src/Pure/Syntax/parser.ML
author paulson
Thu Sep 25 12:09:41 1997 +0200 (1997-09-25)
changeset 3706 e57b5902822f
parent 2229 64acb485ecce
child 4487 9b4c1db5aca1
permissions -rw-r--r--
Generalized and exported biresolution_from_nets_tac to allow the declaration
of Clarify_tac
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(*  Title:      Pure/Syntax/parser.ML
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    ID:         $Id$
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    Author:     Carsten Clasohm, Sonia Mahjoub, and Markus Wenzel, TU Muenchen
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Isabelle's main parser (used for terms and types).
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*)
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signature PARSER =
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  sig
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  type gram
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  val empty_gram: gram
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  val extend_gram: gram -> SynExt.xprod list -> gram
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  val merge_grams: gram -> gram -> gram
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  val pretty_gram: gram -> Pretty.T list
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  datatype parsetree =
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    Node of string * parsetree list |
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    Tip of Lexicon.token
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  val parse: gram -> string -> Lexicon.token list -> parsetree list
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  val branching_level: int ref
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  end;
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structure Parser : PARSER =
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struct
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open Lexicon SynExt;
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(** datatype gram **)
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type nt_tag = int;              (*production for the NTs are stored in an array
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                                  so we can identify NTs by their index*)
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datatype symb = Terminal of token
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              | Nonterminal of nt_tag * int;              (*(tag, precedence)*)
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type nt_gram = ((nt_tag list * token list) *
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                (token option * (symb list * string * int) list) list);
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                                     (*(([dependent_nts], [start_tokens]),
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                                        [(start_token, [(rhs, name, prio)])])*)
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                              (*depent_nts is a list of all NTs whose lookahead
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                                depends on this NT's lookahead*)
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datatype gram =
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  Gram of {nt_count: int, prod_count: int,
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           tags: nt_tag Symtab.table,
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           chains: (nt_tag * nt_tag list) list,              (*[(to, [from])]*)
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           lambdas: nt_tag list,
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           prods: nt_gram Array.array};
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                       (*"tags" is used to map NT names (i.e. strings) to tags;
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                         chain productions are not stored as normal productions
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                         but instead as an entry in "chains";
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                         lambda productions are stored as normal productions
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                         and also as an entry in "lambdas"*)
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val UnknownStart = EndToken;       (*productions for which no starting token is
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                                     known yet are associated with this token*)
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(* get all NTs that are connected with a list of NTs 
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   (used for expanding chain list)*)
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fun connected_with _ [] relatives = relatives
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  | connected_with chains (root :: roots) relatives =
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    let val branches = (assocs chains root) \\ relatives;
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    in connected_with chains (branches @ roots) (branches @ relatives) end;
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(* convert productions to grammar;
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   N.B. that the chains parameter has the form [(from, [to])];
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   prod_count is of type "int option" and is only updated if it is <> None*)
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fun add_prods _ chains lambdas prod_count [] = (chains, lambdas, prod_count)
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  | add_prods prods chains lambdas prod_count
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              ((lhs, new_prod as (rhs, name, pri)) :: ps) =
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    let
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      (*test if new_prod is a chain production*)
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      val (new_chain, chains') =
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        let (*store chain if it does not already exist*)
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            fun store_chain from =
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              let val old_tos = assocs chains from;
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              in if lhs mem old_tos then (None, chains)
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                 else (Some from, overwrite (chains, (from, lhs ins old_tos)))
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              end;
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        in if pri = ~1 then
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             case rhs of [Nonterminal (id, ~1)] => store_chain id
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                       | _ => (None, chains)
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           else (None, chains)
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        end;
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      (*propagate new chain in lookahead and lambda lists;
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        added_starts is used later to associate existing
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        productions with new starting tokens*)
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      val (added_starts, lambdas') =
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        if is_none new_chain then ([], lambdas) else
