96 lines
2.8 KiB
TypeScript
96 lines
2.8 KiB
TypeScript
//---------------------------------------------------------------------------
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// @syndicate-lang/core, an implementation of Syndicate dataspaces for JS.
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// Copyright (C) 2016-2021 Tony Garnock-Jones <tonyg@leastfixedpoint.com>
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <https://www.gnu.org/licenses/>.
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//---------------------------------------------------------------------------
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// Bags and Deltas (which are Bags where item-counts can be negative).
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import { Value, Set, Dictionary } from 'preserves';
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export enum ChangeDescription {
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PRESENT_TO_ABSENT = -1,
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ABSENT_TO_ABSENT = 0,
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ABSENT_TO_PRESENT = 1,
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PRESENT_TO_PRESENT = 2,
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}
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export class Bag {
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_items: Dictionary<number>;
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constructor(s?: Set) {
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this._items = new Dictionary();
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if (s) s.forEach((v) => this._items.set(v, 1));
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}
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get(key: Value): number {
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return this._items.get(key, 0) as number;
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}
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change(key: Value, delta: number, clamp: boolean = false): ChangeDescription {
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let oldCount = this.get(key);
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let newCount = oldCount + delta;
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if (clamp) {
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newCount = Math.max(0, newCount);
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}
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if (newCount === 0) {
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this._items.delete(key);
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return (oldCount === 0)
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? ChangeDescription.ABSENT_TO_ABSENT
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: ChangeDescription.PRESENT_TO_ABSENT;
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} else {
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this._items.set(key, newCount);
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return (oldCount === 0)
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? ChangeDescription.ABSENT_TO_PRESENT
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: ChangeDescription.PRESENT_TO_PRESENT;
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}
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}
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clear() {
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this._items = new Dictionary();
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}
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includes(key: Value): boolean {
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return this._items.has(key);
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}
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get size(): number {
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return this._items.size;
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}
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keys(): IterableIterator<Value> {
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return this._items.keys();
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}
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entries(): IterableIterator<[Value, number]> {
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return this._items.entries();
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}
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forEach(f: (count: number, value: Value) => void) {
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this._items.forEach(f);
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}
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snapshot(): Dictionary<number> {
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return this._items.clone();
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}
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clone(): Bag {
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const b = new Bag();
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b._items = this._items.clone();
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return b;
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}
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}
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