wenzelm@30160: (*  Title:      Tools/eqsubst.ML
wenzelm@29269:     Author:     Lucas Dixon, University of Edinburgh
paulson@15481: 
wenzelm@52235: Perform a substitution using an equation.
wenzelm@18598: *)
dixon@15538: 
wenzelm@18591: signature EQSUBST =
paulson@15481: sig
dixon@19871:   type match =
wenzelm@52234:     ((indexname * (sort * typ)) list (* type instantiations *)
wenzelm@52234:       * (indexname * (typ * term)) list) (* term instantiations *)
wenzelm@52234:     * (string * typ) list (* fake named type abs env *)
wenzelm@52234:     * (string * typ) list (* type abs env *)
wenzelm@52234:     * term (* outer term *)
dixon@19871: 
dixon@19871:   type searchinfo =
wenzelm@52234:     theory
wenzelm@52234:     * int (* maxidx *)
wenzelm@52234:     * Zipper.T (* focusterm to search under *)
dixon@19871: 
wenzelm@49339:   datatype 'a skipseq = SkipMore of int | SkipSeq of 'a Seq.seq Seq.seq
dixon@19871: 
wenzelm@52234:   val skip_first_asm_occs_search: ('a -> 'b -> 'c Seq.seq Seq.seq) -> 'a -> int -> 'b -> 'c skipseq
wenzelm@52234:   val skip_first_occs_search: int -> ('a -> 'b -> 'c Seq.seq Seq.seq) -> 'a -> 'b -> 'c Seq.seq
wenzelm@52234:   val skipto_skipseq: int -> 'a Seq.seq Seq.seq -> 'a skipseq
dixon@19871: 
wenzelm@49339:   (* tactics *)
wenzelm@52234:   val eqsubst_asm_tac: Proof.context -> int list -> thm list -> int -> tactic
wenzelm@52234:   val eqsubst_asm_tac': Proof.context ->
wenzelm@52234:     (searchinfo -> int -> term -> match skipseq) -> int -> thm -> int -> tactic
wenzelm@52234:   val eqsubst_tac: Proof.context ->
wenzelm@52234:     int list -> (* list of occurences to rewrite, use [0] for any *)
wenzelm@52234:     thm list -> int -> tactic
wenzelm@52234:   val eqsubst_tac': Proof.context ->
wenzelm@52234:     (searchinfo -> term -> match Seq.seq) (* search function *)
wenzelm@52234:     -> thm (* equation theorem to rewrite with *)
wenzelm@52234:     -> int (* subgoal number in goal theorem *)
wenzelm@52234:     -> thm (* goal theorem *)
wenzelm@52234:     -> thm Seq.seq (* rewritten goal theorem *)
dixon@19871: 
wenzelm@49339:   (* search for substitutions *)
wenzelm@52234:   val valid_match_start: Zipper.T -> bool
wenzelm@52234:   val search_lr_all: Zipper.T -> Zipper.T Seq.seq
wenzelm@52234:   val search_lr_valid: (Zipper.T -> bool) -> Zipper.T -> Zipper.T Seq.seq
wenzelm@52234:   val searchf_lr_unify_all: searchinfo -> term -> match Seq.seq Seq.seq
wenzelm@52234:   val searchf_lr_unify_valid: searchinfo -> term -> match Seq.seq Seq.seq
wenzelm@52234:   val searchf_bt_unify_valid: searchinfo -> term -> match Seq.seq Seq.seq
dixon@19871: 
wenzelm@49339:   val setup : theory -> theory
paulson@15481: end;
paulson@15481: 
wenzelm@41164: structure EqSubst: EQSUBST =
wenzelm@41164: struct
dixon@19835: 
dixon@19835: (* changes object "=" to meta "==" which prepares a given rewrite rule *)
wenzelm@18598: fun prep_meta_eq ctxt =
wenzelm@51717:   Simplifier.mksimps ctxt #> map Drule.zero_var_indexes;
wenzelm@18598: 
paulson@15481: 
wenzelm@52234: type match =
wenzelm@52235:   ((indexname * (sort * typ)) list (* type instantiations *)
wenzelm@52235:    * (indexname * (typ * term)) list) (* term instantiations *)