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        let (*lookahead of chain's source*)
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            val ((from_nts, from_tks), _) = Array.sub (prods, the new_chain);
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            (*copy from's lookahead to chain's destinations*)
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            fun copy_lookahead [] added = added
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              | copy_lookahead (to :: tos) added =
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                let
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                  val ((to_nts, to_tks), ps) = Array.sub (prods, to);
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                  val new_tks = from_tks \\ to_tks;  (*added lookahead tokens*)
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                in Array.update (prods, to, ((to_nts, to_tks @ new_tks), ps));
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                   copy_lookahead tos (if null new_tks then added
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                                       else (to, new_tks) :: added)
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                end;
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            val tos = connected_with chains' [lhs] [lhs];
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        in (copy_lookahead tos [],
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            (if lhs mem lambdas then tos else []) union lambdas)
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        end;
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      (*test if new production can produce lambda
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        (rhs must either be empty or only consist of lambda NTs)*)
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      val (new_lambda, lambdas') =
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        if forall (fn (Nonterminal (id, _)) => id mem lambdas'
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                    | (Terminal _) => false) rhs then
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          (true, lambdas' union (connected_with chains' [lhs] [lhs]))
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        else
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          (false, lambdas');
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      (*list optional terminal and all nonterminals on which the lookahead
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        of a production depends*)
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      fun lookahead_dependency _ [] nts = (None, nts)
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        | lookahead_dependency _ ((Terminal tk) :: _) nts = (Some tk, nts)
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        | lookahead_dependency lambdas ((Nonterminal (nt, _)) :: symbs) nts =
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            if nt mem lambdas then
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              lookahead_dependency lambdas symbs (nt :: nts)
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            else (None, nt :: nts);
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      (*get all known starting tokens for a nonterminal*)
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      fun starts_for_nt nt = snd (fst (Array.sub (prods, nt)));
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      val token_union = gen_union matching_tokens;
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      (*update prods, lookaheads, and lambdas according to new lambda NTs*)
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      val (added_starts', lambdas') =
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        let
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          (*propagate added lambda NT*)
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          fun propagate_lambda [] added_starts lambdas= (added_starts, lambdas)
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            | propagate_lambda (l :: ls) added_starts lambdas =
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              let
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                (*get lookahead for lambda NT*)
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                val ((dependent, l_starts), _) = Array.sub (prods, l);
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                (*check productions whose lookahead may depend on lamdba NT*)
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                fun examine_prods [] add_lambda nt_dependencies added_tks
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                                  nt_prods =
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                      (add_lambda, nt_dependencies, added_tks, nt_prods)
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                  | examine_prods ((p as (rhs, _, _)) :: ps) add_lambda
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                      nt_dependencies added_tks nt_prods =
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                    let val (tk, nts) = lookahead_dependency lambdas rhs [];
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                    in
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                      if l mem nts then       (*update production's lookahead*)
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                      let
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                        val new_lambda = is_none tk andalso nts subset lambdas;
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                        val new_tks = (if is_some tk then [the tk] else []) @
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                          foldl token_union ([], map starts_for_nt nts) \\
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                          l_starts;
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                        val added_tks' = token_union (new_tks, added_tks);
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                        val nt_dependencies' = nts union nt_dependencies;
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                        (*associate production with new starting tokens*)
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                        fun copy [] nt_prods = nt_prods
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                          | copy (tk :: tks) nt_prods =
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                            let val old_prods = assocs nt_prods tk;
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                                val prods' = p :: old_prods;
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                            in copy tks (overwrite (nt_prods, (tk, prods')))
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                            end;
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                        val nt_prods' =
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                          let val new_opt_tks = map Some new_tks;
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                          in copy ((if new_lambda then [None] else []) @
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                                   new_opt_tks) nt_prods
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                          end;
