Zlib::ZStream

        # Zlib::ZStream < Object

(from ruby core)
---
Zlib::ZStream is the abstract class for the stream which handles the
compressed data. The operations are defined in the subclasses:
Zlib::Deflate for compression, and Zlib::Inflate for decompression.

An instance of Zlib::ZStream has one stream (struct zstream in the
source) and two variable-length buffers which associated to the input
(next_in) of the stream and the output (next_out) of the stream. In this
document, "input buffer" means the buffer for input, and "output buffer"
means the buffer for output.

Data input into an instance of Zlib::ZStream are temporally stored into
the end of input buffer, and then data in input buffer are processed
from the beginning of the buffer until no more output from the stream is
produced (i.e. until avail_out > 0 after processing).  During
processing, output buffer is allocated and expanded automatically to
hold all output data.

Some particular instance methods consume the data in output buffer and
return them as a String.

Here is an ascii art for describing above:

    +================ an instance of Zlib::ZStream ================+
    ||                                                            ||
    ||     +--------+          +-------+          +--------+      ||
    ||  +--| output |<---------|zstream|<---------| input  |<--+  ||
    ||  |  | buffer |  next_out+-------+next_in   | buffer |   |  ||
    ||  |  +--------+                             +--------+   |  ||
    ||  |                                                      |  ||
    +===|======================================================|===+
        |                                                      |
        v                                                      |
    "output data"                                         "input data"

If an error occurs during processing input buffer, an exception which is
a subclass of Zlib::Error is raised.  At that time, both input and
output buffer keep their conditions at the time when the error occurs.

## Method Catalogue

Many of the methods in this class are fairly low-level and unlikely to
be of interest to users.  In fact, users are unlikely to use this class
directly; rather they will be interested in Zlib::Inflate and
Zlib::Deflate.

The higher level methods are listed below.

*   #total_in
*   #total_out
*   #data_type
*   #adler
*   #reset
*   #finish
*   #finished?
*   #close
*   #closed?

---
# Instance methods:

    adler
    avail_in
    avail_out
    avail_out=
    close
    closed?
    data_type
    end
    ended?
    finish
    finished?
    flush_next_in
    flush_next_out
    reset
    stream_end?
    total_in
    total_out