ts-data-forge
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text/typescript
import { Optional } from '../functional/index.mjs';
import { asUint32 } from '../number/index.mjs';
import { tp, unknownToString } from '../others/index.mjs';
/**
* Interface for an immutable map with O(1) lookup performance and functional programming patterns.
*
* This interface defines all methods and properties available on IMap instances. All operations
* that modify the map return new IMap instances, preserving immutability. The underlying implementation
* uses JavaScript's native Map for O(1) average-case performance on get, set, has, and delete operations.
*
* **Immutability Guarantees:**
* - All mutation operations (set, delete, update) return new IMap instances
* - Original IMap instances are never modified
* - Safe for concurrent access and functional programming patterns
*
* **Performance Characteristics:**
* - get/has/delete: O(1) average case
* - set: O(1) average case
* - map/filter operations: O(n)
* - Iteration: O(n)
*
* @template K The type of the keys in the map. Must extend MapSetKeyType (string, number, boolean, etc.)
* @template V The type of the values in the map.
*
* @example
* ```typescript
* // This is a type alias describing an interface, so it's not directly instantiated.
* // See IMap.create for examples of creating IMap instances that conform to this interface.
*
* // Example of how you might use a variable that implements this structure:
* declare const userMap: IMap<string, User>;
*
* // Immutable operations - original map is never modified
* const hasUser = userMap.has("alice"); // O(1)
* const user = userMap.get("alice").unwrapOr(defaultUser); // O(1)
* const newMap = userMap.set("bob", newUser); // O(1) - returns new IMap
* const updated = userMap.update("alice", u => ({ ...u, active: true })); // O(1)
*
* // Functional transformations
* const activeUsers = userMap.map((user, id) => ({ ...user, lastSeen: Date.now() })); // O(n)
* ```
*/
type IMapInterface<K extends MapSetKeyType, V> = Readonly<{
// Getting information
/** The number of elements in the map. */
size: SizeType.Arr;
/**
* Checks if a key exists in the map.
* Allows for wider literal types for keys during checking.
* @param key The key to check.
* @returns `true` if the key exists, `false` otherwise.
*/
has: (key: K | (WidenLiteral<K> & {})) => boolean;
/**
* Retrieves the value associated with a key.
* @param key The key to retrieve.
* @returns The value associated with the key wrapped with Optional.some, or `Optional.none` if the key does not exist.
*/
get: (key: K | (WidenLiteral<K> & {})) => Optional<V>;
// Reducing a value
/**
* Checks if all elements in the map satisfy a predicate.
* @param predicate A function to test each key-value pair.
* @returns `true` if all elements satisfy the predicate, `false` otherwise.
*/
every: ((predicate: (value: V, key: K) => boolean) => boolean) &
/**
* Checks if all elements in the map satisfy a type predicate.
* Narrows the type of values in the map if the predicate returns true for all elements.
* @template W The narrowed type of the values.
* @param predicate A type predicate function.
* @returns `true` if all elements satisfy the predicate, `false` otherwise.
*/
(<W extends V>(
predicate: (value: V, key: K) => value is W,
) => this is IMap<K, W>);
/**
* Checks if at least one element in the map satisfies a predicate.
* @param predicate A function to test each key-value pair.
* @returns `true` if at least one element satisfies the predicate, `false` otherwise.
*/
some: (predicate: (value: V, key: K) => boolean) => boolean;
// Mutation
/**
* Deletes a key-value pair from the map.
* @param key The key to delete.
* @returns A new IMap instance without the specified key.
*/
delete: (key: K) => IMap<K, V>;
/**
* Sets a key-value pair in the map.
* @param key The key to set.
* @param value The value to associate with the key.
* @returns A new IMap instance with the specified key-value pair.
*/
set: (key: K, value: V) => IMap<K, V>;
/**
* Updates the value associated with a key using an updater function.
* @param key The key whose value to update.
* @param updater A function that takes the current value and returns the new value.
* @returns A new IMap instance with the updated value.
*/
update: (key: K, updater: (value: V) => V) => IMap<K, V>;
/**
* Applies a series of mutations to the map.
