159 lines
4.8 KiB
JavaScript
159 lines
4.8 KiB
JavaScript
function createError(message) {
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var err = new Error(message);
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err.source = "ulid";
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return err;
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}
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// These values should NEVER change. If
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// they do, we're no longer making ulids!
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var ENCODING = "0123456789ABCDEFGHJKMNPQRSTVWXYZ"; // Crockford's Base32
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var ENCODING_LEN = ENCODING.length;
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var TIME_MAX = Math.pow(2, 48) - 1;
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var TIME_LEN = 10;
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var RANDOM_LEN = 16;
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function replaceCharAt(str, index, char) {
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if (index > str.length - 1) {
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return str;
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}
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return str.substr(0, index) + char + str.substr(index + 1);
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}
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function incrementBase32(str) {
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var done = undefined;
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var index = str.length;
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var char = void 0;
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var charIndex = void 0;
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var maxCharIndex = ENCODING_LEN - 1;
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while (!done && index-- >= 0) {
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char = str[index];
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charIndex = ENCODING.indexOf(char);
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if (charIndex === -1) {
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throw createError("incorrectly encoded string");
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}
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if (charIndex === maxCharIndex) {
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str = replaceCharAt(str, index, ENCODING[0]);
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continue;
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}
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done = replaceCharAt(str, index, ENCODING[charIndex + 1]);
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}
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if (typeof done === "string") {
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return done;
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}
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throw createError("cannot increment this string");
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}
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function randomChar(prng) {
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var rand = Math.floor(prng() * ENCODING_LEN);
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if (rand === ENCODING_LEN) {
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rand = ENCODING_LEN - 1;
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}
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return ENCODING.charAt(rand);
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}
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function encodeTime(now, len) {
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if (isNaN(now)) {
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throw new Error(now + " must be a number");
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}
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if (now > TIME_MAX) {
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throw createError("cannot encode time greater than " + TIME_MAX);
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}
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if (now < 0) {
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throw createError("time must be positive");
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}
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if (Number.isInteger(now) === false) {
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throw createError("time must be an integer");
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}
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var mod = void 0;
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var str = "";
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for (; len > 0; len--) {
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mod = now % ENCODING_LEN;
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str = ENCODING.charAt(mod) + str;
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now = (now - mod) / ENCODING_LEN;
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}
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return str;
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}
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function encodeRandom(len, prng) {
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var str = "";
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for (; len > 0; len--) {
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str = randomChar(prng) + str;
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}
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return str;
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}
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function decodeTime(id) {
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if (id.length !== TIME_LEN + RANDOM_LEN) {
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throw createError("malformed ulid");
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}
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var time = id.substr(0, TIME_LEN).split("").reverse().reduce(function (carry, char, index) {
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var encodingIndex = ENCODING.indexOf(char);
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if (encodingIndex === -1) {
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throw createError("invalid character found: " + char);
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}
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return carry += encodingIndex * Math.pow(ENCODING_LEN, index);
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}, 0);
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if (time > TIME_MAX) {
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throw createError("malformed ulid, timestamp too large");
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}
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return time;
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}
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function detectPrng() {
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var allowInsecure = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : false;
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var root = arguments[1];
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if (!root) {
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root = typeof window !== "undefined" ? window : null;
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}
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var browserCrypto = root && (root.crypto || root.msCrypto);
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if (browserCrypto) {
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return function () {
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var buffer = new Uint8Array(1);
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browserCrypto.getRandomValues(buffer);
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return buffer[0] / 0xff;
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};
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} else {
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try {
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var nodeCrypto = require("crypto");
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return function () {
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return nodeCrypto.randomBytes(1).readUInt8() / 0xff;
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};
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} catch (e) {}
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}
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if (allowInsecure) {
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try {
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console.error("secure crypto unusable, falling back to insecure Math.random()!");
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} catch (e) {}
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return function () {
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return Math.random();
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};
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}
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throw createError("secure crypto unusable, insecure Math.random not allowed");
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}
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function factory(currPrng) {
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if (!currPrng) {
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currPrng = detectPrng();
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}
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return function ulid(seedTime) {
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if (isNaN(seedTime)) {
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seedTime = Date.now();
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}
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return encodeTime(seedTime, TIME_LEN) + encodeRandom(RANDOM_LEN, currPrng);
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};
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}
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function monotonicFactory(currPrng) {
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if (!currPrng) {
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currPrng = detectPrng();
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}
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var lastTime = 0;
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var lastRandom = void 0;
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return function ulid(seedTime) {
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if (isNaN(seedTime)) {
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seedTime = Date.now();
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}
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if (seedTime <= lastTime) {
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var incrementedRandom = lastRandom = incrementBase32(lastRandom);
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return encodeTime(lastTime, TIME_LEN) + incrementedRandom;
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}
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lastTime = seedTime;
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var newRandom = lastRandom = encodeRandom(RANDOM_LEN, currPrng);
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return encodeTime(seedTime, TIME_LEN) + newRandom;
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};
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}
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var ulid = factory();
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export { replaceCharAt, incrementBase32, randomChar, encodeTime, encodeRandom, decodeTime, detectPrng, factory, monotonicFactory, ulid };
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