wenzelm@52235:   * (string * typ) list (* fake named type abs env *)
wenzelm@52235:   * (string * typ) list (* type abs env *)
wenzelm@52235:   * term; (* outer term *)
dixon@15550: 
wenzelm@52234: type searchinfo =
wenzelm@52235:   theory
wenzelm@52235:   * int (* maxidx *)
wenzelm@52235:   * Zipper.T; (* focusterm to search under *)
dixon@19835: 
dixon@19835: 
dixon@19835: (* skipping non-empty sub-sequences but when we reach the end
dixon@19835:    of the seq, remembering how much we have left to skip. *)
wenzelm@52234: datatype 'a skipseq =
wenzelm@52234:   SkipMore of int |
wenzelm@52234:   SkipSeq of 'a Seq.seq Seq.seq;
wenzelm@52234: 
dixon@19835: (* given a seqseq, skip the first m non-empty seq's, note deficit *)
wenzelm@49339: fun skipto_skipseq m s =
wenzelm@52234:   let
wenzelm@52234:     fun skip_occs n sq =
wenzelm@52234:       (case Seq.pull sq of
wenzelm@52234:         NONE => SkipMore n
wenzelm@52234:       | SOME (h,t) =>
wenzelm@52234:         (case Seq.pull h of
wenzelm@52234:           NONE => skip_occs n t
wenzelm@52234:         | SOME _ => if n <= 1 then SkipSeq (Seq.cons h t) else skip_occs (n - 1) t))
wenzelm@52234:   in skip_occs m s end;
dixon@19835: 
wenzelm@49339: (* note: outerterm is the taget with the match replaced by a bound
wenzelm@52234:    variable : ie: "P lhs" beocmes "%x. P x"
wenzelm@52234:    insts is the types of instantiations of vars in lhs
wenzelm@52234:    and typinsts is the type instantiations of types in the lhs
wenzelm@52234:    Note: Final rule is the rule lifted into the ontext of the
wenzelm@52234:    taget thm. *)
wenzelm@49339: fun mk_foo_match mkuptermfunc Ts t =
wenzelm@52234:   let
wenzelm@52234:     val ty = Term.type_of t
wenzelm@52235:     val bigtype = rev (map snd Ts) ---> ty
wenzelm@52234:     fun mk_foo 0 t = t
wenzelm@52234:       | mk_foo i t = mk_foo (i - 1) (t $ (Bound (i - 1)))
wenzelm@52235:     val num_of_bnds = length Ts
wenzelm@52234:     (* foo_term = "fooabs y0 ... yn" where y's are local bounds *)
wenzelm@52234:     val foo_term = mk_foo num_of_bnds (Bound num_of_bnds)
wenzelm@52234:   in Abs ("fooabs", bigtype, mkuptermfunc foo_term) end;
dixon@19835: 
dixon@19835: (* T is outer bound vars, n is number of locally bound vars *)
dixon@19835: (* THINK: is order of Ts correct...? or reversed? *)
wenzelm@49339: fun mk_fake_bound_name n = ":b_" ^ n;
wenzelm@49339: fun fakefree_badbounds Ts t =
wenzelm@52234:   let val (FakeTs, Ts, newnames) =
wenzelm@52234:     List.foldr (fn ((n, ty), (FakeTs, Ts, usednames)) =>
wenzelm@52234:       let
wenzelm@52234:         val newname = singleton (Name.variant_list usednames) n
wenzelm@52234:       in
wenzelm@52234:         ((mk_fake_bound_name newname, ty) :: FakeTs,
wenzelm@52234:           (newname, ty) :: Ts,
wenzelm@52234:           newname :: usednames)
wenzelm@52234:       end) ([], [], []) Ts
wenzelm@52234:   in (FakeTs, Ts, Term.subst_bounds (map Free FakeTs, t)) end;
dixon@19835: 
dixon@19835: (* before matching we need to fake the bound vars that are missing an
wenzelm@52235:    abstraction. In this function we additionally construct the
wenzelm@52235:    abstraction environment, and an outer context term (with the focus
