PHP's array_map in TypeScript

How to use

Install via yarn add locutus and import: import { array_map } from 'locutus/php/array/array_map'.

Or with CommonJS: const { array_map } = require('locutus/php/array/array_map')

Use a bundler that supports tree-shaking so you only ship the functions you actually use. Vite, webpack, Rollup, and Parcel all handle this. For server-side use this is less of a concern.

Examples

These examples are extracted from test cases that automatically verify our functions against their native counterparts.

#	code	expected result
1	array_map( function (a){return (a * a * a)}, [1, 2, 3, 4, 5] )	[ 1, 8, 27, 64, 125 ]

PHP arrays and TypeScript/JavaScript

Please note that Locutus uses TypeScript/JavaScript objects as substitutes for PHP arrays, they are the closest we can get to this hashtable-like data structure without rolling our own. While many TypeScript/JavaScript implementations preserve the order of object properties, the ECMAScript Language Specification explicitly states that:

The mechanics and order of enumerating the properties is not specified.

In practice most engines preserve insertion order, but if your code depends on key ordering across platforms, keep this caveat in mind.

To influence how Locutus treats objects as arrays, you can check out the locutus.objectsAsArrays setting.

Notes

• If the callback is a string (or object, if an array is supplied), it can only work if the function name is in the global context

Dependencies

This function uses the following Locutus functions:

• _callbackResolver (php/_helpers)

Here's what our current TypeScript equivalent to PHP's array_map looks like.

TSTypeScript JSJavaScript TSStandalone TS JSStandalone JS

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import { resolvePhpCallable } from '../_helpers/_callbackResolver.ts'
import type { PhpCallableDescriptor, PhpList, PhpRuntimeValue } from '../_helpers/_phpTypes.ts'

type ArrayMapValue = PhpRuntimeValue
type ArrayMapInputs = [firstArray: PhpList<ArrayMapValue>, ...restArrays: Array<PhpList<ArrayMapValue>>]
type ArrayMapTupleArgs<TInputs extends readonly PhpList<ArrayMapValue>[]> = [
  ...{
    [K in keyof TInputs]: TInputs[K] extends PhpList<infer TValue> ? TValue | undefined : ArrayMapValue | undefined
  },
]
type ArrayMapCallbackArgsVariadic = Array<ArrayMapValue | undefined>

export function array_map<TInputs extends ArrayMapInputs, TResult>(
  callback: PhpCallableDescriptor<ArrayMapTupleArgs<TInputs>, TResult>,
  ...inputArrays: TInputs
): PhpList<TResult>

export function array_map<TInputs extends ArrayMapInputs>(
  callback: null | undefined,
  ...inputArrays: TInputs
): PhpList<ArrayMapTupleArgs<TInputs>>

export function array_map<TResult = ArrayMapValue>(
  callback: PhpCallableDescriptor<ArrayMapCallbackArgsVariadic, TResult> | null | undefined,
  ...inputArrays: ArrayMapInputs
): PhpList<TResult> | PhpList<ArrayMapCallbackArgsVariadic> {
  //  discuss at: https://locutus.io/php/array_map/
  // original by: Andrea Giammarchi (https://webreflection.blogspot.com)
  // improved by: Kevin van Zonneveld (https://kvz.io)
  // improved by: Brett Zamir (https://brett-zamir.me)
  //    input by: thekid
  //      note 1: If the callback is a string (or object, if an array is supplied),
  //      note 1: it can only work if the function name is in the global context
  //   example 1: array_map( function (a){return (a * a * a)}, [1, 2, 3, 4, 5] )
  //   returns 1: [ 1, 8, 27, 64, 125 ]

  const argc = inputArrays.length + 1
  const itemCount = inputArrays[0]?.length ?? 0

  const resolved =
    callback === null || typeof callback === 'undefined'
      ? null
      : resolvePhpCallable<ArrayMapCallbackArgsVariadic, TResult>(callback, {
          invalidMessage: 'array_map(): Invalid callback',
          missingScopeMessage: (scopeName: string) => 'Object not found: ' + scopeName,
        })

