module BytesLabels:sig..end
Byte sequence operations.
A byte sequence is a mutable data structure that contains a fixed-length sequence of bytes. Each byte can be indexed in constant time for reading or writing.
Given a byte sequence s of length l, we can access each of the
   l bytes of s via its index in the sequence. Indexes start at
   0, and we will call an index valid in s if it falls within the
   range [0...l-1] (inclusive). A position is the point between two
   bytes or at the beginning or end of the sequence.  We call a
   position valid in s if it falls within the range [0...l]
   (inclusive). Note that the byte at index n is between positions
   n and n+1.
Two parameters start and len are said to designate a valid
   range of s if len >= 0 and start and start+len are valid
   positions in s.
Byte sequences can be modified in place, for instance via the set
   and blit functions described below.  See also strings (module
   String), which are almost the same data structure, but cannot be
   modified in place.
Bytes are represented by the OCaml type char.
The labeled version of this module can be used as described in the
   StdLabels module.
val length : bytes -> intReturn the length (number of bytes) of the argument.
val get : bytes -> int -> charget s n returns the byte at index n in argument s.
Invalid_argument if n is not a valid index in s.val set : bytes -> int -> char -> unitset s n c modifies s in place, replacing the byte at index n
    with c.
Invalid_argument if n is not a valid index in s.val create : int -> bytescreate n returns a new byte sequence of length n. The
    sequence is uninitialized and contains arbitrary bytes.
Invalid_argument if n < 0 or n > Sys.max_string_length.val make : int -> char -> bytesmake n c returns a new byte sequence of length n, filled with
    the byte c.
Invalid_argument if n < 0 or n > Sys.max_string_length.val init : int -> f:(int -> char) -> bytesinit n f returns a fresh byte sequence of length n,
    with character i initialized to the result of f i (in increasing
    index order).
Invalid_argument if n < 0 or n > Sys.max_string_length.val empty : bytesA byte sequence of size 0.
val copy : bytes -> bytesReturn a new byte sequence that contains the same bytes as the argument.
val of_string : string -> bytesReturn a new byte sequence that contains the same bytes as the given string.
val to_string : bytes -> stringReturn a new string that contains the same bytes as the given byte sequence.
val sub : bytes -> pos:int -> len:int -> bytessub s ~pos ~len returns a new byte sequence of length len,
    containing the subsequence of s that starts at position pos
    and has length len.
Invalid_argument if pos and len do not designate a
    valid range of s.val sub_string : bytes -> pos:int -> len:int -> stringSame as BytesLabels.sub but return a string instead of a byte sequence.
val extend : bytes -> left:int -> right:int -> bytesextend s ~left ~right returns a new byte sequence that contains
    the bytes of s, with left uninitialized bytes prepended and
    right uninitialized bytes appended to it. If left or right
    is negative, then bytes are removed (instead of appended) from
    the corresponding side of s.
Invalid_argument if the result length is negative or
    longer than Sys.max_string_length bytes.val fill : bytes -> pos:int -> len:int -> char -> unitfill s ~pos ~len c modifies s in place, replacing len
    characters with c, starting at pos.
Invalid_argument if pos and len do not designate a
    valid range of s.val blit : src:bytes -> src_pos:int -> dst:bytes -> dst_pos:int -> len:int -> unitblit ~src ~src_pos ~dst ~dst_pos ~len copies len bytes from sequence
    src, starting at index src_pos, to sequence dst, starting at
    index dst_pos. It works correctly even if src and dst are the
    same byte sequence, and the source and destination intervals
    overlap.
Invalid_argument if src_pos and len do not
    designate a valid range of src, or if dst_pos and len
    do not designate a valid range of dst.val blit_string : src:string -> src_pos:int -> dst:bytes -> dst_pos:int -> len:int -> unitblit ~src ~src_pos ~dst ~dst_pos ~len copies len bytes from string
    src, starting at index src_pos, to byte sequence dst,
    starting at index dst_pos.