* @param actions An array of mutation actions (delete, set, or update).
* @returns A new IMap instance with all mutations applied.
*/
withMutations: (
actions: readonly Readonly<
| { type: 'delete'; key: K }
| { type: 'set'; key: K; value: V }
| { type: 'update'; key: K; updater: (value: V) => V }
>[],
) => IMap<K, V>;
// Sequence algorithms
/**
* Maps the values of the map to new values.
* @template V2 The type of the new values.
* @param mapFn A function that maps a value and key to a new value.
* @returns A new IMap instance with mapped values.
*/
map: <V2>(mapFn: (value: V, key: K) => V2) => IMap<K, V2>;
/**
* Maps the keys of the map to new keys.
* @template K2 The type of the new keys.
* @param mapFn A function that maps a key to a new key.
* @returns A new IMap instance with mapped keys and original values.
*/
mapKeys: <K2 extends MapSetKeyType>(mapFn: (key: K) => K2) => IMap<K2, V>;
/**
* Maps the entries (key-value pairs) of the map to new entries.
* @template K2 The type of the new keys in the entries.
* @template V2 The type of the new values in the entries.
* @param mapFn A function that maps an entry to a new entry.
* @returns A new IMap instance with mapped entries.
*/
mapEntries: <K2 extends MapSetKeyType, V2>(
mapFn: (entry: readonly [K, V]) => readonly [K2, V2],
) => IMap<K2, V2>;
// Side effects
/**
* Executes a callback function for each key-value pair in the map.
* @param callbackfn A function to execute for each element.
*/
forEach: (callbackfn: (value: V, key: K) => void) => void;
// Iterators
/**
* Returns an iterator for the keys in the map.
* @returns An iterable iterator of keys.
*/
keys: () => IterableIterator<K>;
/**
* Returns an iterator for the values in the map.
* @returns An iterable iterator of values.
*/
values: () => IterableIterator<V>;
/**
* Returns an iterator for the entries (key-value pairs) in the map.
* @returns An iterable iterator of entries.
*/
entries: () => IterableIterator<readonly [K, V]>;
// Conversion
/**
* Converts the keys of the map to an array.
* @returns A readonly array of keys.
*/
toKeysArray: () => readonly K[];
/**
* Converts the values of the map to an array.
* @returns A readonly array of values.
*/
toValuesArray: () => readonly V[];
/**
* Converts the entries (key-value pairs) of the map to an array.
* @returns A readonly array of entries.
*/
toEntriesArray: () => readonly (readonly [K, V])[];
/**
* Converts the map to an array of entries (key-value pairs).
* Alias for `toEntriesArray`.
* @returns A readonly array of entries.
*/
toArray: () => readonly (readonly [K, V])[];
/**
* Returns the underlying readonly JavaScript Map.
* @returns The raw ReadonlyMap instance.
*/
toRawMap: () => ReadonlyMap<K, V>;
}>;
/**
* Represents an immutable map with high-performance operations and functional programming support.
*
* IMap is a persistent data structure that provides all the functionality of JavaScript's Map
* while maintaining immutability. All operations that would normally mutate the map instead
* return new IMap instances, making it safe for functional programming and concurrent access.
*
* **Key Features:**
* - **Immutable**: All mutation operations return new instances
* - **High Performance**: O(1) average-case for get/set/has/delete operations
* - **Type Safe**: Full TypeScript support with generic key/value types
* - **Iterable**: Implements standard JavaScript iteration protocols
* - **Functional**: Rich API for map, filter, reduce-style operations
*
* **When to Use:**
* - State management in functional applications
* - Caching with immutable guarantees
* - Data structures that need to be shared across components
* - When you need Map functionality but want immutability
*
* @template K The type of the keys in the map. Must extend MapSetKeyType.
* @template V The type of the values in the map.