  if (resolved) {
    const mapped: PhpList<TResult> = []
    for (let itemIndex = 0; itemIndex < itemCount; itemIndex++) {
      const args: ArrayMapCallbackArgsVariadic = []
      for (let arrayIndex = 0; arrayIndex < argc - 1; arrayIndex++) {
        args.push(inputArrays[arrayIndex]?.[itemIndex])
      }
      mapped[itemIndex] = resolved.fn.apply(resolved.scope, args)
    }
    return mapped
  }

  const mapped: PhpList<ArrayMapCallbackArgsVariadic> = []
  for (let itemIndex = 0; itemIndex < itemCount; itemIndex++) {
    const args: ArrayMapCallbackArgsVariadic = []
    for (let arrayIndex = 0; arrayIndex < argc - 1; arrayIndex++) {
      args.push(inputArrays[arrayIndex]?.[itemIndex])
    }
    mapped[itemIndex] = args
  }

  return mapped
}

import { resolvePhpCallable } from '../_helpers/_callbackResolver.ts'

export function array_map(callback, ...inputArrays) {
  //  discuss at: https://locutus.io/php/array_map/
  // original by: Andrea Giammarchi (https://webreflection.blogspot.com)
  // improved by: Kevin van Zonneveld (https://kvz.io)
  // improved by: Brett Zamir (https://brett-zamir.me)
  //    input by: thekid
  //      note 1: If the callback is a string (or object, if an array is supplied),
  //      note 1: it can only work if the function name is in the global context
  //   example 1: array_map( function (a){return (a * a * a)}, [1, 2, 3, 4, 5] )
  //   returns 1: [ 1, 8, 27, 64, 125 ]

  const argc = inputArrays.length + 1
  const itemCount = inputArrays[0]?.length ?? 0

  const resolved =
    callback === null || typeof callback === 'undefined'
      ? null
      : resolvePhpCallable(callback, {
          invalidMessage: 'array_map(): Invalid callback',
          missingScopeMessage: (scopeName) => 'Object not found: ' + scopeName,
        })

  if (resolved) {
    const mapped = []
    for (let itemIndex = 0; itemIndex < itemCount; itemIndex++) {
      const args = []
      for (let arrayIndex = 0; arrayIndex < argc - 1; arrayIndex++) {
        args.push(inputArrays[arrayIndex]?.[itemIndex])
      }
      mapped[itemIndex] = resolved.fn.apply(resolved.scope, args)
    }
    return mapped
  }

  const mapped = []
  for (let itemIndex = 0; itemIndex < itemCount; itemIndex++) {
    const args = []
    for (let arrayIndex = 0; arrayIndex < argc - 1; arrayIndex++) {
      args.push(inputArrays[arrayIndex]?.[itemIndex])
    }
    mapped[itemIndex] = args
  }

  return mapped
}

// php/_helpers/_phpTypes (Locutus helper dependency)
type PhpNullish = null | undefined

type PhpInput = {} | PhpNullish

type PhpScalar = string | number | boolean

type PhpPrimitive = PhpScalar | bigint

type PhpList<T = PhpInput> = T[]

type PhpAssoc<T = PhpInput> = { [key: string]: T }

type PhpArrayLike<T = PhpInput> = PhpList<T> | PhpAssoc<T>

type PhpFunctionValue = (...args: PhpInput[]) => PhpInput

interface PhpRuntimeAssoc {
  [key: string]: PhpRuntimeValue
}

interface PhpRuntimeList extends Array<PhpRuntimeValue> {}

type PhpRuntimeValue = PhpPrimitive | PhpNullish | PhpRuntimeList | PhpRuntimeAssoc | PhpFunctionValue

type PhpCallableArgs = PhpInput[]

type PhpCallable<TArgs extends PhpCallableArgs = PhpCallableArgs, TResult = PhpInput> = (
  ...args: TArgs
) => TResult

type PhpCallableScope = PhpInput

type PhpCallableTuple<TArgs extends PhpCallableArgs = PhpCallableArgs, TResult = PhpInput> = readonly [
  PhpCallableScope,
  string | PhpCallable<TArgs, TResult>,
]

type PhpCallableDescriptor<TArgs extends PhpCallableArgs = PhpCallableArgs, TResult = PhpInput> =
  | string
  | PhpCallable<TArgs, TResult>
  | PhpCallableTuple<TArgs, TResult>

function isObjectLike(value: PhpInput): value is PhpArrayLike<PhpInput> {
  return typeof value === 'object' && value !== null
}

function isPhpCallable<TArgs extends PhpCallableArgs = PhpCallableArgs, TResult = PhpInput>(
  value: PhpInput,
): value is PhpCallable<TArgs, TResult> {
  return typeof value === 'function'
}

