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arogozinearogozine
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Add defaultIfEmpty
1 parent 645112b commit e7a81a7

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Lines changed: 169 additions & 0 deletions

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‎README.md‎

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@@ -120,6 +120,7 @@ To use library with ES6 modules,
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| concatenate | No | [Sync](tests/unittests/tests/Concatenate.ts) | Equivalent to `.Concat` but renamed to avoid conflict with JS
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| contains | Yes | [Sync](tests/unittests/tests/Contains.ts), [Async](tests/unittests/tests/ContainsAsync.ts)
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| count | Yes | [Sync](tests/unittests/tests/Count.ts), [Async](tests/unittests/tests/CountAsync.ts)
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| defaultIfEmpty | No | [Sync](tests/unittests/tests/DefaultIfEmpty.ts)
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| distinct | Yes | [Sync](tests/unittests/tests/Distinct.ts), [Async](tests/unittests/tests/DistinctAsync.ts)
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| elementAt | No | [Sync](tests/unittests/tests/ElementAt.ts)
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| elementAtOrDefault | No | [Sync](tests/unittests/tests/ElementAtOrDefault.ts)

‎src/async/_private/defaultIfEmpty.ts‎

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import { IAsyncEnumerable } from "../../types"
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import { BasicAsyncEnumerable } from "../BasicAsyncEnumerable"
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export const defaultIfEmpty = <TSource>(source: AsyncIterable<TSource>, defaultValue: TSource | Promise<TSource>): IAsyncEnumerable<TSource> => {
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async function* generator() {
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let found = false
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for await (const value of source) {
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found = true
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yield value
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}
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if (!found) {
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yield defaultValue
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}
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}
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return new BasicAsyncEnumerable(generator)
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}

‎src/initializer/bindLinq.ts‎

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@@ -14,6 +14,7 @@ import { contains } from "./../sync/_private/contains"
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import { containsAsync } from "./../sync/_private/containsAsync"
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import { count } from "./../sync/_private/count"
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import { countAsync } from "./../sync/_private/countAsync"
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import { defaultIfEmpty } from "../sync/_private/defaultIfEmpty"
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import { distinct } from "./../sync/_private/distinct"
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import { distinctAsync } from "./../sync/_private/distinctAsync"
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import { each } from "./../sync/_private/each"
@@ -115,6 +116,7 @@ export const bindLinq = <T, Y extends Iterable<T>>(object: IPrototype<Y>) => {
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bind(containsAsync, "containsAsync")
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bind(count, "count")
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bind(countAsync, "countAsync")
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bind(defaultIfEmpty, "defaultIfEmpty")
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bind(distinct, "distinct")
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bind(distinctAsync, "distinctAsync")
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bind(each, "each")

‎src/initializer/bindLinqAsync.ts‎

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@@ -13,6 +13,7 @@ import { contains } from "./../async/_private/contains"
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import { containsAsync } from "./../async/_private/containsAsync"
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import { count } from "./../async/_private/count"
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import { countAsync } from "./../async/_private/countAsync"
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import { defaultIfEmpty } from "../async/_private/defaultIfEmpty"
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import { distinct } from "./../async/_private/distinct"
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import { distinctAsync } from "./../async/_private/distinctAsync"
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import { each } from "./../async/_private/each"
@@ -110,6 +111,7 @@ export const bindLinqAsync = <T, Y extends AsyncIterable<T>>(object: IPrototype<
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bind(containsAsync, "containsAsync")
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bind(count, "count")
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bind(countAsync, "countAsync")
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bind(defaultIfEmpty, "defaultIfEmpty")
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bind(distinct, "distinct")
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bind(distinctAsync, "distinctAsync")
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bind(each, "each")

‎src/initializer/bindLinqParallel.ts‎

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@@ -13,6 +13,7 @@ import { contains } from "./../parallel/_private/contains"
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import { containsAsync } from "./../parallel/_private/containsAsync"
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import { count } from "./../parallel/_private/count"
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import { countAsync } from "./../parallel/_private/countAsync"
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import { defaultIfEmpty } from "./../parallel/_private/defaultIfEmpty"
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import { distinct } from "./../parallel/_private/distinct"
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import { distinctAsync } from "./../parallel/_private/distinctAsync"
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import { each } from "./../parallel/_private/each"
@@ -109,6 +110,7 @@ export const bindLinqParallel = <T, Y extends AsyncIterable<T>>(object: IPrototy
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bind(containsAsync, "containsAsync")
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bind(count, "count")
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bind(countAsync, "countAsync")
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bind(defaultIfEmpty, "defaultIfEmpty")
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bind(distinct, "distinct")
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bind(distinctAsync, "distinctAsync")
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bind(each, "each")

