android_calculator-4: Extend history functionality

res/values/default_values.xml

@@ -28,6 +28,7 @@
 	<string name="p_calc_round_result">true</string>
 
 	<string name="p_calc_vars">org.solovyev.android.calculator.CalculatorModel_vars</string>
+	<string name="p_calc_history">org.solovyev.android.calculator.CalculatorModel_history</string>
 
 	<string name="p_calc_angle_units_key">org.solovyev.android.calculator.CalculatorActivity_angle_units</string>
 	<string name="p_calc_angle_units">deg</string>

res/values/strings.xml

@@ -299,4 +299,7 @@ Check the \'Round result\' preference in application settings - it should be tur
 	<string name="c_swipe_distance">Swipe distance for buttons</string>
 	<string name="c_swipe_distance_summary">Sets swipe distance for buttons that support additional swipe actions</string>
 
+	<string name="c_comment">Comment</string>
+	<string name="c_history_item_saved">Saved</string>
+
 </resources>

src/main/java/org/solovyev/android/calculator/AbstractHistoryState.java

@@ -1,27 +0,0 @@
-/*
- * Copyright (c) 2009-2011. Created by serso aka se.solovyev.
- * For more information, please, contact se.solovyev@gmail.com
- * or visit http://se.solovyev.org
- */
-
-package org.solovyev.android.calculator;
-
-import org.jetbrains.annotations.NotNull;
-
-import java.util.Date;
-
-/**
- * User: serso
- * Date: 10/15/11
- * Time: 1:45 PM
- */
-public class AbstractHistoryState {
-
-	@NotNull
-	private final Date time = new Date();
-
-	@NotNull
-	public Date getTime() {
-		return time;
-	}
-}

src/main/java/org/solovyev/android/calculator/CalculatorActivity.java

@@ -26,6 +26,7 @@ import jscl.AngleUnit;
 import jscl.NumeralBase;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.solovyev.android.calculator.history.CalculatorHistoryState;
 import org.solovyev.android.calculator.math.MathType;
 import org.solovyev.android.calculator.model.CalculatorEngine;
 import org.solovyev.android.view.FontSizeAdjuster;

src/main/java/org/solovyev/android/calculator/CalculatorDisplay.java

@@ -24,7 +24,7 @@ import org.solovyev.android.view.AutoResizeTextView;
  * Date: 9/17/11
  * Time: 10:58 PM
  */
-public class CalculatorDisplay extends AutoResizeTextView {
+public class CalculatorDisplay extends AutoResizeTextView implements ICalculatorDisplay{
 
 	private boolean valid = true;
 
@@ -52,10 +52,12 @@ public class CalculatorDisplay extends AutoResizeTextView {
 		super(context, attrs, defStyle);
 	}
 
+	@Override
 	public boolean isValid() {
 		return valid;
 	}
 
+	@Override
 	public void setValid(boolean valid) {
 		this.valid = valid;
 		if (valid) {
@@ -63,19 +65,23 @@ public class CalculatorDisplay extends AutoResizeTextView {
 		}
 	}
 
+	@Override
 	@Nullable
 	public String getErrorMessage() {
 		return errorMessage;
 	}
 
+	@Override
 	public void setErrorMessage(@Nullable String errorMessage) {
 		this.errorMessage = errorMessage;
 	}
 
+	@Override
 	public void setJsclOperation(@NotNull JsclOperation jsclOperation) {
 		this.jsclOperation = jsclOperation;
 	}
 
+	@Override
 	@NotNull
 	public JsclOperation getJsclOperation() {
 		return jsclOperation;
@@ -111,12 +117,24 @@ public class CalculatorDisplay extends AutoResizeTextView {
 		resizeText();
 	}
 
+	@Override
 	public void setGenericResult(@Nullable Generic genericResult) {
 		this.genericResult = genericResult;
 	}
 
