(* Title: Pure/General/scan.ML
ID: $Id$
Author: Markus Wenzel and Tobias Nipkow, TU Muenchen
Generic scanners (for potentially infinite input).
*)
infix 5 -- :-- :|-- |-- --| ^^;
infixr 5 ::: @@@;
infix 3 >>;
infixr 0 ||;
signature BASIC_SCAN =
sig
(*error msg handler*)
val !! : ('a * string option -> string) -> ('a -> 'b) -> 'a -> 'b
(*apply function*)
val >> : ('a -> 'b * 'c) * ('b -> 'd) -> 'a -> 'd * 'c
(*alternative*)
val || : ('a -> 'b) * ('a -> 'b) -> 'a -> 'b
(*sequential pairing*)
val -- : ('a -> 'b * 'c) * ('c -> 'd * 'e) -> 'a -> ('b * 'd) * 'e
(*dependent pairing*)
val :-- : ('a -> 'b * 'c) * ('b -> 'c -> 'd * 'e) -> 'a -> ('b * 'd) * 'e
(*projections*)
val :|-- : ('a -> 'b * 'c) * ('b -> 'c -> 'd * 'e) -> 'a -> 'd * 'e
val |-- : ('a -> 'b * 'c) * ('c -> 'd * 'e) -> 'a -> 'd * 'e
val --| : ('a -> 'b * 'c) * ('c -> 'd * 'e) -> 'a -> 'b * 'e
(*concatenation*)
val ^^ : ('a -> string * 'b) * ('b -> string * 'c) -> 'a -> string * 'c
val ::: : ('a -> 'b * 'c) * ('c -> 'b list * 'd) -> 'a -> 'b list * 'd
val @@@ : ('a -> 'b list * 'c) * ('c -> 'b list * 'd) -> 'a -> 'b list * 'd
(*one element literal*)
val $$ : string -> string list -> string * string list
val ~$$ : string -> string list -> string * string list
end;
signature SCAN =
sig
include BASIC_SCAN
val prompt: string -> ('a -> 'b) -> 'a -> 'b
val error: ('a -> 'b) -> 'a -> 'b
val catch: ('a -> 'b) -> 'a -> 'b (*exception Fail*)
val fail: 'a -> 'b
val fail_with: ('a -> string) -> 'a -> 'b
val succeed: 'a -> 'b -> 'a * 'b
val some: ('a -> 'b option) -> 'a list -> 'b * 'a list
val one: ('a -> bool) -> 'a list -> 'a * 'a list
val this: string list -> string list -> string list * string list
val this_string: string -> string list -> string * string list
val many: ('a -> bool) -> 'a list -> 'a list * 'a list
val many1: ('a -> bool) -> 'a list -> 'a list * 'a list
val optional: ('a -> 'b * 'a) -> 'b -> 'a -> 'b * 'a
val option: ('a -> 'b * 'a) -> 'a -> 'b option * 'a
val repeat: ('a -> 'b * 'a) -> 'a -> 'b list * 'a
val repeat1: ('a -> 'b * 'a) -> 'a -> 'b list * 'a
val single: ('a -> 'b * 'a) -> 'a -> 'b list * 'a
val bulk: ('a -> 'b * 'a) -> 'a -> 'b list * 'a
val max: ('a * 'a -> bool) -> ('b -> 'a * 'b) -> ('b -> 'a * 'b) -> 'b -> 'a * 'b
val ahead: ('a -> 'b * 'c) -> 'a -> 'b * 'a
val unless: ('a -> 'b * 'a) -> ('a -> 'c * 'd) -> 'a -> 'c * 'd
val first: ('a -> 'b) list -> 'a -> 'b
val state: 'a * 'b -> 'a * ('a * 'b)
val depend: ('a -> 'b -> ('c * 'd) * 'e) -> 'a * 'b -> 'd * ('c * 'e)
val peek: ('a -> 'b -> 'c * 'd) -> 'a * 'b -> 'c * ('a * 'd)
val pass: 'a -> ('a * 'b -> 'c * ('d * 'e)) -> 'b -> 'c * 'e
val lift: ('a -> 'b * 'c) -> 'd * 'a -> 'b * ('d * 'c)
val unlift: (unit * 'a -> 'b * ('c * 'd)) -> 'a -> 'b * 'd
val trace: ('a list -> 'b * 'c list) -> 'a list -> ('b * 'a list) * 'c list
type 'a stopper
val stopper: ('a list -> 'a) -> ('a -> bool) -> 'a stopper
val is_stopper: 'a stopper -> 'a -> bool
val finite': 'a stopper -> ('b * 'a list -> 'c * ('d * 'a list))
-> 'b * 'a list -> 'c * ('d * 'a list)
val finite: 'a stopper -> ('a list -> 'b * 'a list) -> 'a list -> 'b * 'a list
val read: 'a stopper -> ('a list -> 'b * 'a list) -> 'a list -> 'b option
val drain: string -> (string -> 'a -> 'b list * 'a) -> 'b stopper ->
('c * 'b list -> 'd * ('e * 'b list)) -> ('c * 'b list) * 'a -> ('d * ('e * 'b list)) * 'a
type lexicon
val is_literal: lexicon -> string list -> bool
