src/Pure/Isar/outer_lex.ML
author wenzelm
Mon Jul 09 23:12:45 2007 +0200 (2007-07-09 ago)
changeset 23678 f5d315390edc
parent 22873 decd2ff5f503
child 23682 cf4773532006
permissions -rw-r--r--
Malformed token: error msg;
scan: explicit handling of malformed symbols from previous stage;
source: interactive flag indicates intermittent error_msg;
tuned;
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(*  Title:      Pure/Isar/outer_lex.ML
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    ID:         $Id$
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    Author:     Markus Wenzel, TU Muenchen
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Outer lexical syntax for Isabelle/Isar.
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*)
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signature OUTER_LEX =
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sig
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  datatype token_kind =
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    Command | Keyword | Ident | LongIdent | SymIdent | Var | TypeIdent | TypeVar |
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    Nat | String | AltString | Verbatim | Space | Comment | Sync | Malformed of string | EOF
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  eqtype token
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  val str_of_kind: token_kind -> string
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  val stopper: token * (token -> bool)
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  val not_sync: token -> bool
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  val not_eof: token -> bool
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  val position_of: token -> Position.T
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  val pos_of: token -> string
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  val is_kind: token_kind -> token -> bool
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  val keyword_with: (string -> bool) -> token -> bool
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  val ident_with: (string -> bool) -> token -> bool
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  val name_of: token -> string
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  val is_proper: token -> bool
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  val is_semicolon: token -> bool
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  val is_comment: token -> bool
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  val is_begin_ignore: token -> bool
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  val is_end_ignore: token -> bool
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  val is_blank: token -> bool
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  val is_newline: token -> bool
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  val unparse: token -> string
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  val val_of: token -> string
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  val is_sid: string -> bool
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  val !!! : string -> (Position.T * 'a -> 'b) -> Position.T * 'a -> 'b
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  val incr_line: ('a -> 'b * 'c) -> Position.T * 'a -> 'b * (Position.T * 'c)
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  val keep_line: ('a -> 'b * 'c) -> Position.T * 'a -> 'b * (Position.T * 'c)
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  val scan_blank: Position.T * Symbol.symbol list
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    -> Symbol.symbol * (Position.T * Symbol.symbol list)
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  val scan_string: Position.T * Symbol.symbol list -> string * (Position.T * Symbol.symbol list)
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  val scan: (Scan.lexicon * Scan.lexicon) ->
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    Position.T * Symbol.symbol list -> token * (Position.T * Symbol.symbol list)
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  val source: bool option -> (unit -> (Scan.lexicon * Scan.lexicon)) ->
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    Position.T -> (Symbol.symbol, 'a) Source.source ->
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    (token, Position.T * (Symbol.symbol, 'a) Source.source) Source.source
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  val source_proper: (token, 'a) Source.source ->
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    (token, (token, 'a) Source.source) Source.source
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  val make_lexicon: string list -> Scan.lexicon
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end;
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structure OuterLex: OUTER_LEX =
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struct
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(** tokens **)
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(* datatype token *)
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datatype token_kind =
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  Command | Keyword | Ident | LongIdent | SymIdent | Var | TypeIdent | TypeVar |
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  Nat | String | AltString | Verbatim | Space | Comment | Sync | Malformed of string | EOF;
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datatype token = Token of Position.T * (token_kind * string);
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val str_of_kind =
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 fn Command => "command"
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  | Keyword => "keyword"
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  | Ident => "identifier"
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  | LongIdent => "long identifier"
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  | SymIdent => "symbolic identifier"
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  | Var => "schematic variable"
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  | TypeIdent => "type variable"
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  | TypeVar => "schematic type variable"
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  | Nat => "number"
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  | String => "string"
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  | AltString => "back-quoted string"
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  | Verbatim => "verbatim text"
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  | Space => "white space"
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  | Comment => "comment text"
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  | Sync => "sync marker"
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  | Malformed _ => "bad input"
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  | EOF => "end-of-file";
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(* control tokens *)
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val eof = Token (Position.none, (EOF, ""));
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fun is_eof (Token (_, (EOF, _))) = true
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  | is_eof _ = false;
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val stopper = (eof, is_eof);
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val not_eof = not o is_eof;
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fun not_sync (Token (_, (Sync, _))) = false
