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|
(**************************************************************************)
(* *)
(* OCaml *)
(* *)
(* Xavier Leroy, projet Cristal, INRIA Rocquencourt *)
(* *)
(* Copyright 1996 Institut National de Recherche en Informatique et *)
(* en Automatique. *)
(* *)
(* All rights reserved. This file is distributed under the terms of *)
(* the GNU Lesser General Public License version 2.1, with the *)
(* special exception on linking described in the file LICENSE. *)
(* *)
(**************************************************************************)
type token =
Kwd of string
| Ident of string
| Int of int
| Float of float
| String of string
| Char of char
(* The string buffering machinery *)
let initial_buffer = Bytes.create 32
let buffer = ref initial_buffer
let bufpos = ref 0
let reset_buffer () = buffer := initial_buffer; bufpos := 0
let store c =
if !bufpos >= Bytes.length !buffer then begin
let newbuffer = Bytes.create (2 * !bufpos) in
Bytes.blit !buffer 0 newbuffer 0 !bufpos;
buffer := newbuffer
end;
Bytes.set !buffer !bufpos c;
incr bufpos
let get_string () =
let s = Bytes.sub_string !buffer 0 !bufpos in buffer := initial_buffer; s
(* The lexer *)
let make_lexer keywords =
let kwd_table = Hashtbl.create 17 in
List.iter (fun s -> Hashtbl.add kwd_table s (Kwd s)) keywords;
let ident_or_keyword id =
try Hashtbl.find kwd_table id with
Not_found -> Ident id
and keyword_or_error c =
let s = String.make 1 c in
try Hashtbl.find kwd_table s with
Not_found -> raise (Stream.Error ("Illegal character " ^ s))
in
let rec next_token (strm__ : _ Stream.t) =
match Stream.peek strm__ with
Some (' ' | '\010' | '\013' | '\009' | '\026' | '\012') ->
Stream.junk strm__; next_token strm__
| Some ('A'..'Z' | 'a'..'z' | '_' | '\192'..'\255' as c) ->
Stream.junk strm__;
let s = strm__ in reset_buffer (); store c; ident s
| Some
('!' | '%' | '&' | '$' | '#' | '+' | '/' | ':' | '<' | '=' | '>' |
'?' | '@' | '\\' | '~' | '^' | '|' | '*' as c) ->
Stream.junk strm__;
let s = strm__ in reset_buffer (); store c; ident2 s
| Some ('0'..'9' as c) ->
Stream.junk strm__;
let s = strm__ in reset_buffer (); store c; number s
| Some '\'' ->
Stream.junk strm__;
let c =
try char strm__ with
Stream.Failure -> raise (Stream.Error "")
in
begin match Stream.peek strm__ with
Some '\'' -> Stream.junk strm__; Some (Char c)
| _ -> raise (Stream.Error "")
end
| Some '\"' ->
Stream.junk strm__;
let s = strm__ in reset_buffer (); Some (String (string s))
| Some '-' -> Stream.junk strm__; neg_number strm__
| Some '(' -> Stream.junk strm__; maybe_comment strm__
| Some c -> Stream.junk strm__; Some (keyword_or_error c)
| _ -> None
and ident (strm__ : _ Stream.t) =
match Stream.peek strm__ with
Some
('A'..'Z' | 'a'..'z' | '\192'..'\255' | '0'..'9' | '_' | '\'' as c) ->
Stream.junk strm__; let s = strm__ in store c; ident s
| _ -> Some (ident_or_keyword (get_string ()))
and ident2 (strm__ : _ Stream.t) =
match Stream.peek strm__ with
Some
('!' | '%' | '&' | '$' | '#' | '+' | '-' | '/' | ':' | '<' | '=' |
'>' | '?' | '@' | '\\' | '~' | '^' | '|' | '*' as c) ->
Stream.junk strm__; let s = strm__ in store c; ident2 s
| _ -> Some (ident_or_keyword (get_string ()))
and neg_number (strm__ : _ Stream.t) =
match Stream.peek strm__ with
Some ('0'..'9' as c) ->
Stream.junk strm__;
