Class: Zlib::ZStream

Inherits:
Object
  • Object
show all
Defined in:
ext/zlib/zlib.c,
ext/zlib/zlib.c

Overview

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?

Direct Known Subclasses

Deflate, Inflate

Instance Method Summary collapse

Instance Method Details

#adler ⇒ Object

Returns the adler-32 checksum.



1424
1425
1426
1427
1428
 
# File 'ext/zlib/zlib.c', line 1424

static VALUE
rb_zstream_adler(VALUE obj)
{
    return rb_uint2inum(get_zstream(obj)->stream.adler);
}

#avail_in ⇒ Object

Returns bytes of data in the input buffer. Normally, returns 0.



1384
1385
1386
1387
1388
1389
1390
 
# File 'ext/zlib/zlib.c', line 1384

static VALUE
rb_zstream_avail_in(VALUE obj)
{
    struct zstream *z;
    TypedData_Get_Struct(obj, struct zstream, &zstream_data_type, z);
    return INT2FIX(NIL_P(z->input) ? 0 : (int)(RSTRING_LEN(z->input)));
}

#avail_out ⇒ Object

Returns number of bytes of free spaces in output buffer. Because the free space is allocated automatically, this method returns 0 normally.



1358
1359
1360
1361
1362
1363
1364
 
# File 'ext/zlib/zlib.c', line 1358

static VALUE
rb_zstream_avail_out(VALUE obj)
{
    struct zstream *z;
    TypedData_Get_Struct(obj, struct zstream, &zstream_data_type, z);
    return rb_uint2inum(z->stream.avail_out);
}

#avail_out=(size) ⇒ Object

Allocates size bytes of free space in the output buffer. If there are more than size bytes already in the buffer, the buffer is truncated. Because free space is allocated automatically, you usually don’t need to use this method.



1372
1373
1374
1375
1376
1377
1378
1379
 
# File 'ext/zlib/zlib.c', line 1372

static VALUE
rb_zstream_set_avail_out(VALUE obj, VALUE size)
{
    struct zstream *z = get_zstream(obj);

    zstream_expand_buffer_into(z, FIX2INT(size));
    return size;
}

#close ⇒ Object

Closes the stream. All operations on the closed stream will raise an exception.



1282
1283
1284
1285
1286
1287
 
# File 'ext/zlib/zlib.c', line 1282

static VALUE
rb_zstream_end(VALUE obj)
{
    zstream_end(get_zstream(obj));
    return Qnil;
}

#closed? ⇒ Boolean

Returns true if the stream is closed.

Returns:

  • (Boolean) 


1442
1443
1444
1445
1446
1447
1448
 
# File 'ext/zlib/zlib.c', line 1442

static VALUE
rb_zstream_closed_p(VALUE obj)
{
    struct zstream *z;
    TypedData_Get_Struct(obj, struct zstream, &zstream_data_type, z);
    return ZSTREAM_IS_READY(z) ? Qfalse : Qtrue;
}

#data_type ⇒ Object

Guesses the type of the data which have been inputed into the stream. The returned value is either BINARY, ASCII, or UNKNOWN.



1415
1416
1417
1418
1419
 
# File 'ext/zlib/zlib.c', line 1415

static VALUE
rb_zstream_data_type(VALUE obj)
{
    return INT2FIX(get_zstream(obj)->stream.data_type);
}

#end ⇒ Object

Closes the stream. All operations on the closed stream will raise an exception.



1282
1283
1284
1285
1286
1287
 
# File 'ext/zlib/zlib.c', line 1282

static VALUE
rb_zstream_end(VALUE obj)
{
    zstream_end(get_zstream(obj));
    return Qnil;
}

#ended? ⇒ Boolean

Returns true if the stream is closed.