Invalid_argument if src_pos and len do not
    designate a valid range of src, or if dst_pos and len
    do not designate a valid range of dst.val concat : sep:bytes -> bytes list -> bytesconcat ~sep sl concatenates the list of byte sequences sl,
    inserting the separator byte sequence sep between each, and
    returns the result as a new byte sequence.
Invalid_argument if the result is longer than
    Sys.max_string_length bytes.val cat : bytes -> bytes -> bytescat s1 s2 concatenates s1 and s2 and returns the result
    as a new byte sequence.
Invalid_argument if the result is longer than
    Sys.max_string_length bytes.val iter : f:(char -> unit) -> bytes -> unititer ~f s applies function f in turn to all the bytes of s.
    It is equivalent to f (get s 0); f (get s 1); ...; f (get s.
    (length s - 1)); ()
val iteri : f:(int -> char -> unit) -> bytes -> unitSame as BytesLabels.iter, but the function is applied to the index of
    the byte as first argument and the byte itself as second
    argument.
val map : f:(char -> char) -> bytes -> bytesmap ~f s applies function f in turn to all the bytes of s (in
    increasing index order) and stores the resulting bytes in a new sequence
    that is returned as the result.
val mapi : f:(int -> char -> char) -> bytes -> bytesmapi ~f s calls f with each character of s and its
    index (in increasing index order) and stores the resulting bytes
    in a new sequence that is returned as the result.
val fold_left : f:('a -> char -> 'a) -> init:'a -> bytes -> 'afold_left f x s computes
    f (... (f (f x (get s 0)) (get s 1)) ...) (get s (n-1)),
    where n is the length of s.
val fold_right : f:(char -> 'a -> 'a) -> bytes -> init:'a -> 'afold_right f s x computes
    f (get s 0) (f (get s 1) ( ... (f (get s (n-1)) x) ...)),
    where n is the length of s.
val for_all : f:(char -> bool) -> bytes -> boolfor_all p s checks if all characters in s satisfy the predicate p.
val exists : f:(char -> bool) -> bytes -> boolexists p s checks if at least one character of s satisfies the predicate
    p.
val trim : bytes -> bytesReturn a copy of the argument, without leading and trailing
    whitespace. The bytes regarded as whitespace are the ASCII
    characters ' ', '\012', '\n', '\r', and '\t'.
val escaped : bytes -> bytesReturn a copy of the argument, with special characters represented by escape sequences, following the lexical conventions of OCaml. All characters outside the ASCII printable range (32..126) are escaped, as well as backslash and double-quote.
Invalid_argument if the result is longer than
    Sys.max_string_length bytes.val index : bytes -> char -> intindex s c returns the index of the first occurrence of byte c
    in s.
Not_found if c does not occur in s.val index_opt : bytes -> char -> int optionindex_opt s c returns the index of the first occurrence of byte c
    in s or None if c does not occur in s.
val rindex : bytes -> char -> intrindex s c returns the index of the last occurrence of byte c
    in s.
Not_found if c does not occur in s.val rindex_opt : bytes -> char -> int optionrindex_opt s c returns the index of the last occurrence of byte c
    in s or None if c does not occur in s.
val index_from : bytes -> int -> char -> intindex_from s i c returns the index of the first occurrence of
    byte c in s after position i.  index s c is
    equivalent to index_from s 0 c.
Invalid_argument if i is not a valid position in s.Not_found if c does not occur in s after position i.val index_from_opt : bytes -> int -> char -> int optionindex_from_opt s i c returns the index of the first occurrence of
    byte c in s after position i or None if c does not occur in s
    after position i.
    index_opt s c is equivalent to index_from_opt s 0 c.
Invalid_argument if i is not a valid position in s.val rindex_from : bytes -> int -> char -> intrindex_from s i c returns the index of the last occurrence of
    byte c in s before position i+1.  rindex s c is equivalent
    to rindex_from s (length s - 1) c.