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                      in examine_prods ps (add_lambda orelse new_lambda)
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                           nt_dependencies' added_tks' nt_prods'
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                      end
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                      else                                  (*skip production*)
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                        examine_prods ps add_lambda nt_dependencies
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                                      added_tks nt_prods
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                    end;
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                (*check each NT whose lookahead depends on new lambda NT*)
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                fun process_nts [] added_lambdas added_starts =
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                      (added_lambdas, added_starts)
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                  | process_nts (nt :: nts) added_lambdas added_starts =
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                    let
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                      val (lookahead as (old_nts, old_tks), nt_prods) =
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                        Array.sub (prods, nt);
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                      (*existing productions whose lookahead may depend on l*)
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                      val tk_prods =
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                        assocs nt_prods
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                               (Some (hd l_starts  handle Hd => UnknownStart));
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                      (*add_lambda is true if an existing production of the nt
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                        produces lambda due to the new lambda NT l*)
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                      val (add_lambda, nt_dependencies, added_tks, nt_prods') =
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                        examine_prods tk_prods false [] [] nt_prods;
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                      val added_nts = nt_dependencies \\ old_nts;
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                      val added_lambdas' =
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                        if add_lambda then nt :: added_lambdas
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                        else added_lambdas;
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                    in Array.update (prods, nt,
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                                   ((added_nts @ old_nts, old_tks @ added_tks),
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                                    nt_prods'));
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                                          (*N.B. that because the tks component
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                                            is used to access existing
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                                            productions we have to add new
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                                            tokens at the _end_ of the list*)
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                       if null added_tks then
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                         process_nts nts added_lambdas' added_starts
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                       else
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                         process_nts nts added_lambdas'
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                                      ((nt, added_tks) :: added_starts)
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                    end;
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                val (added_lambdas, added_starts') =
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                  process_nts dependent [] added_starts;
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                val added_lambdas' = added_lambdas \\ lambdas;
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              in propagate_lambda (ls @ added_lambdas') added_starts'
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                                  (added_lambdas' @ lambdas)
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              end;
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        in propagate_lambda (lambdas' \\ lambdas) added_starts lambdas' end;
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      (*insert production into grammar*)
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      val (added_starts', prod_count') =
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        if is_some new_chain then (added_starts', prod_count)
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                                               (*don't store chain production*)
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        else let
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          (*lookahead tokens of new production and on which
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            NTs lookahead depends*)
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          val (start_tk, start_nts) = lookahead_dependency lambdas' rhs [];
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          val start_tks = foldl token_union
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                          (if is_some start_tk then [the start_tk] else [],
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                           map starts_for_nt start_nts);
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          val opt_starts = (if new_lambda then [None]
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                            else if null start_tks then [Some UnknownStart]
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                            else []) @ (map Some start_tks);
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          (*add lhs NT to list of dependent NTs in lookahead*)
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          fun add_nts [] = ()
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            | add_nts (nt :: nts) =
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              let val ((old_nts, old_tks), ps) = Array.sub (prods, nt);
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              in if lhs mem old_nts then ()
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                 else Array.update (prods, nt, ((lhs :: old_nts, old_tks), ps))
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              end;
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          (*add new start tokens to chained NTs' lookahead list;
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            also store new production for lhs NT*)
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          fun add_tks [] added prod_count = (added, prod_count)
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            | add_tks (nt :: nts) added prod_count =
