Module pickle
Below is a list of all pickle functions.
Name | Use |
|---|---|
Convert Lua variables to binary format | |
Convert Lua variables back from binary format |
To use Tarantool binary protocol primitives from Lua, it's necessary to
convert Lua variables to binary format. The pickle.pack() helper
function is prototyped after Perl
pack.
Format specifiers
b, B | converts Lua scalar value to a 1-byte integer, and stores the integer in the resulting string |
|---|---|
s, S | converts Lua scalar value to a 2-byte integer, and stores the integer in the resulting string, low byte first |
i, I | converts Lua scalar value to a 4-byte integer, and stores the integer in the resulting string, low byte first |
l, L | converts Lua scalar value to an 8-byte integer, and stores the integer in the resulting string, low byte first |
n | converts Lua scalar value to a 2-byte integer, and stores the integer in the resulting string, big endian, |
N | converts Lua scalar value to a 4-byte integer, and stores the integer in the resulting string, big endian, |
q, Q | converts Lua scalar value to an 8-byte integer, and stores the integer in the resulting string, big endian, |
f | converts Lua scalar value to a 4-byte float, and stores the float in the resulting string |
d | converts Lua scalar value to a 8-byte double, and stores the double in the resulting string |
a, A | converts Lua scalar value to a sequence of bytes, and stores the sequence in the resulting string |
Parameters:
-
format(string) — string containing format specifiers -
argument(s)(scalar-value) — scalar values to be formatted
Returns
a binary string containing all arguments, packed according to the format specifiers.
Return type
string
A scalar value can be either a variable or a literal. Remember that large integers should be entered with tonumber64() or LL or ULL suffixes.
Possible errors:
- Argument count does not match the format. Note: excess values are simply ignored.
- Expected 8/16/32/64-bit int.
- Unsupported pack format specifier.
Example:
tarantool> pickle = require('pickle')---...tarantool> box.space.tester:insert{0, 'hello world'}---- [0, 'hello world']...tarantool> box.space.tester:update({0}, {{'=', 2, 'bye world'}})---- [0, 'bye world']...tarantool> box.space.tester:update({0}, {> {'=', 2, pickle.pack('iiA', 0, 3, 'hello')}> })---- [0, "\0\0\0\0\x03\0\0\0hello"]...tarantool> box.space.tester:update({0}, {{'=', 2, 4}})---- [0, 4]...tarantool> box.space.tester:update({0}, {{'+', 2, 4}})---- [0, 8]...tarantool> box.space.tester:update({0}, {{'^', 2, 4}})---- [0, 12]...
Counterpart to pickle.pack(). Warning: if format specifier 'A' is
used, it must be the last item.
Parameters:
-
format(string) — none -
binary-string(string) — none
Returns
A list of strings or numbers.
Return type
table
Possible errors:
- Too many bytes: unpacked X, total Y. X < Y.
- Got X bytes (expected: Y+)'. X < Y.
- Unsupported format specifier.
Example:
tarantool> pickle = require('pickle')---...tarantool> tuple = box.space.tester:replace{0}---...tarantool> string.len(tuple[1])---- 1...tarantool> pickle.unpack('b', tuple[1])---- 48...tarantool> pickle.unpack('bsi', pickle.pack('bsi', 255, 65535, 4294967295))---- 255- 65535- 4294967295...tarantool> pickle.unpack('ls', pickle.pack('ls', tonumber64('18446744073709551615'), 65535))---...tarantool> num, num64, str = pickle.unpack('slA', pickle.pack('slA', 666,> tonumber64('666666666666666'), 'string'))---...