*
* @example
* ```typescript
* // Create an immutable map with initial data
* let userPreferences = IMap.create<string, UserPreference>([
* ["theme", { value: "dark", lastModified: Date.now() }],
* ["language", { value: "en", lastModified: Date.now() }]
* ]);
*
* console.log(userPreferences.get("theme").unwrapOr(defaultPreference));
* console.log(userPreferences.size); // Output: 2
*
* // All operations return new instances - original is unchanged
* const updated = userPreferences
* .set("notifications", { value: true, lastModified: Date.now() })
* .update("theme", pref => ({ ...pref, value: "light" }));
*
* console.log(userPreferences.has("notifications")); // false (original unchanged)
* console.log(updated.has("notifications")); // true (new instance)
*
* // Efficient iteration and transformation
* for (const [key, preference] of updated) {
* console.log(`${key}: ${preference.value}`);
* }
*
* // Functional transformations
* const withTimestamps = updated.map((pref, key) => ({
* ...pref,
* accessedAt: Date.now()
* }));
*
* // Type-safe operations with narrowing
* const stringKeys = IMap.create<number | string, any>([[1, "a"], ["b", 2]]);
* const onlyStringKeys = stringKeys.mapKeys(key =>
* typeof key === "string" ? key : key.toString()
* );
* ```
*/
export type IMap<K extends MapSetKeyType, V> = Iterable<readonly [K, V]> &
IMapInterface<K, V>;
/**
* Provides utility functions for IMap.
*/
export namespace IMap {
/**
* Creates a new IMap instance from an iterable of key-value pairs.
*
* This factory function accepts any iterable of [key, value] tuples, including arrays,
* JavaScript Maps, other IMaps, or custom iterables. The resulting IMap will contain
* all the entries from the input iterable.
*
* **Performance:** O(n) where n is the number of entries in the iterable.
*
* @template K The type of the keys. Must extend MapSetKeyType.
* @template V The type of the values.
* @param iterable An iterable of key-value pairs (e.g., Array, Map, IMap, etc.)
* @returns A new IMap instance containing all entries from the iterable.
*
* @example
* ```typescript
* // From array of tuples
* const userScores = IMap.create<string, number>([
* ["alice", 95],
* ["bob", 87],
* ["charlie", 92]
* ]);
* console.log(userScores.get("alice").unwrap()); // Output: 95
*
* // From JavaScript Map
* const jsMap = new Map([["config", { debug: true }], ["env", "production"]]);
* const config = IMap.create(jsMap);
* console.log(config.get("env").unwrap()); // Output: "production"
*
* // From another IMap (creates a copy)
* const originalMap = IMap.create<string, boolean>([["enabled", true]]);
* const copiedMap = IMap.create(originalMap);
* console.log(copiedMap.get("enabled").unwrap()); // Output: true
*
* // Empty map
* const emptyMap = IMap.create<string, number>([]);
* console.log(emptyMap.size); // Output: 0
*
* // From custom iterable
* function* generateEntries(): Generator<[string, number]> {
* for (const i of range(3)) {
* yield [`item${i}`, i * 10];
* }
* }
* const generatedMap = IMap.create(generateEntries());
* console.log(generatedMap.size); // Output: 3
* ```
*/
export const create = <K extends MapSetKeyType, V>(
iterable: Iterable<readonly [K, V]>,
): IMap<K, V> => new IMapClass<K, V>(iterable);
/**
* Checks if two IMap instances are structurally equal.
*
* Two IMaps are considered equal if they have the same size and contain exactly the same
* key-value pairs. The order of entries does not matter for equality comparison.
* Values are compared using JavaScript's `===` operator.
*
* **Performance:** O(n) where n is the size of the smaller map.
*
* @template K The type of the keys.
* @template V The type of the values.
* @param a The first IMap instance to compare.
* @param b The second IMap instance to compare.
* @returns `true` if the maps contain exactly the same key-value pairs, `false` otherwise.