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              let
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                val ((old_nts, old_tks), nt_prods) = Array.sub (prods, nt);
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                val new_tks = gen_rems matching_tokens (start_tks, old_tks);
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                (*store new production*)
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                fun store [] prods is_new =
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                      (prods, if is_some prod_count andalso is_new then
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                                apsome (fn x => x+1) prod_count
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                              else prod_count, is_new)
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                  | store (tk :: tks) prods is_new =
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                    let val tk_prods = assocs prods tk;
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                        (*if prod_count = None then we can assume that
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                          grammar does not contain new production already*)
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                        val (tk_prods', is_new') =
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                          if is_some prod_count then
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                            if new_prod mem tk_prods then (tk_prods, false)
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                            else (new_prod :: tk_prods, true)
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                          else (new_prod :: tk_prods, true);
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                        val prods' = if is_new' then
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                                       overwrite (prods, (tk, tk_prods'))
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                                     else prods;
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                    in store tks prods' (is_new orelse is_new') end;
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                val (nt_prods', prod_count', changed) =
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                  if nt = lhs then store opt_starts nt_prods false
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                              else (nt_prods, prod_count, false);
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              in if not changed andalso null new_tks then ()
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                 else Array.update (prods, nt, ((old_nts, old_tks @ new_tks),
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                                                nt_prods'));
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                 add_tks nts (if null new_tks then added
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                              else (nt, new_tks) :: added) prod_count'
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              end;
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        in add_nts start_nts;
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           add_tks (connected_with chains' [lhs] [lhs]) [] prod_count
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        end;
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      (*associate productions with new lookaheads*)
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      val dummy =
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        let
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          (*propagate added start tokens*)
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          fun add_starts [] = ()
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            | add_starts ((changed_nt, new_tks) :: starts) =
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              let
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                (*token under which old productions which
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                  depend on changed_nt could be stored*)
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                val key =
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                 case find_first (fn t => not (t mem new_tks))
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                                 (starts_for_nt changed_nt) of
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                      None => Some UnknownStart
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                    | t => t;
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                (*copy productions whose lookahead depends on changed_nt;
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                  if key = Some UnknownToken then tk_prods is used to hold
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   317
                  the productions not copied*)
clasohm@1147
   318
                fun update_prods [] result = result
clasohm@1147
   319
                  | update_prods ((p as (rhs, _, _)) :: ps)
clasohm@1147
   320
                      (tk_prods, nt_prods) =
clasohm@1147
   321
                    let
clasohm@1175
   322
                      (*lookahead dependency for production*)
clasohm@1147
   323
                      val (tk, depends) = lookahead_dependency lambdas' rhs [];
wenzelm@18
   324
clasohm@1175
   325
                      (*test if this production has to be copied*)
clasohm@1175
   326
                      val update = changed_nt mem depends;
clasohm@1175
   327
clasohm@1175
   328
                      (*test if production could already be associated with
clasohm@1175
   329
                        a member of new_tks*)
clasohm@1147
   330
                      val lambda = length depends > 1 orelse
clasohm@1175
   331
                                   not (null depends) andalso is_some tk
clasohm@1175
   332
                                   andalso the tk mem new_tks;
clasohm@330
   333
clasohm@1175
   334
                      (*associate production with new starting tokens*)
clasohm@1147
   335
                      fun copy [] nt_prods = nt_prods
clasohm@1147
   336
                        | copy (tk :: tks) nt_prods =
clasohm@1147
   337
                          let
clasohm@1147
   338
                            val tk_prods = assocs nt_prods (Some tk);
clasohm@330
   339
clasohm@1147
   340
                            val tk_prods' =
clasohm@1147
   341
                              if not lambda then p :: tk_prods
clasohm@1147
   342
                              else p ins tk_prods;
clasohm@1147
   343
                                      (*if production depends on lambda NT we
clasohm@1147
   344
                                        have to look for duplicates*)
clasohm@1147
   345
                         in copy tks
clasohm@1147
   346
                                 (overwrite (nt_prods, (Some tk, tk_prods')))
clasohm@1147
   347
                         end;
clasohm@1147
   348
                      val result =
clasohm@1175
   349
                        if update then
clasohm@1175
   350
                          (tk_prods, copy new_tks nt_prods)
clasohm@1175
   351
                        else if key = Some UnknownStart then
clasohm@1175
   352
                          (p :: tk_prods, nt_prods)
clasohm@1175
   353
                        else (tk_prods, nt_prods);
clasohm@1147
   354
