lexicographic-integer
create lexicographic string keys for positive integers without zero-padding
At most, a number will take 10 bytes to store (2 more bytes than a regular
double) but all numbers less than 251 only take a single byte.
example
pack
var lexi = require('lexicographic-integer');
console.log(lexi.pack(12345));
output:
[ 252, 47, 62 ]
unpack
To convert the arrays back into integers, just do .unpack()
:
var lexi = require('lexicographic-integer');
console.log(lexi.unpack([ 252, 47, 62 ]));
output:
12345
hex list
var lexi = require('lexicographic-integer');
for (var n = 0; n < 5; n++) {
console.log(n, lexi.pack(n, 'hex'));
}
console.log('...');
for (var n = 248; n < 257; n++) {
console.log(n, lexi.pack(n, 'hex'));
}
console.log('...');
for (var n = 5000; n < 5005; n++) {
console.log(n, lexi.pack(n, 'hex'));
}
console.log('...');
for (var n = 21378213; n < Number.MAX_VALUE; n *= 1513254198219212) {
console.log(n, lexi.pack(n, 'hex'));
}
output:
0 '00'
1 '01'
2 '02'
3 '03'
4 '04'
...
248 'f8'
249 'f9'
250 'fa'
251 'fb00'
252 'fb01'
253 'fb02'
254 'fb03'
255 'fb04'
256 'fb05'
...
5000 'fc128d'
5001 'fc128e'
5002 'fc128f'
5003 'fc1290'
5004 'fc1291'
...
21378213 'fe014633aa'
3.2350670572674536e+22 'ff2a0db3777bb94c'
4.895478805930646e+37 'ff5d09351659b187'
7.408103855367726e+52 'ff8f0c6004db1f28'
1.121034425997914e+68 'ffc20850f8bf332a'
1.696410051489608e+83 'fff40b2d6c283bb4'
2.5670996323179187e+98 'fffb2b0f05dd909879'
3.884674295852086e+113 'fffb5e0a187f7c58cd'
5.87849968691243e+128 'fffb900d91aaff96fe'
8.895664330450558e+143 'fffbc3091e5fb56b0c'
1.3461401394003201e+159 'fffbf50c417dbf1c6c'
2.03705221733893e+174 'fffc0128083c74d68fa0'
3.08257781987989e+189 'fffc015a0b11d96218aa'
4.6647238272706696e+204 'fffc018c0ee0ce4aceb6'
7.058912915150531e+219 'fffc01bf09ff97d9a0a7'
1.0681929603715358e+235 'fffc01f10d7031e40fc8'
1.6164474817904348e+250 'fffc02240907e1192454'
2.4460959380202488e+265 'fffc02560c2341f2013d'
3.701564947456103e+280 'fffc028908282389ba9c'
5.601408696719025e+295 'fffc02bb0af68aa1140f'
methods
var lexi = require('lexicographic-integer')
lexi.pack(n, encoding='array')
If encoding
is undefined
or 'array'
, return an array of byte values
between 0 and 255, inclusive for the integer n
.
If encoding
is 'hex'
, return a lexicographic hex string for the integer n
.
lexi.unpack(bytes)
Convert an array of bytes
returned by .pack()
back into the original
javascript number.
install
With npm do:
npm install lexicographic-integer
license
MIT