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|
(**
Lexer using sedlex
*)
open Tokens
exception UnclosedQuote
exception LexError of string
exception EOF
(* Extract the location name from the pattern *)
let location_name = Str.regexp {|.* \(.*\)|}
(** Try to read the identifier and check if this is a function, a keyword, or
just a variable.
See the tests [Syntax.Operator2] and [Syntax.Call Nl] for two cases. *)
let build_ident buffer =
let id = Lexbuf.content buffer |> String.uppercase_ascii in
try
let value = Hashtbl.find Idents.keyword_table id in
let _ =
match value with IF | ELIF -> Lexbuf.incr_level buffer | _ -> ()
in
value
with Not_found ->
(* If the identifier does not match a keyword and start with [*], then
try it as a '*' operator. *)
if Char.equal '*' id.[0] then (
Lexbuf.rollback buffer;
let lexbuf = Lexbuf.buffer buffer in
match%sedlex lexbuf with '*' -> STAR | _ -> IDENT id)
else IDENT id
let wait_balance : (Buffer.t -> Lexbuf.t -> 'a) -> Lexbuf.t -> 'a =
fun rule lexbuf ->
let _, position = Lexbuf.positions lexbuf in
Lexbuf.set_start_position lexbuf position;
try
let token = rule (Buffer.create 256) lexbuf in
token
with Not_found -> raise UnclosedQuote
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? Opt ('$' | '*'), letters, Star (digit | letters)]
let location_ident = [%sedlex.regexp? letters | digit]
let location_prefix = [%sedlex.regexp? '!' | '$' | '#' | '^']
let location = [%sedlex.regexp? Opt location_prefix, Plus location_ident]
let rec read_long_string level buf buffer =
let lexbuf = Lexbuf.buffer buffer in
match%sedlex lexbuf with
| '{' ->
Buffer.add_string buf (Sedlexing.Utf8.lexeme lexbuf);
read_long_string (level + 1) buf buffer
| '}' -> (
match level with
| 0 -> Buffer.contents buf
| _ ->
Buffer.add_string buf (Sedlexing.Utf8.lexeme lexbuf);
read_long_string (level - 1) buf buffer)
| eol ->
Buffer.add_string buf (Lexbuf.content buffer);
read_long_string level buf buffer
| any ->
Buffer.add_string buf (Lexbuf.content buffer);
read_long_string level buf buffer
| _ -> raise Not_found
let rec read_dquoted_string buf buffer =
let lexbuf = Lexbuf.buffer buffer in
match%sedlex lexbuf with
| "\"\"" ->
Buffer.add_char buf '"';
read_dquoted_string buf buffer
| '"' -> Buffer.contents buf
| any ->
Buffer.add_string buf (Sedlexing.Utf8.lexeme lexbuf);
read_dquoted_string buf buffer
| _ -> raise Not_found
let rec read_quoted_string buf buffer =
let lexbuf = Lexbuf.buffer buffer in
match%sedlex lexbuf with
| "''" ->
Buffer.add_char buf '\'';
read_quoted_string buf buffer
| '\'' -> Buffer.contents buf
| eol ->
Buffer.add_string buf (Lexbuf.content buffer);
read_quoted_string buf buffer
| any ->
Buffer.add_string buf (Lexbuf.content buffer);
read_quoted_string buf buffer
| _ -> raise Not_found
let rec skip_comment buffer =
let lexbuf = Lexbuf.buffer buffer in
match%sedlex lexbuf with
| '{' ->
let _ = wait_balance (read_long_string 0) buffer in
skip_comment buffer
| '\'' ->
let _ = wait_balance read_quoted_string buffer in
skip_comment buffer
| '"' ->
let _ = wait_balance read_dquoted_string buffer in
skip_comment buffer
| eol ->
(* Ugly hack used in order to put the eol in the front of the next
parsing. *)
Lexbuf.rollback buffer;
COMMENT
| any -> skip_comment buffer
| _ -> raise Not_found
(** Main lexer *)
let rec token : Lexbuf.t -> token =
fun buffer ->
let lexbuf = Lexbuf.buffer buffer in
match%sedlex lexbuf with
| 0Xfeff ->
(* Ignore the BOM *)
token buffer
| '#', Star space, location ->
(* Extract the location name *)
let ident = Lexbuf.content buffer in
let () =
match Str.string_match location_name ident 0 with
| false -> ()
| true -> Sedlexing.set_filename lexbuf (Str.matched_group 1 ident)
in
(* Restart the line number (new location here) *)
Lexbuf.start buffer;
LOCATION_START ident
| '-', Plus '-', Star (Sub (any, ('\r' | '\n'))) ->
Lexbuf.reset_level buffer;
LOCATION_END
| Plus digit -> INTEGER (Lexbuf.content buffer)
| '+' -> PLUS
| '-' -> MINUS
| "+=" -> INCR
| "-=" -> DECR
| "*=" -> MULT_EQUAL
| '/' -> DIV
| '*' -> STAR
| ':' ->
(* We are leaving the block, the comment will be handled again *)
Lexbuf.decr_level buffer;
COLUMN
| '[' -> L_BRACKET
| ']' -> R_BRACKET
| '(' ->
Lexbuf.incr_level buffer;
L_PAREN
| ')' ->
Lexbuf.decr_level buffer;
R_PAREN
| '<' -> LT
| '>' -> GT
| coma -> COMA
| '=' ->
Lexbuf.incr_level buffer;
EQUAL
| ident -> build_ident buffer
| eol ->
Lexbuf.reset_level buffer;
EOL
| '&' ->
Lexbuf.reset_level buffer;
AMPERSAND
| '!' -> if Lexbuf.level buffer > 0 then EXCLAMATION else skip_comment buffer
| spaces -> token buffer
| '\'' -> LITERAL (wait_balance read_quoted_string buffer)
| '"' -> LITERAL (wait_balance read_dquoted_string buffer)
| '{' -> LITERAL (wait_balance (read_long_string 0) buffer)
| eof -> raise EOF
| _ ->
let tok = Lexbuf.content buffer in
let msg = Format.asprintf "Unexpected character %S" tok in
raise @@ LexError msg
let rec discard buffer =
let lexbuf = Lexbuf.buffer buffer in
match%sedlex lexbuf with
| '\'' ->
ignore (wait_balance read_quoted_string buffer);
discard buffer
| '"' ->
ignore (wait_balance read_dquoted_string buffer);
discard buffer
| '{' ->
ignore (wait_balance (read_long_string 0) buffer);
discard buffer
| eof -> raise EOF
| '-', Plus '-', Star (Sub (any, ('\r' | '\n'))) ->
Lexbuf.reset_level buffer;
()
| '!' ->
ignore @@ skip_comment buffer;
discard buffer
| any -> discard buffer
| _ -> raise EOF
|