‎src/parallel/_private/defaultIfEmpty.ts‎

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import { IParallelEnumerable, ParallelGeneratorType, TypedData } from "../../types"
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import { BasicParallelEnumerable } from "../BasicParallelEnumerable"
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export const defaultIfEmpty = <TSource>(source: IParallelEnumerable<TSource>, defaultValue: TSource | Promise<TSource>): IParallelEnumerable<TSource> => {
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const dataFunc = source.dataFunc
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const isPromise = defaultValue instanceof Promise
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let typeData: TypedData<TSource>
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switch (dataFunc.type) {
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case ParallelGeneratorType.PromiseToArray: {
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const generator = () => dataFunc
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.generator()
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.then((values) => {
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if (values.length) {
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return values
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}
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if (isPromise) {
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return defaultValue.then(value => [value])
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}
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else {
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return [defaultValue]
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}
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})
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typeData = {
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generator,
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type: dataFunc.type
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}
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}
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break
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case ParallelGeneratorType.ArrayOfPromises: {
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const generator = () => {
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const promises = dataFunc.generator()
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if (promises.length) {
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return promises
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}
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if (isPromise) {
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return [defaultValue]
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}
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else {
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return [Promise.resolve(defaultValue)]
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}
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}
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typeData = {
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generator,
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type: dataFunc.type
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}
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}
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break
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case ParallelGeneratorType.PromiseOfPromises: {
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const generator = async () => {
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const promises = await dataFunc.generator()
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if (promises.length) {
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return promises
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}
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if (isPromise) {
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return [defaultValue]
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}
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else {
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return [Promise.resolve(defaultValue)]
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}
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}
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typeData = {
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generator,
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type: dataFunc.type
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}
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}
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break
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}
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return new BasicParallelEnumerable(typeData)
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}

‎src/sync/_private/defaultIfEmpty.ts‎

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import { BasicEnumerable } from "../BasicEnumerable"
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export const defaultIfEmpty = <TSource>(source: Iterable<TSource>, defaultValue: TSource) => {
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function* generator() {
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let found = false
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for (const value of source) {
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found = true
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yield value
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}
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if (!found) {
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yield defaultValue
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}
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}
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return new BasicEnumerable(generator)
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}

‎src/types/IAsyncEnumerable.ts‎

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@@ -24,6 +24,12 @@ export interface IAsyncEnumerable<TSource> extends IAsyncParallel<TSource> {
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* @returns An IAsyncEnumerable<T> that contains the concatenated elements of the two sequences.
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*/
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concatenate(second: IAsyncEnumerable<TSource>): IAsyncEnumerable<TSource>
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/**
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* Returns the elements of an IAsyncEnumerable<T>, or a default valued singleton collection if the sequence is empty.
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* @param defaultValue The value, or Promise that gives back that value, to return if the sequence is empty.
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* @returns An IAsyncEnumerable<T> that contains defaultValue if source is empty; otherwise, source.
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*/
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defaultIfEmpty(defaultValue: TSource | Promise<TSource>): IAsyncEnumerable<TSource>
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/**
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* Returns distinct elements from a sequence by using the default
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* or specified equality comparer to compare values.

‎src/types/IEnumerable.ts‎

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@@ -141,6 +141,12 @@ export interface IEnumerable<TSource> extends Iterable<TSource> {
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* @returns The number of elements in the input sequence.
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*/
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countAsync(predicate: (x: TSource) => Promise<boolean>): Promise<number>
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/**
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* Returns the elements of an IEnumerable<T>, or a default valued singleton collection if the sequence is empty.
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* @param defaultValue The value to return if the sequence is empty.
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* @returns An IEnumerable<T> that contains defaultValue if source is empty; otherwise, source.
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*/
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defaultIfEmpty(defaultValue: TSource): IEnumerable<TSource>
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/**
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* Returns distinct elements from a sequence by using the default or specified equality comparer to compare values.
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* @param comparer An IEqualityComparer<T> to compare values. Optional. Defaults to Strict Equality Comparison.

‎src/types/IParallelEnumerable.ts‎

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@@ -31,6 +31,12 @@ export interface IParallelEnumerable<TSource> extends IAsyncParallel<TSource> {
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* @returns An IParallelEnumerable<T> that contains the concatenated elements of the two sequences.
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*/
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concatenate(second: IAsyncParallel<TSource>): IParallelEnumerable<TSource>
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/**
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* Returns the elements of an IParallelEnumerable<T>, or a default valued singleton collection if the sequence is empty.
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* @param defaultValue The value, or Promise that gives back that value, to return if the sequence is empty.
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* @returns An IParallelEnumerable<T> that contains defaultValue if source is empty; otherwise, source.
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*/
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defaultIfEmpty(defaultValue: TSource | Promise<TSource>): IParallelEnumerable<TSource>
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/**
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* Returns distinct elements from a sequence by using the default or specified equality comparer to compare values.
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* @param comparer An IEqualityComparer<T> to compare values. Optional. Defaults to Strict Equality Comparison.

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