src/Pure/Syntax/printer.ML

new year

(*  Title:      Pure/Syntax/printer.ML
    ID:         $Id$
    Author:     Tobias Nipkow and Markus Wenzel, TU Muenchen

Pretty printing of asts, terms, types and print (ast) translation.
*)

signature PRINTER0 =
sig
  val show_types: bool ref
  val show_sorts: bool ref
end;

signature PRINTER =
sig
  include PRINTER0
  structure Symtab: SYMTAB
  structure XGram: XGRAM
  structure Pretty: PRETTY
  local open XGram XGram.Ast in
    val term_to_ast: (string -> (term list -> term) option) -> term -> ast
    val typ_to_ast: (string -> (term list -> term) option) -> typ -> ast
    type prtab
    val empty_prtab: prtab
    val extend_prtab: prtab -> (string prod list) -> (string * (ast list -> ast)) list
      -> prtab
    val mk_prtab: (string prod list) -> (string * (ast list -> ast)) list -> prtab
    val pretty_term_ast: prtab -> ast -> Pretty.T
    val pretty_typ_ast: prtab -> ast -> Pretty.T
  end
end;

functor PrinterFun(structure Symtab: SYMTAB and Lexicon: LEXICON
  and TypeExt: TYPE_EXT and SExtension: SEXTENSION and Pretty: PRETTY
  sharing TypeExt.Extension = SExtension.Extension): PRINTER =
struct

structure Symtab = Symtab;
structure Extension = TypeExt.Extension;
structure XGram = Extension.XGram;
structure Pretty = Pretty;
open XGram XGram.Ast Lexicon TypeExt Extension SExtension;


(** options for printing **)

val show_types = ref false;
val show_sorts = ref false;



(** convert term or typ to ast **)

fun apply_trans name a f args =
  (f args handle
    Match => raise Match
  | exn => (writeln ("Error in " ^ name ^ " for " ^ quote a); raise exn));


fun ast_of_term trf show_types show_sorts tm =
  let
    fun aprop t = Const (apropC, dummyT) $ t;

    fun is_prop tys tm =
      fastype_of1 (tys, tm) = propT handle TERM _ => false;

    fun fix_aprop _ (tm as Const _) = tm
      | fix_aprop _ (tm as Free (x, ty)) =
          if ty = propT then aprop (Free (x, dummyT)) else tm
      | fix_aprop _ (tm as Var (xi, ty)) =
          if ty = propT then aprop (Var (xi, dummyT)) else tm
      | fix_aprop tys (tm as Bound _) =
          if is_prop tys tm then aprop tm else tm
      | fix_aprop tys (Abs (x, ty, t)) = Abs (x, ty, fix_aprop (ty :: tys) t)
      | fix_aprop tys (tm as t1 $ t2) =
          (if is_Const (head_of tm) orelse not (is_prop tys tm)
            then I else aprop) (fix_aprop tys t1 $ fix_aprop tys t2);


    fun prune_typs (t_seen as (Const _, _)) = t_seen
      | prune_typs (t as Free (x, ty), seen) =
          if ty = dummyT then (t, seen)
          else if t mem seen then (Free (x, dummyT), seen)
          else (t, t :: seen)
      | prune_typs (t as Var (xi, ty), seen) =
          if ty = dummyT then (t, seen)
          else if t mem seen then (Var (xi, dummyT), seen)
          else (t, t :: seen)
      | prune_typs (t_seen as (Bound _, _)) = t_seen
      | prune_typs (Abs (x, ty, t), seen) =
          let val (t', seen') = prune_typs (t, seen);
          in (Abs (x, ty, t'), seen') end
      | prune_typs (t1 $ t2, seen) =
          let
            val (t1', seen') = prune_typs (t1, seen);
            val (t2', seen'') = prune_typs (t2, seen');
          in
            (t1' $ t2', seen'')
          end;


