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nanoid.c3
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nanoid.c3
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module nanoid;
import std::math::random;
const char[] ALPHANUMERIC_ALPHABET = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
const char[] ALPHABET = "_-" +++ ALPHANUMERIC_ALPHABET;
const DEFAULT_SIZE = 21;
fault NanoError {
ALPHABET_EMPTY,
ALPHABET_GREATER_THAN_255,
SIZE_NEGATIVE
}
Random rand @noinit;
fn void init() @init {
rand = &&DefaultRandom{};
random::seed_entropy(rand);
}
fn void set_rand(Random rnd) {
if (rnd == null) {
return;
}
rand = rnd;
}
fn String! new(int size = DEFAULT_SIZE, String prefix = "", String sufix = "") {
if (size <= 0) {
return NanoError.SIZE_NEGATIVE?;
}
char[] id = mem::new_array(char, size);
char[] bytes = mem::temp_new_array(char, size);
rand.next_bytes(bytes);
for (int i; i < size; i++) {
id[i] = ALPHABET[bytes[i] & 63];
}
int nidl = size + prefix.len + sufix.len;
if (nidl == size){
return (String)id;
}
char[] nid = ((char*)mem::realloc(id, nidl))[:nidl];
nid[prefix.len:size] = id[..];
if (prefix.len) {
nid[0:prefix.len] = prefix[..];
}
if(sufix.len) {
nid[prefix.len+size..] = sufix[..];
}
return (String)nid[:nidl];
}
fn String! generate(char[] alphabet, int size, String prefix = "", String sufix = "") {
if (alphabet.len == 0) {
return NanoError.ALPHABET_EMPTY?;
}
if (alphabet.len > 255) {
return NanoError.ALPHABET_GREATER_THAN_255?;
}
if (size <= 0) {
return NanoError.SIZE_NEGATIVE?;
}
int mask = (2 << (31 - ((int)((alphabet.len - 1) | 1)).clz())) - 1;
double ceil_arg = 1.6 * (double)(mask * size) / (double)(alphabet.len);
int step = (int)math::ceil(ceil_arg);
char[] id = mem::new_array(char, size);
char[] bytes = mem::temp_new_array(char, step);
for LOOP: (int j=0;;) {
rand.next_bytes(bytes);
for (int i; i < step; i++) {
char cbyte = bytes[i] & (char)mask;
if (cbyte < alphabet.len) {
id[j] = alphabet[cbyte];
j++;
if (j == size) {
break LOOP;
}
}
}
}
int nidl = size + prefix.len + sufix.len;
if (nidl == size){
return (String)id[:size];
}
char[] nid = ((char*)mem::realloc(id, char.sizeof * nidl))[:nidl];
nid[prefix.len:size] = id[..];
if (prefix.len) {
nid[0:prefix.len] = prefix[..];
}
if(sufix.len) {
nid[prefix.len+size..] = sufix[..];
}
return (String) nid;
}
macro String! new_numeric(int size = DEFAULT_SIZE, String prefix = "", String sufix = "") {
return generate(ALPHANUMERIC_ALPHABET[0:10], size, prefix, sufix);
}
macro String! new_alpha(int size = DEFAULT_SIZE, String prefix = "", String sufix = "") {
return generate(ALPHANUMERIC_ALPHABET[26..], size, prefix, sufix);
}
macro String! new_alphanumeric(int size = DEFAULT_SIZE, String prefix = "", String sufix = "") {
return generate(ALPHANUMERIC_ALPHABET, size, prefix, sufix);
}