crocks/Maybe/getPath.js

A collection of well known Algebraic Datatypes for your utter enjoyment.

/** @license ISC License (c) copyright 2019 original and current authors */
/** @author Ian Hofmann-Hicks (evil) */

var ref = require('../core/Maybe');
var Nothing = ref.Nothing;
var Just = ref.Just;

var curry = require('../core/curry')
var isArray = require('../core/isArray')
var isDefined = require('../core/isDefined')
var isEmpty = require('../core/isEmpty')
var isInteger = require('../core/isInteger')
var isNil = require('../core/isNil')
var isString = require('../core/isString')

function fn(name) {
  function getPath(keys, target) {
    if(!isArray(keys)) {
      throw new TypeError((name + ": Array of Non-empty Strings or Integers required for first argument"))
    }

    if(isNil(target)) {
      return Nothing()
    }

    var value = target
    for(var i = 0; i < keys.length; i++) {
      var key = keys[i]

      if(!(isString(key) && !isEmpty(key) || isInteger(key))) {
        throw new TypeError((name + ": Array of Non-empty Strings or Integers required for first argument"))
      }

      if(isNil(value)) {
        return Nothing()
      }

      value = value[key]

      if(!isDefined(value)) {
        return Nothing()
      }
    }

    return Just(value)
  }

  return curry(getPath)
}

var getPath =
  fn('getPath')

getPath.origFn =
  fn

module.exports = getPath