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|
(**
Lexer using sedlex
*)
open Tokens
exception UnclosedQuote of { content : string; line : int }
exception LexError of Lexing.position * string
let pp_pos out { Lexing.pos_lnum; pos_cnum; pos_bol; _ } =
Format.fprintf out "line %d:%d" pos_lnum (pos_cnum - pos_bol)
module type Encoding = sig
val lexeme : Sedlexing.lexbuf -> string
end
(* The comment system is terrible. The same symbol can be used for :
- starting a comment
- inequality operation
In order to manage this, I try to identify the context in a very basic way,
using a flag True False for determining the token to send.
*)
module Bucket = Ephemeron.K1.Bucket
type bucket = (Sedlexing.lexbuf, int) Bucket.t
let is_expression : bucket = Bucket.make ()
let incr_level lexbuf =
match Bucket.find is_expression lexbuf with
| None -> Bucket.add is_expression lexbuf 1
| Some v -> Bucket.add is_expression lexbuf (v + 1)
let decr_level lexbuf =
match Bucket.find is_expression lexbuf with
| None -> ()
| Some v ->
if v > 1 then Bucket.add is_expression lexbuf (v - 1)
else Bucket.remove is_expression lexbuf
let build_ident lexbuf =
let id =
Sedlexing.lexeme lexbuf |> Idents.of_uchars |> String.uppercase_ascii
in
try
let value = Hashtbl.find Idents.keyword_table id in
let _ = match value with IF | ELIF -> incr_level lexbuf | _ -> () in
value
with Not_found -> IDENT id
let incr_level lexbuf =
match Bucket.find is_expression lexbuf with
| None -> Bucket.add is_expression lexbuf 1
| Some v -> Bucket.add is_expression lexbuf (v + 1)
let wait_balance rule lexbuf =
try[@warning "-52"] rule (Buffer.create 17) lexbuf
with Failure "lexing: empty token" ->
let position, _ = Sedlexing.lexing_positions lexbuf in
let line = position.Lexing.pos_lnum
and content = Sedlexing.lexeme lexbuf |> Idents.of_uchars in
(raise (UnclosedQuote { line; content }) [@warning "+52"])
let space = [%sedlex.regexp? ' ' | '\t']
let eol = [%sedlex.regexp? '\r' | '\n' | "\r\n"]
let coma = [%sedlex.regexp? ',']
let digit = [%sedlex.regexp? '0' .. '9']
let letters = [%sedlex.regexp? 'a' .. 'z' | 'A' .. 'Z' | '_']
let spaces = [%sedlex.regexp? Plus space]
let ident = [%sedlex.regexp? ('$' | letters), Star (digit | letters)]
let location_ident = [%sedlex.regexp? letters | digit]
let location_prefix = [%sedlex.regexp? '!' | '$' | '#' | '^']
let location = [%sedlex.regexp? Opt location_prefix, Plus location_ident]
let rec read_long_string level buf lexbuf =
match%sedlex lexbuf with
| '{' ->
Buffer.add_string buf (Sedlexing.Utf8.lexeme lexbuf);
read_long_string (level + 1) buf lexbuf
| '}' -> (
match level with
| 0 -> Buffer.contents buf
| _ ->
Buffer.add_string buf (Sedlexing.Utf8.lexeme lexbuf);
read_long_string (level - 1) buf lexbuf)
| eol ->
Sedlexing.new_line lexbuf;
Buffer.add_string buf (Sedlexing.Utf8.lexeme lexbuf);
read_long_string level buf lexbuf
| any ->
Buffer.add_string buf (Sedlexing.Utf8.lexeme lexbuf);
read_long_string level buf lexbuf
