path: root/src/lib/sedlexing.ml

(* The package sedlex is released under the terms of an MIT-like license. *)
(* See the attached LICENSE file.                                         *)
(* Copyright 2005, 2013 by Alain Frisch and LexiFi.                       *)

exception InvalidCodepoint of int
exception MalFormed

let gen_of_channel chan =
  let f () = try Some (input_char chan) with End_of_file -> None in
  f

let ( >>= ) o f = match o with Some x -> f x | None -> None

(* Absolute position from the beginning of the stream *)
type apos = int

type lexbuf = {
  refill : Uchar.t array -> int -> int -> int;
  mutable buf : Uchar.t array;
  mutable len : int;
  (* Number of meaningful char in buffer *)
  mutable offset : apos;
  (* Position of the first char in buffer
      in the input stream *)
  mutable pos : int;
  (* pos is the index in the buffer *)
  mutable curr_bol : int;
  (* bol is the index in the input stream but not buffer *)
  mutable curr_line : int;
  (* start from 1, if it is 0, we would not track postion info for you *)
  mutable start_pos : int;
  (* First char we need to keep visible *)
  mutable start_bol : int;
  mutable start_line : int;
  mutable marked_pos : int;
  mutable marked_bol : int;
  mutable marked_line : int;
  mutable marked_val : int;
  mutable filename : string;
  mutable finished : bool;
}

let chunk_size = 512

let empty_lexbuf =
  {
    refill = (fun _ _ _ -> assert false);
    buf = [||];
    len = 0;
    offset = 0;
    pos = 0;
    curr_bol = 0;
    curr_line = 0;
    start_pos = 0;
    start_bol = 0;
    start_line = 0;
    marked_pos = 0;
    marked_bol = 0;
    marked_line = 0;
    marked_val = 0;
    filename = "";
    finished = false;
  }

let create f =
  {
    empty_lexbuf with
    refill = f;
    buf = Array.make chunk_size (Uchar.of_int 0);
    curr_line = 1;
  }

let set_position lexbuf position =
  lexbuf.offset <- position.Lexing.pos_cnum - lexbuf.pos;
  lexbuf.curr_bol <- position.Lexing.pos_bol;
  lexbuf.curr_line <- position.Lexing.pos_lnum

let set_filename lexbuf fname = lexbuf.filename <- fname

let fill_buf_from_gen f gen buf pos len =
  let rec aux i =
    if i >= len then len
    else (
      match gen () with
        | Some c ->
            buf.(pos + i) <- f c;
            aux (i + 1)
        | None -> i)
  in
  aux 0

let from_gen s = create (fill_buf_from_gen (fun id -> id) s)

let from_int_array a =
  let len = Array.length a in
  {
    empty_lexbuf with
    buf = Array.init len (fun i -> Uchar.of_int a.(i));
    len;
    finished = true;
  }

let from_uchar_array a =
  let len = Array.length a in
  {
    empty_lexbuf with
    buf = Array.init len (fun i -> a.(i));
    len;
    finished = true;
  }

let refill lexbuf =
  if lexbuf.len + chunk_size > Array.length lexbuf.buf then begin
    let s = lexbuf.start_pos in
    let ls = lexbuf.len - s in
    if ls + chunk_size <= Array.length lexbuf.buf then
      Array.blit lexbuf.buf s lexbuf.buf 0 ls
    else begin
      let newlen = (Array.length lexbuf.buf + chunk_size) * 2 in
      let newbuf = Array.make newlen (Uchar.of_int 0) in
      Array.blit lexbuf.buf s newbuf 0 ls;
      lexbuf.buf <- newbuf
    end;
    lexbuf.len <- ls;
    lexbuf.offset <- lexbuf.offset + s;
    lexbuf.pos <- lexbuf.pos - s;
    lexbuf.marked_pos <- lexbuf.marked_pos - s;
    lexbuf.start_pos <- 0
  end;
  let n = lexbuf.refill lexbuf.buf lexbuf.pos chunk_size in
  if n = 0 then lexbuf.finished <- true else lexbuf.len <- lexbuf.len + n