Invalid_argument if i+1 is not a valid position in s.Not_found if c does not occur in s before position i+1.val rindex_from_opt : bytes -> int -> char -> int optionrindex_from_opt s i c returns the index of the last occurrence
    of byte c in s before position i+1 or None if c does not
    occur in s before position i+1.  rindex_opt s c is equivalent to
    rindex_from s (length s - 1) c.
Invalid_argument if i+1 is not a valid position in s.val contains : bytes -> char -> boolcontains s c tests if byte c appears in s.
val contains_from : bytes -> int -> char -> boolcontains_from s start c tests if byte c appears in s after
    position start.  contains s c is equivalent to contains_from.
    s 0 c
Invalid_argument if start is not a valid position in s.val rcontains_from : bytes -> int -> char -> boolrcontains_from s stop c tests if byte c appears in s before
    position stop+1.
Invalid_argument if stop < 0 or stop+1 is not a valid
    position in s.val uppercase : bytes -> bytesReturn a copy of the argument, with all lowercase letters translated to uppercase, including accented letters of the ISO Latin-1 (8859-1) character set.
val lowercase : bytes -> bytesReturn a copy of the argument, with all uppercase letters translated to lowercase, including accented letters of the ISO Latin-1 (8859-1) character set.
val capitalize : bytes -> bytesReturn a copy of the argument, with the first character set to uppercase, using the ISO Latin-1 (8859-1) character set.
val uncapitalize : bytes -> bytesReturn a copy of the argument, with the first character set to lowercase, using the ISO Latin-1 (8859-1) character set.
val uppercase_ascii : bytes -> bytesReturn a copy of the argument, with all lowercase letters translated to uppercase, using the US-ASCII character set.
val lowercase_ascii : bytes -> bytesReturn a copy of the argument, with all uppercase letters translated to lowercase, using the US-ASCII character set.
val capitalize_ascii : bytes -> bytesReturn a copy of the argument, with the first character set to uppercase, using the US-ASCII character set.
val uncapitalize_ascii : bytes -> bytesReturn a copy of the argument, with the first character set to lowercase, using the US-ASCII character set.
typet =bytes
An alias for the type of byte sequences.
val compare : t -> t -> intval equal : t -> t -> boolThe equality function for byte sequences.
val starts_with : prefix:bytes -> bytes -> boolstarts_with ~prefix s is true if and only if s starts with
    prefix.
val ends_with : suffix:bytes -> bytes -> boolends_with suffix s is true if and only if s ends with suffix.
This section describes unsafe, low-level conversion functions
    between bytes and string. They do not copy the internal data;
    used improperly, they can break the immutability invariant on
    strings provided by the -safe-string option. They are available for
    expert library authors, but for most purposes you should use the
    always-correct BytesLabels.to_string and BytesLabels.of_string instead.
val unsafe_to_string : bytes -> stringUnsafely convert a byte sequence into a string.
To reason about the use of unsafe_to_string, it is convenient to
    consider an "ownership" discipline. A piece of code that
    manipulates some data "owns" it; there are several disjoint ownership
    modes, including:
Unique ownership is linear: passing the data to another piece of code means giving up ownership (we cannot write the data again). A unique owner may decide to make the data shared (giving up mutation rights on it), but shared data may not become uniquely-owned again.
unsafe_to_string s can only be used when the caller owns the byte
   sequence s -- either uniquely or as shared immutable data. The
   caller gives up ownership of s, and gains ownership of the
   returned string.
There are two valid use-cases that respect this ownership discipline:
1. Creating a string by initializing and mutating a byte sequence that is never changed after initialization is performed.
let string_init len f : string =
  let s = Bytes.create len in
  for i = 0 to len - 1 do Bytes.set s i (f i) done;
  Bytes.unsafe_to_string s
   This function is safe because the byte sequence s will never be
   accessed or mutated after unsafe_to_string is called. The
   string_init code gives up ownership of s, and returns the
   ownership of the resulting string to its caller.
Note that it would be unsafe if s was passed as an additional
   parameter to the function f as it could escape this way and be
   mutated in the future -- string_init would give up ownership of
   s to pass it to f, and could not call unsafe_to_string
   safely.