*
* @example
* ```typescript
* // Basic equality comparison
* const preferences1 = IMap.create<string, boolean>([
* ["darkMode", true],
* ["notifications", false]
* ]);
* const preferences2 = IMap.create<string, boolean>([
* ["darkMode", true],
* ["notifications", false]
* ]);
* const preferences3 = IMap.create<string, boolean>([
* ["notifications", false],
* ["darkMode", true] // Order doesn't matter
* ]);
*
* console.log(IMap.equal(preferences1, preferences2)); // true
* console.log(IMap.equal(preferences1, preferences3)); // true (order doesn't matter)
*
* // Different values
* const preferences4 = IMap.create<string, boolean>([
* ["darkMode", false], // Different value
* ["notifications", false]
* ]);
* console.log(IMap.equal(preferences1, preferences4)); // false
*
* // Different keys
* const preferences5 = IMap.create<string, boolean>([
* ["darkMode", true],
* ["sounds", false] // Different key
* ]);
* console.log(IMap.equal(preferences1, preferences5)); // false
*
* // Empty maps
* const empty1 = IMap.create<string, number>([]);
* const empty2 = IMap.create<string, number>([]);
* console.log(IMap.equal(empty1, empty2)); // true
*
* // Note: For deep equality of object values, use a custom comparison
* const users1 = IMap.create<string, User>([["1", { name: "Alice" }]]);
* const users2 = IMap.create<string, User>([["1", { name: "Alice" }]]);
* console.log(IMap.equal(users1, users2)); // false (different object references)
* ```
*/
export const equal = <K extends MapSetKeyType, V>(
a: IMap<K, V>,
b: IMap<K, V>,
): boolean => a.size === b.size && a.every((v, k) => b.get(k) === v);
}
/**
* Internal class implementation for IMap providing immutable map operations.
*
* This class implements the IMap interface using JavaScript's native Map as the underlying
* storage mechanism for optimal performance. All mutation operations create new instances
* rather than modifying the existing map, ensuring immutability.
*
* **Implementation Details:**
* - Uses ReadonlyMap<K, V> internally for type safety and performance
* - Implements copy-on-write semantics for efficiency
* - Provides optional debug messaging for development
*
* @template K The type of the keys. Must extend MapSetKeyType.
* @template V The type of the values.
* @implements IMap
* @implements Iterable
* @internal This class should not be used directly. Use IMap.create() instead.
*/
class IMapClass<K extends MapSetKeyType, V>
implements IMap<K, V>, Iterable<readonly [K, V]>
{
readonly #map: ReadonlyMap<K, V>;
readonly #showNotFoundMessage: boolean;
/**
* Constructs an IMapClass instance with the given entries.
*
* @param iterable An iterable of key-value pairs to populate the map.
* @param showNotFoundMessage Whether to log warning messages when operations
* are performed on non-existent keys. Useful for debugging.
* Defaults to false for production use.
* @internal Use IMap.create() instead of calling this constructor directly.
*/
constructor(
iterable: Iterable<readonly [K, V]>,
showNotFoundMessage: boolean = false,
) {
this.#map = new Map(iterable);
this.#showNotFoundMessage = showNotFoundMessage;
}
/** @inheritdoc */
get size(): SizeType.Arr {
return asUint32(this.#map.size);
}
/** @inheritdoc */
has(key: K | (WidenLiteral<K> & {})): boolean {
// eslint-disable-next-line @typescript-eslint/no-unsafe-type-assertion
return this.#map.has(key as K);
}
/** @inheritdoc */
get(key: K | (WidenLiteral<K> & {})): Optional<V> {
if (!this.has(key)) return Optional.none;
// eslint-disable-next-line @typescript-eslint/no-unsafe-type-assertion, @typescript-eslint/no-non-null-assertion
return Optional.some(this.#map.get(key as K)!);
}
/** @inheritdoc */
every<W extends V>(
