(*  Nominal Function Common

    Author: Christian Urban

Common definitions and other infrastructure for the function package.

*)

signature FUNCTION_DATA =

sig

type info =

 {is_partial : bool,

  defname : string,

    (* contains no logical entities: invariant under morphisms: *)

  add_simps : (binding -> binding) -> string -> (binding -> binding) ->

    Attrib.src list -> thm list -> local_theory -> thm list * local_theory,

  case_names : string list,

  fs : term list,

  R : term,

  psimps: thm list,

  pinducts: thm list,

  simps : thm list option,

  inducts : thm list option,

  termination: thm}

end

structure Function_Data : FUNCTION_DATA =

struct

type info =

 {is_partial : bool,

  defname : string,

    (* contains no logical entities: invariant under morphisms: *)

  add_simps : (binding -> binding) -> string -> (binding -> binding) ->

    Attrib.src list -> thm list -> local_theory -> thm list * local_theory,

  case_names : string list,

  fs : term list,

  R : term,

  psimps: thm list,

  pinducts: thm list,

  simps : thm list option,

  inducts : thm list option,

  termination: thm}

end

structure Nominal_Function_Common =

struct

open Function_Data

local open Function_Lib in

(* Profiling *)

val profile = Unsynchronized.ref false;

fun PROFILE msg = if !profile then timeap_msg msg else I

val acc_const_name = @{const_name accp}

fun mk_acc domT R =

  Const (acc_const_name, (domT --> domT --> HOLogic.boolT) --> domT --> HOLogic.boolT) $ R 

val function_name = suffix "C"

val graph_name = suffix "_graph"

val rel_name = suffix "_rel"

val dom_name = suffix "_dom"

(* Termination rules *)

structure TerminationRule = Generic_Data

(

  type T = thm list

  val empty = []

  val extend = I

  val merge = Thm.merge_thms

);

val get_termination_rules = TerminationRule.get

val store_termination_rule = TerminationRule.map o cons

val apply_termination_rule = resolve_tac o get_termination_rules o Context.Proof

(* Function definition result data *)

datatype function_result = FunctionResult of

 {fs: term list,

  G: term,

  R: term,

  psimps : thm list,

  simple_pinducts : thm list,

  cases : thm,

  termination : thm,

  domintros : thm list option}

fun morph_function_data ({add_simps, case_names, fs, R, psimps, pinducts,

  simps, inducts, termination, defname, is_partial} : info) phi =

    let

      val term = Morphism.term phi val thm = Morphism.thm phi val fact = Morphism.fact phi

      val name = Binding.name_of o Morphism.binding phi o Binding.name

    in

      { add_simps = add_simps, case_names = case_names,

        fs = map term fs, R = term R, psimps = fact psimps,

        pinducts = fact pinducts, simps = Option.map fact simps,

        inducts = Option.map fact inducts, termination = thm termination,

        defname = name defname, is_partial=is_partial }

    end

structure FunctionData = Generic_Data

(

  type T = (term * info) Item_Net.T;

  val empty : T = Item_Net.init (op aconv o pairself fst) (single o fst);

  val extend = I;

  fun merge tabs : T = Item_Net.merge tabs;

)

val get_function = FunctionData.get o Context.Proof;

fun lift_morphism thy f =

  let

    val term = Drule.term_rule thy f

  in

    Morphism.thm_morphism f $> Morphism.term_morphism term

    $> Morphism.typ_morphism (Logic.type_map term)

  end

fun import_function_data t ctxt =

  let

    val thy = Proof_Context.theory_of ctxt

    val ct = cterm_of thy t

    val inst_morph = lift_morphism thy o Thm.instantiate

    fun match (trm, data) =

      SOME (morph_function_data data (inst_morph (Thm.match (cterm_of thy trm, ct))))

      handle Pattern.MATCH => NONE

  in

    get_first match (Item_Net.retrieve (get_function ctxt) t)

  end

fun import_last_function ctxt =

  case Item_Net.content (get_function ctxt) of

    [] => NONE

  | (t, data) :: _ =>

    let

      val ([t'], ctxt') = Variable.import_terms true [t] ctxt

    in

      import_function_data t' ctxt'

    end

val all_function_data = Item_Net.content o get_function

fun add_function_data (data : info as {fs, termination, ...}) =

  FunctionData.map (fold (fn f => Item_Net.update (f, data)) fs)