let new_line lexbuf =
  if lexbuf.curr_line != 0 then lexbuf.curr_line <- lexbuf.curr_line + 1;
  lexbuf.curr_bol <- lexbuf.pos + lexbuf.offset

let next lexbuf =
  if (not lexbuf.finished) && lexbuf.pos = lexbuf.len then refill lexbuf;
  if lexbuf.finished && lexbuf.pos = lexbuf.len then None
  else begin
    let ret = lexbuf.buf.(lexbuf.pos) in
    lexbuf.pos <- lexbuf.pos + 1;
    if ret = Uchar.of_int 10 then new_line lexbuf;
    Some ret
  end

let __private__next_int lexbuf : int =
  if (not lexbuf.finished) && lexbuf.pos = lexbuf.len then refill lexbuf;
  if lexbuf.finished && lexbuf.pos = lexbuf.len then -1
  else begin
    let ret = lexbuf.buf.(lexbuf.pos) in
    lexbuf.pos <- lexbuf.pos + 1;
    if ret = Uchar.of_int 10 then new_line lexbuf;
    Uchar.to_int ret
  end

let mark lexbuf i =
  lexbuf.marked_pos <- lexbuf.pos;
  lexbuf.marked_bol <- lexbuf.curr_bol;
  lexbuf.marked_line <- lexbuf.curr_line;
  lexbuf.marked_val <- i

let start lexbuf =
  lexbuf.start_pos <- lexbuf.pos;
  lexbuf.start_bol <- lexbuf.curr_bol;
  lexbuf.start_line <- lexbuf.curr_line;
  mark lexbuf (-1)

let backtrack lexbuf =
  lexbuf.pos <- lexbuf.marked_pos;
  lexbuf.curr_bol <- lexbuf.marked_bol;
  lexbuf.curr_line <- lexbuf.marked_line;
  lexbuf.marked_val

let rollback lexbuf =
  lexbuf.pos <- lexbuf.start_pos;
  lexbuf.curr_bol <- lexbuf.start_bol;
  lexbuf.curr_line <- lexbuf.start_line

let lexeme_start lexbuf = lexbuf.start_pos + lexbuf.offset
let lexeme_end lexbuf = lexbuf.pos + lexbuf.offset
let loc lexbuf = (lexbuf.start_pos + lexbuf.offset, lexbuf.pos + lexbuf.offset)
let lexeme_length lexbuf = lexbuf.pos - lexbuf.start_pos

let sub_lexeme lexbuf pos len =
  Array.sub lexbuf.buf (lexbuf.start_pos + pos) len

let lexeme lexbuf =
  Array.sub lexbuf.buf lexbuf.start_pos (lexbuf.pos - lexbuf.start_pos)

let lexeme_char lexbuf pos = lexbuf.buf.(lexbuf.start_pos + pos)

let lexing_positions lexbuf =
  let start_p =
    {
      Lexing.pos_fname = lexbuf.filename;
      pos_lnum = lexbuf.start_line;
      pos_cnum = lexbuf.start_pos + lexbuf.offset;
      pos_bol = lexbuf.start_bol;
    }
  and curr_p =
    {
      Lexing.pos_fname = lexbuf.filename;
      pos_lnum = lexbuf.curr_line;
      pos_cnum = lexbuf.pos + lexbuf.offset;
      pos_bol = lexbuf.curr_bol;
    }
  in
  (start_p, curr_p)

let with_tokenizer lexer' lexbuf =
  let lexer () =
    let token = lexer' lexbuf in
    let start_p, curr_p = lexing_positions lexbuf in
    (token, start_p, curr_p)
  in
  lexer

module Latin1 = struct
  let from_gen s = create (fill_buf_from_gen Uchar.of_char s)

