src/Pure/Isar/outer_lex.ML

recovered StringBuilder functionality after subtle change of + and ++ in Scala 2.8.0 Beta 1;

(*  Title:      Pure/Isar/outer_lex.ML
    Author:     Markus Wenzel, TU Muenchen

Outer lexical syntax for Isabelle/Isar.
*)

signature OUTER_LEX =
sig
  datatype token_kind =
    Command | Keyword | Ident | LongIdent | SymIdent | Var | TypeIdent | TypeVar |
    Nat | String | AltString | Verbatim | Space | Comment | InternalValue |
    Malformed | Error of string | Sync | EOF
  datatype value =
    Text of string | Typ of typ | Term of term | Fact of thm list |
    Attribute of morphism -> attribute
  type token
  val str_of_kind: token_kind -> string
  val position_of: token -> Position.T
  val end_position_of: token -> Position.T
  val pos_of: token -> string
  val eof: token
  val is_eof: token -> bool
  val not_eof: token -> bool
  val not_sync: token -> bool
  val stopper: token Scan.stopper
  val kind_of: token -> token_kind
  val is_kind: token_kind -> token -> bool
  val keyword_with: (string -> bool) -> token -> bool
  val ident_with: (string -> bool) -> token -> bool
  val is_proper: token -> bool
  val is_semicolon: token -> bool
  val is_comment: token -> bool
  val is_begin_ignore: token -> bool
  val is_end_ignore: token -> bool
  val is_blank: token -> bool
  val is_newline: token -> bool
  val source_of: token -> string
  val source_position_of: token -> Symbol_Pos.text * Position.T
  val content_of: token -> string
  val unparse: token -> string
  val text_of: token -> string * string
  val get_value: token -> value option
  val map_value: (value -> value) -> token -> token
  val mk_text: string -> token
  val mk_typ: typ -> token
  val mk_term: term -> token
  val mk_fact: thm list -> token
  val mk_attribute: (morphism -> attribute) -> token
  val assignable: token -> token
  val assign: value option -> token -> unit
  val closure: token -> token
  val ident_or_symbolic: string -> bool
  val !!! : string -> (Symbol_Pos.T list -> 'a) -> Symbol_Pos.T list -> 'a
  val source_proper: (token, 'a) Source.source -> (token, (token, 'a) Source.source) Source.source
  val source': {do_recover: bool Option.option} -> (unit -> Scan.lexicon * Scan.lexicon) ->
    (Symbol_Pos.T, 'a) Source.source -> (token, (Symbol_Pos.T, 'a) Source.source) Source.source
  val source: {do_recover: bool Option.option} -> (unit -> Scan.lexicon * Scan.lexicon) ->
    Position.T -> (Symbol.symbol, 'a) Source.source -> (token,
      (Symbol_Pos.T, Position.T * (Symbol.symbol, 'a) Source.source) Source.source) Source.source
  val read_antiq: Scan.lexicon -> (token list -> 'a * token list) ->
    Symbol_Pos.T list * Position.T -> 'a
end;

structure OuterLex: OUTER_LEX =
struct

(** tokens **)

(* token values *)

(*The value slot assigns an (optional) internal value to a token,
  usually as a side-effect of special scanner setup (see also
  args.ML).  Note that an assignable ref designates an intermediate
  state of internalization -- it is NOT meant to persist.*)

datatype value =
  Text of string |
  Typ of typ |
  Term of term |
  Fact of thm list |
  Attribute of morphism -> attribute;

datatype slot =
  Slot |
  Value of value option |
  Assignable of value option Unsynchronized.ref;


(* datatype token *)

datatype token_kind =
  Command | Keyword | Ident | LongIdent | SymIdent | Var | TypeIdent | TypeVar |
  Nat | String | AltString | Verbatim | Space | Comment | InternalValue |
  Malformed | Error of string | Sync | EOF;

datatype token = Token of (Symbol_Pos.text * Position.range) * (token_kind * string) * slot;

val str_of_kind =
 fn Command => "command"
  | Keyword => "keyword"
  | Ident => "identifier"
  | LongIdent => "long identifier"
  | SymIdent => "symbolic identifier"
  | Var => "schematic variable"
  | TypeIdent => "type variable"
  | TypeVar => "schematic type variable"
  | Nat => "number"
  | String => "string"
  | AltString => "back-quoted string"
  | Verbatim => "verbatim text"
  | Space => "white space"
  | Comment => "comment text"
  | InternalValue => "internal value"
  | Malformed => "malformed symbolic character"
  | Error _ => "bad input"
  | Sync => "sync marker"
  | EOF => "end-of-file";


