Checkpoint.

Author: Oren (electricessence)

src/iterables/concat.ts

@@ -0,0 +1,13 @@
+/*
+ * @author electricessence / https://github.com/electricessence/
+ * Licensing: MIT
+ */
+
+import concatThese from './concatThese';
+
+/**
+ * Concatenates the provided sequences.
+ */
+export default function concat<T> (...sequences: Iterable<T>[]): Iterable<T> {
+	return concatThese(sequences);
+}

src/iterables/concatThese.ts

@@ -0,0 +1,17 @@
+/*
+ * @author electricessence / https://github.com/electricessence/
+ * Licensing: MIT
+ */
+
+/**
+ * Concatenates the sequences.
+ */
+export default function* concatThese<T> (sequences: Iterable<Iterable<T>>): Iterable<T> {
+	for(const s of sequences)
+	{
+		for(const e of s)
+		{
+			yield e;
+		}
+	}
+}

src/linq.ts

@@ -3,39 +3,51 @@
  * Licensing: MIT
  */
 
-import {IterableTransform} from './pipe';
+import {IterableFilter, IterableTransform} from './IterableTransform';
 
-export type LinqTransform<TIn, TOut> = (source: Iterable<TIn>) => TOut;
-
-export interface Linqable<T>
-	extends Iterable<T>
-{
-	linq<TResult> (filter: LinqTransform<T, TResult>): TResult;
-}
-
-class Linq<TIn, TOut>
-	implements Linqable<TOut>
+export class Linq<T>
+	implements Iterable<T>
 {
 	constructor (
-		private readonly _source: Iterable<TIn>,
-		private readonly _transform?: IterableTransform<TIn, TOut>)
+		private readonly _source: Iterable<T>)
 	{
 	}
 
-	[Symbol.iterator] (): Iterator<TOut>
+	[Symbol.iterator] (): Iterator<T>
 	{
-		return this._transform(this._source)[Symbol.iterator]();
+		return this._source[Symbol.iterator]();
 	}
 
+	filter (): this
+	filter (...filters: IterableFilter<T>[]): Linq<T>
+	filter (...filters: IterableFilter<T>[]): Linq<T> | this
+	{
+		if(!filters?.length) return this;
+		let iterable = this._source;
+		for(const filter of filters)
+		{
+			iterable = filter(iterable);
+		}
+		return new Linq<T>(iterable);
+	}
 
-	pipe<TResult> (filter: IterableTransform<TOut, TResult>): TResult
+	toArray (): T[]
 	{
-		return new Linq<TOut, TResult>(this, filter);
+		const a: T[] = [];
+		for(const e of this._source)
+		{
+			a.push(e);
+		}
+		return a;
 	}
 
+	resolve<TResolution> (resolution: IterableTransform<T, TResolution>): TResolution
+	{
+		return resolution(this._source);
+	}
 }
 
-export default function linq<T, TResult> (
-	source: Iterable<T>): Pipe<TResult> {
-	return new PipeSource(source, filter);
-}
+// export default function linq<T, TResult> (
+// 	source: Iterable<T>): Pipe<TResult> {
+// 	return new PipeSource(source, filter);
+// }

src/pipe.ts

@@ -5,10 +5,13 @@
 
 /* eslint-disable @typescript-eslint/no-unused-vars */
 
+import ArgumentNullException from '@tsdotnet/exceptions/dist/ArgumentNullException';
+
 /**
  * Returns true if sequence is not empty.
  */
 export default function any<T> (sequence: Iterable<T>): boolean {
+	if(!sequence) throw new ArgumentNullException('sequence');
 	// noinspection LoopStatementThatDoesntLoopJS
 	for(const _ of sequence)
 	{

src/resolutions/any.ts

@@ -3,7 +3,7 @@
  * Licensing: MIT
  */
 
-import IterableTransform from '../IterableTransform';
+import {IterableTransform} from '../IterableTransform';
 import ArgumentOutOfRangeException from '@tsdotnet/exceptions/dist/ArgumentOutOfRangeException';
 import integer from '@tsdotnet/integer';
 

src/resolutions/elementAt.ts

@@ -3,7 +3,7 @@
  * Licensing: MIT
  */
 
-import IterableTransform from '../IterableTransform';
+import {IterableTransform} from '../IterableTransform';
 import integer from '@tsdotnet/integer';
 
 /**

src/resolutions/elementAtOrDefault.ts

@@ -3,14 +3,18 @@
  * Licensing: MIT
  */
 
+import ArgumentNullException from '@tsdotnet/exceptions/dist/ArgumentNullException';
+import InvalidOperationException from '@tsdotnet/exceptions/dist/InvalidOperationException';
+
 /**
  * Returns the first element of a sequence.
  */
-export default function first<T> (elements: Iterable<T>): T {
+export default function first<T> (sequence: Iterable<T>): T {
+	if(!sequence) throw new ArgumentNullException('sequence');
 	// noinspection LoopStatementThatDoesntLoopJS
-	for(const e of elements)
+	for(const e of sequence)
 	{
 		return e;
 	}
-	throw new Error('The sequence is empty.');
+	throw new InvalidOperationException('The sequence is empty.');
 }

src/resolutions/first.ts

@@ -3,10 +3,13 @@
  * Licensing: MIT
  */
 
+import ArgumentNullException from '@tsdotnet/exceptions/dist/ArgumentNullException';
+
 /**
  * Returns the first element of a sequence, or a default value if no element is found.
  */
 export default function firstOrDefault<T> (sequence: Iterable<T>): T | undefined {
+	if(!sequence) throw new ArgumentNullException('sequence');
 	// noinspection LoopStatementThatDoesntLoopJS
 	for(const e of sequence)
 	{

src/resolutions/firstOrDefault.ts

@@ -3,14 +3,17 @@
  * Licensing: MIT
  */
 
+import ArgumentNullException from '@tsdotnet/exceptions/dist/ArgumentNullException';
+
 /**
  * Returns a single, specific element of a sequence.
  */
-export default function single<T> (elements: Iterable<T>): T {
+export default function single<T> (sequence: Iterable<T>): T {
+	if(!sequence) throw new ArgumentNullException('sequence');
 	// noinspection LoopStatementThatDoesntLoopJS
 	let i = 0;
 	let value: T;
-	for(const e of elements)
+	for(const e of sequence)
 	{
 		if(i++) throw new Error('Sequence contains more than one element.');
 		value = e;

src/resolutions/single.ts

@@ -3,14 +3,17 @@
  * Licensing: MIT
  */
 
+import ArgumentNullException from '@tsdotnet/exceptions/dist/ArgumentNullException';
+
 /**
  * Returns a single, specific element of a sequence, or a default value if that element is not found.
  */
-export default function singleOrDefault<T> (elements: Iterable<T>): T | undefined {
+export default function singleOrDefault<T> (sequence: Iterable<T>): T | undefined {
+	if(!sequence) throw new ArgumentNullException('sequence');
 	// noinspection LoopStatementThatDoesntLoopJS
 	let i = 0;
 	let value: T;
-	for(const e of elements)
+	for(const e of sequence)
 	{
 		if(i++) throw new Error('Sequence contains more than one element.');
 		value = e;