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233 lines
5.5 KiB
233 lines
5.5 KiB
export function* chunk<T>(source: T[], size: number): Iterable<T[]> {
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let chunk: T[] = [];
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for (const item of source) {
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if (chunk.length < size) {
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chunk.push(item);
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continue;
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}
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yield chunk;
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chunk = [];
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}
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if (chunk.length > 0) {
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yield chunk;
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}
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}
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export function* chunkByStringLength(source: string[], maxLength: number): Iterable<string[]> {
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let chunk: string[] = [];
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let chunkLength = 0;
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for (const item of source) {
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let length = chunkLength + item.length;
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if (length > maxLength && chunk.length > 0) {
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yield chunk;
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chunk = [];
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length = item.length;
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}
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chunk.push(item);
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chunkLength = length;
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}
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if (chunk.length > 0) {
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yield chunk;
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}
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}
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export function count<T>(source: IterableIterator<T>, predicate?: (item: T) => boolean): number {
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let count = 0;
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let next: IteratorResult<T>;
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while (true) {
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next = source.next();
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if (next.done) break;
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if (predicate === undefined || predicate(next.value)) {
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count++;
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}
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}
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return count;
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}
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export function every<T>(source: Iterable<T> | IterableIterator<T>, predicate: (item: T) => boolean): boolean {
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for (const item of source) {
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if (!predicate(item)) return false;
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}
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return true;
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}
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export function filter<T>(source: Iterable<T | undefined | null> | IterableIterator<T | undefined | null>): Iterable<T>;
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export function filter<T>(source: Iterable<T> | IterableIterator<T>, predicate: (item: T) => boolean): Iterable<T>;
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export function filter<T, U extends T>(
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source: Iterable<T> | IterableIterator<T>,
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predicate: (item: T) => item is U,
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): Iterable<U>;
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export function* filter<T, U extends T = T>(
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source: Iterable<T> | IterableIterator<T>,
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predicate?: ((item: T) => item is U) | ((item: T) => boolean),
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): Iterable<T | U> {
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if (predicate === undefined) {
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for (const item of source) {
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if (item != null) yield item;
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}
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} else {
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for (const item of source) {
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if (predicate(item)) yield item;
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}
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}
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}
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export function* filterMap<T, TMapped>(
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source: Iterable<T> | IterableIterator<T>,
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predicateMapper: (item: T) => TMapped | undefined | null,
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): Iterable<TMapped> {
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for (const item of source) {
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const mapped = predicateMapper(item);
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if (mapped != null) yield mapped;
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}
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}
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export function forEach<T>(source: Iterable<T> | IterableIterator<T>, fn: (item: T, index: number) => void): void {
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let i = 0;
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for (const item of source) {
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fn(item, i);
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i++;
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}
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}
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export function find<T>(source: Iterable<T> | IterableIterator<T>, predicate: (item: T) => boolean): T | null {
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for (const item of source) {
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if (predicate(item)) return item;
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}
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return null;
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}
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export function findIndex<T>(source: Iterable<T> | IterableIterator<T>, predicate: (item: T) => boolean): number {
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let i = 0;
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for (const item of source) {
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if (predicate(item)) return i;
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i++;
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}
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return -1;
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}
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export function first<T>(source: Iterable<T> | IterableIterator<T>): T | undefined {
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return source[Symbol.iterator]().next().value as T | undefined;
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}
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export function* flatMap<T, TMapped>(
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source: Iterable<T> | IterableIterator<T>,
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mapper: (item: T) => Iterable<TMapped>,
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): IterableIterator<TMapped> {
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for (const item of source) {
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yield* mapper(item);
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}
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}
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export function has<T>(source: Iterable<T> | IterableIterator<T>, item: T): boolean {
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return some(source, i => i === item);
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}
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export function isIterable(source: Iterable<any>): boolean {
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return typeof source[Symbol.iterator] === 'function';
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}
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export function join(source: Iterable<any>, separator: string): string {
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const iterator = source[Symbol.iterator]();
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let next = iterator.next();
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if (next.done) return '';
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let result = String(next.value);
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while (true) {
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next = iterator.next();
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if (next.done) break;
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result += `${separator}${next.value}`;
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}
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return result;
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}
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export function last<T>(source: Iterable<T>): T | undefined {
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let item: T | undefined;
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for (item of source) {
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/* noop */
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}
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return item;
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}
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export function* map<T, TMapped>(
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source: Iterable<T> | IterableIterator<T>,
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mapper: (item: T) => TMapped,
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): IterableIterator<TMapped> {
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for (const item of source) {
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yield mapper(item);
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}
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}
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export function next<T>(source: IterableIterator<T>): T {
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return source.next().value as T;
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}
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export function* skip<T>(source: Iterable<T> | IterableIterator<T>, count: number): IterableIterator<T> {
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let i = 0;
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for (const item of source) {
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if (i >= count) yield item;
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i++;
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}
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}
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export function some<T>(source: Iterable<T> | IterableIterator<T>, predicate: (item: T) => boolean): boolean {
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for (const item of source) {
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if (predicate(item)) return true;
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}
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return false;
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}
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export function* take<T>(source: Iterable<T> | IterableIterator<T>, count: number): Iterable<T> {
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if (count > 0) {
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let i = 0;
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for (const item of source) {
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yield item;
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i++;
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if (i >= count) break;
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}
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}
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}
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export function* union<T>(...sources: (Iterable<T> | IterableIterator<T>)[]): Iterable<T> {
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for (const source of sources) {
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for (const item of source) {
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yield item;
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}
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}
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}
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export function uniqueBy<TKey, TValue>(
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source: Iterable<TValue> | IterableIterator<TValue>,
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uniqueKey: (item: TValue) => TKey,
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onDuplicate: (original: TValue, current: TValue) => TValue | void,
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): IterableIterator<TValue> {
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const uniques = new Map<TKey, TValue>();
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for (const current of source) {
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const value = uniqueKey(current);
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const original = uniques.get(value);
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if (original === undefined) {
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uniques.set(value, current);
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} else {
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const updated = onDuplicate(original, current);
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if (updated !== undefined) {
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uniques.set(value, updated);
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}
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}
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}
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return uniques.values();
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}
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