxt searchf instepthm i th =
wenzelm@16978
   384
    let
dixon@16004
   385
      val (cvfsconclthm, searchinfo) = prep_concl_subst i th;
wenzelm@18598
   386
      val stepthms = Seq.of_list (prep_meta_eq ctxt instepthm);
dixon@15538
   387
      fun rewrite_with_thm r =
dixon@15538
   388
          let val (lhs,_) = Logic.dest_equals (Thm.concl_of r);
wenzelm@18598
   389
          in searchf searchinfo lhs
wenzelm@18598
   390
             |> Seq.maps (apply_subst_in_concl i th cvfsconclthm r) end;
wenzelm@18598
   391
    in stepthms |> Seq.maps rewrite_with_thm end;
dixon@15538
   392
dixon@15538
   393
wenzelm@19047
   394
(* distinct subgoals *)
dixon@15959
   395
fun distinct_subgoals th =
wenzelm@19047
   396
  the_default th (SINGLE distinct_subgoals_tac th);
dixon@15538
   397
wenzelm@19047
   398
(* General substitution of multiple occurances using one of
dixon@15936
   399
   the given theorems*)
dixon@19835
   400
dixon@19835
   401
wenzelm@16978
   402
exception eqsubst_occL_exp of
wenzelm@16978
   403
          string * (int list) * (thm list) * int * thm;
wenzelm@16978
   404
fun skip_first_occs_search occ srchf sinfo lhs =
dixon@19835
   405
    case (skipto_skipseq occ (srchf sinfo lhs)) of
dixon@19835
   406
      SkipMore _ => Seq.empty
dixon@19835
   407
    | SkipSeq ss => Seq.flat ss;
dixon@16004
   408
dixon@22727
   409
(* The occL is a list of integers indicating which occurence
dixon@22727
   410
w.r.t. the search order, to rewrite. Backtracking will also find later
dixon@22727
   411
occurences, but all earlier ones are skipped. Thus you can use [0] to
dixon@22727
   412
just find all rewrites. *)
dixon@22727
   413
wenzelm@18598
   414
fun eqsubst_tac ctxt occL thms i th =
dixon@15936
   415
    let val nprems = Thm.nprems_of th in
dixon@15936
   416
      if nprems < i then Seq.empty else
wenzelm@16978
   417
      let val thmseq = (Seq.of_list thms)
wenzelm@16978
   418
        fun apply_occ occ th =
wenzelm@18598
   419
            thmseq |> Seq.maps
dixon@19835
   420
                    (fn r => eqsubst_tac' 
dixon@19835
   421
                               ctxt 
dixon@19835
   422
                               (skip_first_occs_search
dixon@19871
   423
                                  occ searchf_lr_unify_valid) r
dixon@15936
   424
                                 (i + ((Thm.nprems_of th) - nprems))
dixon@15936
   425
                                 th);
wenzelm@16978
   426
        val sortedoccL =
dixon@16004
   427
            Library.sort (Library.rev_order o Library.int_ord) occL;
dixon@15936
   428
      in
dixon@16004
   429
        Seq.map distinct_subgoals (Seq.EVERY (map apply_occ sortedoccL) th)
dixon@15936
   430
      end
dixon@15959
   431
    end
dixon@15959
   432
    handle THM _ => raise eqsubst_occL_exp ("THM",occL,thms,i,th);
dixon@15959
   433
paulson@15481
   434
paulson@15481
   435
(* inthms are the given arguments in Isar, and treated as eqstep with
paulson@15481
   436
   the first one, then the second etc *)
wenzelm@18598
   437
fun eqsubst_meth ctxt occL inthms =
wenzelm@21588
   438
    Method.SIMPLE_METHOD' (eqsubst_tac ctxt occL inthms);
paulson@15481
   439
dixon@16004
   440
(* apply a substitution inside assumption j, keeps asm in the same place *)
wenzelm@16978
   441
fun apply_subst_in_asm i th rule ((cfvs, j, ngoalprems, pth),m) =
wenzelm@16978
   442
    let
dixon@16004
   443
      val th2 = Thm.rotate_rule (j - 1) i th; (* put premice first *)
wenzelm@16978
   444
      val preelimrule =
dixon@16004
   445
          (RWInst.rw m rule pth)
wenzelm@21708
   446
            |> (Seq.hd o prune_params_tac)
dixon@16004
   447
            |> Thm.permute_prems 0 ~1 (* put old asm first *)
