Module Gz
module Gz: sig .. end
Zlib interface
The module Gz redefines most of the I/O functions of
Pervasives to allow I/O on compressed files (using the
zlib library). It doesn't use zlib lower-level
functions, so there might be some way to write a more efficient
interface ; this one is however, very small (and didn't take much
time to write!).
Datatypes & exceptions
type
type
exception Error of string
When exception Error is raised, the channel is automatically closed.
val version : string
Output funcions
type
| |
Default |
| |
Filtered |
| |
Huffman_only |
val open_out : ?compression:int -> ?strategy:zstrategy -> string -> out_channel
open_out opens the given filename for writing.
compression : specifies the level of compression : 0
is no compression, 1 is fastest , 9 is best but slowest. The default
is a compromise (6, I think).
strategy : refer to the zlib manual (i.e the header
file zlib.h)
val setparams : out_channel -> compression:int -> strategy:zstrategy -> unit
setparams modifies the two parameters of an opened channel
These functions output substrings, strings, char or char value
(int argument). The external ones use the zlib
functions, the usual Caml ones are only wrappers around
those. output_string and write will correctly handle
null characters embedded in Caml strings. output_value uses
Marshal module.
val write : out_channel -> buf:string -> pos:int -> len:int -> unit
val output_string : out_channel -> string -> unit
val output_char : out_channel -> char -> unit
val output_byte : out_channel -> int -> unit
val output_newline : out_channel -> unit
val output_endline : out_channel -> string -> unit
val output_value : out_channel -> 'a -> unit
type
| |
Sync_flush |
| |
Full_flush |
| |
Finish_flush |
val flush : ?flush:flush -> out_channel -> unit
The flush function should be used with caution because it can
degrade compression.
flush : defaults to Sync_flush.
val seek_out : out_channel -> offset:int -> unit
seek_out set the position of the next write operation on the
channel. Only forward seeks are supported; seek_out then
compresses a sequence of zeroes up to the new starting position. It
Raises Invalid_argument if called with a negative offset.
val pos_out : out_channel -> int
val close_out : out_channel -> unit
close_out flushes all pending output if necessary, closes the
compressed file and deallocates all the (de)compression state. Any
subsequent use of the channel will raise an Error exception.
Input functions
val open_in : string -> in_channel
read reads characters from the stream and returns the number
of bytes actually read ; it does not raise End_of_file.
input_char and input_line should
appropriately raise End_of_file if necessary.
input_value uses Marshal module.
val read : in_channel -> buf:string -> pos:int -> len:int -> int
val input_char : in_channel -> char
val input_line : in_channel -> string
val input_value : in_channel -> 'a
val rewind : in_channel -> unit
val seek_in : in_channel -> offset:int -> unit
The seek_in function is emulated but can be extremely slow.
val pos_in : in_channel -> int
val close_in : in_channel -> unit
In-memory compression
These functions compress and uncompress from a string to another
string.
val compress : ?compression:int -> string -> pos:int -> len:int -> string
val uncompress : string -> pos:int -> len:int -> string