all files / music-notation/lib/ memoize.js

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'use strict'
 
/**
 * A simple and fast memoization function
 *
 * It helps creating functions that convert from string to pitch in array format.
 * Basically it does two things:
 * - ensure the function only receives strings
 * - memoize the result
 *
 * @name memoize
 * @function
 * @private
 */
module.exports = function (fn) {
  var cache = {}
  return function (str) {
    if (typeof str !== 'string') return null
    return (str in cache) ? cache[str] : cache[str] = fn(str)
  }
}