wenzelm@7674: (*  Title:      Pure/Isar/obtain.ML
wenzelm@7674:     ID:         $Id$
wenzelm@7674:     Author:     Markus Wenzel, TU Muenchen
wenzelm@7674: 
wenzelm@8543: The 'obtain' language element -- generalized existence at the level of
wenzelm@8543: proof texts.
wenzelm@7674: 
wenzelm@9468:   <chain_facts>
wenzelm@9468:   obtain x where "P x" <proof> ==
wenzelm@7674: 
wenzelm@12970:   have "!!thesis. (!!x. P x ==> thesis) ==> thesis"
wenzelm@12970:   proof succeed
wenzelm@9468:     fix thesis
wenzelm@12970:     assume that [intro?]: "!!x. P x ==> thesis"
wenzelm@12970:     <chain_facts> show thesis <proof (insert that)>
wenzelm@12970:   qed
wenzelm@10379:   fix x assm (obtained) "P x"
wenzelm@8094: *)
wenzelm@7674: 
wenzelm@7674: signature OBTAIN =
wenzelm@7674: sig
wenzelm@11890:   val obtain: (string list * string option) list ->
wenzelm@11890:     ((string * Proof.context attribute list) * (string * (string list * string list)) list) list
wenzelm@12970:     -> (Proof.context -> string * (string * thm list) list -> unit) *
wenzelm@12970:       (Proof.context -> thm -> unit) -> Proof.state -> Proof.state Seq.seq
wenzelm@11890:   val obtain_i: (string list * typ option) list ->
wenzelm@11890:     ((string * Proof.context attribute list) * (term * (term list * term list)) list) list
wenzelm@12970:     -> (Proof.context -> string * (string * thm list) list -> unit) *
wenzelm@12970:       (Proof.context -> thm -> unit) -> Proof.state -> Proof.state Seq.seq
wenzelm@7674: end;
wenzelm@7674: 
wenzelm@10379: structure Obtain: OBTAIN =
wenzelm@7674: struct
wenzelm@7674: 
wenzelm@8094: 
wenzelm@11816: (** export_obtain **)
wenzelm@9468: 
wenzelm@11816: fun export_obtain state parms rule _ cprops thm =
wenzelm@9468:   let
wenzelm@9468:     val {sign, prop, maxidx, ...} = Thm.rep_thm thm;
wenzelm@9468:     val cparms = map (Thm.cterm_of sign) parms;
wenzelm@9468: 
wenzelm@9468:     val thm' = thm
wenzelm@11816:       |> Drule.implies_intr_goals cprops
wenzelm@9468:       |> Drule.forall_intr_list cparms
wenzelm@9468:       |> Drule.forall_elim_vars (maxidx + 1);
wenzelm@11816:     val elim_tacs = replicate (length cprops) (Tactic.etac Drule.triv_goal);
wenzelm@9468: 
wenzelm@9468:     val concl = Logic.strip_assums_concl prop;
wenzelm@9468:     val bads = parms inter (Term.term_frees concl);
wenzelm@9468:   in
wenzelm@9468:     if not (null bads) then
wenzelm@9481:       raise Proof.STATE ("Conclusion contains obtained parameters: " ^
wenzelm@12055:         space_implode " " (map (ProofContext.string_of_term (Proof.context_of state)) bads), state)
wenzelm@11764:     else if not (ObjectLogic.is_judgment sign (Logic.strip_assums_concl prop)) then
wenzelm@10379:       raise Proof.STATE ("Conclusions of 'obtain' context must be object-logic judgments", state)
wenzelm@9468:     else (Tactic.rtac thm' THEN' RANGE elim_tacs) 1 rule
wenzelm@9468:   end;
wenzelm@9468: 
wenzelm@9468: 
wenzelm@9468: 
wenzelm@8094: (** obtain(_i) **)
wenzelm@8094: 
wenzelm@7674: val thatN = "that";
wenzelm@7674: 
wenzelm@12970: fun gen_obtain prep_vars prep_propp raw_vars raw_asms print state =
wenzelm@7674:   let
wenzelm@9468:     val _ = Proof.assert_forward_or_chain state;
wenzelm@9468:     val chain_facts = if Proof.is_chain state then Proof.the_facts state else [];
wenzelm@10464:     val thy = Proof.theory_of state;
wenzelm@11764:     val sign = Theory.sign_of thy;
wenzelm@7674: 
wenzelm@8543:     (*obtain vars*)
