@tldraw/state
Version:
tldraw infinite canvas SDK (state).
143 lines (142 loc) • 3.14 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 item to the ArraySet if it is not already present.
*
* @param elem - The element to add.
*/
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 item from the ArraySet if it is present.
*
* @param elem - The element to remove
*/
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");
}
/**
* Run a callback for each element in the ArraySet.
*
* @param visitor - The callback to run for each element.
*/
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");
}
*[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");
}
}
has(elem) {
if (this.array) {
return this.array.indexOf(elem) !== -1;
} else {
return this.set.has(elem);
}
}
clear() {
if (this.set) {
this.set.clear();
} else {
this.arraySize = 0;
this.array = [];
}
}
size() {
if (this.set) {
return this.set.size;
} else {
return this.arraySize;
}
}
}
export {
ARRAY_SIZE_THRESHOLD,
ArraySet
};
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