| _ -> raise Not_found
let rec read_dquoted_string buf lexbuf =
match%sedlex lexbuf with
| "\"\"" ->
Buffer.add_char buf '"';
read_dquoted_string buf lexbuf
| '"' -> Buffer.contents buf
| any ->
Buffer.add_string buf (Sedlexing.Utf8.lexeme lexbuf);
read_dquoted_string buf lexbuf
| _ -> raise Not_found
let rec read_quoted_string buf lexbuf =
match%sedlex lexbuf with
| "''" ->
Buffer.add_char buf '\'';
read_quoted_string buf lexbuf
| '\'' -> Buffer.contents buf
| eol ->
Buffer.add_string buf (Sedlexing.Utf8.lexeme lexbuf);
Sedlexing.new_line lexbuf;
read_quoted_string buf lexbuf
| any ->
Buffer.add_string buf (Sedlexing.Utf8.lexeme lexbuf);
read_quoted_string buf lexbuf
| _ -> raise Not_found
let rec skip_comment lexbuf =
match%sedlex lexbuf with
| '{' ->
let _ = wait_balance (read_long_string 0) lexbuf in
skip_comment lexbuf
| '\'' ->
let _ = wait_balance read_quoted_string lexbuf in
skip_comment lexbuf
| '"' ->
let _ = wait_balance read_dquoted_string lexbuf in
skip_comment lexbuf
| eol ->
(* Ugly hack used in order to put the eol in the front of the next
parsing. *)
Sedlexing.rollback lexbuf;
COMMENT
| any -> skip_comment lexbuf
| _ -> raise Not_found
(** Main lexer *)
let rec token : (module Encoding.S) -> Sedlexing.lexbuf -> token =
fun (module E : Encoding) lexbuf ->
match%sedlex lexbuf with
| 0Xfeff ->
(* Ignore the BOM *)
token (module E) lexbuf
| '#', Star space, location ->
let ident = E.lexeme lexbuf in
LOCATION_START ident
| Plus digit -> INTEGER (E.lexeme lexbuf)
| '+' -> PLUS
| '-' -> MINUS
| "+=" -> INCR
| "-=" -> DECR
| "*=" -> MULT_EQUAL
| '/' -> DIV
| '*' -> STAR
| ':' ->
(* We are leaving the block, the comment will be handled again *)
decr_level lexbuf;
COLUMN
| '-', Plus '-', Star (Sub (any, ('\r' | '\n'))) -> LOCATION_END
| '[' -> L_BRACKET
| ']' -> R_BRACKET
| '(' ->
incr_level lexbuf;
L_PAREN
| ')' ->
decr_level lexbuf;
R_PAREN
| '<' -> LT
| '>' -> GT
| coma -> COMA
| eof ->
Bucket.remove is_expression lexbuf;
EOF
| '=' ->
incr_level lexbuf;
EQUAL
| ident -> build_ident lexbuf
| eol ->
Bucket.add is_expression lexbuf 0;
Sedlexing.new_line lexbuf;
EOL
| '&' ->
Bucket.add is_expression lexbuf 0;
AMPERSAND
| '!' -> (
match Bucket.find is_expression lexbuf with
| Some i when i <> 0 -> EXCLAMATION
| _ -> skip_comment lexbuf)
| spaces -> token (module E) lexbuf
| '\'' -> LITERAL (wait_balance read_quoted_string lexbuf)
| '"' -> LITERAL (wait_balance read_dquoted_string lexbuf)
| '{' -> LITERAL (wait_balance (read_long_string 0) lexbuf)
| _ ->
let position = fst @@ Sedlexing.lexing_positions lexbuf in
let tok = E.lexeme lexbuf in
let msg =
Format.asprintf "Unexpected character %S at %a" tok pp_pos position
in
raise @@ LexError (position, msg)
(** Tokenizer for menhir *)
let lexer :
(module Encoding) ->
Sedlexing.lexbuf ->
unit ->
token * Lexing.position * Lexing.position =
fun (module E : Encoding.S) lexbuf ->
Sedlexing.with_tokenizer (token (module E)) lexbuf
|
