(*  Title:      Pure/Thy/term_style.ML

     Author:     Florian Haftmann, TU Muenchen

 Styles for term printing.

 *)

 signature TERM_STYLE =

 sig

   val setup: string -> (Proof.context -> term -> term) parser -> theory -> theory

   val parse: (term -> term) context_parser

   val parse_bare: (term -> term) context_parser

 end;

 structure Term_Style: TERM_STYLE =

 struct

 (* style data *)

 fun err_dup_style name =

   error ("Duplicate declaration of antiquote style: " ^ quote name);

 structure Styles = Theory_Data

 (

   type T = ((Proof.context -> term -> term) parser * stamp) Symtab.table;

   val empty = Symtab.empty;

   val extend = I;

   fun merge data : T = Symtab.merge (eq_snd (op =)) data

     handle Symtab.DUP dup => err_dup_style dup;

 );

 (* accessors *)

 fun the_style thy name =

   (case Symtab.lookup (Styles.get thy) name of

     NONE => error ("Unknown antiquote style: " ^ quote name)

   | SOME (style, _) => style);

 fun setup name style thy =

   Styles.map (Symtab.update_new (name, (style, stamp ()))) thy

     handle Symtab.DUP _ => err_dup_style name;

 (* style parsing *)

 fun parse_single ctxt = Parse.position (Parse.xname -- Args.parse)

   >> (fn x as ((name, _), _) => fst (Args.context_syntax "style"

        (Scan.lift (the_style (Proof_Context.theory_of ctxt) name))

          (Args.src x) ctxt |>> (fn f => f ctxt)));

 val parse = Args.context :|-- (fn ctxt => Scan.lift 

   (Args.parens (parse_single ctxt ::: Scan.repeat (Args.$$$ "," |-- parse_single ctxt))

       >> fold I

   || Scan.succeed I));

 val parse_bare = Args.context :|-- (fn ctxt => (Output.legacy_feature "Old-style antiquotation style.";

   Scan.lift Args.liberal_name

   >> (fn name => fst (Args.context_syntax "style"

        (Scan.lift (the_style (Proof_Context.theory_of ctxt) name))

           (Args.src (("style", []), Position.none)) ctxt |>> (fn f => f ctxt)))));

 (* predefined styles *)

 fun style_lhs_rhs proj = Scan.succeed (fn ctxt => fn t =>

   let

     val concl =

       Object_Logic.drop_judgment (Proof_Context.theory_of ctxt) (Logic.strip_imp_concl t)

   in

     case concl of (_ $ l $ r) => proj (l, r)

     | _ => error ("Binary operator expected in term: " ^ Syntax.string_of_term ctxt concl)

   end);

 val style_prem = Args.name >> (fn raw_i => fn ctxt => fn t =>

   let

     val i = (the o Int.fromString) raw_i;

     val prems = Logic.strip_imp_prems t;

   in

     if i <= length prems then nth prems (i - 1)

     else error ("Not enough premises for prem " ^ string_of_int i ^

       " in propositon: " ^ Syntax.string_of_term ctxt t)

   end);

 fun style_parm_premise i = Scan.succeed (fn ctxt => fn t =>

   let

     val i_str = string_of_int i;

     val _ = Output.legacy_feature (quote ("prem" ^ i_str)

       ^ " term style encountered; use explicit argument syntax "

       ^ quote ("prem " ^ i_str) ^ " instead.");

     val prems = Logic.strip_imp_prems t;

   in

     if i <= length prems then nth prems (i - 1)

     else error ("Not enough premises for prem" ^ i_str ^

       " in propositon: " ^ Syntax.string_of_term ctxt t)

   end);

 fun isub_symbols (d :: s :: ss) =

       if Symbol.is_ascii_digit d andalso not (String.isPrefix ("\\<^") s)

       then d :: "\\<^isub>" :: isub_symbols (s :: ss)

       else d :: s :: ss

   | isub_symbols cs = cs;

 val isub_name = implode o rev o isub_symbols o rev o Symbol.explode;

 fun isub_term (Free (n, T)) = Free (isub_name n, T)

   | isub_term (Var ((n, idx), T)) =

       if idx <> 0 then Var ((isub_name (n ^ string_of_int idx), 0), T)

       else Var ((isub_name n, 0), T)

   | isub_term (t $ u) = isub_term t $ isub_term u

   | isub_term (Abs (n, T, b)) = Abs (isub_name n, T, isub_term b)

   | isub_term t = t;

 val _ = Context.>> (Context.map_theory

  (setup "lhs" (style_lhs_rhs fst) #>

   setup "rhs" (style_lhs_rhs snd) #>

   setup "prem" style_prem #>

   setup "concl" (Scan.succeed (K Logic.strip_imp_concl)) #>

   setup "isub" (Scan.succeed (K isub_term)) #>

   setup "prem1" (style_parm_premise 1) #>

   setup "prem2" (style_parm_premise 2) #>

   setup "prem3" (style_parm_premise 3) #>

   setup "prem4" (style_parm_premise 4) #>

   setup "prem5" (style_parm_premise 5) #>

   setup "prem6" (style_parm_premise 6) #>

   setup "prem7" (style_parm_premise 7) #>

   setup "prem8" (style_parm_premise 8) #>

   setup "prem9" (style_parm_premise 9) #>

   setup "prem10" (style_parm_premise 10) #>

   setup "prem11" (style_parm_premise 11) #>

   setup "prem12" (style_parm_premise 12) #>

   setup "prem13" (style_parm_premise 13) #>

   setup "prem14" (style_parm_premise 14) #>

   setup "prem15" (style_parm_premise 15) #>

   setup "prem16" (style_parm_premise 16) #>

   setup "prem17" (style_parm_premise 17) #>

   setup "prem18" (style_parm_premise 18) #>

   setup "prem19" (style_parm_premise 19)));

 end;