src/Pure/Isar/find_theorems.ML
author wenzelm
Mon Oct 29 16:13:46 2007 +0100 (2007-10-29)
changeset 25226 502d8676cdd6
parent 24920 2a45e400fdad
child 25992 928594f50893
permissions -rw-r--r--
improved notion of 'nicer' fact names (observe some name space properties);
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(*  Title:      Pure/Isar/find_theorems.ML
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    ID:         $Id$
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    Author:     Rafal Kolanski, NICTA and Tobias Nipkow, TU Muenchen
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Retrieve theorems from proof context.
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*)
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val thms_containing_limit = ref 40;
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signature FIND_THEOREMS =
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sig
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  datatype 'term criterion =
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    Name of string | Intro | Elim | Dest | Simp of 'term | Pattern of 'term
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  val print_theorems: Proof.context -> term option -> int option -> bool ->
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    (bool * string criterion) list -> unit
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end;
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structure FindTheorems: FIND_THEOREMS =
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struct
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(** search criteria **)
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datatype 'term criterion =
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  Name of string | Intro | Elim | Dest | Simp of 'term | Pattern of 'term;
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fun read_criterion _ (Name name) = Name name
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  | read_criterion _ Intro = Intro
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  | read_criterion _ Elim = Elim
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  | read_criterion _ Dest = Dest
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  | read_criterion ctxt (Simp str) = Simp (ProofContext.read_term_pattern ctxt str)
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  | read_criterion ctxt (Pattern str) = Pattern (ProofContext.read_term_pattern ctxt str);
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fun pretty_criterion ctxt (b, c) =
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  let
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    fun prfx s = if b then s else "-" ^ s;
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  in
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    (case c of
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      Name name => Pretty.str (prfx "name: " ^ quote name)
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    | Intro => Pretty.str (prfx "intro")
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    | Elim => Pretty.str (prfx "elim")
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    | Dest => Pretty.str (prfx "dest")
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    | Simp pat => Pretty.block [Pretty.str (prfx "simp:"), Pretty.brk 1,
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        Pretty.quote (Syntax.pretty_term ctxt (Term.show_dummy_patterns pat))]
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    | Pattern pat => Pretty.enclose (prfx " \"") "\""
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        [Syntax.pretty_term ctxt (Term.show_dummy_patterns pat)])
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  end;
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(** search criterion filters **)
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(*generated filters are to be of the form
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  input: (thmref * thm)
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  output: (p:int, s:int) option, where
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    NONE indicates no match
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    p is the primary sorting criterion
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      (eg. number of assumptions in the theorem)
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    s is the secondary sorting criterion
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      (eg. size of the substitution for intro, elim and dest)
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  when applying a set of filters to a thm, fold results in:
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    (biggest p, sum of all s)
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  currently p and s only matter for intro, elim, dest and simp filters,
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  otherwise the default ordering is used.
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*)
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(* matching theorems *)
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fun is_nontrivial thy = Term.is_Const o Term.head_of o ObjectLogic.drop_judgment thy;
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(*extract terms from term_src, refine them to the parts that concern us,
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  if po try match them against obj else vice versa.
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  trivial matches are ignored.
