(*  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_brackets: bool ref

  val show_sorts: bool ref

  val show_types: bool ref

end;

signature PRINTER =

sig

  include PRINTER0

  structure Symtab: SYMTAB

  structure SynExt: SYN_EXT

  local open SynExt SynExt.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 -> xprod list -> prtab

    val merge_prtabs: prtab -> prtab -> prtab

    val pretty_term_ast: prtab -> (string -> (ast list -> ast) option)

      -> ast -> Pretty.T

    val pretty_typ_ast: prtab -> (string -> (ast list -> ast) option)

      -> ast -> Pretty.T

  end

end;

functor PrinterFun(structure Symtab: SYMTAB and TypeExt: TYPE_EXT

  and SExtension: SEXTENSION sharing TypeExt.SynExt = SExtension.Parser.SynExt)

  : PRINTER =

struct

structure Symtab = Symtab;

structure SynExt = TypeExt.SynExt;

open SExtension.Parser.Lexicon SynExt.Ast SynExt TypeExt SExtension;

(** options for printing **)

val show_types = ref false;

val show_sorts = ref false;

val show_brackets = 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 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 (prop_tr' show_sorts tm, [])))

    else ast_of (prop_tr' show_sorts 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;

type prtab = (symb list * int * int) Symtab.table;

(* xprods_to_fmts *)

fun xprod_to_fmt (XProd (_, _, "", _)) = None

  | xprod_to_fmt (XProd (_, xsymbs, const, pri)) =

      let

        fun cons_str s (String s' :: syms) = String (s ^ s') :: syms

          | cons_str s syms = String s :: syms;

        fun arg (s, p) =

          (if s = "type" then TypArg else Arg)

          (if is_terminal s then max_pri else p);

        fun xsyms_to_syms (Delim s :: xsyms) =

              apfst (cons_str s) (xsyms_to_syms xsyms)

          | xsyms_to_syms (Argument s_p :: xsyms) =

              apfst (cons (arg s_p)) (xsyms_to_syms xsyms)

          | xsyms_to_syms (Space s :: xsyms) =

              apfst (cons_str s) (xsyms_to_syms xsyms)

          | xsyms_to_syms (Bg i :: xsyms) =

              let

                val (bsyms, xsyms') = xsyms_to_syms xsyms;

                val (syms, xsyms'') = xsyms_to_syms xsyms';

              in

                (Block (i, bsyms) :: syms, xsyms'')

              end

          | xsyms_to_syms (Brk i :: xsyms) =

              apfst (cons (Break i)) (xsyms_to_syms xsyms)

          | xsyms_to_syms (En :: xsyms) = ([], xsyms)

          | xsyms_to_syms [] = ([], []);

        fun nargs (Arg _ :: syms) = nargs syms + 1

          | nargs (TypArg _ :: syms) = nargs syms + 1

          | nargs (String _ :: syms) = nargs syms

          | nargs (Break _ :: syms) = nargs syms

          | nargs (Block (_, bsyms) :: syms) = nargs syms + nargs bsyms

          | nargs [] = 0;

      in

        (case xsyms_to_syms xsymbs of

          (symbs, []) => Some (const, (symbs, nargs symbs, pri))

        | _ => sys_error "xprod_to_fmt: unbalanced blocks")

      end;

fun xprods_to_fmts xprods =

  gen_distinct eq_fst (mapfilter xprod_to_fmt xprods);

(* empty, extend, merge prtabs *)

fun err_dup_fmts cs =

  error ("Duplicate formats in printer table for " ^ commas_quote cs);

val empty_prtab = Symtab.null;

fun extend_prtab tab xprods =

  Symtab.extend (op =) (tab, xprods_to_fmts xprods)

    handle Symtab.DUPS cs => err_dup_fmts cs;

fun merge_prtabs tab1 tab2 =

  Symtab.merge (op =) (tab1, tab2)

    handle Symtab.DUPS cs => err_dup_fmts cs;

(** pretty term or typ asts **)

fun chain[Block(_,pr)] = chain(pr)

  | chain[Arg _] = true

  | chain _  = false;

fun pretty prtab trf 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

            if type_mode then (astT (t, p) @ Ts, args')

            else (pretty prtab trf 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 (_ :: _, []) = sys_error "synT"

    and parT (pr, args, p, p': int) =

          #1 (synT(if p > p' orelse

                      (!show_brackets andalso p' <> max_pri andalso

                       not(chain pr))

                   then [Block (1, String "(" :: pr @ [String ")"])]

                   else 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 _ _ = sys_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 (trf a, Symtab.lookup (prtab, a)) of

          (None, None) => prefixT tup

        | (None, Some prnp) => prnt prnp

        | (Some f, None) =>

            (astT (trans a f args, p) handle Match => prefixT tup)

        | (Some f, Some 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 prtab trf ast =

  Pretty.blk (0, pretty prtab trf false ast 0);

(* pretty_typ_ast *)

fun pretty_typ_ast prtab trf ast =

  Pretty.blk (0, pretty prtab trf true ast 0);

end;