// php/_helpers/_phpRuntimeState (Locutus helper dependency)
interface LocutusRuntimeContainer {
  php?: PhpAssoc<PhpInput>
}

interface PhpGlobalProcessLike {
  env?: PhpAssoc<string | undefined>
}

interface PhpGlobalBufferLike {
  from?: (...args: PhpInput[]) => PhpInput
}

interface PhpGlobalKnownEntryMap {
  process: PhpGlobalProcessLike
  Buffer: PhpGlobalBufferLike
}

type GlobalWithLocutus = {
  $locutus?: LocutusRuntimeContainer
  [key: string]: PhpInput
}

const globalContext: GlobalWithLocutus =
  typeof window === 'object' && window !== null ? window : typeof global === 'object' && global !== null ? global : {}

function getPhpGlobalEntry<TKey extends keyof PhpGlobalKnownEntryMap>(
  key: TKey,
): PhpGlobalKnownEntryMap[TKey] | undefined

function getPhpGlobalEntry(key: string): PhpInput | undefined

function getPhpGlobalEntry(key: string): PhpInput | undefined {
  const value = globalContext[key]
  return typeof value === 'undefined' ? undefined : value
}

function getPhpObjectEntry(value: PhpInput, key: string): PhpInput | undefined {
  if ((typeof value !== 'object' && typeof value !== 'function') || value === null) {
    return undefined
  }

  let current: object | null = value
  while (current) {
    const descriptor = Object.getOwnPropertyDescriptor(current, key)
    if (descriptor) {
      if (typeof descriptor.get === 'function') {
        const getterValue = descriptor.get.call(value)
        return typeof getterValue === 'undefined' ? undefined : getterValue
      }
      const directValue = descriptor.value
      return typeof directValue === 'undefined' ? undefined : directValue
    }
    current = Object.getPrototypeOf(current)
  }

  return undefined
}

// php/_helpers/_callbackResolver (Locutus helper dependency)
type CallbackValue = PhpInput

interface CallbackResolverOptions {
  invalidMessage: string
  missingScopeMessage?: (scopeName: string) => string
}

interface ResolvedCallback<TArgs extends PhpCallableArgs = PhpCallableArgs, TResult = CallbackValue> {
  fn: PhpCallable<TArgs, TResult>
  scope: CallbackValue
}

function resolvePhpCallable<TArgs extends PhpCallableArgs = PhpCallableArgs, TResult = CallbackValue>(
  callback: PhpCallableDescriptor<TArgs, TResult>,
  options: CallbackResolverOptions,
): ResolvedCallback<TArgs, TResult> {
  if (isPhpCallable<TArgs, TResult>(callback)) {
    return { fn: callback, scope: null }
  }

  if (typeof callback === 'string') {
    const candidate = getPhpGlobalEntry(callback)
    if (isPhpCallable<TArgs, TResult>(candidate)) {
      return { fn: candidate, scope: null }
    }
    throw new Error(options.invalidMessage)
  }

  if (Array.isArray(callback) && callback.length >= 2) {
    const scopeDescriptor = callback[0]
    const callableDescriptor = callback[1]

    let scope: CallbackValue
    if (typeof scopeDescriptor === 'string') {
      scope = getPhpGlobalEntry(scopeDescriptor)
      if (typeof scope === 'undefined' && options.missingScopeMessage) {
        throw new Error(options.missingScopeMessage(scopeDescriptor))
      }
    } else {
      scope = scopeDescriptor
    }

    if (isPhpCallable<TArgs, TResult>(callableDescriptor)) {
      return { fn: callableDescriptor, scope }
    }

