/* @flow */
|
|
export const emptyObject = Object.freeze({})
|
|
// These helpers produce better VM code in JS engines due to their
|
// explicitness and function inlining.
|
export function isUndef (v: any): boolean %checks {
|
return v === undefined || v === null
|
}
|
|
export function isDef (v: any): boolean %checks {
|
return v !== undefined && v !== null
|
}
|
|
export function isTrue (v: any): boolean %checks {
|
return v === true
|
}
|
|
export function isFalse (v: any): boolean %checks {
|
return v === false
|
}
|
|
/**
|
* Check if value is primitive.
|
*/
|
export function isPrimitive (value: any): boolean %checks {
|
return (
|
typeof value === 'string' ||
|
typeof value === 'number' ||
|
// $flow-disable-line
|
typeof value === 'symbol' ||
|
typeof value === 'boolean'
|
)
|
}
|
|
/**
|
* Quick object check - this is primarily used to tell
|
* Objects from primitive values when we know the value
|
* is a JSON-compliant type.
|
*/
|
export function isObject (obj: mixed): boolean %checks {
|
return obj !== null && typeof obj === 'object'
|
}
|
|
/**
|
* Get the raw type string of a value, e.g., [object Object].
|
*/
|
const _toString = Object.prototype.toString
|
|
export function toRawType (value: any): string {
|
return _toString.call(value).slice(8, -1)
|
}
|
|
/**
|
* Strict object type check. Only returns true
|
* for plain JavaScript objects.
|
*/
|
export function isPlainObject (obj: any): boolean {
|
return _toString.call(obj) === '[object Object]'
|
}
|
|
export function isRegExp (v: any): boolean {
|
return _toString.call(v) === '[object RegExp]'
|
}
|
|
/**
|
* Check if val is a valid array index.
|
*/
|
export function isValidArrayIndex (val: any): boolean {
|
const n = parseFloat(String(val))
|
return n >= 0 && Math.floor(n) === n && isFinite(val)
|
}
|
|
export function isPromise (val: any): boolean {
|
return (
|
isDef(val) &&
|
typeof val.then === 'function' &&
|
typeof val.catch === 'function'
|
)
|
}
|
|
/**
|
* Convert a value to a string that is actually rendered.
|
*/
|
export function toString (val: any): string {
|
return val == null
|
? ''
|
: Array.isArray(val) || (isPlainObject(val) && val.toString === _toString)
|
? JSON.stringify(val, null, 2)
|
: String(val)
|
}
|
|
/**
|
* Convert an input value to a number for persistence.
|
* If the conversion fails, return original string.
|
*/
|
export function toNumber (val: string): number | string {
|
const n = parseFloat(val)
|
return isNaN(n) ? val : n
|
}
|
|
/**
|
* Make a map and return a function for checking if a key
|
* is in that map.
|
*/
|
export function makeMap (
|
str: string,
|
expectsLowerCase?: boolean
|
): (key: string) => true | void {
|
const map = Object.create(null)
|
const list: Array<string> = str.split(',')
|
for (let i = 0; i < list.length; i++) {
|
map[list[i]] = true
|
}
|
return expectsLowerCase
|
? val => map[val.toLowerCase()]
|
: val => map[val]
|
}
|
|
/**
|
* Check if a tag is a built-in tag.
|
*/
|
export const isBuiltInTag = makeMap('slot,component', true)
|
|
/**
|
* Check if an attribute is a reserved attribute.
|
*/
|
export const isReservedAttribute = makeMap('key,ref,slot,slot-scope,is')
|
|
/**
|
* Remove an item from an array.
|
*/
|
export function remove (arr: Array<any>, item: any): Array<any> | void {
|
if (arr.length) {
|
const index = arr.indexOf(item)
|
if (index > -1) {
|
return arr.splice(index, 1)
|
}
|
}
|
}
|
|
/**
|
* Check whether an object has the property.
|
*/
|
const hasOwnProperty = Object.prototype.hasOwnProperty
|
export function hasOwn (obj: Object | Array<*>, key: string): boolean {
|
return hasOwnProperty.call(obj, key)
|
}
|
|
/**
|
* Create a cached version of a pure function.
|
*/
|
export function cached<F: Function> (fn: F): F {
|
const cache = Object.create(null)
|
return (function cachedFn (str: string) {
|
const hit = cache[str]
|
return hit || (cache[str] = fn(str))
|
}: any)
|
}
|
|
/**
|
* Camelize a hyphen-delimited string.
|
*/
|
const camelizeRE = /-(\w)/g
|
export const camelize = cached((str: string): string => {
|
return str.replace(camelizeRE, (_, c) => c ? c.toUpperCase() : '')
|
})
|
|
/**
|
* Capitalize a string.
|
*/
|
export const capitalize = cached((str: string): string => {
|
return str.charAt(0).toUpperCase() + str.slice(1)
|
})
|
|
/**
|
* Hyphenate a camelCase string.