(* position *)

fun position_of (Token ((_, (pos, _)), _, _)) = pos;
fun end_position_of (Token ((_, (_, pos)), _, _)) = pos;

val pos_of = Position.str_of o position_of;


(* control tokens *)

fun mk_eof pos = Token (("", (pos, Position.none)), (EOF, ""), Slot);
val eof = mk_eof Position.none;

fun is_eof (Token (_, (EOF, _), _)) = true
  | is_eof _ = false;

val not_eof = not o is_eof;

fun not_sync (Token (_, (Sync, _), _)) = false
  | not_sync _ = true;

val stopper =
  Scan.stopper (fn [] => eof | toks => mk_eof (end_position_of (List.last toks))) is_eof;


(* kind of token *)

fun kind_of (Token (_, (k, _), _)) = k;
fun is_kind k (Token (_, (k', _), _)) = k = k';

fun keyword_with pred (Token (_, (Keyword, x), _)) = pred x
  | keyword_with _ _ = false;

fun ident_with pred (Token (_, (Ident, x), _)) = pred x
  | ident_with _ _ = false;

fun is_proper (Token (_, (Space, _), _)) = false
  | is_proper (Token (_, (Comment, _), _)) = false
  | is_proper _ = true;

fun is_semicolon (Token (_, (Keyword, ";"), _)) = true
  | is_semicolon _ = false;

fun is_comment (Token (_, (Comment, _), _)) = true
  | is_comment _ = false;

fun is_begin_ignore (Token (_, (Comment, "<"), _)) = true
  | is_begin_ignore _ = false;

fun is_end_ignore (Token (_, (Comment, ">"), _)) = true
  | is_end_ignore _ = false;


(* blanks and newlines -- space tokens obey lines *)

fun is_blank (Token (_, (Space, x), _)) = not (String.isSuffix "\n" x)
  | is_blank _ = false;

fun is_newline (Token (_, (Space, x), _)) = String.isSuffix "\n" x
  | is_newline _ = false;


(* token content *)

fun source_of (Token ((source, (pos, _)), _, _)) =
  YXML.string_of (XML.Elem (Markup.tokenN, Position.properties_of pos, [XML.Text source]));

fun source_position_of (Token ((source, (pos, _)), _, _)) = (source, pos);

fun content_of (Token (_, (_, x), _)) = x;


(* unparse *)

fun escape q =
  implode o map (fn s => if s = q orelse s = "\\" then "\\" ^ s else s) o Symbol.explode;

fun unparse (Token (_, (kind, x), _)) =
  (case kind of
    String => x |> quote o escape "\""
  | AltString => x |> enclose "`" "`" o escape "`"
  | Verbatim => x |> enclose "{*" "*}"
  | Comment => x |> enclose "(*" "*)"
  | Malformed => space_implode " " (explode x)
  | Sync => ""
  | EOF => ""
  | _ => x);

fun text_of tok =
  if is_semicolon tok then ("terminator", "")
  else
    let
      val k = str_of_kind (kind_of tok);
      val s = unparse tok
        handle ERROR _ => Symbol.separate_chars (content_of tok);
    in
      if s = "" then (k, "")
      else if size s < 40 andalso not (exists_string (fn c => c = "\n") s) then (k ^ " " ^ s, "")
      else (k, s)
    end;



(** associated values **)

(* access values *)

fun get_value (Token (_, _, Value v)) = v
  | get_value _ = NONE;

fun map_value f (Token (x, y, Value (SOME v))) = Token (x, y, Value (SOME (f v)))
  | map_value _ tok = tok;


(* make values *)

fun mk_value k v = Token ((k, Position.no_range), (InternalValue, k), Value (SOME v));

val mk_text = mk_value "<text>" o Text;
val mk_typ = mk_value "<typ>" o Typ;
val mk_term = mk_value "<term>" o Term;
val mk_fact = mk_value "<fact>" o Fact;
val mk_attribute = mk_value "<attribute>" o Attribute;


(* static binding *)

(*1st stage: make empty slots assignable*)
fun assignable (Token (x, y, Slot)) = Token (x, y, Assignable (Unsynchronized.ref NONE))
  | assignable tok = tok;

(*2nd stage: assign values as side-effect of scanning*)
fun assign v (Token (_, _, Assignable r)) = r := v
  | assign _ _ = ();

(*3rd stage: static closure of final values*)
fun closure (Token (x, y, Assignable (Unsynchronized.ref v))) = Token (x, y, Value v)
  | closure tok = tok;



(** scanners **)

open Basic_Symbol_Pos;

fun !!! msg = Symbol_Pos.!!! ("Outer lexical error: " ^ msg);


