87 lines
2.0 KiB
JavaScript
87 lines
2.0 KiB
JavaScript
import { filterHelper, flatMapHelper, joinHelper, mapHelper, nilHelper, takeNHelper, takeWhileHelper, } from './StreamHelpers.js';
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const safeSymbolIterator = Symbol.iterator;
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export class Stream {
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static nil() {
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return new Stream(nilHelper());
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}
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static of(...elements) {
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return new Stream(elements[safeSymbolIterator]());
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}
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constructor(g) {
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this.g = g;
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}
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next() {
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return this.g.next();
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}
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[Symbol.iterator]() {
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return this.g;
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}
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map(f) {
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return new Stream(mapHelper(this.g, f));
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}
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flatMap(f) {
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return new Stream(flatMapHelper(this.g, f));
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}
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dropWhile(f) {
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let foundEligible = false;
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function* helper(v) {
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if (foundEligible || !f(v)) {
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foundEligible = true;
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yield v;
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}
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}
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return this.flatMap(helper);
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}
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drop(n) {
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if (n <= 0) {
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return this;
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}
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let idx = 0;
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function helper() {
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return idx++ < n;
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}
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return this.dropWhile(helper);
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}
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takeWhile(f) {
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return new Stream(takeWhileHelper(this.g, f));
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}
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take(n) {
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return new Stream(takeNHelper(this.g, n));
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}
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filter(f) {
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return new Stream(filterHelper(this.g, f));
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}
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every(f) {
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for (const v of this.g) {
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if (!f(v)) {
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return false;
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}
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}
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return true;
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}
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has(f) {
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for (const v of this.g) {
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if (f(v)) {
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return [true, v];
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}
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}
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return [false, null];
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}
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join(...others) {
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return new Stream(joinHelper(this.g, others));
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}
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getNthOrLast(nth) {
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let remaining = nth;
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let last = null;
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for (const v of this.g) {
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if (remaining-- === 0)
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return v;
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last = v;
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}
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return last;
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}
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}
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export function stream(g) {
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return new Stream(g);
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}
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