val literal: lexicon -> (string * 'a) list -> (string * 'a) list * (string * 'a) list
val empty_lexicon: lexicon
val extend_lexicon: string list -> lexicon -> lexicon
val make_lexicon: string list list -> lexicon
val dest_lexicon: lexicon -> string list
val merge_lexicons: lexicon * lexicon -> lexicon
end;
structure Scan: SCAN =
struct
(** scanners **)
(* exceptions *)
exception MORE of string option; (*need more input (prompt)*)
exception FAIL of string option; (*try alternatives (reason of failure)*)
exception ABORT of string; (*dead end*)
fun !! err scan xs = scan xs handle FAIL msg => raise ABORT (err (xs, msg));
fun permissive scan xs = scan xs handle MORE _ => raise FAIL NONE | ABORT _ => raise FAIL NONE;
fun strict scan xs = scan xs handle MORE _ => raise FAIL NONE;
fun prompt str scan xs = scan xs handle MORE NONE => raise MORE (SOME str);
fun error scan xs = scan xs handle ABORT msg => Library.error msg;
fun catch scan xs = scan xs
handle ABORT msg => raise Fail msg
| FAIL msg => raise Fail (the_default "Syntax error." msg);
(* scanner combinators *)
fun (scan >> f) xs = scan xs |>> f;
fun (scan1 || scan2) xs = scan1 xs handle FAIL _ => scan2 xs;
fun (scan1 :-- scan2) xs =
let
val (x, ys) = scan1 xs;
val (y, zs) = scan2 x ys;
in ((x, y), zs) end;
fun (scan1 -- scan2) = scan1 :-- (fn _ => scan2);
fun (scan1 :|-- scan2) = scan1 :-- scan2 >> #2;
fun (scan1 |-- scan2) = scan1 -- scan2 >> #2;
fun (scan1 --| scan2) = scan1 -- scan2 >> #1;
fun (scan1 ^^ scan2) = scan1 -- scan2 >> op ^;
fun (scan1 ::: scan2) = scan1 -- scan2 >> op ::;
fun (scan1 @@@ scan2) = scan1 -- scan2 >> op @;
(* generic scanners *)
fun fail _ = raise FAIL NONE;
fun fail_with msg_of xs = raise FAIL (SOME (msg_of xs));
fun succeed y xs = (y, xs);
fun some _ [] = raise MORE NONE
| some f (x :: xs) =
(case f x of SOME y => (y, xs) | _ => raise FAIL NONE);
fun one _ [] = raise MORE NONE
| one pred (x :: xs) =
if pred x then (x, xs) else raise FAIL NONE;
fun $$ a = one (fn s: string => s = a);
fun ~$$ a = one (fn s: string => s <> a);
fun this ys xs =
let
fun drop_prefix [] xs = xs
| drop_prefix (_ :: _) [] = raise MORE NONE
| drop_prefix (y :: ys) (x :: xs) =
if (y: string) = x then drop_prefix ys xs else raise FAIL NONE;
in (ys, drop_prefix ys xs) end;
fun this_string s = this (explode s) >> K s; (*primitive string -- no symbols here!*)
fun many _ [] = raise MORE NONE
| many pred (lst as x :: xs) =
if pred x then apfst (cons x) (many pred xs)
else ([], lst);
fun many1 pred = one pred ::: many pred;
fun optional scan def = scan || succeed def;
fun option scan = (scan >> SOME) || succeed NONE;
fun repeat scan =
let
fun rep ys xs =
(case (SOME (scan xs) handle FAIL _ => NONE) of
NONE => (rev ys, xs)
| SOME (y, xs') => rep (y :: ys) xs');
in rep [] end;
fun repeat1 scan = scan ::: repeat scan;
fun single scan = scan >> (fn x => [x]);
fun bulk scan = scan -- repeat (permissive scan) >> (op ::);
fun max leq scan1 scan2 xs =
(case (option scan1 xs, option scan2 xs) of
((NONE, _), (NONE, _)) => raise FAIL NONE (*looses FAIL msg!*)
| ((SOME tok1, xs'), (NONE, _)) => (tok1, xs')
| ((NONE, _), (SOME tok2, xs')) => (tok2, xs')
| ((SOME tok1, xs1'), (SOME tok2, xs2')) =>
if leq (tok2, tok1) then (tok1, xs1') else (tok2, xs2'));
fun ahead scan xs = (fst (scan xs), xs);
fun unless test scan =
ahead (option test) :-- (fn NONE => scan | _ => fail) >> #2;