                    in update_prods ps result end;
clasohm@330
   355
clasohm@1147
   356
                (*copy existing productions for new starting tokens*)
clasohm@1175
   357
                fun process_nts [] added = added
clasohm@1175
   358
                  | process_nts (nt :: nts) added =
clasohm@1147
   359
                    let
clasohm@1147
   360
                      val (lookahead as (old_nts, old_tks), nt_prods) =
clasohm@1147
   361
                        Array.sub (prods, nt);
clasohm@377
   362
clasohm@1147
   363
                      val tk_prods = assocs nt_prods key;
clasohm@1147
   364
clasohm@1175
   365
                      (*associate productions with new lookahead tokens*)
clasohm@1147
   366
                      val (tk_prods', nt_prods') =
clasohm@1147
   367
                        update_prods tk_prods ([], nt_prods);
clasohm@330
   368
clasohm@1147
   369
                      val nt_prods' =
clasohm@1175
   370
                        if key = Some UnknownStart then
clasohm@1147
   371
                          overwrite (nt_prods', (key, tk_prods'))
clasohm@1147
   372
                        else nt_prods';
wenzelm@18
   373
clasohm@1175
   374
                      val added_tks =
clasohm@1175
   375
                        gen_rems matching_tokens (new_tks, old_tks);
clasohm@1147
   376
                    in if null added_tks then
clasohm@1147
   377
                         (Array.update (prods, nt, (lookahead, nt_prods'));
clasohm@1175
   378
                          process_nts nts added)
clasohm@1147
   379
                       else
clasohm@1147
   380
                         (Array.update (prods, nt,
clasohm@1147
   381
                            ((old_nts, added_tks @ old_tks), nt_prods'));
clasohm@1175
   382
                          process_nts nts ((nt, added_tks) :: added))
clasohm@1147
   383
                    end;
wenzelm@18
   384
clasohm@1175
   385
                val ((dependent, _), _) = Array.sub (prods, changed_nt);
clasohm@1175
   386
              in add_starts (starts @ (process_nts dependent [])) end;
clasohm@1147
   387
        in add_starts added_starts' end;
clasohm@1147
   388
  in add_prods prods chains' lambdas' prod_count ps end;
wenzelm@237
   389
wenzelm@18
   390
wenzelm@237
   391
(* pretty_gram *)
wenzelm@18
   392
clasohm@1147
   393
fun pretty_gram (Gram {tags, prods, chains, ...}) =
wenzelm@237
   394
  let
wenzelm@237
   395
    fun pretty_name name = [Pretty.str (name ^ " =")];
wenzelm@18
   396
clasohm@1147
   397
    val taglist = Symtab.dest tags;
clasohm@1147
   398
wenzelm@237
   399
    fun pretty_symb (Terminal (Token s)) = Pretty.str (quote s)
wenzelm@237
   400
      | pretty_symb (Terminal tok) = Pretty.str (str_of_token tok)
clasohm@1147
   401
      | pretty_symb (Nonterminal (tag, p)) =
clasohm@1147
   402
        let val name = fst (the (find_first (fn (n, t) => t = tag) taglist));
clasohm@1147
   403
        in Pretty.str (name ^ "[" ^ string_of_int p ^ "]") end;
wenzelm@18
   404
wenzelm@237
   405
    fun pretty_const "" = []
wenzelm@237
   406
      | pretty_const c = [Pretty.str ("=> " ^ quote c)];
wenzelm@237
   407
wenzelm@237
   408
    fun pretty_pri p = [Pretty.str ("(" ^ string_of_int p ^ ")")];
wenzelm@237
   409
clasohm@1147
   410
    fun pretty_prod name (symbs, const, pri) =
wenzelm@237
   411
      Pretty.block (Pretty.breaks (pretty_name name @
wenzelm@237
   412
        map pretty_symb symbs @ pretty_const const @ pretty_pri pri));
clasohm@1147
   413
clasohm@1147
   414
    fun pretty_nt (name, tag) =
clasohm@1147
   415
      let
clasohm@1147
   416
        fun prod_of_chain from = ([Nonterminal (from, ~1)], "", ~1);
clasohm@1147
   417
clasohm@1147
   418
        val nt_prods =
clasohm@1147
   419
          foldl (op union) ([], map snd (snd (Array.sub (prods, tag)))) @
clasohm@1147
   420
          map prod_of_chain (assocs chains tag);
clasohm@1147
   421
      in map (pretty_prod name) nt_prods end;
clasohm@1147
   422
        
clasohm@1147
   423
  in flat (map pretty_nt taglist) end;
clasohm@1147
   424
clasohm@1147
   425
clasohm@1438
   426
(** Operations on gramars **)
clasohm@1147
   427
clasohm@1438
   428
(*The mother of all grammars*)
clasohm@1147
   429
val empty_gram = Gram {nt_count = 0, prod_count = 0,
clasohm@1147
   430
                       tags = Symtab.null, chains = [], lambdas = [],
clasohm@1147
   431
                       prods = Array.array (0, (([], []), []))};
clasohm@1147
   432
clasohm@1438
   433
clasohm@1438
   434
(*Invert list of chain productions*)
clasohm@1147
   435
fun inverse_chains [] result = result
clasohm@1147
   436
  | inverse_chains ((root, branches) :: cs) result =
clasohm@1147
   437
    let fun add [] result = result
clasohm@1147
   438
          | add (id :: ids) result =
clasohm@1147
   439
            let val old = assocs result id;
clasohm@1147
   440
            in add ids (overwrite (result, (id, root :: old))) end;
clasohm@1147
   441
    in inverse_chains cs (add branches result) end;
clasohm@1147
   442
clasohm@1438
   443
clasohm@1438
   444
(*Add productions to a grammar*)
clasohm@1147
   445
fun extend_gram gram [] = gram
clasohm@1147
   446
  | extend_gram (Gram {nt_count, prod_count, tags, chains, lambdas, prods})
clasohm@1147
   447
                xprods =
clasohm@1147
   448
  let
clasohm@1438
   449
    (*Get tag for existing nonterminal or create a new one*)
clasohm@1147
   450
    fun get_tag nt_count tags nt =
clasohm@1147
   451
      case Symtab.lookup (tags, nt) of
clasohm@1147
   452
        Some tag => (nt_count, tags, tag)
clasohm@1147
   453
      | None => (nt_count+1, Symtab.update_new ((nt, nt_count), tags),
clasohm@1147
   454
                 nt_count);
clasohm@1438
   455
clasohm@1438
   456
    (*Convert symbols to the form used by the parser;
clasohm@1438
   457
      delimiters and predefined terms are stored as terminals,
clasohm@1438
   458
      nonterminals are converted to integer tags*)
clasohm@1147
   459
    fun symb_of [] nt_count tags result = (nt_count, tags, rev result)
clasohm@1147
   460
      | symb_of ((Delim s) :: ss) nt_count tags result =
clasohm@1147
   461
          symb_of ss nt_count tags ((Terminal (Token s)) :: result)
clasohm@1147
   462
      | symb_of ((Argument (s, p)) :: ss) nt_count tags result =
clasohm@1147
   463
          let
clasohm@1147
   464
            val (nt_count', tags', new_symb) =
clasohm@1147
   465
              case predef_term s of
clasohm@1147
   466
                None =>
clasohm@1147
   467
                  let val (nt_count', tags', s_tag) = get_tag nt_count tags s;
clasohm@1147
   468
                  in (nt_count', tags', Nonterminal (s_tag, p)) end
clasohm@1147
   469
              | Some tk => (nt_count, tags, Terminal tk);
clasohm@1147
   470
          in symb_of ss nt_count' tags' (new_symb :: result) end
clasohm@1147
   471
      | symb_of (_ :: ss) nt_count tags result =
clasohm@1147
   472
          symb_of ss nt_count tags result;
clasohm@1147
   473
clasohm@1438
   474
    (*Convert list of productions by invoking symb_of for each of them*)
clasohm@1147
   475
    fun prod_of [] nt_count prod_count tags result =
clasohm@1147
   476
          (nt_count, prod_count, tags, result)
clasohm@1147
   477
      | prod_of ((XProd (lhs, xsymbs, const, pri)) :: ps)
clasohm@1147
   478
                nt_count prod_count tags result =
clasohm@1147
   479
        let val (nt_count', tags', lhs_tag) = get_tag nt_count tags lhs;
clasohm@1147
   480
clasohm@1147
   481
            val (nt_count'', tags'', prods) =
clasohm@1147
   482
              symb_of xsymbs nt_count' tags' [];
clasohm@1147
   483
        in prod_of ps nt_count'' (prod_count+1) tags''
clasohm@1147
   484
                   ((lhs_tag, (prods, const, pri)) :: result)
clasohm@1147
   485