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  returns: smallest substitution size*)
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fun is_matching_thm (extract_terms, refine_term) ctxt po obj term_src =
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  let
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    val thy = ProofContext.theory_of ctxt;
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    fun matches pat =
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      is_nontrivial thy pat andalso
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      Pattern.matches thy (if po then (pat, obj) else (obj, pat));
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    fun substsize pat =
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      let val (_, subst) =
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        Pattern.match thy (if po then (pat, obj) else (obj, pat)) (Vartab.empty, Vartab.empty)
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      in Vartab.fold (fn (_, (_, t)) => fn n => size_of_term t + n) subst 0 end;
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    fun bestmatch [] = NONE
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     |  bestmatch xs = SOME (foldr1 Int.min xs);
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    val match_thm = matches o refine_term;
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  in
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    map (substsize o refine_term)
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        (filter match_thm (extract_terms term_src)) |> bestmatch
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  end;
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(* filter_name *)
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fun match_string pat str =
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  let
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    fun match [] _ = true
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      | match (p :: ps) s =
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          size p <= size s andalso
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            (case try (unprefix p) s of
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              SOME s' => match ps s'
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            | NONE => match (p :: ps) (String.substring (s, 1, size s - 1)));
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  in match (space_explode "*" pat) str end;
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fun filter_name str_pat (thmref, _) =
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  if match_string str_pat (PureThy.name_of_thmref thmref)
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  then SOME (0, 0) else NONE;
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(* filter intro/elim/dest rules *)
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fun filter_dest ctxt goal (_, thm) =
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  let
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    val extract_dest =
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     (fn thm => if Thm.no_prems thm then [] else [Thm.full_prop_of thm],
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      hd o Logic.strip_imp_prems);
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    val prems = Logic.prems_of_goal goal 1;
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    fun try_subst prem = is_matching_thm extract_dest ctxt true prem thm;
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    val successful = prems |> map_filter try_subst;
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  in
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    (*if possible, keep best substitution (one with smallest size)*)
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    (*dest rules always have assumptions, so a dest with one
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      assumption is as good as an intro rule with none*)
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    if not (null successful)
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    then SOME (Thm.nprems_of thm - 1, foldr1 Int.min successful) else NONE
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  end;
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fun filter_intro ctxt goal (_, thm) =
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  let
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    val extract_intro = (single o Thm.full_prop_of, Logic.strip_imp_concl);
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    val concl = Logic.concl_of_goal goal 1;
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    val ss = is_matching_thm extract_intro ctxt true concl thm;
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  in
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    if is_some ss then SOME (Thm.nprems_of thm, the ss) else NONE
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  end;
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fun filter_elim ctxt goal (_, thm) =
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  if not (Thm.no_prems thm) then
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    let
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      val rule = Thm.full_prop_of thm;
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      val prems = Logic.prems_of_goal goal 1;
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      val goal_concl = Logic.concl_of_goal goal 1;
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      val rule_mp = (hd o Logic.strip_imp_prems) rule;
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      val rule_concl = Logic.strip_imp_concl rule;
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      fun combine t1 t2 = Const ("combine", dummyT --> dummyT) $ (t1 $ t2);
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      val rule_tree = combine rule_mp rule_concl;
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      fun goal_tree prem = (combine prem goal_concl);
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      fun try_subst prem =
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        is_matching_thm (single, I) ctxt true (goal_tree prem) rule_tree;
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      val successful = prems |> map_filter try_subst;
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    in
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    (*elim rules always have assumptions, so an elim with one
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      assumption is as good as an intro rule with none*)
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      if is_nontrivial (ProofContext.theory_of ctxt) (Thm.major_prem_of thm)
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        andalso not (null successful)
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      then SOME (Thm.nprems_of thm - 1, foldr1 Int.min successful) else NONE
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    end
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  else NONE
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(* filter_simp *)
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fun filter_simp ctxt t (_, thm) =
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  let
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    val (_, {mk_rews = {mk, ...}, ...}) =
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      MetaSimplifier.rep_ss (Simplifier.local_simpset_of ctxt);
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    val extract_simp =
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      (map Thm.full_prop_of o mk, #1 o Logic.dest_equals o Logic.strip_imp_concl);
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    val ss = is_matching_thm extract_simp ctxt false t thm
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  in
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    if is_some ss then SOME (Thm.nprems_of thm, the ss) else NONE
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  end;
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(* filter_pattern *)
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fun filter_pattern ctxt pat (_, thm) =
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  if Pattern.matches_subterm (ProofContext.theory_of ctxt) (pat, Thm.full_prop_of thm)
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  then SOME (0, 0) else NONE;
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(* interpret criteria as filters *)
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local
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fun err_no_goal c =
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  error ("Current goal required for " ^ c ^ " search criterion");
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fun filter_crit _ _ (Name name) = filter_name name
