22 lines
923 B
TypeScript
22 lines
923 B
TypeScript
export interface EditHistory<T> { past: T[]; present: T; future: T[] }
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const LIMIT = 40;
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export function createEditHistory<T>(present: T): EditHistory<T> {
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return { past: [], present, future: [] };
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}
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export function commitEdit<T>(history: EditHistory<T>, present: T): EditHistory<T> {
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if (present === history.present) return history;
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return { past: [...history.past, history.present].slice(-LIMIT), present, future: [] };
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}
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export function undoEdit<T>(history: EditHistory<T>): EditHistory<T> {
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if (!history.past.length) return history;
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return { past: history.past.slice(0, -1), present: history.past.at(-1)!, future: [history.present, ...history.future] };
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}
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export function redoEdit<T>(history: EditHistory<T>): EditHistory<T> {
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if (!history.future.length) return history;
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return { past: [...history.past, history.present].slice(-LIMIT), present: history.future[0], future: history.future.slice(1) };
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}
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