module Marshal: BatMarshal
typeextern_flags =
Stdlib.Marshal.extern_flags
=
| |
No_sharing |
(* | Don't preserve sharing | *) |
| |
Closures |
(* | Send function closures | *) |
| |
Compat_32 |
(* | Ensure 32-bit compatibility | *) |
The flags to the Marshal.to_*
functions below.
val output : 'b BatInnerIO.output -> ?sharing:bool -> ?closures:bool -> 'a -> unit
output out v
writes the representation of v
on chan
.
sharing
: If true
(default value), circularities
and sharing inside the value v
are detected and preserved
in the sequence of bytes produced. In particular, this
guarantees that marshaling always terminates. Sharing
between values marshaled by successive calls to
output
is not detected, though. If false
, sharing is ignored.
This results in faster marshaling if v
contains no shared
substructures, but may cause slower marshaling and larger
byte representations if v
actually contains sharing,
or even non-termination if v
contains cycles.closures
: If false
(default value) marshaling fails when
it encounters a functional value inside v
: only ``pure'' data
structures, containing neither functions nor objects, can safely
be transmitted between different programs. If true
, functional
values will be marshaled as a position in the code of the
program. In this case, the output of marshaling can only be read
back in processes that run exactly the same program, with
exactly the same compiled code. (This is checked at
un-marshaling time, using an MD5 digest of the code transmitted
along with the code position.)val to_bytes : 'a -> extern_flags list -> Stdlib.Bytes.t
Marshal.to_bytes v flags
returns a byte sequence containing
the representation of v
.
The flags
argument has the same meaning as for
Marshal.output
.
val to_string : 'a -> extern_flags list -> string
Same as to_bytes
but return the result as a string instead of
a byte sequence.
val to_buffer : Stdlib.Bytes.t -> int -> int -> 'a -> extern_flags list -> int
Marshal.to_buffer buff ofs len v flags
marshals the value v
,
storing its byte representation in the sequence buff
,
starting at index ofs
, and writing at most
len
bytes. It returns the number of bytes
actually written to the sequence. If the byte representation
of v
does not fit in len
characters, the exception Failure
is raised.
val input : BatInnerIO.input -> 'a
input inp
reads from inp
the
byte representation of a structured value, as produced by
one of the Marshal.to_*
functions, and reconstructs and
returns the corresponding value.
val from_bytes : Stdlib.Bytes.t -> int -> 'a
Marshal.from_bytes buff ofs
unmarshals a structured value
like Marshal.from_channel
does, except that the byte
representation is not read from a channel, but taken from
the byte sequence buff
, starting at position ofs
.
The byte sequence is not mutated.
val from_string : string -> int -> 'a
Same as from_bytes
but take a string as argument instead of a
byte sequence.
val header_size : int
The bytes representing a marshaled value are composed of
a fixed-size header and a variable-sized data part,
whose size can be determined from the header.
Marshal.header_size
is the size, in bytes, of the header.
Marshal.data_size
buff ofs
is the size, in bytes,
of the data part, assuming a valid header is stored in
buff
starting at position ofs
.
Finally, Marshal.total_size
buff ofs
is the total size,
in bytes, of the marshaled value.
Both Marshal.data_size
and Marshal.total_size
raise Failure
if buff
, ofs
does not contain a valid header.
To read the byte representation of a marshaled value into
a byte sequence, the program needs to read first
Marshal.header_size
bytes into the sequence,
then determine the length of the remainder of the
representation using Marshal.data_size
,
make sure the sequence is large enough to hold the remaining
data, then read it, and finally call Marshal.from_bytes
to unmarshal the value.
val data_size : Stdlib.Bytes.t -> int -> int
See Marshal.header_size
.
val total_size : Stdlib.Bytes.t -> int -> int
See Marshal.header_size
.
val to_channel : 'b BatInnerIO.output -> 'a -> extern_flags list -> unit
BatMarshal.output
insteadval from_channel : BatInnerIO.input -> 'a
BatMarshal.input
instead