wenzelm@11890:     val (vars_ctxt, vars) = foldl_map prep_vars (Proof.context_of state, raw_vars);
wenzelm@8094:     val xs = flat (map fst vars);
wenzelm@10582:     val fix_ctxt = vars_ctxt |> ProofContext.fix_i vars;
wenzelm@7674: 
wenzelm@8543:     (*obtain asms*)
wenzelm@11890:     val (asms_ctxt, proppss) = prep_propp (fix_ctxt, map snd raw_asms);
wenzelm@10464:     val asm_props = flat (map (map fst) proppss);
wenzelm@11890:     val asms = map fst raw_asms ~~ proppss;
wenzelm@10464: 
wenzelm@10582:     val _ = ProofContext.warn_extra_tfrees fix_ctxt asms_ctxt;
wenzelm@7674: 
wenzelm@12970:     (*obtain statements*)
wenzelm@12404:     val thesisN = Term.variant xs (Syntax.internal AutoBind.thesisN);
wenzelm@12970:     val bind_thesis = ProofContext.bind_skolem fix_ctxt [thesisN];
wenzelm@12970:     val bound_thesis = bind_thesis (ObjectLogic.fixed_judgment sign thesisN);
wenzelm@12970:     val bound_thesis_raw as (bound_thesis_name, _) =
wenzelm@12970:       Term.dest_Free (bind_thesis (Free (thesisN, propT)));
wenzelm@12970:     val bound_thesis_var =
wenzelm@12970:       foldl_aterms (fn (v, Free (x, T)) => if x = bound_thesis_name then (x, T) else v
wenzelm@12970:         | (v, t) => v) (bound_thesis_raw, bound_thesis);
wenzelm@9468: 
wenzelm@10582:     fun occs_var x = Library.get_first (fn t =>
wenzelm@10582:       ProofContext.find_free t (ProofContext.get_skolem fix_ctxt x)) asm_props;
wenzelm@10582:     val raw_parms = map occs_var xs;
wenzelm@10582:     val parms = mapfilter I raw_parms;
wenzelm@10582:     val parm_names =
skalberg@15531:       mapfilter (fn (SOME (Free a), x) => SOME (a, x) | _ => NONE) (raw_parms ~~ xs);
wenzelm@10582: 
wenzelm@10582:     val that_prop =
wenzelm@10582:       Term.list_all_free (map #1 parm_names, Logic.list_implies (asm_props, bound_thesis))
wenzelm@10582:       |> Library.curry Logic.list_rename_params (map #2 parm_names);
wenzelm@12970:     val obtain_prop =
wenzelm@12970:       Logic.list_rename_params ([AutoBind.thesisN],
wenzelm@12970:         Term.list_all_free ([bound_thesis_var], Logic.mk_implies (that_prop, bound_thesis)));
wenzelm@7674: 
wenzelm@9468:     fun after_qed st = st
skalberg@15531:       |> Method.local_qed false NONE print
wenzelm@9468:       |> Seq.map (fn st' => st'
wenzelm@9468:         |> Proof.fix_i vars
wenzelm@11816:         |> Proof.assm_i (export_obtain state parms (Proof.the_fact st')) asms);
wenzelm@7674:   in
wenzelm@8094:     state
wenzelm@9468:     |> Proof.enter_forward
wenzelm@12970:     |> Proof.have_i Seq.single true [(("", []), [(obtain_prop, ([], []))])]
skalberg@15531:     |> Method.proof (SOME (Method.Basic (K Method.succeed))) |> Seq.hd
skalberg@15531:     |> Proof.fix_i [([thesisN], NONE)]
skalberg@15531:     |> Proof.assume_i [((thatN, [ContextRules.intro_query_local NONE]), [(that_prop, ([], []))])]
wenzelm@10379:     |> (fn state' =>
wenzelm@12970:         state'
wenzelm@12970:         |> Proof.from_facts chain_facts
wenzelm@12970:         |> Proof.show_i (K I) after_qed false [(("", []), [(bound_thesis, ([], []))])] false
wenzelm@12970:         |> Method.refine (Method.Basic (K (Method.insert (Proof.the_facts state')))))
wenzelm@7674:   end;
wenzelm@7674: 
wenzelm@11890: val obtain = gen_obtain ProofContext.read_vars ProofContext.read_propp;
wenzelm@11890: val obtain_i = gen_obtain ProofContext.cert_vars ProofContext.cert_propp;
wenzelm@8094: 
wenzelm@8094: end;