87 lines
2.5 KiB
TypeScript
87 lines
2.5 KiB
TypeScript
/// SPDX-License-Identifier: GPL-3.0-or-later
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/// SPDX-FileCopyrightText: Copyright © 2016-2021 Tony Garnock-Jones <tonyg@leastfixedpoint.com>
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export class SpanResult<T> {
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readonly searchTarget: number;
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readonly start: number;
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readonly items: Array<{ end: number, item: T }> = [];
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constructor(searchTarget: number, start: number) {
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this.searchTarget = searchTarget;
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this.start = start;
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}
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get offset(): number {
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return this.searchTarget - this.start;
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}
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get firstItem(): T {
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return this.items[0].item;
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}
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get lastItem(): T {
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return this.items[this.items.length - 1].item;
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}
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}
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export class SpanIndex<T> {
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readonly index: Array<[number, Array<[number, T]>]> = [];
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get(pos: number): SpanResult<T> | null {
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if (this.index.length === 0) return null;
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let lo = 0;
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let hi = this.index.length;
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// console.log(`\nsearching for ${target}`);
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while (true) {
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if (lo === hi) {
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if (lo === 0) return null;
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const e = this.index[lo - 1];
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if (e[0] > pos) throw new Error("INTERNAL ERROR: bad binary search (1)");
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if (this.index[lo]?.[0] <= pos) throw new Error("INTERNAL ERROR: bad binary search (2)");
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// console.log(`found ${JSON.stringify(e)}, ${JSON.stringify(items[lo] ?? null)}`);
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const r = new SpanResult<T>(pos, e[0]);
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e[1].forEach(([end, item]) => {
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if (pos < end) {
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r.items.push({ end, item });
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}
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});
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return (r.items.length > 0) ? r : null;
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}
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const mid = (lo + hi) >> 1;
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const e = this.index[mid];
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// console.log(`${target} lo ${lo} hi ${hi} mid ${mid} probe ${JSON.stringify([e[0], e[1].target])}`);
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if (e[0] <= pos) {
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lo = mid + 1;
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} else {
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hi = mid;
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}
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}
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}
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}
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export class SpanInfo<T> {
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readonly spans: Map<number, Array<[number, T]>> = new Map();
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add(start: number, end: number, t: T) {
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if (!this.spans.has(start)) {
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this.spans.set(start, []);
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}
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this.spans.get(start)!.push([end, t]);
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}
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index(): SpanIndex<T> {
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const i = new SpanIndex<T>();
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this.spans.forEach((ends, start) => {
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ends.sort((a, b) => a[0] - b[0]);
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i.index.push([start, ends]);
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});
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i.index.sort((a, b) => a[0] - b[0]);
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return i;
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}
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}
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