        end;
clasohm@1147
   486
clasohm@1438
   487
    val (nt_count', prod_count', tags', xprods') =
clasohm@1147
   488
      prod_of xprods nt_count prod_count tags [];
clasohm@1147
   489
clasohm@1438
   490
    (*Copy array containing productions of old grammar;
clasohm@1438
   491
      this has to be done to preserve the old grammar while being able
clasohm@1438
   492
      to change the array's content*)
clasohm@1147
   493
    val prods' =
clasohm@1147
   494
      let fun get_prod i = if i < nt_count then Array.sub (prods, i)
clasohm@1147
   495
                           else (([], []), []);
clasohm@1147
   496
      in Array.tabulate (nt_count', get_prod) end;
clasohm@1147
   497
clasohm@1147
   498
    val fromto_chains = inverse_chains chains [];
clasohm@1147
   499
clasohm@1438
   500
    (*Add new productions to old ones*)
clasohm@1147
   501
    val (fromto_chains', lambdas', _) =
clasohm@1438
   502
      add_prods prods' fromto_chains lambdas None xprods';
clasohm@1147
   503
clasohm@1147
   504
    val chains' = inverse_chains fromto_chains' [];
clasohm@1177
   505
  in Gram {nt_count = nt_count', prod_count = prod_count', tags = tags',
clasohm@1147
   506
           chains = chains', lambdas = lambdas', prods = prods'}
wenzelm@18
   507
  end;
wenzelm@18
   508
wenzelm@18
   509
clasohm@1438
   510
(*Merge two grammars*)
clasohm@1147
   511
fun merge_grams gram_a gram_b =
clasohm@1147
   512
  let
clasohm@1147
   513
    (*find out which grammar is bigger*)
clasohm@1147
   514
    val (Gram {nt_count = nt_count1, prod_count = prod_count1, tags = tags1,
clasohm@1147
   515
               chains = chains1, lambdas = lambdas1, prods = prods1},
clasohm@1147
   516
         Gram {nt_count = nt_count2, prod_count = prod_count2, tags = tags2,
clasohm@1147
   517
               chains = chains2, lambdas = lambdas2, prods = prods2}) =
clasohm@1147
   518
      let val Gram {prod_count = count_a, ...} = gram_a;
clasohm@1147
   519
          val Gram {prod_count = count_b, ...} = gram_b;
clasohm@1147
   520
      in if count_a > count_b then (gram_a, gram_b)
clasohm@1147
   521
                              else (gram_b, gram_a)
clasohm@1147
   522
      end;
clasohm@1147
   523
clasohm@1147
   524
    (*get existing tag from grammar1 or create a new one*)
clasohm@1147
   525
    fun get_tag nt_count tags nt =
clasohm@1147
   526
      case Symtab.lookup (tags, nt) of
clasohm@1147
   527
        Some tag => (nt_count, tags, tag)
clasohm@1147
   528
      | None => (nt_count+1, Symtab.update_new ((nt, nt_count), tags),
clasohm@1147
   529
                nt_count)
clasohm@1147
   530
clasohm@1147
   531
    val ((nt_count1', tags1'), tag_table) =
clasohm@1147
   532
      let val tag_list = Symtab.dest tags2;
clasohm@1147
   533
clasohm@1147
   534
          val table = Array.array (nt_count2, ~1);
clasohm@1147
   535
clasohm@1147
   536
          fun store_tag nt_count tags ~1 = (nt_count, tags)
clasohm@1147
   537
            | store_tag nt_count tags tag =
clasohm@1147
   538
              let val (nt_count', tags', tag') =
clasohm@1147
   539
                   get_tag nt_count tags
clasohm@1147
   540
                     (fst (the (find_first (fn (n, t) => t = tag) tag_list)));
clasohm@1147
   541
              in Array.update (table, tag, tag');
clasohm@1147
   542
                 store_tag nt_count' tags' (tag-1)
clasohm@1147
   543
              end;
clasohm@1147
   544
      in (store_tag nt_count1 tags1 (nt_count2-1), table) end;
clasohm@1147
   545
    
clasohm@1147
   546
    (*convert grammar2 tag to grammar1 tag*)
clasohm@1147
   547
    fun convert_tag tag = Array.sub (tag_table, tag);
clasohm@1147
   548
clasohm@1147
   549
    (*convert chain list to raw productions*)
clasohm@1147
   550
    fun mk_chain_prods [] result = result
clasohm@1147
   551
      | mk_chain_prods ((to, froms) :: cs) result =
clasohm@1147
   552
        let
clasohm@1147
   553
          val to_tag = convert_tag to;
clasohm@1147
   554
clasohm@1147
   555
          fun make [] result = result
clasohm@1147
   556
            | make (from :: froms) result = make froms ((to_tag,
clasohm@1147
   557
                ([Nonterminal (convert_tag from, ~1)], "", ~1)) :: result);
clasohm@1147
   558
        in mk_chain_prods cs (make froms [] @ result) end;
clasohm@1147
   559
        
clasohm@1147
   560
    val chain_prods = mk_chain_prods chains2 [];
clasohm@1147
   561
clasohm@1147
   562
    (*convert prods2 array to productions*)
clasohm@1147
   563
    fun process_nt ~1 result = result
clasohm@1147
   564
      | process_nt nt result =
clasohm@1147
   565
        let
clasohm@1147
   566
          val nt_prods = foldl (op union)
clasohm@1147
   567
                             ([], map snd (snd (Array.sub (prods2, nt))));
clasohm@1147
   568
          val lhs_tag = convert_tag nt;
clasohm@1147
   569
clasohm@1147
   570
          (*convert tags in rhs*)
clasohm@1147
   571
          fun process_rhs [] result = result
clasohm@1147
   572
            | process_rhs (Terminal tk :: rhs) result =
clasohm@1147
   573
                process_rhs rhs (result @ [Terminal tk])
clasohm@1147
   574
            | process_rhs (Nonterminal (nt, prec) :: rhs) result =
clasohm@1147
   575
                process_rhs rhs
clasohm@1147
   576
                            (result @ [Nonterminal (convert_tag nt, prec)]);
clasohm@1147
   577
clasohm@1147
   578
          (*convert tags in productions*)
clasohm@1147
   579
          fun process_prods [] result = result
clasohm@1147
   580
            | process_prods ((rhs, id, prec) :: ps) result =
clasohm@1147
   581
                process_prods ps ((lhs_tag, (process_rhs rhs [], id, prec))
clasohm@1147
   582
                                  :: result);
clasohm@1147
   583
        in process_nt (nt-1) (process_prods nt_prods [] @ result) end;
clasohm@1147
   584
clasohm@1147
   585
    val raw_prods = chain_prods @ process_nt (nt_count2-1) [];
clasohm@1147
   586
clasohm@1147
   587
    val prods1' =
clasohm@1147
   588
      let fun get_prod i = if i < nt_count1 then Array.sub (prods1, i)
clasohm@1147
   589
                           else (([], []), []);
clasohm@1147
   590
      in Array.tabulate (nt_count1', get_prod) end;
clasohm@1147
   591
clasohm@1147
   592
    val fromto_chains = inverse_chains chains1 [];
clasohm@1147
   593
clasohm@1147
   594
    val (fromto_chains', lambdas', Some prod_count1') =
clasohm@1147
   595
      add_prods prods1' fromto_chains lambdas1 (Some prod_count1) raw_prods;
clasohm@1147
   596
clasohm@1147
   597
    val chains' = inverse_chains fromto_chains' [];
clasohm@1147
   598
  in Gram {nt_count = nt_count1', prod_count = prod_count1',
clasohm@1147
   599
           tags = tags1', chains = chains', lambdas = lambdas',
clasohm@1147
   600
           prods = prods1'}
clasohm@1147
   601
  end;
clasohm@1147
   602
wenzelm@18
   603
clasohm@1438
   604
(** Parser **)
wenzelm@18
   605
wenzelm@237
   606
datatype parsetree =
wenzelm@237
   607
  Node of string * parsetree list |
wenzelm@237
   608
  Tip of token;
wenzelm@237
   609
wenzelm@18
   610
type state =
clasohm@1147
   611
  nt_tag * int *                (*identification and production precedence*)
clasohm@1147
   612
  parsetree list *              (*already parsed nonterminals on rhs*)
clasohm@1147
   613
  symb list *                   (*rest of rhs*)
clasohm@1147
   614
  string *                      (*name of production*)
clasohm@1147
   615
  int;                          (*index for previous state list*)
wenzelm@18
   616
wenzelm@18
   617
clasohm@330
   618
(*Get all rhss with precedence >= minPrec*)
clasohm@330
   619
fun getRHS minPrec = filter (fn (_, _, prec:int) => prec >= minPrec);
wenzelm@237
   620
clasohm@330
   621
(*Get all rhss with precedence >= minPrec and < maxPrec*)
clasohm@330