predicate: (value: V, key: K) => value is W,
): this is IMap<K, W>;
/** @inheritdoc */
every(predicate: (value: V, key: K) => boolean): boolean;
/** @inheritdoc */
every(predicate: (value: V, key: K) => boolean): boolean {
for (const [k, v] of this.entries()) {
if (!predicate(v, k)) return false;
}
return true;
}
/** @inheritdoc */
some(predicate: (value: V, key: K) => boolean): boolean {
for (const [k, v] of this.entries()) {
if (predicate(v, k)) return true;
}
return false;
}
/** @inheritdoc */
delete(key: K): IMap<K, V> {
if (!this.has(key)) {
if (this.#showNotFoundMessage) {
const keyStr = unknownToString(key);
console.warn(`IMap.delete: key not found: ${keyStr}`);
}
return this;
}
return IMap.create(
Array.from(this.#map).filter(([k]) => !Object.is(k, key)),
);
}
/** @inheritdoc */
set(key: K, value: V): IMap<K, V> {
if (value === this.get(key)) return this; // has no changes
if (!this.has(key)) {
return IMap.create([...this.#map, tp(key, value)]);
} else {
return IMap.create(
Array.from(this.#map, ([k, v]) => tp(k, Object.is(k, key) ? value : v)),
);
}
}
/** @inheritdoc */
update(key: K, updater: (value: V) => V): IMap<K, V> {
const curr = this.get(key);
if (Optional.isNone(curr)) {
if (this.#showNotFoundMessage) {
const keyStr = unknownToString(key);
console.warn(`IMap.update: key not found: ${keyStr}`);
}
return this;
}
return IMap.create(
Array.from(this.#map, ([k, v]) =>
tp(k, Object.is(k, key) ? updater(curr.value) : v),
),
);
}
/** @inheritdoc */
withMutations(
actions: readonly Readonly<
| { type: 'delete'; key: K }
| { type: 'set'; key: K; value: V }
| { type: 'update'; key: K; updater: (value: V) => V }
>[],
): IMap<K, V> {
const mut_result = new Map<K, V>(this.#map);
for (const action of actions) {
switch (action.type) {
case 'delete':
mut_result.delete(action.key);
break;
case 'set':
mut_result.set(action.key, action.value);
break;
case 'update': {
const { key } = action;
const curr = mut_result.get(key);
if (!mut_result.has(key) || curr === undefined) {
if (this.#showNotFoundMessage) {
const keyStr = unknownToString(key);
console.warn(`IMap.withMutations: key not found: ${keyStr}`);
}
break;
}
mut_result.set(key, action.updater(curr));
break;
}
}
}
return IMap.create(mut_result);
}
/** @inheritdoc */
map<V2>(mapFn: (value: V, key: K) => V2): IMap<K, V2> {
return IMap.create(this.toArray().map(([k, v]) => tp(k, mapFn(v, k))));
}
/** @inheritdoc */
mapKeys<K2 extends MapSetKeyType>(mapFn: (key: K) => K2): IMap<K2, V> {
return IMap.create(this.toArray().map(([k, v]) => tp(mapFn(k), v)));
}
/** @inheritdoc */
mapEntries<K2 extends MapSetKeyType, V2>(
mapFn: (entry: readonly [K, V]) => readonly [K2, V2],
): IMap<K2, V2> {
return IMap.create(this.toArray().map(mapFn));
}
/** @inheritdoc */
forEach(callbackfn: (value: V, key: K) => void): void {
for (const [key, value] of this.#map.entries()) {
callbackfn(value, key);
}
}
/**
* @inheritdoc
*/
[Symbol.iterator](): Iterator<readonly [K, V]> {
return this.#map[Symbol.iterator]();
}
/** @inheritdoc */
keys(): IterableIterator<K> {
return this.#map.keys();
}
/** @inheritdoc */
values(): IterableIterator<V> {
return this.#map.values();
}
/** @inheritdoc */
entries(): IterableIterator<readonly [K, V]> {
return this.#map.entries();
}
/** @inheritdoc */
toKeysArray(): readonly K[] {
return Array.from(this.keys());
}
/** @inheritdoc */
toValuesArray(): readonly V[] {
return Array.from(this.values());
}
/** @inheritdoc */
toEntriesArray(): readonly (readonly [K, V])[] {
return Array.from(this.entries());
}
/** @inheritdoc */
toArray(): readonly (readonly [K, V])[] {
return Array.from(this.entries());
}
/** @inheritdoc */
toRawMap(): ReadonlyMap<K, V> {
return this.#map;
}
}