dixon@16004
   448
            |> IsaND.unfix_frees cfvs (* unfix any global params *)
dixon@16004
   449
            |> RWInst.beta_eta_contract; (* normal form *)
wenzelm@16978
   450
  (*    val elimrule =
dixon@16004
   451
          preelimrule
dixon@16004
   452
            |> Tactic.make_elim (* make into elim rule *)
dixon@16004
   453
            |> Thm.lift_rule (th2, i); (* lift into context *)
dixon@16007
   454
   *)
dixon@16004
   455
    in
dixon@16004
   456
      (* ~j because new asm starts at back, thus we subtract 1 *)
dixon@16007
   457
      Seq.map (Thm.rotate_rule (~j) ((Thm.nprems_of rule) + i))
dixon@16007
   458
      (Tactic.dtac preelimrule i th2)
dixon@16007
   459
wenzelm@16978
   460
      (* (Thm.bicompose
dixon@16004
   461
                 false (* use unification *)
dixon@16004
   462
                 (true, (* elim resolution *)
dixon@16007
   463
                  elimrule, (2 + (Thm.nprems_of rule)) - ngoalprems)
dixon@16007
   464
                 i th2) *)
dixon@16004
   465
    end;
paulson@15481
   466
paulson@15481
   467
dixon@15538
   468
(* prepare to substitute within the j'th premise of subgoal i of gth,
dixon@15538
   469
using a meta-level equation. Note that we assume rule has var indicies
dixon@15538
   470
zero'd. Note that we also assume that premt is the j'th premice of
dixon@15538
   471
subgoal i of gth. Note the repetition of work done for each
dixon@15538
   472
assumption, i.e. this can be made more efficient for search over
dixon@15538
   473
multiple assumptions.  *)
wenzelm@16978
   474
fun prep_subst_in_asm i gth j =
wenzelm@16978
   475
    let
paulson@15481
   476
      val th = Thm.incr_indexes 1 gth;
paulson@15481
   477
      val tgt_term = Thm.prop_of th;
paulson@15481
   478
wenzelm@22578
   479
      val sgn = Thm.theory_of_thm th;
paulson@15481
   480
      val ctermify = Thm.cterm_of sgn;
paulson@15481
   481
      val trivify = Thm.trivial o ctermify;
paulson@15481
   482
paulson@15481
   483
      val (fixedbody, fvs) = IsaND.fix_alls_term i tgt_term;
paulson@15481
   484
      val cfvs = rev (map ctermify fvs);
paulson@15481
   485
haftmann@18011
   486
      val asmt = nth (Logic.strip_imp_prems fixedbody) (j - 1);
dixon@15538
   487
      val asm_nprems = length (Logic.strip_imp_prems asmt);
dixon@15538
   488
dixon@15538
   489
      val pth = trivify asmt;
dixon@27033
   490
      val maxidx = Thm.maxidx_of th;
dixon@15538
   491
dixon@19835
   492
      val ft = ((Z.move_down_right (* trueprop *)
dixon@19835
   493
                 o Z.mktop
dixon@16004
   494
                 o Thm.prop_of) pth)
dixon@16004
   495
    in ((cfvs, j, asm_nprems, pth), (sgn, maxidx, ft)) end;
paulson@15481
   496
dixon@15538
   497
(* prepare subst in every possible assumption *)
wenzelm@16978
   498
fun prep_subst_in_asms i gth =
dixon@16004
   499
    map (prep_subst_in_asm i gth)
dixon@19835
   500
        ((fn l => Library.upto (1, length l))
dixon@16004
   501
           (Logic.prems_of_goal (Thm.prop_of gth) i));
dixon@15538
   502
dixon@15538
   503
dixon@15538
   504
(* substitute in an assumption using an object or meta level equality *)
wenzelm@18598
   505
fun eqsubst_asm_tac' ctxt searchf skipocc instepthm i th =
wenzelm@16978
   506
    let
dixon@16004
   507
      val asmpreps = prep_subst_in_asms i th;
wenzelm@18598
   508
      val stepthms = Seq.of_list (prep_meta_eq ctxt instepthm);
dixon@16004
   509
      fun rewrite_with_thm r =
dixon@16004
   510
          let val (lhs,_) = Logic.dest_equals (Thm.concl_of r)
dixon@16004
   511
            fun occ_search occ [] = Seq.empty
dixon@16004
   512
