@tldraw/state
Version:
tldraw infinite canvas SDK (state).
227 lines (226 loc) • 5.38 kB
JavaScript
const ARRAY_SIZE_THRESHOLD = 8;
class ArraySet {
arraySize = 0;
array = Array(ARRAY_SIZE_THRESHOLD);
set = null;
/**
* Get whether this ArraySet has any elements.
*
* @returns True if this ArraySet has any elements, false otherwise.
*/
// eslint-disable-next-line no-restricted-syntax
get isEmpty() {
if (this.array) {
return this.arraySize === 0;
}
if (this.set) {
return this.set.size === 0;
}
throw new Error("no set or array");
}
/**
* Add an element to the ArraySet if it is not already present.
*
* @param elem - The element to add to the set
* @returns `true` if the element was added, `false` if it was already present
* @example
* ```ts
* const arraySet = new ArraySet<string>()
*
* console.log(arraySet.add('hello')) // true
* console.log(arraySet.add('hello')) // false (already exists)
* ```
*/
add(elem) {
if (this.array) {
const idx = this.array.indexOf(elem);
if (idx !== -1) {
return false;
}
if (this.arraySize < ARRAY_SIZE_THRESHOLD) {
this.array[this.arraySize] = elem;
this.arraySize++;
return true;
} else {
this.set = new Set(this.array);
this.array = null;
this.set.add(elem);
return true;
}
}
if (this.set) {
if (this.set.has(elem)) {
return false;
}
this.set.add(elem);
return true;
}
throw new Error("no set or array");
}
/**
* Remove an element from the ArraySet if it is present.
*
* @param elem - The element to remove from the set
* @returns `true` if the element was removed, `false` if it was not present
* @example
* ```ts
* const arraySet = new ArraySet<string>()
* arraySet.add('hello')
*
* console.log(arraySet.remove('hello')) // true
* console.log(arraySet.remove('hello')) // false (not present)
* ```
*/
remove(elem) {
if (this.array) {
const idx = this.array.indexOf(elem);
if (idx === -1) {
return false;
}
this.array[idx] = void 0;
this.arraySize--;
if (idx !== this.arraySize) {
this.array[idx] = this.array[this.arraySize];
this.array[this.arraySize] = void 0;
}
return true;
}
if (this.set) {
if (!this.set.has(elem)) {
return false;
}
this.set.delete(elem);
return true;
}
throw new Error("no set or array");
}
/**
* Execute a callback function for each element in the ArraySet.
*
* @param visitor - A function to call for each element in the set
* @example
* ```ts
* const arraySet = new ArraySet<string>()
* arraySet.add('hello')
* arraySet.add('world')
*
* arraySet.visit((item) => {
* console.log(item) // 'hello', 'world'
* })
* ```
*/
visit(visitor) {
if (this.array) {
for (let i = 0; i < this.arraySize; i++) {
const elem = this.array[i];
if (typeof elem !== "undefined") {
visitor(elem);
}
}
return;
}
if (this.set) {
this.set.forEach(visitor);
return;
}
throw new Error("no set or array");
}
/**
* Make the ArraySet iterable, allowing it to be used in for...of loops and with spread syntax.
*
* @returns An iterator that yields each element in the set
* @example
* ```ts
* const arraySet = new ArraySet<number>()
* arraySet.add(1)
* arraySet.add(2)
*
* for (const item of arraySet) {
* console.log(item) // 1, 2
* }
*
* const items = [...arraySet] // [1, 2]
* ```
*/
*[Symbol.iterator]() {
if (this.array) {
for (let i = 0; i < this.arraySize; i++) {
const elem = this.array[i];
if (typeof elem !== "undefined") {
yield elem;
}
}
} else if (this.set) {
yield* this.set;
} else {
throw new Error("no set or array");
}
}
/**
* Check whether an element is present in the ArraySet.
*
* @param elem - The element to check for
* @returns `true` if the element is present, `false` otherwise
* @example
* ```ts
* const arraySet = new ArraySet<string>()
* arraySet.add('hello')
*
* console.log(arraySet.has('hello')) // true
* console.log(arraySet.has('world')) // false
* ```
*/
has(elem) {
if (this.array) {
return this.array.indexOf(elem) !== -1;
} else {
return this.set.has(elem);
}
}
/**
* Remove all elements from the ArraySet.
*
* @example
* ```ts
* const arraySet = new ArraySet<string>()
* arraySet.add('hello')
* arraySet.add('world')
*
* arraySet.clear()
* console.log(arraySet.size()) // 0
* ```
*/
clear() {
if (this.set) {
this.set.clear();
} else {
this.arraySize = 0;
this.array = [];
}
}
/**
* Get the number of elements in the ArraySet.
*
* @returns The number of elements in the set
* @example
* ```ts
* const arraySet = new ArraySet<string>()
* console.log(arraySet.size()) // 0
*
* arraySet.add('hello')
* console.log(arraySet.size()) // 1
* ```
*/
size() {
if (this.set) {
return this.set.size;
} else {
return this.arraySize;
}
}
}
export {
ARRAY_SIZE_THRESHOLD,
ArraySet
};
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