rubico/dist/x/findIndex.es.js

[a]synchronous functional programming

/**
 * rubico v2.6.2
 * https://github.com/a-synchronous/rubico
 * (c) 2019-2024 Richard Tong
 * rubico may be freely distributed under the MIT license.
 */

const isArray = Array.isArray

const isPromise = value => value != null && typeof value.then == 'function'

const thunkConditional = (
  conditionalExpression, thunkOnTruthy, thunkOnFalsy,
) => conditionalExpression ? thunkOnTruthy() : thunkOnFalsy()

const __ = Symbol.for('placeholder')

const always = value => function getter() { return value }

// argument resolver for curry3
const curry3ResolveArg0 = (
  baseFunc, arg1, arg2,
) => function arg0Resolver(arg0) {
  return baseFunc(arg0, arg1, arg2)
}

// argument resolver for curry3
const curry3ResolveArg1 = (
  baseFunc, arg0, arg2,
) => function arg1Resolver(arg1) {
  return baseFunc(arg0, arg1, arg2)
}

// argument resolver for curry3
const curry3ResolveArg2 = (
  baseFunc, arg0, arg1,
) => function arg2Resolver(arg2) {
  return baseFunc(arg0, arg1, arg2)
}

const curry3 = function (baseFunc, arg0, arg1, arg2) {
  if (arg0 == __) {
    return curry3ResolveArg0(baseFunc, arg1, arg2)
  }
  if (arg1 == __) {
    return curry3ResolveArg1(baseFunc, arg0, arg2)
  }
  return curry3ResolveArg2(baseFunc, arg0, arg1)
}

const thunkify3 = (func, arg0, arg1, arg2) => function thunk() {
  return func(arg0, arg1, arg2)
}

const findIndexAsync = async function (predicate, array, index) {
  const length = array.length
  while (++index < length) {
    let predication = predicate(array[index])
    if (isPromise(predication)) {
      predication = await predication
    }
    if (predication) {
      return index
    }
  }
  return -1
}

const findIndex = predicate => function findingIndex(array) {
  const length = array.length
  let index = -1
  while (++index < length) {
    const predication = predicate(array[index])
    if (isPromise(predication)) {
      return predication.then(curry3(
        thunkConditional,
        __,
        always(index),
        thunkify3(findIndexAsync, predicate, array, index),
      ))
    }
    if (predication) {
      return index
    }
  }
  return -1
}

export default findIndex