  #> store_termination_rule termination

(* Simp rules for termination proofs *)

structure Termination_Simps = Named_Thms

(

  val name = "termination_simp"

  val description = "simplification rules for termination proofs"

)

(* Default Termination Prover *)

structure TerminationProver = Generic_Data

(

  type T = Proof.context -> tactic

  val empty = (fn _ => error "Termination prover not configured")

  val extend = I

  fun merge (a, _) = a

)

val set_termination_prover = TerminationProver.put

val get_termination_prover = TerminationProver.get o Context.Proof

(* Configuration management *)

datatype nominal_function_opt

  = Sequential

  | Default of string

  | DomIntros

  | No_Partials

  | Invariant of string

datatype nominal_function_config = NominalFunctionConfig of

 {sequential: bool,

  default: string option,

  domintros: bool,

  partials: bool,

  inv: string option}

fun apply_opt Sequential (NominalFunctionConfig {sequential, default, domintros, partials, inv}) =

    NominalFunctionConfig 

      {sequential=true, default=default, domintros=domintros, partials=partials, inv=inv}

  | apply_opt (Default d) (NominalFunctionConfig {sequential, default, domintros, partials, inv}) =

    NominalFunctionConfig 

      {sequential=sequential, default=SOME d, domintros=domintros, partials=partials, inv=inv}

  | apply_opt DomIntros (NominalFunctionConfig {sequential, default, domintros, partials, inv}) =

    NominalFunctionConfig 

      {sequential=sequential, default=default, domintros=true, partials=partials, inv=inv}

  | apply_opt No_Partials (NominalFunctionConfig {sequential, default, domintros, partials, inv}) =

    NominalFunctionConfig 

      {sequential=sequential, default=default, domintros=domintros, partials=false, inv=inv}

  | apply_opt (Invariant s) (NominalFunctionConfig {sequential, default, domintros, partials, inv}) =

    NominalFunctionConfig 

      {sequential=sequential, default=default, domintros=domintros, partials=partials, inv = SOME s}

val nominal_default_config =

  NominalFunctionConfig { sequential=false, default=NONE,

    domintros=false, partials=true, inv=NONE}

(* Analyzing function equations *)

fun split_def ctxt check_head geq =

  let

    fun input_error msg = cat_lines [msg, Syntax.string_of_term ctxt geq]

    val qs = Term.strip_qnt_vars "all" geq

    val imp = Term.strip_qnt_body "all" geq

    val (gs, eq) = Logic.strip_horn imp

    val (f_args, rhs) = HOLogic.dest_eq (HOLogic.dest_Trueprop eq)

      handle TERM _ => error (input_error "Not an equation")

    val (head, args) = strip_comb f_args

    val fname = fst (dest_Free head) handle TERM _ => ""

    val _ = check_head fname

  in

    (fname, qs, gs, args, rhs)

  end

(* Check for all sorts of errors in the input *)

fun check_defs ctxt fixes eqs =

  let

    val fnames = map (fst o fst) fixes

    fun check geq =

      let

        fun input_error msg = error (cat_lines [msg, Syntax.string_of_term ctxt geq])

        fun check_head fname =

          member (op =) fnames fname orelse

          input_error ("Illegal equation head. Expected " ^ commas_quote fnames)

        val (fname, qs, gs, args, rhs) = split_def ctxt check_head geq

        val _ = length args > 0 orelse input_error "Function has no arguments:"

        fun add_bvs t is = add_loose_bnos (t, 0, is)

        val rvs = (subtract (op =) (fold add_bvs args []) (add_bvs rhs []))

                    |> map (fst o nth (rev qs))

        val _ = null rvs orelse input_error

          ("Variable" ^ plural " " "s " rvs ^ commas_quote rvs ^

           " occur" ^ plural "s" "" rvs ^ " on right hand side only:")

