Add type guards for better type inference
This commit is contained in:
Sam Verschueren
parent
64ced4d33c
commit
ff99cea8da
2 changed files with 56 additions and 44 deletions
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@ -1,5 +1,12 @@
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import * as util from 'util';
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type TypedArray = Int8Array | Uint8Array | Uint8ClampedArray | Int16Array | Uint16Array | Int32Array | Uint32Array | Float32Array | Float64Array;
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type Primitive = null | undefined | string | number | boolean | Symbol;
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export interface ArrayLike {
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length: number;
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}
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export const enum TypeName {
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null = 'null',
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boolean = 'boolean',
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@ -36,7 +43,7 @@ export const enum TypeName {
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}
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const toString = Object.prototype.toString;
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const isOfType = (type: string) => (value: any) => typeof value === type; // tslint:disable-line:strict-type-predicates
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const isOfType = <T>(type: string) => (value: any): value is T => typeof value === type; // tslint:disable-line:strict-type-predicates
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const getObjectType = (value: any): TypeName | null => {
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const objectName = toString.call(value).slice(8, -1) as string;
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@ -48,7 +55,7 @@ const getObjectType = (value: any): TypeName | null => {
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return null;
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};
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const isObjectOfType = (type: TypeName) => (value: any) => getObjectType(value) === type;
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const isObjectOfType = <T>(type: TypeName) => (value: any): value is T => getObjectType(value) === type;
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function is(value: any): TypeName { // tslint:disable-line:only-arrow-functions
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if (value === null) {
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@ -105,60 +112,60 @@ namespace is { // tslint:disable-line:no-namespace
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const isObject = (value: any) => typeof value === 'object';
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// tslint:disable:variable-name
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export const undefined = isOfType('undefined');
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export const string = isOfType('string');
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export const number = isOfType('number');
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export const function_ = isOfType('function');
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export const null_ = (value: any) => value === null;
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export const undefined = isOfType<undefined>('undefined');
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export const string = isOfType<string>('string');
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export const number = isOfType<number>('number');
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export const function_ = isOfType<Function>('function');
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export const null_ = (value: any): value is null => value === null;
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export const class_ = (value: any) => function_(value) && value.toString().startsWith('class ');
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export const boolean = (value: any) => value === true || value === false;
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export const symbol = isOfType('symbol');
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export const boolean = (value: any): value is boolean => value === true || value === false;
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export const symbol = isOfType<Symbol>('symbol');
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// tslint:enable:variable-name
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export const array = Array.isArray;
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export const buffer = Buffer.isBuffer;
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export const nullOrUndefined = (value: any) => null_(value) || undefined(value);
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export const nullOrUndefined = (value: any): value is null | undefined => null_(value) || undefined(value);
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export const object = (value: any) => !nullOrUndefined(value) && (function_(value) || isObject(value));
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export const iterable = (value: any) => !nullOrUndefined(value) && function_(value[Symbol.iterator]);
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export const generator = (value: any) => iterable(value) && function_(value.next) && function_(value.throw);
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export const iterable = <T = any>(value: any): value is Iterator<T> => !nullOrUndefined(value) && function_(value[Symbol.iterator]);
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export const generator = (value: any): value is Generator => iterable(value) && function_(value.next) && function_(value.throw);
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export const nativePromise = isObjectOfType(TypeName.Promise);
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export const nativePromise = isObjectOfType<Promise<any>>(TypeName.Promise);
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const hasPromiseAPI = (value: any) =>
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const hasPromiseAPI = <T = any>(value: any): value is Promise<T> =>
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!null_(value) &&
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isObject(value) &&
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function_(value.then) &&
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function_(value.catch);
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export const promise = (value: any) => nativePromise(value) || hasPromiseAPI(value);
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export const promise = <T = any>(value: any): value is Promise<T> => nativePromise(value) || hasPromiseAPI<T>(value);
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const isFunctionOfType = (type: TypeName) => isObjectOfType(type);
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export const generatorFunction = isFunctionOfType(TypeName.GeneratorFunction);
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export const asyncFunction = isFunctionOfType(TypeName.AsyncFunction);
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export const boundFunction = (value: any) => function_(value) && !value.hasOwnProperty('prototype');
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const isFunctionOfType = <T>(type: TypeName) => isObjectOfType<T>(type);
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export const generatorFunction = isFunctionOfType<GeneratorFunction>(TypeName.GeneratorFunction);
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export const asyncFunction = isFunctionOfType<Function>(TypeName.AsyncFunction);
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export const boundFunction = (value: any): value is Function => function_(value) && !value.hasOwnProperty('prototype');
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export const regExp = isObjectOfType(TypeName.RegExp);
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export const date = isObjectOfType(TypeName.Date);
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export const error = isObjectOfType(TypeName.Error);
