crocks/predicates/pathSatisfies.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 (evilsoft) */

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

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

function fn(name) {
  // pathSatisfies: [ (String | Integer) ] -> (a -> Boolean) -> b -> Boolean
  // pathSatisfies: [ (String | Integer) ] -> Pred a -> b -> Boolean
  function pathSatisfies(keys, pred, x) {
    if(!isArray(keys)) {
      throw new TypeError(err(name))
    }

    if(!isPredOrFunc(pred)) {
      throw new TypeError(
        (name + ": Second argument must be a Pred or predicate Function")
      )
    }

    if(isNil(x)) {
      return false
    }

    var target = x
    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(target)) {
        return false
      }

      target = target[key]
    }

    return !!predOrFunc(pred, target)
  }

  return curry(pathSatisfies)
}

var pathSatisfies =
  fn('pathSatisfies')

pathSatisfies.origFn =
  fn

module.exports = pathSatisfies