wenzelm@52235:    abstracted out) for use in rewriting with RWInst.rw *)
wenzelm@49339: fun prep_zipper_match z =
wenzelm@52234:   let
wenzelm@52234:     val t = Zipper.trm z
wenzelm@52234:     val c = Zipper.ctxt z
wenzelm@52234:     val Ts = Zipper.C.nty_ctxt c
wenzelm@52234:     val (FakeTs', Ts', t') = fakefree_badbounds Ts t
wenzelm@52234:     val absterm = mk_foo_match (Zipper.C.apply c) Ts' t'
wenzelm@52234:   in
wenzelm@52234:     (t', (FakeTs', Ts', absterm))
wenzelm@52234:   end;
dixon@19835: 
wenzelm@49339: (* Unification with exception handled *)
dixon@19835: (* given theory, max var index, pat, tgt; returns Seq of instantiations *)
wenzelm@52235: fun clean_unify thy ix (a as (pat, tgt)) =
wenzelm@52234:   let
wenzelm@52234:     (* type info will be re-derived, maybe this can be cached
wenzelm@52234:        for efficiency? *)
wenzelm@52234:     val pat_ty = Term.type_of pat;
wenzelm@52234:     val tgt_ty = Term.type_of tgt;
wenzelm@52235:     (* FIXME is it OK to ignore the type instantiation info?
wenzelm@52234:        or should I be using it? *)
wenzelm@52234:     val typs_unify =
wenzelm@52235:       SOME (Sign.typ_unify thy (pat_ty, tgt_ty) (Vartab.empty, ix))
wenzelm@52234:         handle Type.TUNIFY => NONE;
wenzelm@52234:   in
wenzelm@52234:     (case typs_unify of
wenzelm@52234:       SOME (typinsttab, ix2) =>
dixon@19835:         let
wenzelm@52234:           (* FIXME is it right to throw away the flexes?
wenzelm@52234:              or should I be using them somehow? *)
dixon@19835:           fun mk_insts env =
dixon@19835:             (Vartab.dest (Envir.type_env env),
wenzelm@32032:              Vartab.dest (Envir.term_env env));
wenzelm@32032:           val initenv =
wenzelm@32032:             Envir.Envir {maxidx = ix2, tenv = Vartab.empty, tyenv = typinsttab};
wenzelm@52235:           val useq = Unify.smash_unifiers thy [a] initenv
wenzelm@52234:             handle ListPair.UnequalLengths => Seq.empty
wenzelm@52234:               | Term.TERM _ => Seq.empty;
dixon@19835:           fun clean_unify' useq () =
wenzelm@52234:             (case (Seq.pull useq) of
wenzelm@52234:                NONE => NONE
wenzelm@52234:              | SOME (h, t) => SOME (mk_insts h, Seq.make (clean_unify' t)))
wenzelm@52234:             handle ListPair.UnequalLengths => NONE
wenzelm@52234:               | Term.TERM _ => NONE;
dixon@19835:         in
dixon@19835:           (Seq.make (clean_unify' useq))
dixon@19835:         end
wenzelm@52234:     | NONE => Seq.empty)
wenzelm@52234:   end;
dixon@19835: 
wenzelm@49339: (* Unification for zippers *)
dixon@19835: (* Note: Ts is a modified version of the original names of the outer
wenzelm@52235:    bound variables. New names have been introduced to make sure they are
wenzelm@52235:    unique w.r.t all names in the term and each other. usednames' is
wenzelm@52235:    oldnames + new names. *)
wenzelm@52235: fun clean_unify_z thy maxidx pat z =
wenzelm@52235:   let val (t, (FakeTs, Ts, absterm)) = prep_zipper_match z in
wenzelm@49339:     Seq.map (fn insts => (insts, FakeTs, Ts, absterm))
wenzelm@52235:       (clean_unify thy maxidx (t, pat))
wenzelm@52234:   end;
