44 lines
1.2 KiB
TypeScript
44 lines
1.2 KiB
TypeScript
/**
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* Data structure allowing for the insertion and removal of
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* elements in a LIFO manner in `O(1)` time.
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* @author MindfulMinun
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* @since 2022-10-22
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*/
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export class Stack<T> implements Iterable<T> {
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#elements: Record<number, T>
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#head: number
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constructor(initials?: Iterable<T>) {
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this.#elements = {}
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this.#head = 0
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if (!initials) return
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for (const el of initials) this.push(el)
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}
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/** Add an element to the stack */
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push(element: T): void {
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this.#elements[this.#head++] = element
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}
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/** Remove an element from the stack and return it. */
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pop(): T | undefined {
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if (this.length === 0) return undefined
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const el = this.#elements[--this.#head]
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delete this.#elements[this.#head]
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return el
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}
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/** Preview the topmost element of the stack without removing it. */
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peek(): T | undefined {
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if (this.length === 0) return undefined
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return this.#elements[this.#head - 1]
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}
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/** The number of elements remaining in the stack */
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get length(): number { return this.#head }
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*[Symbol.iterator](): Generator<NonNullable<T>, void, unknown> {
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while (this.length !== 0) yield this.pop()!
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}
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}
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