HORIZON PROJECT

var wrappy = require('wrappy')

module.exports = wrappy(once)

module.exports.strict = wrappy(onceStrict)

once.proto = once(function () {

  Object.defineProperty(Function.prototype, 'once', {

    value: function () {

      return once(this)

    },

    configurable: true

  })

  Object.defineProperty(Function.prototype, 'onceStrict', {

    value: function () {

      return onceStrict(this)

    },

    configurable: true

  })

})

function once (fn) {

  var f = function () {

    if (f.called) return f.value

    f.called = true

    return f.value = fn.apply(this, arguments)

  }

  f.called = false

  return f

}

function onceStrict (fn) {

  var f = function () {

    if (f.called)

      throw new Error(f.onceError)

    f.called = true

    return f.value = fn.apply(this, arguments)

  }

  var name = fn.name || 'Function wrapped with `once`'

  f.onceError = name + " shouldn't be called more than once"

  f.called = false

  return f

}