Class: Zlib::ZStream
- Inherits:
-
Object
- Object
- Zlib::ZStream
- Defined in:
- ext/rubysl/zlib/zlib.c,
ext/rubysl/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?
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.
1091 1092 1093 |
# File 'ext/rubysl/zlib/zlib.c', line 1091 static VALUE rb_zstream_adler(obj) VALUE obj; |
#avail_in ⇒ Object
Returns bytes of data in the input buffer. Normally, returns 0.
1047 1048 1049 |
# File 'ext/rubysl/zlib/zlib.c', line 1047 static VALUE rb_zstream_avail_in(obj) VALUE obj; |
#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.
1018 1019 1020 |
# File 'ext/rubysl/zlib/zlib.c', line 1018 static VALUE rb_zstream_avail_out(obj) VALUE obj; |
#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.
1033 1034 1035 |
# File 'ext/rubysl/zlib/zlib.c', line 1033 static VALUE rb_zstream_set_avail_out(obj, size) VALUE obj, size; |
#close ⇒ Object
Closes the stream. All operations on the closed stream will raise an exception.
944 945 946 |
# File 'ext/rubysl/zlib/zlib.c', line 944 static VALUE rb_zstream_end(obj) VALUE obj; |
#closed? ⇒ Boolean
Returns true if the stream is closed.
1111 1112 1113 |
# File 'ext/rubysl/zlib/zlib.c', line 1111 static VALUE rb_zstream_closed_p(obj) VALUE obj; |
#data_type ⇒ Object
Guesses the type of the data which have been inputed into the stream. The returned value is either Zlib::BINARY
, Zlib::ASCII
, or Zlib::UNKNOWN
.
1081 1082 1083 |
# File 'ext/rubysl/zlib/zlib.c', line 1081 static VALUE rb_zstream_data_type(obj) VALUE obj; |
#end ⇒ Object
Closes the stream. All operations on the closed stream will raise an exception.
944 945 946 |
# File 'ext/rubysl/zlib/zlib.c', line 944 static VALUE rb_zstream_end(obj) VALUE obj; |
#ended? ⇒ Boolean
Returns true if the stream is closed.
1111 1112 1113 |
# File 'ext/rubysl/zlib/zlib.c', line 1111 static VALUE rb_zstream_closed_p(obj) VALUE obj; |
#finish ⇒ Object
Finishes the stream and flushes output buffer. See Zlib::Deflate#finish and Zlib::Inflate#finish for details of this behavior.
968 969 970 |
# File 'ext/rubysl/zlib/zlib.c', line 968 static VALUE rb_zstream_finish(obj) VALUE obj; |
#finished? ⇒ Boolean
Returns true if the stream is finished.
1101 1102 1103 |
# File 'ext/rubysl/zlib/zlib.c', line 1101 static VALUE rb_zstream_finished_p(obj) VALUE obj; |
#flush_next_in ⇒ Object
Flushes input buffer and returns all data in that buffer.
985 986 987 |
# File 'ext/rubysl/zlib/zlib.c', line 985 static VALUE rb_zstream_flush_next_in(obj) VALUE obj; |
#flush_next_out ⇒ Object
Flushes output buffer and returns all data in that buffer.
1001 1002 1003 |
# File 'ext/rubysl/zlib/zlib.c', line 1001 static VALUE rb_zstream_flush_next_out(obj) VALUE obj; |
#reset ⇒ Object
Resets and initializes the stream. All data in both input and output buffer are discarded.
956 957 958 |
# File 'ext/rubysl/zlib/zlib.c', line 956 static VALUE rb_zstream_reset(obj) VALUE obj; |
#stream_end? ⇒ Boolean
Returns true if the stream is finished.
1101 1102 1103 |
# File 'ext/rubysl/zlib/zlib.c', line 1101 static VALUE rb_zstream_finished_p(obj) VALUE obj; |
#total_in ⇒ Object
Returns the total bytes of the input data to the stream. FIXME
1059 1060 1061 |
# File 'ext/rubysl/zlib/zlib.c', line 1059 static VALUE rb_zstream_total_in(obj) VALUE obj; |
#total_out ⇒ Object
Returns the total bytes of the output data from the stream. FIXME
1069 1070 1071 |
# File 'ext/rubysl/zlib/zlib.c', line 1069 static VALUE rb_zstream_total_out(obj) VALUE obj; |