|
*/
|
const hyphenateRE = /\B([A-Z])/g
|
export const hyphenate = cached((str: string): string => {
|
return str.replace(hyphenateRE, '-$1').toLowerCase()
|
})
|
|
/**
|
* Simple bind polyfill for environments that do not support it,
|
* e.g., PhantomJS 1.x. Technically, we don't need this anymore
|
* since native bind is now performant enough in most browsers.
|
* But removing it would mean breaking code that was able to run in
|
* PhantomJS 1.x, so this must be kept for backward compatibility.
|
*/
|
|
/* istanbul ignore next */
|
function polyfillBind (fn: Function, ctx: Object): Function {
|
function boundFn (a) {
|
const l = arguments.length
|
return l
|
? l > 1
|
? fn.apply(ctx, arguments)
|
: fn.call(ctx, a)
|
: fn.call(ctx)
|
}
|
|
boundFn._length = fn.length
|
return boundFn
|
}
|
|
function nativeBind (fn: Function, ctx: Object): Function {
|
return fn.bind(ctx)
|
}
|
|
export const bind = Function.prototype.bind
|
? nativeBind
|
: polyfillBind
|
|
/**
|
* Convert an Array-like object to a real Array.
|
*/
|
export function toArray (list: any, start?: number): Array<any> {
|
start = start || 0
|
let i = list.length - start
|
const ret: Array<any> = new Array(i)
|
while (i--) {
|
ret[i] = list[i + start]
|
}
|
return ret
|
}
|
|
/**
|
* Mix properties into target object.
|
*/
|
export function extend (to: Object, _from: ?Object): Object {
|
for (const key in _from) {
|
to[key] = _from[key]
|
}
|
return to
|
}
|
|
/**
|
* Merge an Array of Objects into a single Object.
|
*/
|
export function toObject (arr: Array<any>): Object {
|
const res = {}
|
for (let i = 0; i < arr.length; i++) {
|
if (arr[i]) {
|
extend(res, arr[i])
|
}
|
}
|
return res
|
}
|
|
/* eslint-disable no-unused-vars */
|
|
/**
|
* Perform no operation.
|
* Stubbing args to make Flow happy without leaving useless transpiled code
|
* with ...rest (https://flow.org/blog/2017/05/07/Strict-Function-Call-Arity/).
|
*/
|
export function noop (a?: any, b?: any, c?: any) {}
|
|
/**
|
* Always return false.
|
*/
|
export const no = (a?: any, b?: any, c?: any) => false
|
|
/* eslint-enable no-unused-vars */
|
|
/**
|
* Return the same value.
|
*/
|
export const identity = (_: any) => _
|
|
/**
|
* Generate a string containing static keys from compiler modules.
|
*/
|
export function genStaticKeys (modules: Array<ModuleOptions>): string {
|
return modules.reduce((keys, m) => {
|
return keys.concat(m.staticKeys || [])
|
}, []).join(',')
|
}
|
|
/**
|
* Check if two values are loosely equal - that is,
|
* if they are plain objects, do they have the same shape?
|
*/
|
export function looseEqual (a: any, b: any): boolean {
|
if (a === b) return true
|
const isObjectA = isObject(a)
|
const isObjectB = isObject(b)
|
if (isObjectA && isObjectB) {
|
try {
|
const isArrayA = Array.isArray(a)
|
const isArrayB = Array.isArray(b)
|
if (isArrayA && isArrayB) {
|
return a.length === b.length && a.every((e, i) => {
|
return looseEqual(e, b[i])
|
})
|
} else if (a instanceof Date && b instanceof Date) {
|
return a.getTime() === b.getTime()
|
} else if (!isArrayA && !isArrayB) {
|
const keysA = Object.keys(a)
|
const keysB = Object.keys(b)
|
return keysA.length === keysB.length && keysA.every(key => {
|
return looseEqual(a[key], b[key])
|
})
|
} else {
|
/* istanbul ignore next */
|
return false
|
}
|
} catch (e) {
|
/* istanbul ignore next */
|
return false
|
}
|
} else if (!isObjectA && !isObjectB) {
|
return String(a) === String(b)
|
} else {
|
return false
|
}
|
}
|
|
/**
|
* Return the first index at which a loosely equal value can be
|
* found in the array (if value is a plain object, the array must
|
* contain an object of the same shape), or -1 if it is not present.
|
*/
|
export function looseIndexOf (arr: Array<mixed>, val: mixed): number {
|
for (let i = 0; i < arr.length; i++) {
|
if (looseEqual(arr[i], val)) return i
|
}
|
return -1
|
}
|
|
/**
|
* Ensure a function is called only once.
|
*/
|
export function once (fn: Function): Function {
|
let called = false
|
return function () {
|
if (!called) {
|
called = true
|
fn.apply(this, arguments)
|
}
|
}
|
}
|