We have provided the String.init, String.map and
   String.mapi functions to cover most cases of building
   new strings. You should prefer those over to_string or
   unsafe_to_string whenever applicable.
2. Temporarily giving ownership of a byte sequence to a function that expects a uniquely owned string and returns ownership back, so that we can mutate the sequence again after the call ended.
let bytes_length (s : bytes) =
  String.length (Bytes.unsafe_to_string s)
   In this use-case, we do not promise that s will never be mutated
   after the call to bytes_length s. The String.length function
   temporarily borrows unique ownership of the byte sequence
   (and sees it as a string), but returns this ownership back to
   the caller, which may assume that s is still a valid byte
   sequence after the call. Note that this is only correct because we
   know that String.length does not capture its argument -- it could
   escape by a side-channel such as a memoization combinator.
The caller may not mutate s while the string is borrowed (it has
   temporarily given up ownership). This affects concurrent programs,
   but also higher-order functions: if String.length returned
   a closure to be called later, s should not be mutated until this
   closure is fully applied and returns ownership.
val unsafe_of_string : string -> bytesUnsafely convert a shared string to a byte sequence that should not be mutated.
The same ownership discipline that makes unsafe_to_string
    correct applies to unsafe_of_string: you may use it if you were
    the owner of the string value, and you will own the return
    bytes in the same mode.
In practice, unique ownership of string values is extremely difficult to reason about correctly. You should always assume strings are shared, never uniquely owned.
For example, string literals are implicitly shared by the compiler, so you never uniquely own them.
let incorrect = Bytes.unsafe_of_string "hello"
let s = Bytes.of_string "hello"
    The first declaration is incorrect, because the string literal
    "hello" could be shared by the compiler with other parts of the
    program, and mutating incorrect is a bug. You must always use
    the second version, which performs a copy and is thus correct.
Assuming unique ownership of strings that are not string
    literals, but are (partly) built from string literals, is also
    incorrect. For example, mutating unsafe_of_string ("foo" ^ s)
    could mutate the shared string "foo" -- assuming a rope-like
    representation of strings. More generally, functions operating on
    strings will assume shared ownership, they do not preserve unique
    ownership. It is thus incorrect to assume unique ownership of the
    result of unsafe_of_string.
The only case we have reasonable confidence is safe is if the
    produced bytes is shared -- used as an immutable byte
    sequence. This is possibly useful for incremental migration of
    low-level programs that manipulate immutable sequences of bytes
    (for example Marshal.from_bytes) and previously used the
    string type for this purpose.
val split_on_char : sep:char -> bytes -> bytes listsplit_on_char sep s returns the list of all (possibly empty)
    subsequences of s that are delimited by the sep character.
The function's output is specified by the following invariants:
sep as a separator returns a
      byte sequence equal to the input (Bytes.concat (Bytes.make 1 sep)
      (Bytes.split_on_char sep s) = s).sep character.val to_seq : t -> char Seq.tIterate on the string, in increasing index order. Modifications of the string during iteration will be reflected in the sequence.
val to_seqi : t -> (int * char) Seq.tIterate on the string, in increasing order, yielding indices along chars
val of_seq : char Seq.t -> tCreate a string from the generator
The functions in this section binary encode and decode integers to and from byte sequences.
All following functions raise Invalid_argument if the space
    needed at index i to decode or encode the integer is not
    available.
Little-endian (resp. big-endian) encoding means that least
    (resp. most) significant bytes are stored first.  Big-endian is
    also known as network byte order.  Native-endian encoding is
    either little-endian or big-endian depending on Sys.big_endian.
32-bit and 64-bit integers are represented by the int32 and
    int64 types, which can be interpreted either as signed or
    unsigned numbers.