+	@Override
 	@Nullable
 	public Generic getGenericResult() {
 		return genericResult;
 	}
+
+	@Override
+	public int getSelection() {
+		return this.getSelectionStart();
+	}
+
+	@Override
+	public void setSelection(int selection) {
+		// not supported by TextView
+	}
 }

src/main/java/org/solovyev/android/calculator/CalculatorHistory.java

@@ -1,83 +0,0 @@
-/*
- * Copyright (c) 2009-2011. Created by serso aka se.solovyev.
- * For more information, please, contact se.solovyev@gmail.com
- * or visit http://se.solovyev.org
- */
-
-package org.solovyev.android.calculator;
-
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
-import org.solovyev.common.utils.history.HistoryAction;
-import org.solovyev.common.utils.history.HistoryHelper;
-import org.solovyev.common.utils.history.SimpleHistoryHelper;
-
-import java.util.List;
-
-/**
- * User: serso
- * Date: 10/9/11
- * Time: 6:35 PM
- */
-public enum CalculatorHistory implements HistoryHelper<CalculatorHistoryState> {
-
-	instance;
-
-	private final HistoryHelper<CalculatorHistoryState> historyHelper = new SimpleHistoryHelper<CalculatorHistoryState>();
-
-	@Override
-	public boolean isEmpty() {
-		return this.historyHelper.isEmpty();
-	}
-
-	@Override
-	public CalculatorHistoryState getLastHistoryState() {
-		return this.historyHelper.getLastHistoryState();
-	}
-
-	@Override
-	public boolean isUndoAvailable() {
-		return historyHelper.isUndoAvailable();
-	}
-
-	@Override
-	public CalculatorHistoryState undo(@Nullable CalculatorHistoryState currentState) {
-		return historyHelper.undo(currentState);
-	}
-
-	@Override
-	public boolean isRedoAvailable() {
-		return historyHelper.isRedoAvailable();
-	}
-
-	@Override
-	public CalculatorHistoryState redo(@Nullable CalculatorHistoryState currentState) {
-		return historyHelper.redo(currentState);
-	}
-
-	@Override
-	public boolean isActionAvailable(@NotNull HistoryAction historyAction) {
-		return historyHelper.isActionAvailable(historyAction);
-	}
-
-	@Override
-	public CalculatorHistoryState doAction(@NotNull HistoryAction historyAction, @Nullable CalculatorHistoryState currentState) {
-		return historyHelper.doAction(historyAction, currentState);
-	}
-
-	@Override
-	public void addState(@Nullable CalculatorHistoryState currentState) {
-		historyHelper.addState(currentState);
-	}
-
-	@NotNull
-	@Override
-	public List<CalculatorHistoryState> getStates() {
-		return historyHelper.getStates();
-	}
-
-	@Override
-	public void clear() {
-		this.historyHelper.clear();
-	}
-}

src/main/java/org/solovyev/android/calculator/CalculatorHistoryActivity.java

@@ -6,13 +6,20 @@
 
 package org.solovyev.android.calculator;
 
+import android.app.AlertDialog;
 import android.app.ListActivity;
 import android.content.Context;
+import android.content.DialogInterface;
 import android.os.Bundle;
+import android.preference.PreferenceManager;
 import android.view.*;
 import android.widget.*;
 import org.jetbrains.annotations.NotNull;
+import org.solovyev.android.calculator.history.CalculatorHistory;
+import org.solovyev.android.calculator.history.CalculatorHistoryState;
+import org.solovyev.android.calculator.history.EditorHistoryState;
 import org.solovyev.android.calculator.jscl.JsclOperation;
+import org.solovyev.android.view.prefs.ResourceCache;
 import org.solovyev.common.utils.Filter;
 import org.solovyev.common.utils.FilterRule;
 import org.solovyev.common.utils.FilterRulesChain;
@@ -31,6 +38,9 @@ import java.util.List;
  */
 public class CalculatorHistoryActivity extends ListActivity {
 
+	@NotNull
+	private HistoryArrayAdapter adapter;
+
 	@Override
 	protected void onCreate(Bundle savedInstanceState) {
 		super.onCreate(savedInstanceState);
@@ -43,7 +53,8 @@ public class CalculatorHistoryActivity extends ListActivity {
 			this.finish();
 		}
 
-		setListAdapter(new HistoryArrayAdapter(this, R.layout.history, R.id.history_item, historyList));
+		adapter = new HistoryArrayAdapter(this, R.layout.history, R.id.history_item, historyList);
+		setListAdapter(adapter);
 