Returns:

  • (Boolean) 


1442
1443
1444
1445
1446
1447
1448
 
# File 'ext/zlib/zlib.c', line 1442

static VALUE
rb_zstream_closed_p(VALUE obj)
{
    struct zstream *z;
    TypedData_Get_Struct(obj, struct zstream, &zstream_data_type, z);
    return ZSTREAM_IS_READY(z) ? Qfalse : Qtrue;
}

#finish ⇒ String #finish {|chunk| ... } ⇒ nil

Finishes the stream and flushes output buffer. If a block is given each chunk is yielded to the block until the input buffer has been flushed to the output buffer.

Overloads:

  • #finish ⇒ String

    Returns:

    • (String)
  • #finish {|chunk| ... } ⇒ nil

    Yields:

    • (chunk)

    Returns:

    • (nil) 


1309
1310
1311
1312
1313
1314
1315
1316
1317
 
# File 'ext/zlib/zlib.c', line 1309

static VALUE
rb_zstream_finish(VALUE obj)
{
    struct zstream *z = get_zstream(obj);

    zstream_run(z, (Bytef*)"", 0, Z_FINISH);

    return zstream_detach_buffer(z);
}

#finished? ⇒ Boolean

Returns true if the stream is finished.

Returns:

  • (Boolean) 


1433
1434
1435
1436
1437
 
# File 'ext/zlib/zlib.c', line 1433

static VALUE
rb_zstream_finished_p(VALUE obj)
{
    return ZSTREAM_IS_FINISHED(get_zstream(obj)) ? Qtrue : Qfalse;
}

#flush_next_in ⇒ Object 



1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
 
# File 'ext/zlib/zlib.c', line 1324

static VALUE
rb_zstream_flush_next_in(VALUE obj)
{
    struct zstream *z;
    VALUE dst;

    TypedData_Get_Struct(obj, struct zstream, &zstream_data_type, z);
    dst = zstream_detach_input(z);
    return dst;
}

#flush_next_out ⇒ String #flush_next_out {|chunk| ... } ⇒ nil

Flushes output buffer and returns all data in that buffer. If a block is given each chunk is yielded to the block until the current output buffer has been flushed.

Overloads:

  • #flush_next_out ⇒ String

    Returns:

    • (String)
  • #flush_next_out {|chunk| ... } ⇒ nil

    Yields:

    • (chunk)

    Returns:

    • (nil) 


1344
1345
1346
1347
1348
1349
1350
1351
1352
 
# File 'ext/zlib/zlib.c', line 1344

static VALUE
rb_zstream_flush_next_out(VALUE obj)
{
    struct zstream *z;

    TypedData_Get_Struct(obj, struct zstream, &zstream_data_type, z);

    return zstream_detach_buffer(z);
}

#reset ⇒ Object

Resets and initializes the stream. All data in both input and output buffer are discarded.



1293
1294
1295
1296
1297
1298
 
# File 'ext/zlib/zlib.c', line 1293

static VALUE
rb_zstream_reset(VALUE obj)
{
    zstream_reset(get_zstream(obj));
    return Qnil;
}

#stream_end? ⇒ Boolean

Returns true if the stream is finished.

Returns:

  • (Boolean) 


1433
1434
1435
1436
1437
 
# File 'ext/zlib/zlib.c', line 1433

static VALUE
rb_zstream_finished_p(VALUE obj)
{
    return ZSTREAM_IS_FINISHED(get_zstream(obj)) ? Qtrue : Qfalse;
}

#total_in ⇒ Object

Returns the total bytes of the input data to the stream. FIXME



1395
1396
1397
1398
1399
 
# File 'ext/zlib/zlib.c', line 1395

static VALUE
rb_zstream_total_in(VALUE obj)
{
    return rb_uint2inum(get_zstream(obj)->stream.total_in);
}

#total_out ⇒ Object

Returns the total bytes of the output data from the stream. FIXME



1404
1405
1406
1407
1408
 
# File 'ext/zlib/zlib.c', line 1404

static VALUE
rb_zstream_total_out(VALUE obj)
{
    return rb_uint2inum(get_zstream(obj)->stream.total_out);
}