    fun ast_of (Const (a, _)) = trans a []
      | ast_of (Free (x, ty)) = constrain x (Free (x, dummyT)) ty
      | ast_of (Var (xi, ty)) = constrain (string_of_vname xi) (Var (xi, dummyT)) ty
      | ast_of (Bound i) = Variable ("B." ^ string_of_int i)
      | ast_of (t as Abs _) = ast_of (abs_tr' t)
      | ast_of (t as _ $ _) =
          (case strip_comb t of
            (Const (a, _), args) => trans a args
          | (f, args) => Appl (map ast_of (f :: args)))

    and trans a args =
      (case trf a of
        Some f => ast_of (apply_trans "print translation" a f args)
      | None => raise Match)
          handle Match => mk_appl (Constant a) (map ast_of args)

    and constrain x t ty =
      if show_types andalso ty <> dummyT then
        ast_of (Const (constrainC, dummyT) $ t $ term_of_typ show_sorts ty)
      else Variable x;
  in
    if show_types then ast_of (#1 (prune_typs (fix_aprop [] tm, [])))
    else ast_of (fix_aprop [] tm)
  end;


(* term_to_ast *)

fun term_to_ast trf tm =
  ast_of_term trf (! show_types) (! show_sorts) tm;


(* typ_to_ast *)

fun typ_to_ast trf ty =
  ast_of_term trf false false (term_of_typ (! show_sorts) ty);



(** type prtab **)

datatype symb =
  Arg of int |
  TypArg of int |
  String of string |
  Break of int |
  Block of int * symb list;

datatype format =
  Prnt of symb list * int * int |
  Trns of ast list -> ast |
  TorP of (ast list -> ast) * (symb list * int * int);

type prtab = format Symtab.table;


(* empty_prtab *)

val empty_prtab = Symtab.null;



(** extend_prtab **)

fun extend_prtab prtab prods trfuns =
  let
    fun nargs (Arg _ :: symbs) = nargs symbs + 1
      | nargs (TypArg _ :: symbs) = nargs symbs + 1
      | nargs (String _ :: symbs) = nargs symbs
      | nargs (Break _ :: symbs) = nargs symbs
      | nargs (Block (_, bsymbs) :: symbs) = nargs symbs + nargs bsymbs
      | nargs [] = 0;

    fun merge (s, String s' :: l) = String (s ^ s') :: l
      | merge (s, l) = String s :: l;

    fun mk_prnp sy c p =
      let
        val constr = (c = constrainC orelse c = constrainIdtC);

        fun syn2pr (Terminal s :: sy) =
              let val (symbs, sy') = syn2pr sy;
              in (merge (s, symbs), sy') end
          | syn2pr (Space s :: sy) =
              let val (symbs, sy') = syn2pr sy;
              in (merge (s, symbs), sy') end
          | syn2pr (Nonterminal (s, p) :: sy) =
              let
                val (symbs, sy') = syn2pr sy;
                val symb =
                  (if constr andalso s = "type" then TypArg else Arg)
                    (if is_terminal s then 0 else p);
              in (symb :: symbs, sy') end
          | syn2pr (Bg i :: sy) =
              let
                val (bsymbs, sy') = syn2pr sy;
                val (symbs, sy'') = syn2pr sy';
              in (Block (i, bsymbs) :: symbs, sy'') end
          | syn2pr (Brk i :: sy) =
              let val (symbs, sy') = syn2pr sy;
              in (Break i :: symbs, sy') end
          | syn2pr (En :: sy) = ([], sy)
          | syn2pr [] = ([], []);

        val (pr, _) = syn2pr sy;
      in
        (pr, nargs pr, p)
      end;

    fun trns_err c = error ("More than one parse ast translation for " ^ quote c);

    fun add_fmt tab c fmt x = Symtab.update ((c, fmt x), tab);

    fun add_prod (tab, Prod (_, _, "", _)) = tab
      | add_prod (tab, Prod (_, sy, c, p)) =
          (case Symtab.lookup (tab, c) of
            None => add_fmt tab c Prnt (mk_prnp sy c p)
          | Some (Prnt _) => add_fmt tab c Prnt (mk_prnp sy c p)
          | Some (Trns f) => add_fmt tab c TorP (f, mk_prnp sy c p)
          | Some (TorP (f, _)) => add_fmt tab c TorP (f, mk_prnp sy c p));

    fun add_tr (tab, (c, f)) =
      (case Symtab.lookup (tab, c) of
        None => add_fmt tab c Trns f
      | Some (Prnt pr) => add_fmt tab c TorP (f, pr)
      | Some (Trns _) => trns_err c
      | Some (TorP _) => trns_err c);
  in
    Symtab.balance (foldl add_prod (foldl add_tr (prtab, trfuns), prods))
  end;