 		final ListView lv = getListView();
 		lv.setTextFilterEnabled(true);
@@ -70,15 +81,62 @@ public class CalculatorHistoryActivity extends ListActivity {
 				CalculatorHistoryActivity.this.finish();
 			}
 		});
+
+		lv.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
+			@Override
+			public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {
+				final CalculatorHistoryState historyState = (CalculatorHistoryState) parent.getItemAtPosition(position);
+
+				final Context context = CalculatorHistoryActivity.this;
+
+				final CharSequence[] items = {context.getText(R.string.c_save), context.getText(R.string.c_remove)};
+
+				AlertDialog.Builder builder = new AlertDialog.Builder(context);
+				builder.setItems(items, new DialogInterface.OnClickListener() {
+					public void onClick(DialogInterface dialog, int item) {
+						if (item == 0) {
+							if (!historyState.isSaved()) {
+								historyState.setSaved(true);
+								CalculatorHistory.instance.getSavedHistory().addState(historyState);
+								CalculatorHistory.instance.save(context);
+								CalculatorHistoryActivity.this.adapter.notifyDataSetChanged();
+								Toast.makeText(context, "History item was successfully saved!", Toast.LENGTH_LONG).show();
+							} else {
+								Toast.makeText(context, "History item was already saved!", Toast.LENGTH_LONG).show();
+							}
+						} else if (item == 1) {
+							if (historyState.isSaved()) {
+								historyState.setSaved(false);
+								CalculatorHistory.instance.save(context);
+								CalculatorHistory.instance.getSavedHistory().clear();
+								CalculatorHistory.instance.load(context, PreferenceManager.getDefaultSharedPreferences(context));
+								CalculatorHistoryActivity.this.adapter.notifyDataSetChanged();
+								Toast.makeText(context, "History item was removed!", Toast.LENGTH_LONG).show();
+							}
+						}
+					}
+				});
+				builder.create().show();
+				return true;
+			}
+		});
 	}
 
 	private static List<CalculatorHistoryState> getHistoryList() {
 		final List<CalculatorHistoryState> calculatorHistoryStates = new ArrayList<CalculatorHistoryState>(CalculatorHistory.instance.getStates());
+		calculatorHistoryStates.addAll(CalculatorHistory.instance.getSavedHistory().getStates());
 
 		Collections.sort(calculatorHistoryStates, new Comparator<CalculatorHistoryState>() {
 			@Override
 			public int compare(CalculatorHistoryState state1, CalculatorHistoryState state2) {
-				return state2.getTime().compareTo(state1.getTime());
+				if ( state1.isSaved() == state2.isSaved() ) {
+					return state2.getTime().compareTo(state1.getTime());
+				} else if ( state1.isSaved() ) {
+					return -1;
+				} else if ( state2.isSaved() ) {
+					return 1;
+				}
+				return 0;
 			}
 		});
 
@@ -111,7 +169,21 @@ public class CalculatorHistoryActivity extends ListActivity {
 			time.setText(new SimpleDateFormat().format(state.getTime()));
 
 			final TextView editor = (TextView) result.findViewById(R.id.history_item);
-			editor.setText(state.getEditorState().getText() + getIdentitySign(state.getDisplayState().getJsclOperation()) + state.getDisplayState().getEditorHistoryState().getText());
+			final StringBuilder historyText = new StringBuilder();
+			historyText.append(state.getEditorState().getText());
+			historyText.append(getIdentitySign(state.getDisplayState().getJsclOperation()));
+			historyText.append(state.getDisplayState().getEditorState().getText());
+			final String comment = state.getComment();
+			if (!StringUtils.isEmpty(comment)) {
+				historyText.append("\n");
+				historyText.append(ResourceCache.instance.getCaption("c_comment")).append(": ");
+				historyText.append(comment);
+			}
+			if ( state.isSaved() ) {
+				historyText.append("\n");
+				historyText.append(ResourceCache.instance.getCaption("c_history_item_saved"));
+			}
+			editor.setText(historyText);
 
 			return result;
 		}
@@ -147,6 +219,7 @@ public class CalculatorHistoryActivity extends ListActivity {
 
 	private void clearHistory() {
 		CalculatorHistory.instance.clear();
+
 		Toast.makeText(this, R.string.c_history_is_empty, Toast.LENGTH_SHORT).show();
 		this.finish();
 	}

src/main/java/org/solovyev/android/calculator/CalculatorModel.java

@@ -22,6 +22,9 @@ import jscl.math.Generic;
 import jscl.math.function.Constant;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.solovyev.android.calculator.history.CalculatorHistory;
+import org.solovyev.android.calculator.history.CalculatorHistoryState;
+import org.solovyev.android.calculator.history.TextViewEditorAdapter;
 import org.solovyev.android.calculator.jscl.JsclOperation;
 import org.solovyev.android.calculator.math.MathType;
 import org.solovyev.android.calculator.model.CalculatorEngine;
@@ -335,8 +338,8 @@ public enum CalculatorModel implements CursorControl, HistoryControl<CalculatorH
 	public void setCurrentHistoryState(@NotNull CalculatorHistoryState editorHistoryState) {
 		synchronized (CalculatorHistory.instance) {
 			Log.d(this.getClass().getName(), "Saved history found: " + editorHistoryState);
-			setValuesFromHistory(this.editor, editorHistoryState.getEditorState());
+
-			setValuesFromHistory(this.display, editorHistoryState.getDisplayState());
+			editorHistoryState.setValuesFromHistory(new TextViewEditorAdapter(this.editor), this.display);
 