   622
fun getRHS' minPrec maxPrec =
clasohm@330
   623
  filter (fn (_, _, prec:int) => prec >= minPrec andalso prec < maxPrec);
wenzelm@18
   624
clasohm@330
   625
(*Make states using a list of rhss*)
clasohm@330
   626
fun mkStates i minPrec lhsID rhss =
clasohm@330
   627
  let fun mkState (rhs, id, prodPrec) = (lhsID, prodPrec, [], rhs, id, i);
clasohm@330
   628
  in map mkState rhss end;
clasohm@697
   629
clasohm@330
   630
(*Add parse tree to list and eliminate duplicates 
clasohm@330
   631
  saving the maximum precedence*)
clasohm@330
   632
fun conc (t, prec:int) [] = (None, [(t, prec)])
clasohm@330
   633
  | conc (t, prec) ((t', prec') :: ts) =
clasohm@330
   634
      if t = t' then
clasohm@330
   635
        (Some prec', if prec' >= prec then (t', prec') :: ts 
clasohm@330
   636
                     else (t, prec) :: ts)
clasohm@330
   637
      else
clasohm@330
   638
        let val (n, ts') = conc (t, prec) ts
clasohm@330
   639
        in (n, (t', prec') :: ts') end;
wenzelm@18
   640
clasohm@330
   641
(*Update entry in used*)
clasohm@697
   642
fun update_trees ((B, (i, ts)) :: used) (A, t) =
wenzelm@237
   643
  if A = B then
wenzelm@237
   644
    let val (n, ts') = conc t ts
wenzelm@237
   645
    in ((A, (i, ts')) :: used, n) end
wenzelm@237
   646
  else
clasohm@697
   647
    let val (used', n) = update_trees used (A, t)
wenzelm@237
   648
    in ((B, (i, ts)) :: used', n) end;
wenzelm@18
   649
clasohm@330
   650
(*Replace entry in used*)
clasohm@697
   651
fun update_prec (A, prec) used =
clasohm@697
   652
  let fun update ((hd as (B, (_, ts))) :: used, used') =
clasohm@330
   653
        if A = B
clasohm@330
   654
        then used' @ ((A, (prec, ts)) :: used)
clasohm@330
   655
        else update (used, hd :: used')
clasohm@330
   656
  in update (used, []) end;
wenzelm@18
   657
clasohm@330
   658
fun getS A maxPrec Si =
wenzelm@237
   659
  filter
clasohm@1147
   660
    (fn (_, _, _, Nonterminal (B, prec) :: _, _, _)
clasohm@330
   661
          => A = B andalso prec <= maxPrec
wenzelm@237
   662
      | _ => false) Si;
wenzelm@18
   663
clasohm@330
   664
fun getS' A maxPrec minPrec Si =
wenzelm@237
   665
  filter
clasohm@1147
   666
    (fn (_, _, _, Nonterminal (B, prec) :: _, _, _)
clasohm@330
   667
          => A = B andalso prec > minPrec andalso prec <= maxPrec
wenzelm@237
   668
      | _ => false) Si;
wenzelm@18
   669
clasohm@330
   670
fun getStates Estate i ii A maxPrec =
wenzelm@237
   671
  filter
clasohm@1147
   672
    (fn (_, _, _, Nonterminal (B, prec) :: _, _, _)
clasohm@330
   673
          => A = B andalso prec <= maxPrec
wenzelm@237
   674
      | _ => false)
wenzelm@237
   675
    (Array.sub (Estate, ii));
wenzelm@18
   676
wenzelm@18
   677
clasohm@1147
   678
fun movedot_term (A, j, ts, Terminal a :: sa, id, i) c =
wenzelm@237
   679
  if valued_token c then
clasohm@697
   680
    (A, j, ts @ [Tip c], sa, id, i)
wenzelm@237
   681
  else (A, j, ts, sa, id, i);
wenzelm@18
   682
clasohm@1147
   683
fun movedot_nonterm ts (A, j, tss, Nonterminal _ :: sa, id, i) =
wenzelm@237
   684
  (A, j, tss @ ts, sa, id, i);
wenzelm@18
   685
wenzelm@237
   686
fun movedot_lambda _ [] = []
clasohm@1147
   687
  | movedot_lambda (B, j, tss, Nonterminal (A, k) :: sa, id, i) ((t, ki) :: ts) =
wenzelm@237
   688
      if k <= ki then
wenzelm@237
   689
        (B, j, tss @ t, sa, id, i) ::
clasohm@1147
   690
          movedot_lambda (B, j, tss, Nonterminal (A, k) :: sa, id, i) ts
clasohm@1147
   691
      else movedot_lambda (B, j, tss, Nonterminal (A, k) :: sa, id, i) ts;
wenzelm@18
   692
wenzelm@18
   693
clasohm@1147
   694
val warned = ref false;                            (*flag for warning message*)
clasohm@1147
   695
val branching_level = ref 200;                   (*trigger value for warnings*)
wenzelm@18
   696
clasohm@1147
   697
(*get all productions of a NT and NTs chained to it which can
clasohm@1147
   698
  be started by specified token*)
clasohm@1147
   699
fun prods_for prods chains include_none tk nts =
clasohm@1147
   700
let (*similar to token_assoc but does not automatically include 'None' key*)
clasohm@1147
   701
    fun token_assoc2 (list, key) =
clasohm@1147
   702
      let fun assoc [] result = result
clasohm@1147
   703
            | assoc ((keyi, pi) :: pairs) result =
clasohm@1147
   704
                if is_some keyi andalso matching_tokens (the keyi, key)
clasohm@1147
   705
                   orelse include_none andalso is_none keyi then 
clasohm@1147
   706
                  assoc pairs (pi @ result)
clasohm@1147
   707
                else assoc pairs result;
clasohm@1147
   708
      in assoc list [] end;
clasohm@1147
   709
clasohm@1147
   710
    fun get_prods [] result = result
clasohm@1147
   711
      | get_prods (nt :: nts) result =
clasohm@1147
   712
        let val nt_prods = snd (Array.sub (prods, nt));
clasohm@1147
   713
        in get_prods nts ((token_assoc2 (nt_prods, tk)) @ result) end;
clasohm@1147
   714
in get_prods (connected_with chains nts nts) [] end;
clasohm@1147
   715
clasohm@1147
   716
clasohm@1147
   717
fun PROCESSS prods chains Estate i c states =
wenzelm@18
   718
let
clasohm@1147
   719
fun all_prods_for nt = prods_for prods chains true c [nt];
clasohm@330
   720
wenzelm@237
   721
fun processS used [] (Si, Sii) = (Si, Sii)
wenzelm@237
   722
  | processS used (S :: States) (Si, Sii) =
wenzelm@237
   723
      (case S of
clasohm@1147
   724
        (_, _, _, Nonterminal (nt, minPrec) :: _, _, _) =>
clasohm@330
   725
          let                                       (*predictor operation*)
clasohm@697
   726
            val (used', new_states) =
clasohm@1147
   727
              (case assoc (used, nt) of
clasohm@330
   728
                Some (usedPrec, l) =>       (*nonterminal has been processed*)
clasohm@330
   729
                  if usedPrec <= minPrec then
clasohm@330
   730
                                      (*wanted precedence has been processed*)
clasohm@330
   731
                    (used, movedot_lambda S l)
clasohm@330
   732
                  else            (*wanted precedence hasn't been parsed yet*)
clasohm@1147
   733
                    let
clasohm@1147
   734
                      val tk_prods = all_prods_for nt;
clasohm@1147
   735
                      
clasohm@1147
   736
                      val States' = mkStates i minPrec nt
clasohm@1147
   737
                                      (getRHS' minPrec usedPrec tk_prods);
clasohm@1147
   738
                    in (update_prec (nt, minPrec) used, 
clasohm@330
   739
                        movedot_lambda S l @ States')
wenzelm@237
   740
                    end
wenzelm@18
   741
clasohm@330
   742
              | None =>           (*nonterminal is parsed for the first time*)
clasohm@1147
   743
                  let val tk_prods = all_prods_for nt;
clasohm@1147
   744
                      val States' = mkStates i minPrec nt
clasohm@1147
   745
                                      (getRHS minPrec tk_prods);
clasohm@1147
   746
                  in ((nt, (minPrec, [])) :: used, States') end);
clasohm@697
   747
clasohm@1147
   748
            val dummy =
clasohm@1147
   749
              if not (!warned) andalso
clasohm@1147
   750
                 length (new_states @ States) > (!branching_level) then
berghofe@1580
   751
                (warning "Currently parsed expression could be \
clasohm@1147
   752
                         \extremely ambiguous.";
clasohm@1147
   753
                 warned := true)
clasohm@1147
   754
              else ();
wenzelm@18
   755
          in
clasohm@697
   756
            processS used' (new_states @ States) (S :: Si, Sii)
wenzelm@18
   757
          end
clasohm@1147
   758
      | (_, _, _, Terminal a :: _, _, _) =>               (*scanner operation*)
wenzelm@237
   759
          processS used States