  let from_string s =
    let len = String.length s in
    {
      empty_lexbuf with
      buf = Array.init len (fun i -> Uchar.of_char s.[i]);
      len;
      finished = true;
    }

  let from_channel ic = from_gen (gen_of_channel ic)

  let to_latin1 c =
    if Uchar.is_char c then Uchar.to_char c
    else raise (InvalidCodepoint (Uchar.to_int c))

  let lexeme_char lexbuf pos = to_latin1 (lexeme_char lexbuf pos)

  let sub_lexeme lexbuf pos len =
    let s = Bytes.create len in
    for i = 0 to len - 1 do
      Bytes.set s i (to_latin1 lexbuf.buf.(lexbuf.start_pos + pos + i))
    done;
    Bytes.to_string s

  let lexeme lexbuf = sub_lexeme lexbuf 0 (lexbuf.pos - lexbuf.start_pos)
end

module Utf8 = struct
  module Helper = struct
    (* http://www.faqs.org/rfcs/rfc3629.html *)

    let width = Array.make 256 (-1)

    let () =
      for i = 0 to 127 do
        width.(i) <- 1
      done;
      for i = 192 to 223 do
        width.(i) <- 2
      done;
      for i = 224 to 239 do
        width.(i) <- 3
      done;
      for i = 240 to 247 do
        width.(i) <- 4
      done

    let next s i =
      match s.[i] with
        | '\000' .. '\127' as c -> Char.code c
        | '\192' .. '\223' as c ->
            let n1 = Char.code c in
            let n2 = Char.code s.[i + 1] in
            if n2 lsr 6 != 0b10 then raise MalFormed;
            ((n1 land 0x1f) lsl 6) lor (n2 land 0x3f)
        | '\224' .. '\239' as c ->
            let n1 = Char.code c in
            let n2 = Char.code s.[i + 1] in
            let n3 = Char.code s.[i + 2] in
            if n2 lsr 6 != 0b10 || n3 lsr 6 != 0b10 then raise MalFormed;
            let p =
              ((n1 land 0x0f) lsl 12)
              lor ((n2 land 0x3f) lsl 6)
              lor (n3 land 0x3f)
            in
            if p >= 0xd800 && p <= 0xdf00 then raise MalFormed;
            p
        | '\240' .. '\247' as c ->
            let n1 = Char.code c in
            let n2 = Char.code s.[i + 1] in
            let n3 = Char.code s.[i + 2] in
            let n4 = Char.code s.[i + 3] in
            if n2 lsr 6 != 0b10 || n3 lsr 6 != 0b10 || n4 lsr 6 != 0b10 then
              raise MalFormed;
            ((n1 land 0x07) lsl 18)
            lor ((n2 land 0x3f) lsl 12)
            lor ((n3 land 0x3f) lsl 6)
            lor (n4 land 0x3f)
        | _ -> raise MalFormed

    let from_gen s =
      Gen.next s >>= function
      | '\000' .. '\127' as c -> Some (Uchar.of_char c)
      | '\192' .. '\223' as c ->
          let n1 = Char.code c in
          Gen.next s >>= fun c2 ->
          let n2 = Char.code c2 in
          if n2 lsr 6 != 0b10 then raise MalFormed;
          Some (Uchar.of_int (((n1 land 0x1f) lsl 6) lor (n2 land 0x3f)))
      | '\224' .. '\239' as c ->
          let n1 = Char.code c in
          Gen.next s >>= fun c2 ->
          let n2 = Char.code c2 in
          Gen.next s >>= fun c3 ->
          let n3 = Char.code c3 in
          if n2 lsr 6 != 0b10 || n3 lsr 6 != 0b10 then raise MalFormed;
          Some
            (Uchar.of_int
               (((n1 land 0x0f) lsl 12)
               lor ((n2 land 0x3f) lsl 6)
               lor (n3 land 0x3f)))
      | '\240' .. '\247' as c ->
          let n1 = Char.code c in
          Gen.next s >>= fun c2 ->
          let n2 = Char.code c2 in
          Gen.next s >>= fun c3 ->
          let n3 = Char.code c3 in
          Gen.next s >>= fun c4 ->
          let n4 = Char.code c4 in
          if n2 lsr 6 != 0b10 || n3 lsr 6 != 0b10 || n4 lsr 6 != 0b10 then
            raise MalFormed;
          Some
            (Uchar.of_int
               (((n1 land 0x07) lsl 18)
               lor ((n2 land 0x3f) lsl 12)
               lor ((n3 land 0x3f) lsl 6)
               lor (n4 land 0x3f)))
      | _ -> raise MalFormed