 			final String expression = this.editor.getText().toString();
 			if ( !StringUtils.isEmpty(expression) ) {
@@ -350,37 +353,14 @@ public enum CalculatorModel implements CursorControl, HistoryControl<CalculatorH
 		}
 	}
 
-	private void setValuesFromHistory(@NotNull CalculatorDisplay display, CalculatorDisplayHistoryState editorHistoryState) {
-		setValuesFromHistory(display, editorHistoryState.getEditorHistoryState());
-		display.setValid(editorHistoryState.isValid());
-		display.setErrorMessage(editorHistoryState.getErrorMessage());
-		display.setJsclOperation(editorHistoryState.getJsclOperation());
-		display.setGenericResult(editorHistoryState.getGenericResult());
-	}
-
-	private void setValuesFromHistory(@NotNull TextView editText, EditorHistoryState editorHistoryState) {
-		editText.setText(editorHistoryState.getText());
-		if (editText instanceof EditText) {
-			((EditText) editText).setSelection(editorHistoryState.getCursorPosition());
-		}
-	}
-
 	@Override
 	@NotNull
 	public CalculatorHistoryState getCurrentHistoryState() {
 		synchronized (CalculatorHistory.instance) {
-			return new CalculatorHistoryState(getEditorHistoryState(this.editor), getCalculatorDisplayHistoryState(this.display));
+			return CalculatorHistoryState.newInstance(new TextViewEditorAdapter(this.editor), this.display);
 		}
 	}
 
-	private EditorHistoryState getEditorHistoryState(@NotNull TextView textView) {
-		return EditorHistoryState.newInstance(textView);
-	}
-
-	private CalculatorDisplayHistoryState getCalculatorDisplayHistoryState(@NotNull CalculatorDisplay display) {
-		return CalculatorDisplayHistoryState.newInstance(display);
-	}
-
 	@NotNull
 	public CalculatorDisplay getDisplay() {
 		return display;

src/main/java/org/solovyev/android/calculator/ICalculatorDisplay.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2009-2011. Created by serso aka se.solovyev.
+ * For more information, please, contact se.solovyev@gmail.com
+ * or visit http://se.solovyev.org
+ */
+
+package org.solovyev.android.calculator;
+
+import jscl.math.Generic;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+import org.solovyev.android.calculator.history.Editor;
+import org.solovyev.android.calculator.jscl.JsclOperation;
+
+/**
+ * User: serso
+ * Date: 12/17/11
+ * Time: 9:45 PM
+ */
+public interface ICalculatorDisplay extends Editor{
+
+	boolean isValid();
+
+	void setValid(boolean valid);
+
+	@Nullable
+	String getErrorMessage();
+
+	void setErrorMessage(@Nullable String errorMessage);
+
+	void setJsclOperation(@NotNull JsclOperation jsclOperation);
+
+	@NotNull
+	JsclOperation getJsclOperation();
+
+	void setGenericResult(@Nullable Generic genericResult);
+
+	@Nullable
+	Generic getGenericResult();
+}

src/main/java/org/solovyev/android/calculator/history/AbstractHistoryState.java

@@ -0,0 +1,59 @@
+/*
+ * Copyright (c) 2009-2011. Created by serso aka se.solovyev.
+ * For more information, please, contact se.solovyev@gmail.com
+ * or visit http://se.solovyev.org
+ */
+
+package org.solovyev.android.calculator.history;
+
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+import org.simpleframework.xml.Element;
+import org.simpleframework.xml.Transient;
+
+import java.util.Date;
+
+/**
+ * User: serso
+ * Date: 10/15/11
+ * Time: 1:45 PM
+ */
+public class AbstractHistoryState {
+
+	@Element
+	@NotNull
+	private Date time = new Date();
+
+	@Element(required = false)
+	@Nullable
+	private String comment;
+
+	@Transient
+	private boolean saved;
+
+	@NotNull
+	public Date getTime() {
+		return time;
+	}
+
+	public void setTime(@NotNull Date time) {
+		this.time = time;
+	}
+
+	@Nullable
+	public String getComment() {
+		return comment;
+	}
+
+	public void setComment(@Nullable String comment) {
+		this.comment = comment;
+	}
+
+	public boolean isSaved() {
+		return saved;
+	}
+
+	public void setSaved(boolean saved) {
+		this.saved = saved;
+	}
+}

src/main/java/org/solovyev/android/calculator/history/CalculatorDisplayHistoryState.java