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  | not_sync _ = true;
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(* get position *)
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fun position_of (Token (pos, _)) = pos;
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val pos_of = Position.str_of o position_of;
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(* kind of token *)
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fun is_kind k (Token (_, (k', _))) = k = k';
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fun keyword_with pred (Token (_, (Keyword, x))) = pred x
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  | keyword_with _ _ = false;
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fun ident_with pred (Token (_, (Ident, x))) = pred x
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  | ident_with _ _ = false;
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fun is_proper (Token (_, (Space, _))) = false
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  | is_proper (Token (_, (Comment, _))) = false
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  | is_proper _ = true;
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fun is_semicolon (Token (_, (Keyword, ";"))) = true
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  | is_semicolon _ = false;
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fun is_comment (Token (_, (Comment, _))) = true
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  | is_comment _ = false;
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fun is_begin_ignore (Token (_, (Comment, "<"))) = true
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  | is_begin_ignore _ = false;
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fun is_end_ignore (Token (_, (Comment, ">"))) = true
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  | is_end_ignore _ = false;
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(* blanks and newlines -- space tokens obey lines *)
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fun is_blank (Token (_, (Space, x))) = not (String.isSuffix "\n" x)
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  | is_blank _ = false;
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fun is_newline (Token (_, (Space, x))) = String.isSuffix "\n" x
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  | is_newline _ = false;
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(* token content *)
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fun name_of (tok as Token (_, (k, x))) =
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  if is_semicolon tok then "terminator"
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  else if x = "" then str_of_kind k
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  else str_of_kind k ^ " " ^ quote x;
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fun escape q =
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  implode o map (fn s => if s = q orelse s = "\\" then "\\" ^ s else s) o Symbol.explode;
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fun unparse (Token (_, (kind, x))) =
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  (case kind of
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    String => x |> quote o escape "\""
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  | AltString => x |> enclose "`" "`" o escape "`"
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  | Verbatim => x |> enclose "{*" "*}"
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  | Comment => x |> enclose "(*" "*)"
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  | _ => x);
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fun val_of (Token (_, (_, x))) = x;
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fun token_leq (Token (_, (_, x)), Token (_, (_, x'))) = x <= x';
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(** scanners **)
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fun change_prompt scan = Scan.prompt "# " scan;
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(* diagnostics *)
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fun lex_err msg ((pos, cs), _) = "Outer lexical error" ^ Position.str_of pos ^ ": " ^ msg cs;
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fun !!! msg scan = Scan.!! (lex_err (K msg)) scan;
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(* line numbering *)
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fun incr_line scan = Scan.depend (fn pos => scan >> pair (Position.inc pos));
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val keep_line = Scan.lift;
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val scan_blank =
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  incr_line ($$ "\n") ||
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  keep_line (Scan.one Symbol.is_blank);
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(* scan symbolic idents *)
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val is_sym_char = member (op =) (explode "!#$%&*+-/<=>?@^_|~");
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val scan_symid =
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  Scan.many1 is_sym_char >> implode ||
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  Scan.one Symbol.is_symbolic;
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fun is_symid str =
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  (case try Symbol.explode str of
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    SOME [s] => Symbol.is_symbolic s orelse is_sym_char s
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  | SOME ss => forall is_sym_char ss
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  | _ => false);
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fun is_sid "begin" = false
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  | is_sid ":" = true
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  | is_sid "::" = true
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  | is_sid s = is_symid s orelse Syntax.is_identifier s;
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(* scan strings *)
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local
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fun scan_str q =
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  scan_blank ||
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  keep_line ($$ "\\") |-- !!! "bad escape character in string"
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      (scan_blank || keep_line ($$ q || $$ "\\")) ||
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  keep_line (Scan.one (fn s => s <> q andalso s <> "\\" andalso
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    Symbol.not_sync s andalso Symbol.not_eof s));
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fun scan_strs q =
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  keep_line ($$ q) |--
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    !!! "missing quote at end of string"
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      (change_prompt ((Scan.repeat (scan_str q) >> implode) --| keep_line ($$ q)));
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in
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val scan_string = scan_strs "\"";
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val scan_alt_string = scan_strs "`";
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end;
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(* scan verbatim text *)
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val scan_verb =