(* scan symbolic idents *)

val is_sym_char = member (op =) (explode "!#$%&*+-/<=>?@^_|~");

val scan_symid =
  Scan.many1 (is_sym_char o symbol) ||
  Scan.one (Symbol.is_symbolic o symbol) >> single;

fun is_symid str =
  (case try Symbol.explode str of
    SOME [s] => Symbol.is_symbolic s orelse is_sym_char s
  | SOME ss => forall is_sym_char ss
  | _ => false);

fun ident_or_symbolic "begin" = false
  | ident_or_symbolic ":" = true
  | ident_or_symbolic "::" = true
  | ident_or_symbolic s = Syntax.is_identifier s orelse is_symid s;


(* scan verbatim text *)

val scan_verb =
  $$$ "*" --| Scan.ahead (~$$$ "}") ||
  Scan.one (fn (s, _) => s <> "*" andalso Symbol.is_regular s) >> single;

val scan_verbatim =
  (Symbol_Pos.scan_pos --| $$$ "{" --| $$$ "*") -- !!! "missing end of verbatim text"
    (Symbol_Pos.change_prompt
      ((Scan.repeat scan_verb >> flat) -- ($$$ "*" |-- $$$ "}" |-- Symbol_Pos.scan_pos)));


(* scan space *)

fun is_space s = Symbol.is_blank s andalso s <> "\n";

val scan_space =
  Scan.many1 (is_space o symbol) @@@ Scan.optional ($$$ "\n") [] ||
  Scan.many (is_space o symbol) @@@ $$$ "\n";


(* scan comment *)

val scan_comment =
  Symbol_Pos.scan_pos -- (Symbol_Pos.scan_comment_body !!! -- Symbol_Pos.scan_pos);


(* scan malformed symbols *)

val scan_malformed =
  $$$ Symbol.malformed |--
    Symbol_Pos.change_prompt (Scan.many (Symbol.is_regular o symbol))
  --| Scan.option ($$$ Symbol.end_malformed);



(** token sources **)

fun source_proper src = src |> Source.filter is_proper;

local

fun token_leq ((_, syms1), (_, syms2)) = length syms1 <= length syms2;

fun token k ss =
  Token ((Symbol_Pos.implode ss, Symbol_Pos.range ss), (k, Symbol_Pos.untabify_content ss), Slot);

fun token_range k (pos1, (ss, pos2)) =
  Token (Symbol_Pos.implode_range pos1 pos2 ss, (k, Symbol_Pos.untabify_content ss), Slot);

fun scan (lex1, lex2) = !!! "bad input"
  (Symbol_Pos.scan_string >> token_range String ||
    Symbol_Pos.scan_alt_string >> token_range AltString ||
    scan_verbatim >> token_range Verbatim ||
    scan_comment >> token_range Comment ||
    scan_space >> token Space ||
    scan_malformed >> token Malformed ||
    Scan.one (Symbol.is_sync o symbol) >> (token Sync o single) ||
    (Scan.max token_leq
      (Scan.max token_leq
        (Scan.literal lex2 >> pair Command)
        (Scan.literal lex1 >> pair Keyword))
      (Syntax.scan_longid >> pair LongIdent ||
        Syntax.scan_id >> pair Ident ||
        Syntax.scan_var >> pair Var ||
        Syntax.scan_tid >> pair TypeIdent ||
        Syntax.scan_tvar >> pair TypeVar ||
        Syntax.scan_nat >> pair Nat ||
        scan_symid >> pair SymIdent) >> uncurry token));

fun recover msg =
  Scan.many ((Symbol.is_regular andf (not o Symbol.is_blank)) o symbol)
  >> (single o token (Error msg));

in

fun source' {do_recover} get_lex =
  Source.source Symbol_Pos.stopper (Scan.bulk (fn xs => scan (get_lex ()) xs))
    (Option.map (rpair recover) do_recover);

fun source do_recover get_lex pos src =
  Symbol_Pos.source pos src
  |> source' do_recover get_lex;

end;


(* read_antiq *)

fun read_antiq lex scan (syms, pos) =
  let
    fun err msg = cat_error msg ("Malformed antiquotation" ^ Position.str_of pos ^ ":\n" ^
      "@{" ^ Symbol_Pos.content syms ^ "}");

    val res =
      Source.of_list syms
      |> source' {do_recover = NONE} (K (lex, Scan.empty_lexicon))
      |> source_proper
      |> Source.source stopper (Scan.error (Scan.bulk scan)) NONE
      |> Source.exhaust;
  in (case res of [x] => x | _ => err "") handle ERROR msg => err msg end;

end;