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Reverted ASet
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Zakary Timson
2025-07-07 14:34:29 -04:00
parent 59bce9d28d
commit 388a09718b
1 changed files with 43 additions and 165 deletions
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208
src/aset.ts
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@ -2,16 +2,11 @@ import {isEqual} from './objects.ts';
/**
* An array which functions as a set. It guarantees unique elements
* and provides set functions for comparisons.
*
* This optimized version uses a Map internally for efficient lookups
* while maintaining an array for ordered iteration and array-like methods.
* and provides set functions for comparisons
*/
export class ASet<T> extends Array<T> {
private readonly _valueMap: Map<string, T>; // Stores string representation -> actual value for quick lookups
export class ASet<T> extends Array {
/** Number of elements in set */
get size(): number {
get size() {
return this.length;
}
@ -21,236 +16,119 @@ export class ASet<T> extends Array<T> {
*/
constructor(elements: T[] = []) {
super();
this._valueMap = new Map<string, T>(); // Initialize the map
if (Array.isArray(elements)) {
if(!!elements?.['forEach'])
elements.forEach(el => this.add(el));
}
}
/**
* Helper to generate a unique key for the map.
* This is crucial for using a Map with custom equality.
* For primitive types, `String(el)` is often sufficient.
* For objects, you'll need a robust serialization or a unique ID.
* If isEqual handles deep equality, the key generation must reflect that.
*
* @param el Element to generate a key for
* @returns A string key
*/
private _getKey(el: T): string {
// IMPORTANT: This is a critical point for isEqual to work correctly with Map.
// If isEqual performs deep comparison, _getKey must produce the same string
// for deeply equal objects. JSON.stringify can work for simple objects,
// but can fail for objects with circular references, functions, or undefined values.
// For more complex scenarios, consider a library like 'fast-json-stable-stringify'
// or a custom hashing function that respects isEqual.
try {
return JSON.stringify(el);
} catch (e) {
// Fallback for objects that cannot be stringified (e.g., circular structures)
// This might lead to less optimal performance or incorrect uniqueness for such objects.
// A more robust solution for complex objects might involve unique object IDs
// or a custom comparison function for Map keys if JS allowed it.
return String(el);
}
}
/**
* Add elements to set if unique.
* Optimized to use the internal Map for O(1) average time lookups.
* Add elements to set if unique
* @param items
*/
add(...items: T[]): this {
for (const item of items) {
const key = this._getKey(item);
if (!this._valueMap.has(key)) {
// Also ensures isEqual is respected by checking against existing values
let found = false;
for (const existingItem of this) {
if (isEqual(existingItem, item)) {
found = true;
break;
}
}
if (!found) {
super.push(item); // Add to the array
this._valueMap.set(key, item); // Add to the map
}
}
}
add(...items: T[]) {
items.filter(el => !this.has(el)).forEach(el => this.push(el));
return this;
}
/**
* Remove all elements.
* Optimized to clear both the array and the map.
* Remove all elements
*/
clear(): this {
super.splice(0, this.length);
this._valueMap.clear();
clear() {
this.splice(0, this.length);
return this;
}
/**
* Delete elements from set.
* Optimized to use the internal Map for O(1) average time lookups for key existence.
* Still requires array splice which can be O(N) in worst case for shifting.
* Delete elements from set
* @param items Elements that will be deleted
*/
delete(...items: T[]): this {
for (const item of items) {
const key = this._getKey(item);
if (this._valueMap.has(key)) {
// Find the actual element in the array using isEqual
const index = super.findIndex((el: T) => isEqual(el, item));
if (index !== -1) {
super.splice(index, 1); // Remove from the array
this._valueMap.delete(key); // Remove from the map
}
}
}
delete(...items: T[]) {
items.forEach(el => {
const index = this.indexOf(el);
if(index != -1) this.splice(index, 1);
})
return this;
}
/**
* Create list of elements this set has which the comparison set does not.
* Optimized to use `has` which is now faster.
* Create list of elements this set has which the comparison set does not
* @param {ASet<T>} set Set to compare against
* @return {ASet<T>} Different elements
*/
difference(set: ASet<T>): ASet<T> {
const result = new ASet<T>();
for (const el of this) {
if (!set.has(el)) {
result.add(el);
}
}
return result;
difference(set: ASet<T>) {
return new ASet<T>(this.filter(el => !set.has(el)));
}
/**
* Check if set includes element.
* Optimized to use the internal Map for O(1) average time lookups.