        val _ = forall (not o Term.exists_subterm

          (fn Free (n, _) => member (op =) fnames n | _ => false)) (gs @ args)

          orelse input_error "Defined function may not occur in premises or arguments"

        val freeargs = map (fn t => subst_bounds (rev (map Free qs), t)) args

        val funvars = filter (fn q => exists (exists_subterm (fn (Free q') $ _ => q = q' | _ => false)) freeargs) qs

        val _ = null funvars orelse (warning (cat_lines

          ["Bound variable" ^ plural " " "s " funvars ^

          commas_quote (map fst funvars) ^ " occur" ^ plural "s" "" funvars ^

          " in function position.", "Misspelled constructor???"]); true)

      in

        (fname, length args)

      end

    val grouped_args = AList.group (op =) (map check eqs)

    val _ = grouped_args

      |> map (fn (fname, ars) =>

        length (distinct (op =) ars) = 1

        orelse error ("Function " ^ quote fname ^

          " has different numbers of arguments in different equations"))

    val not_defined = subtract (op =) (map fst grouped_args) fnames

    val _ = null not_defined

      orelse error ("No defining equations for function" ^

        plural " " "s " not_defined ^ commas_quote not_defined)

    fun check_sorts ((fname, fT), _) =

      Sorts.of_sort (Sign.classes_of (Proof_Context.theory_of ctxt)) (fT, HOLogic.typeS)

      orelse error (cat_lines

      ["Type of " ^ quote fname ^ " is not of sort " ^ quote "type" ^ ":",

       Syntax.string_of_typ (Config.put show_sorts true ctxt) fT])

    val _ = map check_sorts fixes

  in

    ()

  end

(* Preprocessors *)

type fixes = ((string * typ) * mixfix) list

type 'a spec = (Attrib.binding * 'a list) list

type preproc = nominal_function_config -> Proof.context -> fixes -> term spec ->

  (term list * (thm list -> thm spec) * (thm list -> thm list list) * string list)

val fname_of = fst o dest_Free o fst o strip_comb o fst o HOLogic.dest_eq o

  HOLogic.dest_Trueprop o Logic.strip_imp_concl o snd o dest_all_all

fun mk_case_names i "" k = mk_case_names i (string_of_int (i + 1)) k

  | mk_case_names _ n 0 = []

  | mk_case_names _ n 1 = [n]

  | mk_case_names _ n k = map (fn i => n ^ "_" ^ string_of_int i) (1 upto k)

fun empty_preproc check _ ctxt fixes spec =

  let

    val (bnds, tss) = split_list spec

    val ts = flat tss

    val _ = check ctxt fixes ts

    val fnames = map (fst o fst) fixes

    val indices = map (fn eq => find_index (curry op = (fname_of eq)) fnames) ts

    fun sort xs = partition_list (fn i => fn (j,_) => i = j) 0 (length fnames - 1) 

      (indices ~~ xs) |> map (map snd)

    (* using theorem names for case name currently disabled *)

    val cnames = map_index (fn (i, _) => mk_case_names i "" 1) bnds |> flat

  in

    (ts, curry op ~~ bnds o Library.unflat tss, sort, cnames)

  end

structure Preprocessor = Generic_Data

(

  type T = preproc

  val empty : T = empty_preproc check_defs

  val extend = I

  fun merge (a, _) = a

)

val get_preproc = Preprocessor.get o Context.Proof

val set_preproc = Preprocessor.map o K

local

  val option_parser = Parse.group "option"

    ((Parse.reserved "sequential" >> K Sequential)

     || ((Parse.reserved "default" |-- Parse.term) >> Default)

     || (Parse.reserved "domintros" >> K DomIntros)

     || (Parse.reserved "no_partials" >> K No_Partials))

  fun config_parser default =

    (Scan.optional (Parse.$$$ "(" |-- Parse.!!! (Parse.list1 option_parser) --| Parse.$$$ ")") [])

     >> (fn opts => fold apply_opt opts default)

in

  fun function_parser default_cfg =

      config_parser default_cfg -- Parse.fixes -- Parse_Spec.where_alt_specs

end

end

end