crocks/predicates/pathEq.js

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

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

var curry = require('../core/curry')
var equals = require('../core/equals')
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')

var err = function (name) { return (name + ": First argument must be an Array of non-empty Strings or Integers"); }

function fn(name) {
  // pathEq :: [ String | Number ] -> a -> Object -> Boolean
  function pathEq(keys, value, target) {
    if(!isArray(keys)) {
      throw new TypeError(err(name))
    }

    if(isNil(target)) {
      return false
    }

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

      if(!(isString(key) && !isEmpty(key) || isInteger(key))) {
        throw new TypeError(err(name))
      }

      if(isNil(acc)) {
        return false
      }

      acc = acc[key]

      if(!isDefined(acc)) {
        return false
      }
    }

    return equals(acc, value)
  }

  return curry(pathEq)
}

var pathEq =
  fn('pathEq')

pathEq.origFn =
  fn

module.exports = pathEq