* Check if set includes element
* @param {T} el Element to look for
* @return {boolean} True if element was found, false otherwise
*/
has(el: T): boolean {
const key = this._getKey(el);
// First check map for existence. If it exists, then verify with isEqual
// as the key might be generic but isEqual is precise.
if (this._valueMap.has(key)) {
const storedValue = this._valueMap.get(key);
// This second check with isEqual is necessary if _getKey doesn't perfectly
// represent the equality criteria of isEqual, which is often the case
// for complex objects where JSON.stringify might produce different strings
// for isEqual objects (e.g., key order in objects).
// If _getKey is guaranteed to produce identical keys for isEqual objects,
// this isEqual check can be simplified or removed for performance.
return isEqual(storedValue, el);
}
return false;
has(el: T) {
return this.indexOf(el) != -1;
}
/**
* Find index number of element, or -1 if it doesn't exist. Matches by equality not reference.
* This method still inherently needs to iterate the array to find the *index*.
* While `has` can be O(1), `indexOf` for custom equality remains O(N).
* Find index number of element, or -1 if it doesn't exist. Matches by equality not reference
*
* @param {T} search Element to find
* @param {number} fromIndex Starting index position
* @return {number} Element index number or -1 if missing
*/
indexOf(search: T, fromIndex?: number): number {
// Can't use the map directly for index lookup, must iterate the array
return super.findIndex((el: T) => isEqual(el, search), fromIndex);
}
/**
* Create list of elements this set has in common with the comparison set.
* Optimized to use `has` which is now faster.
* Create list of elements this set has in common with the comparison set
* @param {ASet<T>} set Set to compare against
* @return {ASet<T>} Set of common elements
* @return {boolean} Set of common elements
*/
intersection(set: ASet<T>): ASet<T> {
const result = new ASet<T>();
// Iterate over the smaller set for efficiency
const [smallerSet, largerSet] = this.size < set.size ? [this, set] : [set, this];
for (const el of smallerSet) {
if (largerSet.has(el)) {
result.add(el);
}
}
return result;
intersection(set: ASet<T>) {
return new ASet<T>(this.filter(el => set.has(el)));
}
/**
* Check if this set has no elements in common with the comparison set.
* Optimized to use `intersection` and check its size.
* Check if this set has no elements in common with the comparison set
* @param {ASet<T>} set Set to compare against
* @return {boolean} True if nothing in common, false otherwise
*/
isDisjointFrom(set: ASet<T>): boolean {
return this.intersection(set).size === 0;
isDisjointFrom(set: ASet<T>) {
return this.intersection(set).size == 0;
}
/**
* Check if all elements in this set are included in the comparison set.
* Optimized to use `has` which is now faster.
* Check if all elements in this set are included in the comparison set
* @param {ASet<T>} set Set to compare against
* @return {boolean} True if all elements are included, false otherwise
*/
isSubsetOf(set: ASet<T>): boolean {
if (this.size > set.size) { // A larger set cannot be a subset of a smaller one
return false;
}
for (const el of this) {
if (!set.has(el)) {
return false;
}
}
return true;
isSubsetOf(set: ASet<T>) {
return this.findIndex(el => !set.has(el)) == -1;
}
/**
* Check if all elements from comparison set are included in this set.
* Optimized to use `has` which is now faster.
* Check if all elements from comparison set are included in this set
* @param {ASet<T>} set Set to compare against
* @return {boolean} True if all elements are included, false otherwise
*/
isSuperset(set: ASet<T>): boolean {
if (this.size < set.size) { // A smaller set cannot be a superset of a larger one
return false;
}
for (const el of set) {
if (!this.has(el)) {
return false;
}
}
return true;
isSuperset(set: ASet<T>) {
return set.findIndex(el => !this.has(el)) == -1;
}
/**
* Create list of elements that are only in one set but not both (XOR).
* Uses optimized `difference` method.
* Create list of elements that are only in one set but not both (XOR)
* @param {ASet<T>} set Set to compare against
* @return {ASet<T>} New set of unique elements
*/
symmetricDifference(set: ASet<T>): ASet<T> {
return new ASet<T>([...this.difference(set), ...set.difference(this)]);
symmetricDifference(set: ASet<T>) {
return new ASet([...this.difference(set), ...set.difference(this)]);
}
/**
* Create joined list of elements included in this & the comparison set.
* Uses optimized `add` method.
* @param {ASet<T> | Array<T>} set Set to join
* Create joined list of elements included in this & the comparison set
* @param {ASet<T>} set Set join
* @return {ASet<T>} New set of both previous sets combined
*/
union(set: ASet<T> | Array<T>): ASet<T> {
const result = new ASet<T>(this);
result.add(...Array.from(set));
return result;
union(set: ASet<T> | Array<T>) {
return new ASet([...this, ...set]);
}
}