12.9.2 Unpacker Objects
The Unpacker class offers the following methods:
- reset(data)
-
Resets the string buffer with the given data.
- get_position()
-
Returns the current unpack position in the data buffer.
- set_position(position)
-
Sets the data buffer unpack position to position. You should be
careful about using get_position() and set_position().
- get_buffer()
-
Returns the current unpack data buffer as a string.
- done()
-
Indicates unpack completion. Raises an Error exception
if all of the data has not been unpacked.
In addition, every data type that can be packed with a Packer,
can be unpacked with an Unpacker. Unpacking methods are of the
form unpack_type(), and take no arguments. They return the
unpacked object.
- unpack_float()
-
Unpacks a single-precision floating point number.
- unpack_double()
-
Unpacks a double-precision floating point number, similarly to
unpack_float().
In addition, the following methods unpack strings, bytes, and opaque
data:
- unpack_fstring(n)
-
Unpacks and returns a fixed length string. n is the number of
characters expected. Padding with null bytes to guaranteed 4 byte
alignment is assumed.
- unpack_fopaque(n)
-
Unpacks and returns a fixed length opaque data stream, similarly to
unpack_fstring().
- unpack_string()
-
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 unpack_fstring().
- unpack_opaque()
-
Unpacks and returns a variable length opaque data string, similarly to
unpack_string().
- unpack_bytes()
-
Unpacks and returns a variable length byte stream, similarly to
unpack_string().
The following methods support unpacking arrays and lists:
- unpack_list(unpack_item)
-
Unpacks and returns a list of homogeneous items. The list is unpacked
one element at a time
by first unpacking an unsigned integer flag. If the flag is
1,
then the item is unpacked and appended to the list. A flag of
0 indicates the end of the list. unpack_item is the
function that is called to unpack the items.
- unpack_farray(n, unpack_item)
-
Unpacks and returns (as a list) a fixed length array of homogeneous
items. n is number of list elements to expect in the buffer.
As above, unpack_item is the function used to unpack each element.
- unpack_array(unpack_item)
-
Unpacks and returns a variable length list of homogeneous items.
First, the length of the list is unpacked as an unsigned integer, then
each element is unpacked as in unpack_farray() above.
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