dixon@19835: 
dixon@15550: 
wenzelm@52234: fun bot_left_leaf_of (l $ _) = bot_left_leaf_of l
wenzelm@52234:   | bot_left_leaf_of (Abs (_, _, t)) = bot_left_leaf_of t
dixon@19835:   | bot_left_leaf_of x = x;
dixon@15538: 
dixon@19975: (* Avoid considering replacing terms which have a var at the head as
dixon@19975:    they always succeed trivially, and uninterestingly. *)
dixon@19835: fun valid_match_start z =
wenzelm@52234:   (case bot_left_leaf_of (Zipper.trm z) of
wenzelm@52234:     Var _ => false
wenzelm@52234:   | _ => true);
dixon@19975: 
dixon@15814: (* search from top, left to right, then down *)
dixon@19871: val search_lr_all = ZipperSearch.all_bl_ur;
paulson@15481: 
dixon@15814: (* search from top, left to right, then down *)
dixon@19871: fun search_lr_valid validf =
wenzelm@52234:   let
wenzelm@52234:     fun sf_valid_td_lr z =
wenzelm@52234:       let val here = if validf z then [Zipper.Here z] else [] in
wenzelm@52234:         (case Zipper.trm z of
wenzelm@52234:           _ $ _ =>
wenzelm@52234:             [Zipper.LookIn (Zipper.move_down_left z)] @ here @
wenzelm@52234:             [Zipper.LookIn (Zipper.move_down_right z)]
wenzelm@52234:         | Abs _ => here @ [Zipper.LookIn (Zipper.move_down_abs z)]
wenzelm@52234:         | _ => here)
wenzelm@52234:       end;
wenzelm@52234:   in Zipper.lzy_search sf_valid_td_lr end;
dixon@15814: 
narboux@23064: (* search from bottom to top, left to right *)
narboux@23064: fun search_bt_valid validf =
wenzelm@52234:   let
wenzelm@52234:     fun sf_valid_td_lr z =
wenzelm@52234:       let val here = if validf z then [Zipper.Here z] else [] in
wenzelm@52234:         (case Zipper.trm z of
wenzelm@52234:           _ $ _ =>
wenzelm@52234:             [Zipper.LookIn (Zipper.move_down_left z),
wenzelm@52234:              Zipper.LookIn (Zipper.move_down_right z)] @ here
wenzelm@52234:         | Abs _ => [Zipper.LookIn (Zipper.move_down_abs z)] @ here
wenzelm@52234:         | _ => here)
wenzelm@52234:       end;
wenzelm@52234:   in Zipper.lzy_search sf_valid_td_lr end;
narboux@23064: 
wenzelm@52235: fun searchf_unify_gen f (thy, maxidx, z) lhs =
wenzelm@52235:   Seq.map (clean_unify_z thy maxidx lhs) (Zipper.limit_apply f z);
narboux@23064: 
dixon@15814: (* search all unifications *)
wenzelm@52234: val searchf_lr_unify_all = searchf_unify_gen search_lr_all;
paulson@15481: 
dixon@15814: (* search only for 'valid' unifiers (non abs subterms and non vars) *)
wenzelm@52234: val searchf_lr_unify_valid = searchf_unify_gen (search_lr_valid valid_match_start);
dixon@15929: 
wenzelm@52234: val searchf_bt_unify_valid = searchf_unify_gen (search_bt_valid valid_match_start);
dixon@15814: 
dixon@15538: (* apply a substitution in the conclusion of the theorem th *)
dixon@15538: (* cfvs are certified free var placeholders for goal params *)
dixon@15538: (* conclthm is a theorem of for just the conclusion *)
dixon@15538: (* m is instantiation/match information *)
dixon@15538: (* rule is the equation for substitution *)
wenzelm@49340: fun apply_subst_in_concl ctxt i th (cfvs, conclthm) rule m =
wenzelm@52234:   RWInst.rw ctxt m rule conclthm
wenzelm@52234:   |> IsaND.unfix_frees cfvs