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  scan_blank ||
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  keep_line ($$ "*" --| Scan.ahead (~$$ "}")) ||
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  keep_line (Scan.one (fn s => s <> "*" andalso Symbol.not_sync s andalso Symbol.not_eof s));
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val scan_verbatim =
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  keep_line ($$ "{" -- $$ "*") |--
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    !!! "missing end of verbatim text"
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      (change_prompt ((Scan.repeat scan_verb >> implode) --| keep_line ($$ "*" -- $$ "}")));
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(* scan space *)
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fun is_space s = Symbol.is_blank s andalso s <> "\n";
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val scan_space =
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  (keep_line (Scan.many1 is_space) -- Scan.optional (incr_line ($$ "\n")) "" ||
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    keep_line (Scan.many is_space) -- incr_line ($$ "\n")) >> (fn (cs, c) => implode cs ^ c);
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(* scan nested comments *)
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val scan_cmt =
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  Scan.lift scan_blank ||
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  Scan.depend (fn d => keep_line ($$ "(" ^^ $$ "*") >> pair (d + 1)) ||
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  Scan.depend (fn 0 => Scan.fail | d => keep_line ($$ "*" ^^ $$ ")") >> pair (d - 1)) ||
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  Scan.lift (keep_line ($$ "*" --| Scan.ahead (~$$ ")"))) ||
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  Scan.lift (keep_line (Scan.one (fn s =>
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    s <> "*" andalso Symbol.not_sync s andalso Symbol.not_eof s)));
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val scan_comment =
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  keep_line ($$ "(" -- $$ "*") |--
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    !!! "missing end of comment"
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      (change_prompt
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        (Scan.pass 0 (Scan.repeat scan_cmt >> implode) --| keep_line ($$ "*" -- $$ ")")));
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(* scan malformed symbols *)
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local
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val scan_mal =
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  scan_blank ||
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  keep_line (Scan.one (fn s =>
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    s <> Symbol.end_malformed andalso Symbol.not_sync s andalso Symbol.not_eof s));
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in
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val scan_malformed =
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  keep_line ($$ Symbol.malformed) |--
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    change_prompt (Scan.repeat scan_mal >> (Output.escape o implode))
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      --| keep_line (Scan.option ($$ Symbol.end_malformed));
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end;
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(* scan token *)
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fun scan (lex1, lex2) =
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  let
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    val scanner = Scan.state :-- (fn pos =>
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      let
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        fun token k x = Token (pos, (k, x));
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        fun sync _ = token Sync Symbol.sync;
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      in
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        scan_string >> token String ||
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        scan_alt_string >> token AltString ||
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        scan_verbatim >> token Verbatim ||
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        scan_space >> token Space ||
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        scan_comment >> token Comment ||
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        scan_malformed >> token (Malformed "Malformed symbolic character.") ||
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        keep_line (Scan.one Symbol.is_sync >> sync) ||
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        keep_line (Scan.max token_leq
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          (Scan.max token_leq
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            (Scan.literal lex1 >> (token Keyword o implode))
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            (Scan.literal lex2 >> (token Command o implode)))
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          (Syntax.scan_longid >> token LongIdent ||
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            Syntax.scan_id >> token Ident ||
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            Syntax.scan_var >> token Var ||
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            Syntax.scan_tid >> token TypeIdent ||
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            Syntax.scan_tvar >> token TypeVar ||
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            Syntax.scan_nat >> token Nat ||
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            scan_symid >> token SymIdent))
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      end) >> #2;
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  in !! (lex_err (fn cs => "bad input " ^ quote (Symbol.beginning 10 cs))) scanner end;
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(* token sources *)
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local
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val is_junk = (not o Symbol.is_blank) andf Symbol.not_sync andf Symbol.not_eof;
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fun recover interactive msg x =
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  (if interactive then Output.error_msg msg else ();
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    (Scan.state :-- (fn pos => keep_line (Scan.many is_junk)
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      >> (fn xs => [Token (pos, (Malformed msg, implode xs))])) >> #2) x);
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in
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fun source do_recover get_lex pos src =
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  Source.source' pos Symbol.stopper (Scan.bulk (fn xs => scan (get_lex ()) xs))
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    (Option.map recover do_recover) src;
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end;
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fun source_proper src = src |> Source.filter is_proper;
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(* lexicons *)
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val make_lexicon = Scan.make_lexicon o map Symbol.explode;
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end;