    if (typeof callableDescriptor === 'string' && (isObjectLike(scope) || typeof scope === 'function')) {
      const candidate = getPhpObjectEntry(scope, callableDescriptor)
      if (isPhpCallable<TArgs, TResult>(candidate)) {
        return { fn: candidate, scope }
      }
    }
  }

  throw new Error(options.invalidMessage)
}

// php/array/array_map (target function module)
type ArrayMapValue = PhpRuntimeValue

type ArrayMapInputs = [firstArray: PhpList<ArrayMapValue>, ...restArrays: Array<PhpList<ArrayMapValue>>]

type ArrayMapTupleArgs<TInputs extends readonly PhpList<ArrayMapValue>[]> = [
  ...{
    [K in keyof TInputs]: TInputs[K] extends PhpList<infer TValue> ? TValue | undefined : ArrayMapValue | undefined
  },
]

type ArrayMapCallbackArgsVariadic = Array<ArrayMapValue | undefined>

function array_map<TInputs extends ArrayMapInputs, TResult>(
  callback: PhpCallableDescriptor<ArrayMapTupleArgs<TInputs>, TResult>,
  ...inputArrays: TInputs
): PhpList<TResult>

function array_map<TInputs extends ArrayMapInputs>(
  callback: null | undefined,
  ...inputArrays: TInputs
): PhpList<ArrayMapTupleArgs<TInputs>>

function array_map<TResult = ArrayMapValue>(
  callback: PhpCallableDescriptor<ArrayMapCallbackArgsVariadic, TResult> | null | undefined,
  ...inputArrays: ArrayMapInputs
): PhpList<TResult> | PhpList<ArrayMapCallbackArgsVariadic> {
  //  discuss at: https://locutus.io/php/array_map/
  // original by: Andrea Giammarchi (https://webreflection.blogspot.com)
  // improved by: Kevin van Zonneveld (https://kvz.io)
  // improved by: Brett Zamir (https://brett-zamir.me)
  //    input by: thekid
  //      note 1: If the callback is a string (or object, if an array is supplied),
  //      note 1: it can only work if the function name is in the global context
  //   example 1: array_map( function (a){return (a * a * a)}, [1, 2, 3, 4, 5] )
  //   returns 1: [ 1, 8, 27, 64, 125 ]

  const argc = inputArrays.length + 1
  const itemCount = inputArrays[0]?.length ?? 0

  const resolved =
    callback === null || typeof callback === 'undefined'
      ? null
      : resolvePhpCallable<ArrayMapCallbackArgsVariadic, TResult>(callback, {
          invalidMessage: 'array_map(): Invalid callback',
          missingScopeMessage: (scopeName: string) => 'Object not found: ' + scopeName,
        })

  if (resolved) {
    const mapped: PhpList<TResult> = []
    for (let itemIndex = 0; itemIndex < itemCount; itemIndex++) {
      const args: ArrayMapCallbackArgsVariadic = []
      for (let arrayIndex = 0; arrayIndex < argc - 1; arrayIndex++) {
        args.push(inputArrays[arrayIndex]?.[itemIndex])
      }
      mapped[itemIndex] = resolved.fn.apply(resolved.scope, args)
    }
    return mapped
  }

  const mapped: PhpList<ArrayMapCallbackArgsVariadic> = []
  for (let itemIndex = 0; itemIndex < itemCount; itemIndex++) {
    const args: ArrayMapCallbackArgsVariadic = []
    for (let arrayIndex = 0; arrayIndex < argc - 1; arrayIndex++) {
      args.push(inputArrays[arrayIndex]?.[itemIndex])
    }
    mapped[itemIndex] = args
  }

  return mapped
}

// php/_helpers/_phpTypes (Locutus helper dependency)
function isObjectLike(value) {
  return typeof value === 'object' && value !== null
}

function isPhpCallable(value) {
  return typeof value === 'function'
}

// php/_helpers/_phpRuntimeState (Locutus helper dependency)
const globalContext =
  typeof window === 'object' && window !== null ? window : typeof global === 'object' && global !== null ? global : {}