8-bit and 16-bit integers are represented by the int type,
    which has more bits than the binary encoding.  These extra bits
    are handled as follows:
int values sign-extend
    (resp. zero-extend) their result.int values truncate their input to their least significant
    bytes.val get_uint8 : bytes -> int -> intget_uint8 b i is b's unsigned 8-bit integer starting at byte index i.
val get_int8 : bytes -> int -> intget_int8 b i is b's signed 8-bit integer starting at byte index i.
val get_uint16_ne : bytes -> int -> intget_uint16_ne b i is b's native-endian unsigned 16-bit integer
    starting at byte index i.
val get_uint16_be : bytes -> int -> intget_uint16_be b i is b's big-endian unsigned 16-bit integer
    starting at byte index i.
val get_uint16_le : bytes -> int -> intget_uint16_le b i is b's little-endian unsigned 16-bit integer
    starting at byte index i.
val get_int16_ne : bytes -> int -> intget_int16_ne b i is b's native-endian signed 16-bit integer
    starting at byte index i.
val get_int16_be : bytes -> int -> intget_int16_be b i is b's big-endian signed 16-bit integer
    starting at byte index i.
val get_int16_le : bytes -> int -> intget_int16_le b i is b's little-endian signed 16-bit integer
    starting at byte index i.
val get_int32_ne : bytes -> int -> int32get_int32_ne b i is b's native-endian 32-bit integer
    starting at byte index i.
val get_int32_be : bytes -> int -> int32get_int32_be b i is b's big-endian 32-bit integer
    starting at byte index i.
val get_int32_le : bytes -> int -> int32get_int32_le b i is b's little-endian 32-bit integer
    starting at byte index i.
val get_int64_ne : bytes -> int -> int64get_int64_ne b i is b's native-endian 64-bit integer
    starting at byte index i.
val get_int64_be : bytes -> int -> int64get_int64_be b i is b's big-endian 64-bit integer
    starting at byte index i.
val get_int64_le : bytes -> int -> int64get_int64_le b i is b's little-endian 64-bit integer
    starting at byte index i.
val set_uint8 : bytes -> int -> int -> unitset_uint8 b i v sets b's unsigned 8-bit integer starting at byte index
    i to v.
val set_int8 : bytes -> int -> int -> unitset_int8 b i v sets b's signed 8-bit integer starting at byte index
    i to v.
val set_uint16_ne : bytes -> int -> int -> unitset_uint16_ne b i v sets b's native-endian unsigned 16-bit integer
    starting at byte index i to v.
val set_uint16_be : bytes -> int -> int -> unitset_uint16_be b i v sets b's big-endian unsigned 16-bit integer
    starting at byte index i to v.
val set_uint16_le : bytes -> int -> int -> unitset_uint16_le b i v sets b's little-endian unsigned 16-bit integer
    starting at byte index i to v.
val set_int16_ne : bytes -> int -> int -> unitset_int16_ne b i v sets b's native-endian signed 16-bit integer
    starting at byte index i to v.
val set_int16_be : bytes -> int -> int -> unitset_int16_be b i v sets b's big-endian signed 16-bit integer
    starting at byte index i to v.
val set_int16_le : bytes -> int -> int -> unitset_int16_le b i v sets b's little-endian signed 16-bit integer
    starting at byte index i to v.
val set_int32_ne : bytes -> int -> int32 -> unitset_int32_ne b i v sets b's native-endian 32-bit integer
    starting at byte index i to v.
val set_int32_be : bytes -> int -> int32 -> unitset_int32_be b i v sets b's big-endian 32-bit integer
    starting at byte index i to v.
val set_int32_le : bytes -> int -> int32 -> unitset_int32_le b i v sets b's little-endian 32-bit integer
    starting at byte index i to v.
val set_int64_ne : bytes -> int -> int64 -> unitset_int64_ne b i v sets b's native-endian 64-bit integer
    starting at byte index i to v.
val set_int64_be : bytes -> int -> int64 -> unitset_int64_be b i v sets b's big-endian 64-bit integer
    starting at byte index i to v.
val set_int64_le : bytes -> int -> int64 -> unitset_int64_le b i v sets b's little-endian 64-bit integer
    starting at byte index i to v.