@@ -3,11 +3,15 @@
  * For more information, please, contact se.solovyev@gmail.com
  */
 
-package org.solovyev.android.calculator;
+package org.solovyev.android.calculator.history;
 
 import jscl.math.Generic;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.simpleframework.xml.Element;
+import org.simpleframework.xml.Root;
+import org.simpleframework.xml.Transient;
+import org.solovyev.android.calculator.ICalculatorDisplay;
 import org.solovyev.android.calculator.jscl.JsclOperation;
 
 /**
@@ -15,30 +19,38 @@ import org.solovyev.android.calculator.jscl.JsclOperation;
  * Date: 9/17/11
  * Time: 11:05 PM
  */
+
+@Root
 public class CalculatorDisplayHistoryState {
 
+	@Transient
 	private boolean valid = true;
 
+	@Transient
 	@Nullable
 	private String errorMessage = null;
 
+	@Element
 	@NotNull
-	private EditorHistoryState editorHistoryState;
+	private EditorHistoryState editorState;
 
+	@Element
 	@NotNull
 	private JsclOperation jsclOperation;
 
+	@Transient
 	@Nullable
 	private Generic genericResult;
 
 	private CalculatorDisplayHistoryState() {
+		// for xml
 	}
 
 	@NotNull
-	public static CalculatorDisplayHistoryState newInstance(@NotNull CalculatorDisplay display) {
+	public static CalculatorDisplayHistoryState newInstance(@NotNull ICalculatorDisplay display) {
 		final CalculatorDisplayHistoryState result = new CalculatorDisplayHistoryState();
 
-		result.editorHistoryState = EditorHistoryState.newInstance(display);
+		result.editorState = EditorHistoryState.newInstance(display);
 		result.valid = display.isValid();
 		result.jsclOperation = display.getJsclOperation();
 		result.genericResult = display.getGenericResult();
@@ -47,13 +59,22 @@ public class CalculatorDisplayHistoryState {
 		return result;
 	}
 
+	public void setValuesFromHistory(@NotNull ICalculatorDisplay display) {
+		this.getEditorState().setValuesFromHistory(display);
+		display.setValid(this.isValid());
+		display.setErrorMessage(this.getErrorMessage());
+		display.setJsclOperation(this.getJsclOperation());
+		display.setGenericResult(this.getGenericResult());
+	}
+
+
 	public boolean isValid() {
 		return valid;
 	}
 
 	@NotNull
-	public EditorHistoryState getEditorHistoryState() {
+	public EditorHistoryState getEditorState() {
-		return editorHistoryState;
+		return editorState;
 	}
 
 	@NotNull
@@ -71,6 +92,7 @@ public class CalculatorDisplayHistoryState {
 		return genericResult;
 	}
 
+
 	@Override
 	public boolean equals(Object o) {
 		if (this == o) return true;
@@ -78,9 +100,7 @@ public class CalculatorDisplayHistoryState {
 
 		CalculatorDisplayHistoryState that = (CalculatorDisplayHistoryState) o;
 
-		if (valid != that.valid) return false;
+		if (!editorState.equals(that.editorState)) return false;
-		if (!editorHistoryState.equals(that.editorHistoryState)) return false;
-		if (errorMessage != null ? !errorMessage.equals(that.errorMessage) : that.errorMessage != null) return false;
 		if (jsclOperation != that.jsclOperation) return false;
 
 		return true;
@@ -88,9 +108,7 @@ public class CalculatorDisplayHistoryState {
 
 	@Override
 	public int hashCode() {
-		int result = (valid ? 1 : 0);
+		int result = editorState.hashCode();
-		result = 31 * result + (errorMessage != null ? errorMessage.hashCode() : 0);
-		result = 31 * result + editorHistoryState.hashCode();
 		result = 31 * result + jsclOperation.hashCode();
 		return result;
 	}
@@ -100,7 +118,7 @@ public class CalculatorDisplayHistoryState {
 		return "CalculatorDisplayHistoryState{" +
 				"valid=" + valid +
 				", errorMessage='" + errorMessage + '\'' +
-				", editorHistoryState=" + editorHistoryState +
+				", editorHistoryState=" + editorState +
 				", jsclOperation=" + jsclOperation +
 				'}';
 	}

