Class: Zlib::ZStream
- Inherits:
-
Object
- Object
- Zlib::ZStream
- Defined in:
- 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?
Instance Method Summary collapse
-
#adler ⇒ Object
Returns the adler-32 checksum.
-
#avail_in ⇒ Object
Returns bytes of data in the input buffer.
-
#avail_out ⇒ Object
Returns number of bytes of free spaces in output buffer.
-
#avail_out= ⇒ Object
Allocates
size
bytes of free space in the output buffer. -
#close ⇒ Object
Closes the stream.
-
#closed? ⇒ Boolean
Returns true if the stream is closed.
-
#data_type ⇒ Object
Guesses the type of the data which have been inputed into the stream.
-
#end ⇒ Object
Closes the stream.
-
#ended? ⇒ Boolean
Returns true if the stream is closed.
-
#finish ⇒ Object
Finishes the stream and flushes output buffer.
-
#finished? ⇒ Boolean
Returns true if the stream is finished.
-
#flush_next_in ⇒ Object
Flushes input buffer and returns all data in that buffer.
-
#flush_next_out ⇒ Object
Flushes output buffer and returns all data in that buffer.
-
#reset ⇒ Object
Resets and initializes the stream.
-
#stream_end? ⇒ Boolean
Returns true if the stream is finished.
-
#total_in ⇒ Object
Returns the total bytes of the input data to the stream.
-
#total_out ⇒ Object
Returns the total bytes of the output data from the stream.
Instance Method Details
#adler ⇒ Object
Returns the adler-32 checksum.
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# File 'zlib.c', line 1190
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.
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# File 'zlib.c', line 1150
static VALUE
rb_zstream_avail_in(VALUE obj)
{
struct zstream *z;
Data_Get_Struct(obj, struct zstream, 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.
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# File 'zlib.c', line 1123
static VALUE
rb_zstream_avail_out(VALUE obj)
{
struct zstream *z;
Data_Get_Struct(obj, struct zstream, z);
return rb_uint2inum(z->stream.avail_out);
}
|
#avail_out= ⇒ 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.
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# File 'zlib.c', line 1137
static VALUE
rb_zstream_set_avail_out(VALUE obj, VALUE size)
{
struct zstream *z = get_zstream(obj);
Check_Type(size, T_FIXNUM);
zstream_expand_buffer_into(z, FIX2INT(size));
return size;
}
|
#close ⇒ Object
Closes the stream. All operations on the closed stream will raise an exception.
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# File 'zlib.c', line 1054
static VALUE
rb_zstream_end(VALUE obj)
{
zstream_end(get_zstream(obj));
return Qnil;
}
|
#closed? ⇒ Boolean
Returns true if the stream is closed.
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# File 'zlib.c', line 1208
static VALUE
rb_zstream_closed_p(VALUE obj)
{
struct zstream *z;
Data_Get_Struct(obj, struct zstream, 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
.
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# File 'zlib.c', line 1181
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.
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# File 'zlib.c', line 1054
static VALUE
rb_zstream_end(VALUE obj)
{
zstream_end(get_zstream(obj));
return Qnil;
}
|
#ended? ⇒ Boolean
Returns true if the stream is closed.
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# File 'zlib.c', line 1208
static VALUE
rb_zstream_closed_p(VALUE obj)
{
struct zstream *z;
Data_Get_Struct(obj, struct zstream, z);
return ZSTREAM_IS_READY(z) ? Qfalse : Qtrue;
}
|
#finish ⇒ Object
Finishes the stream and flushes output buffer. See Zlib::Deflate#finish and Zlib::Inflate#finish for details of this behavior.
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# File 'zlib.c', line 1076
static VALUE
rb_zstream_finish(VALUE obj)
{
struct zstream *z = get_zstream(obj);
VALUE dst;
zstream_run(z, (Bytef*)"", 0, Z_FINISH);
dst = zstream_detach_buffer(z);
OBJ_INFECT(dst, obj);
return dst;
}
|
#finished? ⇒ Boolean
Returns true if the stream is finished.
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# File 'zlib.c', line 1199
static VALUE
rb_zstream_finished_p(VALUE obj)
{
return ZSTREAM_IS_FINISHED(get_zstream(obj)) ? Qtrue : Qfalse;
}
|
#flush_next_in ⇒ Object
Flushes input buffer and returns all data in that buffer.
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# File 'zlib.c', line 1092
static VALUE
rb_zstream_flush_next_in(VALUE obj)
{
struct zstream *z;
VALUE dst;
Data_Get_Struct(obj, struct zstream, z);
dst = zstream_detach_input(z);
OBJ_INFECT(dst, obj);
return dst;
}
|
#flush_next_out ⇒ Object
Flushes output buffer and returns all data in that buffer.
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# File 'zlib.c', line 1107
static VALUE
rb_zstream_flush_next_out(VALUE obj)
{
struct zstream *z;
VALUE dst;
Data_Get_Struct(obj, struct zstream, z);
dst = zstream_detach_buffer(z);
OBJ_INFECT(dst, obj);
return dst;
}
|
#reset ⇒ Object
Resets and initializes the stream. All data in both input and output buffer are discarded.
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# File 'zlib.c', line 1065
static VALUE
rb_zstream_reset(VALUE obj)
{
zstream_reset(get_zstream(obj));
return Qnil;
}
|
#stream_end? ⇒ Boolean
Returns true if the stream is finished.
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# File 'zlib.c', line 1199
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
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# File 'zlib.c', line 1161
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
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# File 'zlib.c', line 1170
static VALUE
rb_zstream_total_out(VALUE obj)
{
return rb_uint2inum(get_zstream(obj)->stream.total_out);
}
|