wenzelm@52234:   |> RWInst.beta_eta_contract
wenzelm@52234:   |> (fn r => Tactic.rtac r i th);
paulson@15481: 
paulson@15481: (* substitute within the conclusion of goal i of gth, using a meta
dixon@15538: equation rule. Note that we assume rule has var indicies zero'd *)
wenzelm@49340: fun prep_concl_subst ctxt i gth =
wenzelm@52234:   let
wenzelm@52234:     val th = Thm.incr_indexes 1 gth;
wenzelm@52234:     val tgt_term = Thm.prop_of th;
paulson@15481: 
wenzelm@52235:     val thy = Thm.theory_of_thm th;
wenzelm@52235:     val cert = Thm.cterm_of thy;
paulson@15481: 
wenzelm@52234:     val (fixedbody, fvs) = IsaND.fix_alls_term ctxt i tgt_term;
wenzelm@52235:     val cfvs = rev (map cert fvs);
paulson@15481: 
wenzelm@52234:     val conclterm = Logic.strip_imp_concl fixedbody;
wenzelm@52235:     val conclthm = Thm.trivial (cert conclterm);
wenzelm@52234:     val maxidx = Thm.maxidx_of th;
wenzelm@52234:     val ft =
wenzelm@52234:       (Zipper.move_down_right (* ==> *)
wenzelm@52234:        o Zipper.move_down_left (* Trueprop *)
wenzelm@52234:        o Zipper.mktop
wenzelm@52234:        o Thm.prop_of) conclthm
wenzelm@52234:   in
wenzelm@52235:     ((cfvs, conclthm), (thy, maxidx, ft))
wenzelm@52234:   end;
paulson@15481: 
paulson@15481: (* substitute using an object or meta level equality *)
wenzelm@18598: fun eqsubst_tac' ctxt searchf instepthm i th =
wenzelm@52234:   let
wenzelm@52234:     val (cvfsconclthm, searchinfo) = prep_concl_subst ctxt i th;
wenzelm@52234:     val stepthms = Seq.of_list (prep_meta_eq ctxt instepthm);
wenzelm@52234:     fun rewrite_with_thm r =
wenzelm@52234:       let val (lhs,_) = Logic.dest_equals (Thm.concl_of r) in
wenzelm@52234:         searchf searchinfo lhs
wenzelm@52234:         |> Seq.maps (apply_subst_in_concl ctxt i th cvfsconclthm r)
wenzelm@52234:       end;
wenzelm@52234:   in stepthms |> Seq.maps rewrite_with_thm end;
dixon@15538: 
dixon@15538: 
wenzelm@19047: (* distinct subgoals *)
wenzelm@52234: fun distinct_subgoals th = the_default th (SINGLE distinct_subgoals_tac th);
wenzelm@52234: 
dixon@15538: 
wenzelm@19047: (* General substitution of multiple occurances using one of
wenzelm@52235:    the given theorems *)
dixon@19835: 
wenzelm@16978: fun skip_first_occs_search occ srchf sinfo lhs =
wenzelm@52234:   (case (skipto_skipseq occ (srchf sinfo lhs)) of
wenzelm@52234:     SkipMore _ => Seq.empty
wenzelm@52234:   | SkipSeq ss => Seq.flat ss);
dixon@16004: 
dixon@22727: (* The occL is a list of integers indicating which occurence
dixon@22727: w.r.t. the search order, to rewrite. Backtracking will also find later
dixon@22727: occurences, but all earlier ones are skipped. Thus you can use [0] to
dixon@22727: just find all rewrites. *)
dixon@22727: 
wenzelm@18598: fun eqsubst_tac ctxt occL thms i th =
wenzelm@52234:   let val nprems = Thm.nprems_of th in
wenzelm@52234:     if nprems < i then Seq.empty else
wenzelm@52234:     let
wenzelm@52234:       val thmseq = (Seq.of_list thms);
wenzelm@52234:       fun apply_occ occ th =
wenzelm@52234:         thmseq |> Seq.maps (fn r =>
wenzelm@52234:           eqsubst_tac' ctxt
wenzelm@52234:             (skip_first_occs_search occ searchf_lr_unify_valid) r