    let compute_len s pos bytes =
      let rec aux n i =
        if i >= pos + bytes then if i = pos + bytes then n else raise MalFormed
        else (
          let w = width.(Char.code s.[i]) in
          if w > 0 then aux (succ n) (i + w) else raise MalFormed)
      in
      aux 0 pos

    let rec blit_to_int s spos a apos n =
      if n > 0 then begin
        a.(apos) <- next s spos;
        blit_to_int s (spos + width.(Char.code s.[spos])) a (succ apos) (pred n)
      end

    let to_int_array s pos bytes =
      let n = compute_len s pos bytes in
      let a = Array.make n 0 in
      blit_to_int s pos a 0 n;
      a

    (**************************)

    let store b p =
      if p <= 0x7f then Buffer.add_char b (Char.chr p)
      else if p <= 0x7ff then (
        Buffer.add_char b (Char.chr (0xc0 lor (p lsr 6)));
        Buffer.add_char b (Char.chr (0x80 lor (p land 0x3f))))
      else if p <= 0xffff then (
        if p >= 0xd800 && p < 0xe000 then raise MalFormed;
        Buffer.add_char b (Char.chr (0xe0 lor (p lsr 12)));
        Buffer.add_char b (Char.chr (0x80 lor ((p lsr 6) land 0x3f)));
        Buffer.add_char b (Char.chr (0x80 lor (p land 0x3f))))
      else if p <= 0x10ffff then (
        Buffer.add_char b (Char.chr (0xf0 lor (p lsr 18)));
        Buffer.add_char b (Char.chr (0x80 lor ((p lsr 12) land 0x3f)));
        Buffer.add_char b (Char.chr (0x80 lor ((p lsr 6) land 0x3f)));
        Buffer.add_char b (Char.chr (0x80 lor (p land 0x3f))))
      else raise MalFormed

    let from_uchar_array a apos len =
      let b = Buffer.create (len * 4) in
      let rec aux apos len =
        if len > 0 then (
          store b (Uchar.to_int a.(apos));
          aux (succ apos) (pred len))
        else Buffer.contents b
      in
      aux apos len

    let gen_from_char_gen s () = from_gen s
  end

  let from_channel ic = from_gen (Helper.gen_from_char_gen (gen_of_channel ic))

  let from_gen s =
    create (fill_buf_from_gen (fun id -> id) (Helper.gen_from_char_gen s))

  let from_string s = from_int_array (Helper.to_int_array s 0 (String.length s))

  let sub_lexeme lexbuf pos len =
    Helper.from_uchar_array lexbuf.buf (lexbuf.start_pos + pos) len

  let lexeme lexbuf = sub_lexeme lexbuf 0 (lexbuf.pos - lexbuf.start_pos)
end

module Utf16 = struct
  type byte_order = Little_endian | Big_endian

  module Helper = struct
    (* http://www.ietf.org/rfc/rfc2781.txt *)

    let number_of_char_pair bo c1 c2 =
      match bo with
        | Little_endian -> (Char.code c2 lsl 8) + Char.code c1
        | Big_endian -> (Char.code c1 lsl 8) + Char.code c2