              | occ_search occ ((asminfo, searchinfo)::moreasms) =
wenzelm@16978
   513
                (case searchf searchinfo occ lhs of
dixon@19835
   514
                   SkipMore i => occ_search i moreasms
dixon@19835
   515
                 | SkipSeq ss =>
wenzelm@19861
   516
                   Seq.append (Seq.map (Library.pair asminfo) (Seq.flat ss))
wenzelm@19861
   517
                               (occ_search 1 moreasms))
dixon@16004
   518
                              (* find later substs also *)
wenzelm@16978
   519
          in
wenzelm@18598
   520
            occ_search skipocc asmpreps |> Seq.maps (apply_subst_in_asm i th r)
dixon@16004
   521
          end;
wenzelm@18598
   522
    in stepthms |> Seq.maps rewrite_with_thm end;
dixon@15538
   523
dixon@16004
   524
wenzelm@16978
   525
fun skip_first_asm_occs_search searchf sinfo occ lhs =
dixon@19835
   526
    skipto_skipseq occ (searchf sinfo lhs);
dixon@16004
   527
wenzelm@18598
   528
fun eqsubst_asm_tac ctxt occL thms i th =
wenzelm@16978
   529
    let val nprems = Thm.nprems_of th
dixon@15538
   530
    in
dixon@16004
   531
      if nprems < i then Seq.empty else
wenzelm@16978
   532
      let val thmseq = (Seq.of_list thms)
wenzelm@16978
   533
        fun apply_occ occK th =
wenzelm@18598
   534
            thmseq |> Seq.maps
wenzelm@16978
   535
                    (fn r =>
wenzelm@18598
   536
                        eqsubst_asm_tac' ctxt (skip_first_asm_occs_search
dixon@19871
   537
                                            searchf_lr_unify_valid) occK r
dixon@16004
   538
                                         (i + ((Thm.nprems_of th) - nprems))
dixon@16004
   539
                                         th);
wenzelm@16978
   540
        val sortedoccs =
dixon@16004
   541
            Library.sort (Library.rev_order o Library.int_ord) occL
dixon@16004
   542
      in
dixon@16004
   543
        Seq.map distinct_subgoals
dixon@16004
   544
                (Seq.EVERY (map apply_occ sortedoccs) th)
dixon@16004
   545
      end
dixon@16004
   546
    end
dixon@16004
   547
    handle THM _ => raise eqsubst_occL_exp ("THM",occL,thms,i,th);
paulson@15481
   548
paulson@15481
   549
(* inthms are the given arguments in Isar, and treated as eqstep with
paulson@15481
   550
   the first one, then the second etc *)
wenzelm@18598
   551
fun eqsubst_asm_meth ctxt occL inthms =
wenzelm@21588
   552
    Method.SIMPLE_METHOD' (eqsubst_asm_tac ctxt occL inthms);
paulson@15481
   553
paulson@15481
   554
(* syntax for options, given "(asm)" will give back true, without
paulson@15481
   555
   gives back false *)
paulson@15481
   556
val options_syntax =
paulson@15481
   557
    (Args.parens (Args.$$$ "asm") >> (K true)) ||
paulson@15481
   558
     (Scan.succeed false);
dixon@15936
   559
dixon@15929
   560
val ith_syntax =
wenzelm@27809
   561
    Scan.optional (Args.parens (Scan.repeat OuterParse.nat)) [0];
paulson@15481
   562
wenzelm@18598
   563
(* combination method that takes a flag (true indicates that subst
wenzelm@18598
   564
should be done to an assumption, false = apply to the conclusion of
wenzelm@18598
   565
the goal) as well as the theorems to use *)
wenzelm@18598
   566
fun subst_meth src =
wenzelm@18988
   567
  Method.syntax ((Scan.lift options_syntax) -- (Scan.lift ith_syntax) -- Attrib.thms) src
haftmann@21879
   568
  #> (fn (((asmflag, occL), inthms), ctxt) =>
wenzelm@18598
   569
    (if asmflag then eqsubst_asm_meth else eqsubst_meth) ctxt occL inthms);
paulson@15481
   570
wenzelm@18598
   571
wenzelm@16978
   572
val setup =
wenzelm@18833
   573
  Method.add_method ("subst", subst_meth, "single-step substitution");
paulson@15481
   574
wenzelm@16978
   575
end;