67 lines
1.4 KiB
TypeScript
67 lines
1.4 KiB
TypeScript
import { Data, Page, PageState } from 'types'
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import { BaseCommand } from './commands/command'
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import storage from './storage'
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// A singleton to manage history changes.
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class History<T extends Data> {
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private stack: BaseCommand<T>[] = []
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private pointer = -1
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private maxLength = 100
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private _enabled = true
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execute = (data: T, command: BaseCommand<T>) => {
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command.redo(data, true)
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if (this.disabled) return
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this.stack = this.stack.slice(0, this.pointer + 1)
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this.stack.push(command)
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this.pointer++
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if (this.stack.length > this.maxLength) {
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this.stack = this.stack.slice(this.stack.length - this.maxLength)
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this.pointer = this.maxLength - 1
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}
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storage.save(data)
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}
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undo = (data: T) => {
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if (this.pointer === -1) return
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const command = this.stack[this.pointer]
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command.undo(data)
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if (this.disabled) return
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this.pointer--
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storage.save(data)
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}
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redo = (data: T) => {
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if (this.pointer === this.stack.length - 1) return
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const command = this.stack[this.pointer + 1]
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command.redo(data, false)
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if (this.disabled) return
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this.pointer++
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storage.save(data)
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}
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disable = () => {
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this._enabled = false
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}
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enable = () => {
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this._enabled = true
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}
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pop() {
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if (this.stack.length > 0) {
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this.stack.pop()
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this.pointer--
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}
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}
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get disabled() {
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return !this._enabled
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}
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}
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export default new History()
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