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40
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1 module doodle.undo.undo;
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2
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3 // http://doc.trolltech.com/4.2/qundo.html
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4 // http://www.codeproject.com/KB/cs/undo_support.aspx
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5
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6 // rename Action to Edit?
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7
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8 // Related design patterns: Command, Memento
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9
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10 // Action represents and encapsulates the information needed
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11 // Consider command merging and time-stamping of commands
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12
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13 abstract class Action {
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14 void undo();
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15 void redo();
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16 //string description() const;
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17 // bool merge(Action other);
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18 // time-stamp
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19 }
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20
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21 final class CompoundAction {
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22 this(in Action[] sub_actions) {
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23 mSubActions = sub_actions.dup;
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24 }
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25
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26 void undo() {
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27 foreach_reverse(a; mSubActions) { a.undo(); }
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28 }
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29
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30 void redo() {
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31 foreach(a; mSubActions) { a.redo(); }
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32 }
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33
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34 private {
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35 Action[] mSubActions;
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36 }
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37 }
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38
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39 interface IUndoManagerObserver {
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40 void canUndo(in bool value, in string description);
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41 void canRedo(in bool value, in string description);
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42 }
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43
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44 interface IUndoManager {
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45 void addAction(Action action);
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46 void undo();
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47 void redo();
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48 // bool can_undo() const;
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49 // bool can_redo() const;
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50 }
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51
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52 class UndoManager : IUndoManager {
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53 this(int max_undo_level = -1) {
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54 }
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55
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56 void addAction(Action action);
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57 void undo();
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58 void redo();
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59
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60 // IUndoManager overrides:
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61
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62 private {
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63 Action[] mUndoActions;
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64 Action[] mRedoActions;
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65 }
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66 }
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