63 lines
1.3 KiB
TypeScript
63 lines
1.3 KiB
TypeScript
// imported from https://github.com/unshiftio/yeast
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'use strict'
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const alphabet = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz-_'.split('')
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, length = 64
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, map = {}
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let seed = 0
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, i = 0
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, prev
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/**
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* Return a string representing the specified number.
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*
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* @param {Number} num The number to convert.
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* @returns {String} The string representation of the number.
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* @api public
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*/
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export function encode(num) {
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let encoded = ''
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do {
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encoded = alphabet[num % length] + encoded
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num = Math.floor(num / length)
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} while (num > 0)
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return encoded
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}
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/**
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* Return the integer value specified by the given string.
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*
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* @param {String} str The string to convert.
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* @returns {Number} The integer value represented by the string.
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* @api public
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*/
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export function decode(str) {
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let decoded = 0
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for (i = 0; i < str.length; i++) {
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decoded = decoded * length + map[str.charAt(i)]
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}
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return decoded
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}
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/**
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* Yeast: A tiny growing id generator.
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*
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* @returns {String} A unique id.
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* @api public
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*/
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export function yeast() {
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const now = encode(+new Date())
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if (now !== prev) return seed = 0, prev = now
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return now + '.' + encode(seed++)
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}
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//
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// Map each character to its index.
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//
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for (; i < length; i++) map[alphabet[i]] = i
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