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  | filter_crit _ NONE Intro = err_no_goal "intro"
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  | filter_crit _ NONE Elim = err_no_goal "elim"
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  | filter_crit _ NONE Dest = err_no_goal "dest"
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  | filter_crit ctxt (SOME goal) Intro = filter_intro ctxt goal
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  | filter_crit ctxt (SOME goal) Elim = filter_elim ctxt goal
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  | filter_crit ctxt (SOME goal) Dest = filter_dest ctxt goal
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  | filter_crit ctxt _ (Simp pat) = filter_simp ctxt pat
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  | filter_crit ctxt _ (Pattern pat) = filter_pattern ctxt pat;
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fun opt_not x = if is_some x then NONE else SOME (0, 0);
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fun opt_add (SOME (a, x)) (SOME (b, y)) = SOME (Int.max (a, b), x + y : int)
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 |  opt_add _ _ = NONE;
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in
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fun filter_criterion ctxt opt_goal (b, c) =
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  (if b then I else opt_not) o filter_crit ctxt opt_goal c;
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fun all_filters filters thms =
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  let
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    fun eval_filters filters thm =
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      fold opt_add (map (fn f => f thm) filters) (SOME (0, 0));
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    (*filters return: (number of assumptions, substitution size) option, so
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      sort (desc. in both cases) according to number of assumptions first,
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      then by the substitution size*)
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    fun thm_ord (((p0, s0), _), ((p1, s1), _)) =
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      prod_ord int_ord int_ord ((p1, s1), (p0, s0));
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  in
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    map (`(eval_filters filters)) thms
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    |> map_filter (fn (SOME x, y) => SOME (x, y) | (NONE, _) => NONE)
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    |> sort thm_ord |> map #2
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  end;
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end;
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(* removing duplicates, preferring nicer names, roughly n log n *)
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local
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val hidden_ord = bool_ord o pairself NameSpace.is_hidden;
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val qual_ord = int_ord o pairself (length o NameSpace.explode);
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val txt_ord = int_ord o pairself size;
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fun nicer_name x y =
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  (case hidden_ord (x, y) of
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    EQUAL => (case qual_ord (x, y) of EQUAL => txt_ord (x, y) | ord => ord)
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  | ord => ord) <> GREATER;
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in
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fun nicer (Fact _) _ = true
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  | nicer (PureThy.Name x) (PureThy.Name y) = nicer_name x y
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  | nicer (PureThy.Name _) (Fact _) = false
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  | nicer (PureThy.Name _) _ = true
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  | nicer (NameSelection (x, _)) (NameSelection (y, _)) = nicer_name x y
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  | nicer (NameSelection _) _ = false;
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end;
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fun rem_thm_dups xs =
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  let
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    fun rem_cdups xs =
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      let
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        fun rem_c rev_seen [] = rev rev_seen
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          | rem_c rev_seen [x] = rem_c (x::rev_seen) []
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          | rem_c rev_seen ((x as ((n,t),_))::(y as ((n',t'),_))::xs) =
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            if Thm.eq_thm_prop (t,t')
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            then if nicer n n'
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                 then rem_c rev_seen (x::xs)
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                 else rem_c rev_seen (y::xs)
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            else rem_c (x::rev_seen) (y::xs)
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      in rem_c [] xs end;
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  in ListPair.zip (xs, 1 upto length xs)
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     |> sort (Term.fast_term_ord o pairself (prop_of o #2 o #1))
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     |> rem_cdups
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     |> sort (int_ord o pairself #2)
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     |> map #1
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  end;
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(* print_theorems *)
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fun find_thms ctxt spec =
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  (PureThy.thms_containing (ProofContext.theory_of ctxt) spec
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    |> maps PureThy.selections) @
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  (ProofContext.lthms_containing ctxt spec
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    |> maps PureThy.selections
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    |> distinct (fn ((r1, th1), (r2, th2)) =>
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        r1 = r2 andalso Thm.eq_thm_prop (th1, th2)));
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fun print_theorems ctxt opt_goal opt_limit rem_dups raw_criteria =
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  let
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    val criteria = map (apsnd (read_criterion ctxt)) raw_criteria;
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    val filters = map (filter_criterion ctxt opt_goal) criteria;
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    val raw_matches = all_filters filters (find_thms ctxt ([], []));
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    val matches =
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      if rem_dups
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      then rem_thm_dups raw_matches
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      else raw_matches;
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    val len = length matches;
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    val limit = the_default (! thms_containing_limit) opt_limit;
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    val thms = Library.drop (len - limit, matches);
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    fun prt_fact (thmref, thm) =
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      ProofContext.pretty_fact ctxt (PureThy.string_of_thmref thmref, [thm]);
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  in
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    Pretty.big_list "searched for:" (map (pretty_criterion ctxt) criteria) :: Pretty.str "" ::
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     (if null thms then [Pretty.str "nothing found"]
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      else
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        [Pretty.str ("found " ^ string_of_int len ^ " theorems" ^
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          (if len <= limit then "" else " (" ^ string_of_int limit ^ " displayed)") ^ ":"),
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         Pretty.str ""] @
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        map prt_fact thms)
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    |> Pretty.chunks |> Pretty.writeln
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  end;
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end;