fun first [] = fail
| first (scan :: scans) = scan || first scans;
(* state based scanners *)
fun state (st, xs) = (st, (st, xs));
fun depend scan (st, xs) =
let val ((st', y), xs') = scan st xs
in (y, (st', xs')) end;
fun peek scan = depend (fn st => scan st >> pair st);
fun pass st scan xs =
let val (y, (_, xs')) = scan (st, xs)
in (y, xs') end;
fun lift scan (st, xs) =
let val (y, xs') = scan xs
in (y, (st, xs')) end;
fun unlift scan = pass () scan;
(* trace input *)
fun trace scan xs =
let val (y, xs') = scan xs
in ((y, Library.take (length xs - length xs', xs)), xs') end;
(* stopper *)
datatype 'a stopper = Stopper of ('a list -> 'a) * ('a -> bool);
fun stopper mk_stopper is_stopper = Stopper (mk_stopper, is_stopper);
fun is_stopper (Stopper (_, is_stopper)) = is_stopper;
(* finite scans *)
fun finite' (Stopper (mk_stopper, is_stopper)) scan (state, input) =
let
fun lost () = raise ABORT "Bad scanner: lost stopper of finite scan!";
fun stop [] = lost ()
| stop lst =
let val (xs, x) = split_last lst
in if is_stopper x then ((), xs) else lost () end;
in
if exists is_stopper input then
raise ABORT "Stopper may not occur in input of finite scan!"
else (strict scan --| lift stop) (state, input @ [mk_stopper input])
end;
fun finite stopper scan = unlift (finite' stopper (lift scan));
fun read stopper scan xs =
(case error (finite stopper (option scan)) xs of
(y as SOME _, []) => y
| _ => NONE);
(* infinite scans -- draining state-based source *)
fun drain def_prompt get stopper scan ((state, xs), src) =
(scan (state, xs), src) handle MORE prompt =>
(case get (the_default def_prompt prompt) src of
([], _) => (finite' stopper scan (state, xs), src)
| (xs', src') => drain def_prompt get stopper scan ((state, xs @ xs'), src'));
(** datatype lexicon -- position tree **)
datatype lexicon = Lexicon of (bool * lexicon) Symtab.table;
val empty_lexicon = Lexicon Symtab.empty;
fun is_literal _ [] = false
| is_literal (Lexicon tab) (chs as c :: cs) =
(case Symtab.lookup tab c of
SOME (tip, lex) => tip andalso null cs orelse is_literal lex cs
| NONE => false);
(* scan longest match *)
fun literal lexicon =
let
fun finish (SOME (res, rest)) = (rev res, rest)
| finish NONE = raise FAIL NONE;
fun scan _ res (Lexicon tab) [] = if Symtab.is_empty tab then finish res else raise MORE NONE
| scan path res (Lexicon tab) (chs as c :: cs) =
(case Symtab.lookup tab (fst c) of
SOME (tip, lex) =>
let val path' = c :: path
in scan path' (if tip then SOME (path', cs) else res) lex cs end
| NONE => finish res);
in scan [] NONE lexicon end;
(* build lexicons *)
fun extend_lexicon chrs lexicon =
let
fun ext [] lex = lex
| ext (chs as c :: cs) (Lexicon tab) =
(case Symtab.lookup tab c of
SOME (tip, lex) => Lexicon (Symtab.update (c, (tip orelse null cs, ext cs lex)) tab)
| NONE => Lexicon (Symtab.update (c, (null cs, ext cs empty_lexicon)) tab));
in if is_literal lexicon chrs then lexicon else ext chrs lexicon end;
fun make_lexicon chrss = fold extend_lexicon chrss empty_lexicon;
(* merge lexicons *)
fun dest path (Lexicon tab) = Symtab.fold (fn (d, (tip, lex)) =>
let
val path' = d :: path;
val content = dest path' lex;
in append (if tip then rev path' :: content else content) end) tab [];
val dest_lexicon = map implode o dest [];
fun merge_lexicons (lex1, lex2) = fold extend_lexicon (dest [] lex2) lex1;
end;
structure BasicScan: BASIC_SCAN = Scan;
open BasicScan;