(* mk_prtab *)

val mk_prtab = extend_prtab empty_prtab;



(** pretty term/typ asts **)

(*pretty assumes a syntax derived from Pure, otherwise it may loop forever*)

fun pretty tab type_mode ast0 p0 =
  let
    val trans = apply_trans "print ast translation";

    val appT = if type_mode then tappl_ast_tr' else appl_ast_tr';

    fun synT ([], args) = ([], args)
      | synT (Arg p :: symbs, t :: args) =
          let val (Ts, args') = synT (symbs, args);
          in (astT (t, p) @ Ts, args') end
      | synT (TypArg p :: symbs, t :: args) =
          let val (Ts, args') = synT (symbs, args);
          in (pretty tab true t p @ Ts, args') end
      | synT (String s :: symbs, args) =
          let val (Ts, args') = synT (symbs, args);
          in (Pretty.str s :: Ts, args') end
      | synT (Block (i, bsymbs) :: symbs, args) =
          let
            val (bTs, args') = synT (bsymbs, args);
            val (Ts, args'') = synT (symbs, args');
          in (Pretty.blk (i, bTs) :: Ts, args'') end
      | synT (Break i :: symbs, args) =
          let val (Ts, args') = synT (symbs, args);
          in ((if i < 0 then Pretty.fbrk else Pretty.brk i) :: Ts, args') end
      | synT (_ :: _, []) = error "synT"

    and parT (pr, args, p, p': int) =
      if p > p' then
        #1 (synT ([Block (1, String "(" :: pr @ [String ")"])], args))
      else #1 (synT (pr, args))

    and prefixT (_, a, [], _) = [Pretty.str a]
      | prefixT (c, _, args, p) = astT (appT (c, args), p)

    and splitT 0 ([x], ys) = (x, ys)
      | splitT 0 (rev_xs, ys) = (Appl (rev rev_xs), ys)
      | splitT n (rev_xs, y :: ys) = splitT (n - 1) (y :: rev_xs, ys)
      | splitT _ _ = error "splitT"

    and combT (tup as (c, a, args, p)) =
      let
        val nargs = length args;

        fun prnt (pr, n, p') =
          if nargs = n then parT (pr, args, p, p')
          else if nargs < n orelse type_mode then prefixT tup
          else astT (appT (splitT n ([c], args)), p);
      in
        (case Symtab.lookup (tab, a) of
          None => prefixT tup
        | Some (Prnt prnp) => prnt prnp
        | Some (Trns f) =>
            (astT (trans a f args, p) handle Match => prefixT tup)
        | Some (TorP (f, prnp)) =>
            (astT (trans a f args, p) handle Match => prnt prnp))
      end

    and astT (c as Constant a, p) = combT (c, a, [], p)
      | astT (Variable x, _) = [Pretty.str x]
      | astT (Appl ((c as Constant a) :: (args as _ :: _)), p) =
          combT (c, a, args, p)
      | astT (Appl (f :: (args as _ :: _)), p) = astT (appT (f, args), p)
      | astT (ast as Appl _, _) = raise_ast "pretty: malformed ast" [ast];
  in
    astT (ast0, p0)
  end;


(* pretty_term_ast *)

fun pretty_term_ast tab ast =
  Pretty.blk (0, pretty tab false ast 0);


(* pretty_typ_ast *)

fun pretty_typ_ast tab ast =
  Pretty.blk (0, pretty tab true ast 0);


end;