1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 | export default { past: [], present: undefined, future: [], thereIsAPresent: function() { return this.present != undefined; }, thereIsAPast: function() { return this.past.length > 0; }, thereIsAFuture: function() { return this.future.length > 0; }, setPresent: function(state) { this.present = state; }, movePresentToPast: function() { this.past.push(this.present); }, movePresentToFuture: function() { this.future.push(this.present); }, movePastToPresent: function() { this.setPresent(this.past.pop()); }, moveFutureToPresent: function() { this.setPresent(this.future.pop()); }, push: function(currentState) { if(this.thereIsAPresent()) { this.movePresentToPast(); } this.setPresent(currentState); }, undo: function() { if(this.thereIsAPresent()) { this.movePresentToFuture(); // Moving back in time this.movePastToPresent(); // Moving back in time } }, redo: function() { if(!this.thereIsAFuture()) { // No future! return; } if(this.thereIsAPresent()) { this.movePresentToPast(); // Moving forward in time } this.moveFutureToPresent(); // Moving forward in time }, gotoState: function(i) { const index = Number(i); const allstates = [...this.past, this.present, ...this.future]; this.present = allstates[index] this.past = allstates.slice(0, index) this.future = allstates.slice(index+1, allstates.length) } } |
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