wenzelm@52235:             (i + (Thm.nprems_of th - nprems)) th);
wenzelm@52234:       val sortedoccL = Library.sort (rev_order o int_ord) occL;
wenzelm@52234:     in
wenzelm@52234:       Seq.map distinct_subgoals (Seq.EVERY (map apply_occ sortedoccL) th)
wenzelm@52234:     end
wenzelm@52234:   end;
dixon@15959: 
paulson@15481: 
paulson@15481: (* inthms are the given arguments in Isar, and treated as eqstep with
paulson@15481:    the first one, then the second etc *)
wenzelm@52234: fun eqsubst_meth ctxt occL inthms = SIMPLE_METHOD' (eqsubst_tac ctxt occL inthms);
paulson@15481: 
dixon@16004: (* apply a substitution inside assumption j, keeps asm in the same place *)
wenzelm@52234: fun apply_subst_in_asm ctxt i th rule ((cfvs, j, _, pth),m) =
wenzelm@52234:   let
wenzelm@52234:     val th2 = Thm.rotate_rule (j - 1) i th; (* put premice first *)
wenzelm@52234:     val preelimrule =
wenzelm@52234:       RWInst.rw ctxt m rule pth
wenzelm@52234:       |> (Seq.hd o prune_params_tac)
wenzelm@52234:       |> Thm.permute_prems 0 ~1 (* put old asm first *)
wenzelm@52234:       |> IsaND.unfix_frees cfvs (* unfix any global params *)
wenzelm@52234:       |> RWInst.beta_eta_contract; (* normal form *)
wenzelm@52234:   in
wenzelm@52234:     (* ~j because new asm starts at back, thus we subtract 1 *)
wenzelm@52235:     Seq.map (Thm.rotate_rule (~ j) (Thm.nprems_of rule + i))
dixon@16007:       (Tactic.dtac preelimrule i th2)
wenzelm@52234:   end;
paulson@15481: 
paulson@15481: 
dixon@15538: (* prepare to substitute within the j'th premise of subgoal i of gth,
dixon@15538: using a meta-level equation. Note that we assume rule has var indicies
dixon@15538: zero'd. Note that we also assume that premt is the j'th premice of
dixon@15538: subgoal i of gth. Note the repetition of work done for each
dixon@15538: assumption, i.e. this can be made more efficient for search over
dixon@15538: multiple assumptions.  *)
wenzelm@49340: fun prep_subst_in_asm ctxt i gth j =
wenzelm@52234:   let
wenzelm@52234:     val th = Thm.incr_indexes 1 gth;
wenzelm@52234:     val tgt_term = Thm.prop_of th;
paulson@15481: 
wenzelm@52235:     val thy = Thm.theory_of_thm th;
wenzelm@52235:     val cert = Thm.cterm_of thy;
paulson@15481: 
wenzelm@52234:     val (fixedbody, fvs) = IsaND.fix_alls_term ctxt i tgt_term;
wenzelm@52235:     val cfvs = rev (map cert fvs);
paulson@15481: 
wenzelm@52234:     val asmt = nth (Logic.strip_imp_prems fixedbody) (j - 1);
wenzelm@52234:     val asm_nprems = length (Logic.strip_imp_prems asmt);
wenzelm@52234: 
wenzelm@52235:     val pth = Thm.trivial (cert asmt);
wenzelm@52234:     val maxidx = Thm.maxidx_of th;
dixon@15538: 
wenzelm@52234:     val ft =
wenzelm@52234:       (Zipper.move_down_right (* trueprop *)
wenzelm@52234:          o Zipper.mktop
wenzelm@52234:          o Thm.prop_of) pth
wenzelm@52235:   in ((cfvs, j, asm_nprems, pth), (thy, maxidx, ft)) end;
paulson@15481: 
dixon@15538: (* prepare subst in every possible assumption *)
wenzelm@49340: fun prep_subst_in_asms ctxt i gth =
wenzelm@52234:   map (prep_subst_in_asm ctxt i gth)
wenzelm@52234:     ((fn l => Library.upto (1, length l))
