Class: Zlib::ZStream

Inherits:
Object
  • Object
show all
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?

Direct Known Subclasses

Deflate, Inflate

Instance Method Summary collapse

Instance Method Details

#adler ⇒ Object

Returns the adler-32 checksum.



1190
1191
1192
1193
1194
 
# 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.



1150
1151
1152
1153
1154
1155
1156
 
# 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.



1123
1124
1125
1126
1127
1128
1129
 
# 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.



1137
1138
1139
1140
1141
1142
1143
1144
1145
 
# 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.



1054
1055
1056
1057
1058
1059
 
# 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.

Returns:

  • (Boolean) 


1208
1209
1210
1211
1212
1213
1214
 
# 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.



1181
1182
1183
1184
1185
 
# 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.



1054
1055
1056
1057
1058
1059
 
# 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.

Returns:

  • (Boolean) 


1208
1209
1210
1211
1212
1213
1214
 
# 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.



1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
 
# 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.

Returns:

  • (Boolean) 


1199
1200
1201
1202
1203
 
# 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.



1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
 
# 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.



1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
 
# 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.



1065
1066
1067
1068
1069
1070
 
# 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.

Returns:

  • (Boolean) 


1199
1200
1201
1202
1203
 
# 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



1161
1162
1163
1164
1165
 
# 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



1170
1171
1172
1173
1174
 
# File 'zlib.c', line 1170

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