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module Uchar = struct
include Uchar
let rep: Uchar.t = of_int(0xFFFD)
end
module List = struct
include List
let rec find_opt p = function
| [] -> None
| x :: l -> if p x then Some x else find_opt p l
end
module Buffer = struct
include Buffer
let add_utf_8_uchar b u = match Uchar.to_int u with
| u when u < 0 -> assert false
| u when u <= 0x007F ->
Buffer.add_char b (Char.unsafe_chr u)
| u when u <= 0x07FF ->
Buffer.add_char b (Char.unsafe_chr (0xC0 lor (u lsr 6)));
Buffer.add_char b (Char.unsafe_chr (0x80 lor (u land 0x3F)))
| u when u <= 0xFFFF ->
Buffer.add_char b (Char.unsafe_chr (0xE0 lor (u lsr 12)));
Buffer.add_char b (Char.unsafe_chr (0x80 lor ((u lsr 6) land 0x3F)));
Buffer.add_char b (Char.unsafe_chr (0x80 lor (u land 0x3F)))
| u when u <= 0x10FFFF ->
Buffer.add_char b (Char.unsafe_chr (0xF0 lor (u lsr 18)));
Buffer.add_char b (Char.unsafe_chr (0x80 lor ((u lsr 12) land 0x3F)));
Buffer.add_char b (Char.unsafe_chr (0x80 lor ((u lsr 6) land 0x3F)));
Buffer.add_char b (Char.unsafe_chr (0x80 lor (u land 0x3F)))
| _ -> assert false
end