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<title>12.17.2 Unpacker Objects
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<H2><A NAME=
"SECTION00141720000000000000000"></A><A NAME=
"xdr-unpacker-objects"></A>
The
<tt class=
"class">Unpacker
</tt> class offers the following methods:
<dl><dt><table cellpadding=
"0" cellspacing=
"0"><tr valign=
"baseline">
<td><nobr><b><tt id='l2h-
4177' xml:id='l2h-
4177'
class=
"method">reset
</tt></b>(
</nobr></td>
<td><var>data
</var>)
</td></tr></table></dt>
Resets the string buffer with the given
<var>data
</var>.
<dl><dt><table cellpadding=
"0" cellspacing=
"0"><tr valign=
"baseline">
<td><nobr><b><tt id='l2h-
4178' xml:id='l2h-
4178'
class=
"method">get_position
</tt></b>(
</nobr></td>
<td><var></var>)
</td></tr></table></dt>
Returns the current unpack position in the data buffer.
<dl><dt><table cellpadding=
"0" cellspacing=
"0"><tr valign=
"baseline">
<td><nobr><b><tt id='l2h-
4179' xml:id='l2h-
4179'
class=
"method">set_position
</tt></b>(
</nobr></td>
<td><var>position
</var>)
</td></tr></table></dt>
Sets the data buffer unpack position to
<var>position
</var>. You should be
careful about using
<tt class=
"method">get_position()
</tt> and
<tt class=
"method">set_position()
</tt>.
<dl><dt><table cellpadding=
"0" cellspacing=
"0"><tr valign=
"baseline">
<td><nobr><b><tt id='l2h-
4180' xml:id='l2h-
4180'
class=
"method">get_buffer
</tt></b>(
</nobr></td>
<td><var></var>)
</td></tr></table></dt>
Returns the current unpack data buffer as a string.
<dl><dt><table cellpadding=
"0" cellspacing=
"0"><tr valign=
"baseline">
<td><nobr><b><tt id='l2h-
4181' xml:id='l2h-
4181'
class=
"method">done
</tt></b>(
</nobr></td>
<td><var></var>)
</td></tr></table></dt>
Indicates unpack completion. Raises an
<tt class=
"exception">Error
</tt> exception
if all of the data has not been unpacked.
In addition, every data type that can be packed with a
<tt class=
"class">Packer
</tt>,
can be unpacked with an
<tt class=
"class">Unpacker
</tt>. Unpacking methods are of the
form
<code>unpack_
<var>type
</var>()
</code>, and take no arguments. They return the
<dl><dt><table cellpadding=
"0" cellspacing=
"0"><tr valign=
"baseline">
<td><nobr><b><tt id='l2h-
4182' xml:id='l2h-
4182'
class=
"method">unpack_float
</tt></b>(
</nobr></td>
<td><var></var>)
</td></tr></table></dt>
Unpacks a single-precision floating point number.
<dl><dt><table cellpadding=
"0" cellspacing=
"0"><tr valign=
"baseline">
<td><nobr><b><tt id='l2h-
4183' xml:id='l2h-
4183'
class=
"method">unpack_double
</tt></b>(
</nobr></td>
<td><var></var>)
</td></tr></table></dt>
Unpacks a double-precision floating point number, similarly to
<tt class=
"method">unpack_float()
</tt>.
In addition, the following methods unpack strings, bytes, and opaque
<dl><dt><table cellpadding=
"0" cellspacing=
"0"><tr valign=
"baseline">
<td><nobr><b><tt id='l2h-
4184' xml:id='l2h-
4184'
class=
"method">unpack_fstring
</tt></b>(
</nobr></td>
<td><var>n
</var>)
</td></tr></table></dt>
Unpacks and returns a fixed length string.
<var>n
</var> is the number of
characters expected. Padding with null bytes to guaranteed
4 byte
<dl><dt><table cellpadding=
"0" cellspacing=
"0"><tr valign=
"baseline">
<td><nobr><b><tt id='l2h-
4185' xml:id='l2h-
4185'
class=
"method">unpack_fopaque
</tt></b>(
</nobr></td>
<td><var>n
</var>)
</td></tr></table></dt>
Unpacks and returns a fixed length opaque data stream, similarly to
<tt class=
"method">unpack_fstring()
</tt>.
<dl><dt><table cellpadding=
"0" cellspacing=
"0"><tr valign=
"baseline">
<td><nobr><b><tt id='l2h-
4186' xml:id='l2h-
4186'
class=
"method">unpack_string
</tt></b>(
</nobr></td>
<td><var></var>)
</td></tr></table></dt>
Unpacks and returns a variable length string. The length of the
string is first unpacked as an unsigned integer, then the string data
is unpacked with
<tt class=
"method">unpack_fstring()
</tt>.
<dl><dt><table cellpadding=
"0" cellspacing=
"0"><tr valign=
"baseline">
<td><nobr><b><tt id='l2h-
4187' xml:id='l2h-
4187'
class=
"method">unpack_opaque
</tt></b>(
</nobr></td>
<td><var></var>)
</td></tr></table></dt>
Unpacks and returns a variable length opaque data string, similarly to
<tt class=
"method">unpack_string()
</tt>.
<dl><dt><table cellpadding=
"0" cellspacing=
"0"><tr valign=
"baseline">
<td><nobr><b><tt id='l2h-
4188' xml:id='l2h-
4188'
class=
"method">unpack_bytes
</tt></b>(
</nobr></td>
<td><var></var>)
</td></tr></table></dt>
Unpacks and returns a variable length byte stream, similarly to
<tt class=
"method">unpack_string()
</tt>.
The following methods support unpacking arrays and lists:
<dl><dt><table cellpadding=
"0" cellspacing=
"0"><tr valign=
"baseline">
<td><nobr><b><tt id='l2h-
4189' xml:id='l2h-
4189'
class=
"method">unpack_list
</tt></b>(
</nobr></td>
<td><var>unpack_item
</var>)
</td></tr></table></dt>
Unpacks and returns a list of homogeneous items. The list is unpacked
by first unpacking an unsigned integer flag. If the flag is
<code>1</code>,
then the item is unpacked and appended to the list. A flag of
<code>0</code> indicates the end of the list.
<var>unpack_item
</var> is the
function that is called to unpack the items.
<dl><dt><table cellpadding=
"0" cellspacing=
"0"><tr valign=
"baseline">
<td><nobr><b><tt id='l2h-
4190' xml:id='l2h-
4190'
class=
"method">unpack_farray
</tt></b>(
</nobr></td>
<td><var>n, unpack_item
</var>)
</td></tr></table></dt>
Unpacks and returns (as a list) a fixed length array of homogeneous
items.
<var>n
</var> is number of list elements to expect in the buffer.
As above,
<var>unpack_item
</var> is the function used to unpack each element.
<dl><dt><table cellpadding=
"0" cellspacing=
"0"><tr valign=
"baseline">
<td><nobr><b><tt id='l2h-
4191' xml:id='l2h-
4191'
class=
"method">unpack_array
</tt></b>(
</nobr></td>
<td><var>unpack_item
</var>)
</td></tr></table></dt>
Unpacks and returns a variable length
<var>list
</var> of homogeneous items.
First, the length of the list is unpacked as an unsigned integer, then
each element is unpacked as in
<tt class=
"method">unpack_farray()
</tt> above.
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<span class=
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2.4.2, documentation updated on
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2005.
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