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export const map = isObjectOfType(TypeName.Map);
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export const set = isObjectOfType(TypeName.Set);
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export const weakMap = isObjectOfType(TypeName.WeakMap);
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export const weakSet = isObjectOfType(TypeName.WeakSet);
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export const regExp = isObjectOfType<RegExp>(TypeName.RegExp);
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export const date = isObjectOfType<Date>(TypeName.Date);
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export const error = isObjectOfType<Error>(TypeName.Error);
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export const map = isObjectOfType<Map<any, any>>(TypeName.Map);
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export const set = isObjectOfType<Set<any>>(TypeName.Set);
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export const weakMap = isObjectOfType<WeakMap<any, any>>(TypeName.WeakMap);
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export const weakSet = isObjectOfType<WeakSet<any>>(TypeName.WeakSet);
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export const int8Array = isObjectOfType(TypeName.Int8Array);
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export const uint8Array = isObjectOfType(TypeName.Uint8Array);
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export const uint8ClampedArray = isObjectOfType(TypeName.Uint8ClampedArray);
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export const int16Array = isObjectOfType(TypeName.Int16Array);
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export const uint16Array = isObjectOfType(TypeName.Uint16Array);
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export const int32Array = isObjectOfType(TypeName.Int32Array);
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export const uint32Array = isObjectOfType(TypeName.Uint32Array);
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export const float32Array = isObjectOfType(TypeName.Float32Array);
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export const float64Array = isObjectOfType(TypeName.Float64Array);
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export const int8Array = isObjectOfType<Int8Array>(TypeName.Int8Array);
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export const uint8Array = isObjectOfType<Uint8Array>(TypeName.Uint8Array);
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export const uint8ClampedArray = isObjectOfType<Uint8ClampedArray>(TypeName.Uint8ClampedArray);
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export const int16Array = isObjectOfType<Int16Array>(TypeName.Int16Array);
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export const uint16Array = isObjectOfType<Uint16Array>(TypeName.Uint16Array);
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export const int32Array = isObjectOfType<Int32Array>(TypeName.Int32Array);
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export const uint32Array = isObjectOfType<Uint32Array>(TypeName.Uint32Array);
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export const float32Array = isObjectOfType<Float32Array>(TypeName.Float32Array);
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export const float64Array = isObjectOfType<Float64Array>(TypeName.Float64Array);
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export const arrayBuffer = isObjectOfType(TypeName.ArrayBuffer);
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export const sharedArrayBuffer = isObjectOfType(TypeName.SharedArrayBuffer);
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export const dataView = isObjectOfType(TypeName.DataView);
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export const arrayBuffer = isObjectOfType<ArrayBuffer>(TypeName.ArrayBuffer);
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export const sharedArrayBuffer = isObjectOfType<SharedArrayBuffer>(TypeName.SharedArrayBuffer);
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export const dataView = isObjectOfType<DataView>(TypeName.DataView);
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export const directInstanceOf = (instance: any, klass: any) => Object.getPrototypeOf(instance) === klass.prototype;
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@ -175,10 +182,10 @@ namespace is { // tslint:disable-line:no-namespace
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'symbol'
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]);
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export const primitive = (value: any) => null_(value) || primitiveTypes.has(typeof value);
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export const primitive = (value: any): value is Primitive => null_(value) || primitiveTypes.has(typeof value);
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export const integer = (value: any) => Number.isInteger(value);
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export const safeInteger = (value: any) => Number.isSafeInteger(value);
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export const integer = (value: any): value is number => Number.isInteger(value);
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export const safeInteger = (value: any): value is number => Number.isSafeInteger(value);
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export const plainObject = (value: any) => {
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// From: https://github.com/sindresorhus/is-plain-obj/blob/master/index.js
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@ -200,7 +207,7 @@ namespace is { // tslint:disable-line:no-namespace
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TypeName.Float32Array,
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TypeName.Float64Array
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]);
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export const typedArray = (value: any) => {
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export const typedArray = (value: any): value is TypedArray => {
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const objectType = getObjectType(value);
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if (objectType === null) {
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@ -211,11 +218,11 @@ namespace is { // tslint:disable-line:no-namespace
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};
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const isValidLength = (value: any) => safeInteger(value) && value > -1;
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export const arrayLike = (value: any) => !nullOrUndefined(value) && !function_(value) && isValidLength(value.length);
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export const arrayLike = (value: any): value is ArrayLike => !nullOrUndefined(value) && !function_(value) && isValidLength(value.length);
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export const inRange = (value: number, range: number | number[]) => {
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if (number(range)) {
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return value >= Math.min(0, range as number) && value <= Math.max(range as number, 0);
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return value >= Math.min(0, range) && value <= Math.max(range, 0);
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}
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if (array(range) && range.length === 2) {
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@ -7,6 +7,11 @@
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"declaration": true,
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"pretty": true,
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"newLine": "lf",
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"lib": [
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"dom",
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"es2016",
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"es2017.sharedmemory"
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],
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"stripInternal": true,
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"noImplicitAny": true,
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"noImplicitReturns": true,
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