let s = strm__ in reset_buffer (); store '-'; store c; number s
| _ -> let s = strm__ in reset_buffer (); store '-'; ident2 s
and number (strm__ : _ Stream.t) =
match Stream.peek strm__ with
Some ('0'..'9' as c) ->
Stream.junk strm__; let s = strm__ in store c; number s
| Some '.' ->
Stream.junk strm__; let s = strm__ in store '.'; decimal_part s
| Some ('e' | 'E') ->
Stream.junk strm__; let s = strm__ in store 'E'; exponent_part s
| _ -> Some (Int (int_of_string (get_string ())))
and decimal_part (strm__ : _ Stream.t) =
match Stream.peek strm__ with
Some ('0'..'9' as c) ->
Stream.junk strm__; let s = strm__ in store c; decimal_part s
| Some ('e' | 'E') ->
Stream.junk strm__; let s = strm__ in store 'E'; exponent_part s
| _ -> Some (Float (float_of_string (get_string ())))
and exponent_part (strm__ : _ Stream.t) =
match Stream.peek strm__ with
Some ('+' | '-' as c) ->
Stream.junk strm__; let s = strm__ in store c; end_exponent_part s
| _ -> end_exponent_part strm__
and end_exponent_part (strm__ : _ Stream.t) =
match Stream.peek strm__ with
Some ('0'..'9' as c) ->
Stream.junk strm__; let s = strm__ in store c; end_exponent_part s
| _ -> Some (Float (float_of_string (get_string ())))
and string (strm__ : _ Stream.t) =
match Stream.peek strm__ with
Some '\"' -> Stream.junk strm__; get_string ()
| Some '\\' ->
Stream.junk strm__;
let c =
try escape strm__ with
Stream.Failure -> raise (Stream.Error "")
in
let s = strm__ in store c; string s
| Some c -> Stream.junk strm__; let s = strm__ in store c; string s
| _ -> raise Stream.Failure
and char (strm__ : _ Stream.t) =
match Stream.peek strm__ with
Some '\\' ->
Stream.junk strm__;
begin try escape strm__ with
Stream.Failure -> raise (Stream.Error "")
end
| Some c -> Stream.junk strm__; c
| _ -> raise Stream.Failure
and escape (strm__ : _ Stream.t) =
match Stream.peek strm__ with
Some 'n' -> Stream.junk strm__; '\n'
| Some 'r' -> Stream.junk strm__; '\r'
| Some 't' -> Stream.junk strm__; '\t'
| Some ('0'..'9' as c1) ->
Stream.junk strm__;
begin match Stream.peek strm__ with
Some ('0'..'9' as c2) ->
Stream.junk strm__;
begin match Stream.peek strm__ with
Some ('0'..'9' as c3) ->
Stream.junk strm__;
Char.chr
((Char.code c1 - 48) * 100 + (Char.code c2 - 48) * 10 +
(Char.code c3 - 48))
| _ -> raise (Stream.Error "")
end
| _ -> raise (Stream.Error "")
end
| Some c -> Stream.junk strm__; c
| _ -> raise Stream.Failure
and maybe_comment (strm__ : _ Stream.t) =
match Stream.peek strm__ with
Some '*' ->
Stream.junk strm__; let s = strm__ in comment s; next_token s
| _ -> Some (keyword_or_error '(')
and comment (strm__ : _ Stream.t) =
match Stream.peek strm__ with
Some '(' -> Stream.junk strm__; maybe_nested_comment strm__
| Some '*' -> Stream.junk strm__; maybe_end_comment strm__
| Some _ -> Stream.junk strm__; comment strm__
| _ -> raise Stream.Failure
and maybe_nested_comment (strm__ : _ Stream.t) =
match Stream.peek strm__ with
Some '*' -> Stream.junk strm__; let s = strm__ in comment s; comment s
| Some _ -> Stream.junk strm__; comment strm__
| _ -> raise Stream.Failure
and maybe_end_comment (strm__ : _ Stream.t) =
match Stream.peek strm__ with
Some ')' -> Stream.junk strm__; ()
| Some '*' -> Stream.junk strm__; maybe_end_comment strm__
| Some _ -> Stream.junk strm__; comment strm__
| _ -> raise Stream.Failure
in
fun input -> Stream.from (fun _count -> next_token input)
|