function getPhpGlobalEntry(key) {
  const value = globalContext[key]
  return typeof value === 'undefined' ? undefined : value
}

function getPhpObjectEntry(value, key) {
  if ((typeof value !== 'object' && typeof value !== 'function') || value === null) {
    return undefined
  }

  let current = value
  while (current) {
    const descriptor = Object.getOwnPropertyDescriptor(current, key)
    if (descriptor) {
      if (typeof descriptor.get === 'function') {
        const getterValue = descriptor.get.call(value)
        return typeof getterValue === 'undefined' ? undefined : getterValue
      }
      const directValue = descriptor.value
      return typeof directValue === 'undefined' ? undefined : directValue
    }
    current = Object.getPrototypeOf(current)
  }

  return undefined
}

// php/_helpers/_callbackResolver (Locutus helper dependency)
function resolvePhpCallable(callback, options) {
  if (isPhpCallable(callback)) {
    return { fn: callback, scope: null }
  }

  if (typeof callback === 'string') {
    const candidate = getPhpGlobalEntry(callback)
    if (isPhpCallable(candidate)) {
      return { fn: candidate, scope: null }
    }
    throw new Error(options.invalidMessage)
  }

  if (Array.isArray(callback) && callback.length >= 2) {
    const scopeDescriptor = callback[0]
    const callableDescriptor = callback[1]

    let scope
    if (typeof scopeDescriptor === 'string') {
      scope = getPhpGlobalEntry(scopeDescriptor)
      if (typeof scope === 'undefined' && options.missingScopeMessage) {
        throw new Error(options.missingScopeMessage(scopeDescriptor))
      }
    } else {
      scope = scopeDescriptor
    }

    if (isPhpCallable(callableDescriptor)) {
      return { fn: callableDescriptor, scope }
    }

    if (typeof callableDescriptor === 'string' && (isObjectLike(scope) || typeof scope === 'function')) {
      const candidate = getPhpObjectEntry(scope, callableDescriptor)
      if (isPhpCallable(candidate)) {
        return { fn: candidate, scope }
      }
    }
  }

  throw new Error(options.invalidMessage)
}

// php/array/array_map (target function module)

function array_map(callback, ...inputArrays) {
  //  discuss at: https://locutus.io/php/array_map/
  // original by: Andrea Giammarchi (https://webreflection.blogspot.com)
  // improved by: Kevin van Zonneveld (https://kvz.io)
  // improved by: Brett Zamir (https://brett-zamir.me)
  //    input by: thekid
  //      note 1: If the callback is a string (or object, if an array is supplied),
  //      note 1: it can only work if the function name is in the global context
  //   example 1: array_map( function (a){return (a * a * a)}, [1, 2, 3, 4, 5] )
  //   returns 1: [ 1, 8, 27, 64, 125 ]

  const argc = inputArrays.length + 1
  const itemCount = inputArrays[0]?.length ?? 0

  const resolved =
    callback === null || typeof callback === 'undefined'
      ? null
      : resolvePhpCallable(callback, {
          invalidMessage: 'array_map(): Invalid callback',
          missingScopeMessage: (scopeName) => 'Object not found: ' + scopeName,
        })

  if (resolved) {
    const mapped = []
    for (let itemIndex = 0; itemIndex < itemCount; itemIndex++) {
      const args = []
      for (let arrayIndex = 0; arrayIndex < argc - 1; arrayIndex++) {
        args.push(inputArrays[arrayIndex]?.[itemIndex])
      }
      mapped[itemIndex] = resolved.fn.apply(resolved.scope, args)
    }
    return mapped
  }

  const mapped = []
  for (let itemIndex = 0; itemIndex < itemCount; itemIndex++) {
    const args = []
    for (let arrayIndex = 0; arrayIndex < argc - 1; arrayIndex++) {
      args.push(inputArrays[arrayIndex]?.[itemIndex])
    }
    mapped[itemIndex] = args
  }

  return mapped
}

Improve this function

Locutus is a community effort following The McDonald's Theory: we ship first iterations, hoping others will improve them. If you see something that could be better, we'd love your contribution.

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