wenzelm@52234:       (Logic.prems_of_goal (Thm.prop_of gth) i));
dixon@15538: 
dixon@15538: 
dixon@15538: (* substitute in an assumption using an object or meta level equality *)
wenzelm@18598: fun eqsubst_asm_tac' ctxt searchf skipocc instepthm i th =
wenzelm@52234:   let
wenzelm@52234:     val asmpreps = prep_subst_in_asms ctxt i th;
wenzelm@52234:     val stepthms = Seq.of_list (prep_meta_eq ctxt instepthm);
wenzelm@52234:     fun rewrite_with_thm r =
wenzelm@52234:       let
wenzelm@52234:         val (lhs,_) = Logic.dest_equals (Thm.concl_of r);
wenzelm@52234:         fun occ_search occ [] = Seq.empty
wenzelm@52234:           | occ_search occ ((asminfo, searchinfo)::moreasms) =
wenzelm@52234:               (case searchf searchinfo occ lhs of
wenzelm@52234:                 SkipMore i => occ_search i moreasms
wenzelm@52234:               | SkipSeq ss =>
wenzelm@52234:                   Seq.append (Seq.map (Library.pair asminfo) (Seq.flat ss))
wenzelm@52234:                     (occ_search 1 moreasms)) (* find later substs also *)
wenzelm@52234:       in
wenzelm@52234:         occ_search skipocc asmpreps |> Seq.maps (apply_subst_in_asm ctxt i th r)
wenzelm@52234:       end;
wenzelm@52234:   in stepthms |> Seq.maps rewrite_with_thm end;
dixon@15538: 
dixon@16004: 
wenzelm@16978: fun skip_first_asm_occs_search searchf sinfo occ lhs =
wenzelm@52234:   skipto_skipseq occ (searchf sinfo lhs);
dixon@16004: 
wenzelm@18598: fun eqsubst_asm_tac ctxt occL thms i th =
wenzelm@52234:   let val nprems = Thm.nprems_of th in
wenzelm@52234:     if nprems < i then Seq.empty
wenzelm@52234:     else
wenzelm@52234:       let
wenzelm@52234:         val thmseq = Seq.of_list thms;
wenzelm@16978:         fun apply_occ occK th =
wenzelm@52234:           thmseq |> Seq.maps (fn r =>
wenzelm@52234:             eqsubst_asm_tac' ctxt
wenzelm@52234:               (skip_first_asm_occs_search searchf_lr_unify_valid) occK r
wenzelm@52235:               (i + (Thm.nprems_of th - nprems)) th);
wenzelm@52234:         val sortedoccs = Library.sort (rev_order o int_ord) occL;
dixon@16004:       in
wenzelm@52234:         Seq.map distinct_subgoals (Seq.EVERY (map apply_occ sortedoccs) th)
dixon@16004:       end
wenzelm@52234:   end;
paulson@15481: 
paulson@15481: (* inthms are the given arguments in Isar, and treated as eqstep with
paulson@15481:    the first one, then the second etc *)
wenzelm@18598: fun eqsubst_asm_meth ctxt occL inthms =
wenzelm@52234:   SIMPLE_METHOD' (eqsubst_asm_tac ctxt occL inthms);
paulson@15481: 
wenzelm@18598: (* combination method that takes a flag (true indicates that subst
wenzelm@31301:    should be done to an assumption, false = apply to the conclusion of
wenzelm@31301:    the goal) as well as the theorems to use *)
wenzelm@16978: val setup =
wenzelm@31301:   Method.setup @{binding subst}
wenzelm@44095:     (Args.mode "asm" -- Scan.lift (Scan.optional (Args.parens (Scan.repeat Parse.nat)) [0]) --
wenzelm@44095:         Attrib.thms >>
wenzelm@44095:       (fn ((asm, occL), inthms) => fn ctxt =>
wenzelm@44095:         (if asm then eqsubst_asm_meth else eqsubst_meth) ctxt occL inthms))
wenzelm@31301:     "single-step substitution";
paulson@15481: 
wenzelm@16978: end;