wenzelm@237
   760
            (S :: Si,
wenzelm@237
   761
              if matching_tokens (a, c) then movedot_term S c :: Sii else Sii)
clasohm@330
   762
      | (A, prec, ts, [], id, j) =>                   (*completer operation*)
clasohm@697
   763
          let val tt = if id = "" then ts else [Node (id, ts)] in
clasohm@330
   764
            if j = i then                             (*lambda production?*)
wenzelm@237
   765
              let
clasohm@697
   766
                val (used', O) = update_trees used (A, (tt, prec));
wenzelm@237
   767
              in
clasohm@1147
   768
                case O of
wenzelm@237
   769
                  None =>
clasohm@1147
   770
                    let val Slist = getS A prec Si;
clasohm@1147
   771
                        val States' = map (movedot_nonterm tt) Slist;
clasohm@1147
   772
                    in processS used' (States' @ States) (S :: Si, Sii) end
wenzelm@237
   773
                | Some n =>
clasohm@1147
   774
                    if n >= prec then processS used' States (S :: Si, Sii)
wenzelm@237
   775
                    else
clasohm@1147
   776
                      let val Slist = getS' A prec n Si;
clasohm@1147
   777
                          val States' = map (movedot_nonterm tt) Slist;
clasohm@1147
   778
                      in processS used' (States' @ States) (S :: Si, Sii) end
clasohm@330
   779
              end 
wenzelm@237
   780
            else
clasohm@1147
   781
              let val Slist = getStates Estate i j A prec
clasohm@1147
   782
              in processS used (map (movedot_nonterm tt) Slist @ States)
clasohm@1147
   783
                          (S :: Si, Sii)
clasohm@682
   784
              end
wenzelm@237
   785
          end)
clasohm@682
   786
in processS [] states ([], []) end;
wenzelm@18
   787
wenzelm@18
   788
clasohm@362
   789
fun syntax_error toks allowed =
clasohm@362
   790
  error 
clasohm@362
   791
  ((if toks = [] then
clasohm@362
   792
      "error: unexpected end of input\n"
clasohm@362
   793
    else
clasohm@367
   794
      "Syntax error at: " ^ quote (space_implode " " (map str_of_token 
clasohm@367
   795
        ((rev o tl o rev) toks)))
clasohm@362
   796
      ^ "\n")
clasohm@362
   797
   ^ "Expected tokens: " 
clasohm@362
   798
   ^ space_implode ", " (map (quote o str_of_token) allowed));
wenzelm@18
   799
clasohm@1147
   800
fun produce prods chains stateset i indata prev_token =
clasohm@1147
   801
                                      (*prev_token is used for error messages*)
wenzelm@237
   802
  (case Array.sub (stateset, i) of
clasohm@1147
   803
    [] => let fun some_prods_for tk nt = prods_for prods chains false tk [nt];
clasohm@373
   804
clasohm@373
   805
              (*test if tk is a lookahead for a given minimum precedence*)
clasohm@1147
   806
              fun reduction _ minPrec _ (Terminal _ :: _, _, prec:int) =
clasohm@373
   807
                    if prec >= minPrec then true
clasohm@373
   808
                    else false
clasohm@1147
   809
                | reduction tk minPrec checked 
clasohm@1147
   810
                            (Nonterminal (nt, nt_prec) :: _, _, prec) =
clasohm@1147
   811
                  if prec >= minPrec andalso not (nt mem checked) then
clasohm@1147
   812
                    let val chained = connected_with chains [nt] [nt];
clasohm@1147
   813
                    in exists
clasohm@1147
   814
                         (reduction tk nt_prec (chained @ checked))
clasohm@1147
   815
                         (some_prods_for tk nt)
clasohm@1147
   816
                    end
clasohm@1147
   817
                  else false;
clasohm@373
   818
clasohm@373
   819
              (*compute a list of allowed starting tokens 
clasohm@373
   820
                for a list of nonterminals considering precedence*)
clasohm@1147
   821
              fun get_starts [] result = result
clasohm@1147
   822
                | get_starts ((nt, minPrec:int) :: nts) result =
clasohm@1147
   823
                  let fun get [] result = result
clasohm@1147
   824
                        | get ((Some tk, prods) :: ps) result =
clasohm@1147
   825
                            if not (null prods) andalso
clasohm@1147
   826
                               exists (reduction tk minPrec [nt]) prods
clasohm@1147
   827
                            then get ps (tk :: result)
clasohm@1147
   828
                            else get ps result
clasohm@1147
   829
                        | get ((None, _) :: ps) result = get ps result;
clasohm@1147
   830
clasohm@1147
   831
                      val (_, nt_prods) = Array.sub (prods, nt);
clasohm@362
   832
clasohm@1147
   833
                      val chained = map (fn nt => (nt, minPrec))
clasohm@1147
   834
                                        (assocs chains nt);
clasohm@1147
   835
                  in get_starts (chained @ nts)
clasohm@1147
   836
                                ((get nt_prods []) union result)
clasohm@1147
   837
                  end;
clasohm@1147
   838
clasohm@1147
   839
              val nts =
clasohm@1147
   840
                mapfilter (fn (_, _, _, Nonterminal (a, prec) :: _, _, _) => 
clasohm@1147
   841
                           Some (a, prec) | _ => None)
clasohm@1147
   842
                          (Array.sub (stateset, i-1));
clasohm@1147
   843
              val allowed =
clasohm@1147
   844
                distinct (get_starts nts [] @
clasohm@1147
   845
                  (mapfilter (fn (_, _, _, Terminal a :: _, _, _) => Some a
clasohm@1147
   846
                               | _ => None)
clasohm@1147
   847
                             (Array.sub (stateset, i-1))));
clasohm@362
   848
          in syntax_error (if prev_token = EndToken then indata
clasohm@362
   849
                           else prev_token :: indata) allowed
clasohm@362
   850
          end
wenzelm@237
   851
  | s =>
wenzelm@237
   852
    (case indata of
clasohm@1147
   853
       [] => Array.sub (stateset, i)
clasohm@1147
   854
     | c :: cs =>
clasohm@1147
   855
       let val (si, sii) = PROCESSS prods chains stateset i c s;
clasohm@1147
   856
       in Array.update (stateset, i, si);
clasohm@1147
   857
          Array.update (stateset, i + 1, sii);
clasohm@1147
   858
          produce prods chains stateset (i + 1) cs c
clasohm@1147
   859
       end));
wenzelm@18
   860
wenzelm@18
   861
paulson@2229
   862
fun get_trees l = mapfilter (fn (_, _, [pt], _, _, _) => Some pt | _ => None) 
paulson@2229
   863
                            l;
wenzelm@18
   864
clasohm@1147
   865
fun earley prods tags chains startsymbol indata =
wenzelm@237
   866
  let
clasohm@1147
   867
    val start_tag = case Symtab.lookup (tags, startsymbol) of
clasohm@1147
   868
                       Some tag => tag
clasohm@624
   869
                     | None   => error ("parse: Unknown startsymbol " ^ 
clasohm@624
   870
                                        quote startsymbol);
clasohm@1147
   871
    val S0 = [(~1, 0, [], [Nonterminal (start_tag, 0), Terminal EndToken],
clasohm@1147
   872
               "", 0)];
clasohm@330
   873
    val s = length indata + 1;
wenzelm@237
   874
    val Estate = Array.array (s, []);
wenzelm@237
   875
  in
wenzelm@237
   876
    Array.update (Estate, 0, S0);
clasohm@1147
   877
    warned := false;
clasohm@1147
   878
    get_trees (produce prods chains Estate 0 indata EndToken)
wenzelm@237
   879
  end;
wenzelm@18
   880
wenzelm@18
   881
clasohm@1147
   882
fun parse (Gram {tags, prods, chains, ...}) start toks =
clasohm@624
   883
let val r =
clasohm@1147
   884
  (case earley prods tags chains start toks of
wenzelm@237
   885
    [] => sys_error "parse: no parse trees"
clasohm@330
   886
  | pts => pts);
clasohm@624
   887
in r end
wenzelm@18
   888
wenzelm@18
   889
end;