    let char_pair_of_number bo num =
      match bo with
        | Little_endian ->
            (Char.chr (num land 0xFF), Char.chr ((num lsr 8) land 0xFF))
        | Big_endian ->
            (Char.chr ((num lsr 8) land 0xFF), Char.chr (num land 0xFF))

    let next_in_gen bo s =
      Gen.next s >>= fun c1 ->
      Gen.next s >>= fun c2 -> Some (number_of_char_pair bo c1 c2)

    let from_gen bo s w1 =
      if w1 = 0xfffe then raise (InvalidCodepoint w1);
      if w1 < 0xd800 || 0xdfff < w1 then Some (Uchar.of_int w1)
      else if w1 <= 0xdbff then (
        next_in_gen bo s >>= fun w2 ->
        if w2 < 0xdc00 || w2 > 0xdfff then raise MalFormed;
        let upper10 = (w1 land 0x3ff) lsl 10 and lower10 = w2 land 0x3ff in
        Some (Uchar.of_int (0x10000 + upper10 + lower10)))
      else raise MalFormed

    let gen_from_char_gen opt_bo s =
      let bo = ref opt_bo in
      fun () ->
        Gen.next s >>= fun c1 ->
        Gen.next s >>= fun c2 ->
        let o =
          match !bo with
            | Some o -> o
            | None ->
                let o =
                  match (Char.code c1, Char.code c2) with
                    | 0xff, 0xfe -> Little_endian
                    | _ -> Big_endian
                in
                bo := Some o;
                o
        in
        from_gen o s (number_of_char_pair o c1 c2)

    let compute_len opt_bo str pos bytes =
      let s =
        gen_from_char_gen opt_bo
          (Gen.init ~limit:(bytes - pos) (fun i -> str.[i + pos]))
      in
      let l = ref 0 in
      Gen.iter (fun _ -> incr l) s;
      !l

    let blit_to_int opt_bo s spos a apos bytes =
      let s =
        gen_from_char_gen opt_bo
          (Gen.init ~limit:(bytes - spos) (fun i -> s.[i + spos]))
      in
      let p = ref apos in
      Gen.iter
        (fun x ->
          a.(!p) <- x;
          incr p)
        s

    let to_uchar_array opt_bo s pos bytes =
      let len = compute_len opt_bo s pos bytes in
      let a = Array.make len (Uchar.of_int 0) in
      blit_to_int opt_bo s pos a 0 bytes;
      a

    let store bo buf code =
      if code < 0x10000 then (
        let c1, c2 = char_pair_of_number bo code in
        Buffer.add_char buf c1;
        Buffer.add_char buf c2)
      else (
        let u' = code - 0x10000 in
        let w1 = 0xd800 + (u' lsr 10) and w2 = 0xdc00 + (u' land 0x3ff) in
        let c1, c2 = char_pair_of_number bo w1
        and c3, c4 = char_pair_of_number bo w2 in
        Buffer.add_char buf c1;
        Buffer.add_char buf c2;
        Buffer.add_char buf c3;
        Buffer.add_char buf c4)

    let from_uchar_array bo a apos len bom =
      let b = Buffer.create ((len * 4) + 2) in
      (* +2 for the BOM *)
      if bom then store bo b 0xfeff;
      (* first, store the BOM *)
      let rec aux apos len =
        if len > 0 then (
          store bo b (Uchar.to_int a.(apos));
          aux (succ apos) (pred len))
        else Buffer.contents b
      in
      aux apos len
  end

  let from_gen s opt_bo = from_gen (Helper.gen_from_char_gen opt_bo s)
  let from_channel ic opt_bo = from_gen (gen_of_channel ic) opt_bo

  let from_string s opt_bo =
    let a = Helper.to_uchar_array opt_bo s 0 (String.length s) in
    from_uchar_array a

  let sub_lexeme lb pos len bo bom =
    Helper.from_uchar_array bo lb.buf (lb.start_pos + pos) len bom

  let lexeme lb bo bom = sub_lexeme lb 0 (lb.pos - lb.start_pos) bo bom
end