(*  Title:      Pure/facts.ML

     Author:     Makarius

 Environment of named facts, optionally indexed by proposition.

 *)

 signature FACTS =

 sig

   val the_single: string -> thm list -> thm

   datatype interval = FromTo of int * int | From of int | Single of int

   datatype ref =

     Named of (string * Position.T) * interval list option |

     Fact of string

   val named: string -> ref

   val string_of_ref: ref -> string

   val name_of_ref: ref -> string

   val pos_of_ref: ref -> Position.T

   val map_name_of_ref: (string -> string) -> ref -> ref

   val select: ref -> thm list -> thm list

   val selections: string * thm list -> (ref * thm) list

   type T

   val empty: T

   val space_of: T -> Name_Space.T

   val is_concealed: T -> string -> bool

   val intern: T -> xstring -> string

   val extern: Proof.context -> T -> string -> xstring

   val lookup: Context.generic -> T -> string -> (bool * thm list) option

   val defined: T -> string -> bool

   val fold_static: (string * thm list -> 'a -> 'a) -> T -> 'a -> 'a

   val dest_static: T list -> T -> (string * thm list) list

   val extern_static: Proof.context -> T list -> T -> (xstring * thm list) list

   val props: T -> thm list

   val could_unify: T -> term -> thm list

   val merge: T * T -> T

   val add_global: Context.generic -> binding * thm list -> T -> string * T

   val add_local: Context.generic -> bool -> binding * thm list -> T -> string * T

   val add_dynamic: Context.generic -> binding * (Context.generic -> thm list) -> T -> string * T

   val del: string -> T -> T

   val hide: bool -> string -> T -> T

 end;

 structure Facts: FACTS =

 struct

 (** fact references **)

 fun the_single _ [th] : thm = th

   | the_single name _ = error ("Expected singleton fact " ^ quote name);

 (* datatype interval *)

 datatype interval =

   FromTo of int * int |

   From of int |

   Single of int;

 fun string_of_interval (FromTo (i, j)) = string_of_int i ^ "-" ^ string_of_int j

   | string_of_interval (From i) = string_of_int i ^ "-"

   | string_of_interval (Single i) = string_of_int i;

 fun interval n iv =

   let fun err () = raise Fail ("Bad interval specification " ^ string_of_interval iv) in

     (case iv of

       FromTo (i, j) => if i <= j then i upto j else err ()

     | From i => if i <= n then i upto n else err ()

     | Single i => [i])

   end;

 (* datatype ref *)

 datatype ref =

   Named of (string * Position.T) * interval list option |

   Fact of string;

 fun named name = Named ((name, Position.none), NONE);

 fun name_pos_of_ref (Named (name_pos, _)) = name_pos

   | name_pos_of_ref (Fact _) = error "Illegal literal fact";

 val name_of_ref = #1 o name_pos_of_ref;

 val pos_of_ref = #2 o name_pos_of_ref;

 fun map_name_of_ref f (Named ((name, pos), is)) = Named ((f name, pos), is)

   | map_name_of_ref _ r = r;

 fun string_of_ref (Named ((name, _), NONE)) = name

   | string_of_ref (Named ((name, _), SOME is)) =

       name ^ enclose "(" ")" (commas (map string_of_interval is))

   | string_of_ref (Fact _) = error "Illegal literal fact";

 (* select *)

 fun select (Fact _) ths = ths

   | select (Named (_, NONE)) ths = ths

   | select (Named ((name, pos), SOME ivs)) ths =

       let

         val n = length ths;

         fun err msg =

           error (msg ^ " for " ^ quote name ^ " (length " ^ string_of_int n ^ ")" ^

             Position.str_of pos);

         fun sel i =

           if i < 1 orelse i > n then err ("Bad subscript " ^ string_of_int i)

           else nth ths (i - 1);

         val is = maps (interval n) ivs handle Fail msg => err msg;

       in map sel is end;

 (* selections *)

 fun selections (name, [th]) = [(Named ((name, Position.none), NONE), th)]

   | selections (name, ths) = map2 (fn i => fn th =>

       (Named ((name, Position.none), SOME [Single i]), th)) (1 upto length ths) ths;

 (** fact environment **)

 (* datatypes *)

 datatype fact = Static of thm list | Dynamic of Context.generic -> thm list;

 datatype T = Facts of

  {facts: fact Name_Space.table,

   props: thm Net.net};

 fun make_facts facts props = Facts {facts = facts, props = props};

 val empty = make_facts (Name_Space.empty_table "fact") Net.empty;

 (* named facts *)

 fun facts_of (Facts {facts, ...}) = facts;

 val space_of = #1 o facts_of;

 val table_of = #2 o facts_of;

 val is_concealed = Name_Space.is_concealed o space_of;

 val intern = Name_Space.intern o space_of;

 fun extern ctxt = Name_Space.extern ctxt o space_of;

 val defined = Symtab.defined o table_of;

 fun lookup context facts name =

   (case Symtab.lookup (table_of facts) name of

     NONE => NONE

   | SOME (Static ths) => SOME (true, ths)

   | SOME (Dynamic f) => SOME (false, f context));

 fun fold_static f =

   Symtab.fold (fn (name, Static ths) => f (name, ths) | _ => I) o table_of;

 (* content difference *)

 fun diff_table prev_facts facts =

   fold_static (fn (name, ths) =>

     if exists (fn prev => defined prev name) prev_facts then I

     else cons (name, ths)) facts [];

 fun dest_static prev_facts facts =

   sort_wrt #1 (diff_table prev_facts facts);

 fun extern_static ctxt prev_facts facts =

   sort_wrt #1 (diff_table prev_facts facts |> map (apfst (extern ctxt facts)));

 (* indexed props *)

 val prop_ord = Term_Ord.term_ord o pairself Thm.full_prop_of;

 fun props (Facts {props, ...}) = sort_distinct prop_ord (Net.content props);

 fun could_unify (Facts {props, ...}) = Net.unify_term props;

 (* merge facts *)

 fun merge (Facts {facts = facts1, props = props1}, Facts {facts = facts2, props = props2}) =

   let

     val facts' = Name_Space.merge_tables (facts1, facts2);

     val props' = Net.merge (is_equal o prop_ord) (props1, props2);

   in make_facts facts' props' end;

 (* add static entries *)

 local

 fun add context strict do_props (b, ths) (Facts {facts, props}) =

   let

     val (name, facts') =

       if Binding.is_empty b then ("", facts)

       else Name_Space.define context strict (b, Static ths) facts;

     val props' =

       if do_props

       then fold (fn th => Net.insert_term (K false) (Thm.full_prop_of th, th)) ths props

       else props;

   in (name, make_facts facts' props') end;

 in

 fun add_global context = add context true false;

 fun add_local context = add context false;

 end;

 (* add dynamic entries *)

 fun add_dynamic context (b, f) (Facts {facts, props}) =

   let val (name, facts') = Name_Space.define context true (b, Dynamic f) facts;

   in (name, make_facts facts' props) end;

 (* remove entries *)

 fun del name (Facts {facts = (space, tab), props}) =

   let

     val space' = Name_Space.hide true name space handle ERROR _ => space;

     val tab' = Symtab.delete_safe name tab;

   in make_facts (space', tab') props end;

 fun hide fully name (Facts {facts = (space, tab), props}) =

   make_facts (Name_Space.hide fully name space, tab) props;

 end;