src/main/java/org/solovyev/android/calculator/history/CalculatorHistory.java

@@ -0,0 +1,113 @@
+/*
+ * Copyright (c) 2009-2011. Created by serso aka se.solovyev.
+ * For more information, please, contact se.solovyev@gmail.com
+ * or visit http://se.solovyev.org
+ */
+
+package org.solovyev.android.calculator.history;
+
+import android.content.Context;
+import android.content.SharedPreferences;
+import android.preference.PreferenceManager;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+import org.solovyev.android.calculator.R;
+import org.solovyev.common.utils.history.HistoryAction;
+import org.solovyev.common.utils.history.HistoryHelper;
+import org.solovyev.common.utils.history.SimpleHistoryHelper;
+
+import java.util.List;
+
+/**
+ * User: serso
+ * Date: 10/9/11
+ * Time: 6:35 PM
+ */
+public enum CalculatorHistory implements HistoryHelper<CalculatorHistoryState> {
+
+	instance;
+
+	@NotNull
+	private final HistoryHelper<CalculatorHistoryState> history = new SimpleHistoryHelper<CalculatorHistoryState>();
+
+	@NotNull
+	private final HistoryHelper<CalculatorHistoryState> savedHistory = new SimpleHistoryHelper<CalculatorHistoryState>();
+
+	@Override
+	public boolean isEmpty() {
+		return this.history.isEmpty();
+	}
+
+	@Override
+	public CalculatorHistoryState getLastHistoryState() {
+		return this.history.getLastHistoryState();
+	}
+
+	@Override
+	public boolean isUndoAvailable() {
+		return history.isUndoAvailable();
+	}
+
+	@Override
+	public CalculatorHistoryState undo(@Nullable CalculatorHistoryState currentState) {
+		return history.undo(currentState);
+	}
+
+	@Override
+	public boolean isRedoAvailable() {
+		return history.isRedoAvailable();
+	}
+
+	@Override
+	public CalculatorHistoryState redo(@Nullable CalculatorHistoryState currentState) {
+		return history.redo(currentState);
+	}
+
+	@Override
+	public boolean isActionAvailable(@NotNull HistoryAction historyAction) {
+		return history.isActionAvailable(historyAction);
+	}
+
+	@Override
+	public CalculatorHistoryState doAction(@NotNull HistoryAction historyAction, @Nullable CalculatorHistoryState currentState) {
+		return history.doAction(historyAction, currentState);
+	}
+
+	@Override
+	public void addState(@Nullable CalculatorHistoryState currentState) {
+		history.addState(currentState);
+	}
+
+	@NotNull
+	@Override
+	public List<CalculatorHistoryState> getStates() {
+		return history.getStates();
+	}
+
+	@Override
+	public void clear() {
+		this.history.clear();
+	}
+
+	@NotNull
+	public HistoryHelper<CalculatorHistoryState> getSavedHistory() {
+		return savedHistory;
+	}
+
+	public void load(@Nullable Context context, @Nullable SharedPreferences preferences) {
+		if (context != null && preferences != null) {
+			final String value = preferences.getString(context.getString(R.string.p_calc_history), null);
+			HistoryUtils.fromXml(value, this.savedHistory);
+		}
+	}
+
+	public void save(@NotNull Context context) {
+		final SharedPreferences settings = PreferenceManager.getDefaultSharedPreferences(context);
+		final SharedPreferences.Editor editor = settings.edit();
+
+		editor.putString(context.getString(R.string.p_calc_history), HistoryUtils.toXml(this.savedHistory));
+
+		editor.commit();
+	}
+
+}

src/main/java/org/solovyev/android/calculator/history/CalculatorHistoryState.java

@@ -3,29 +3,46 @@
  * For more information, please, contact se.solovyev@gmail.com
  */
 
-package org.solovyev.android.calculator;
+package org.solovyev.android.calculator.history;
 
 import org.jetbrains.annotations.NotNull;
+import org.simpleframework.xml.Element;
+import org.simpleframework.xml.Root;
+import org.solovyev.android.calculator.ICalculatorDisplay;
 
 /**
  * User: serso
  * Date: 9/11/11
  * Time: 12:16 AM
  */
-public class CalculatorHistoryState extends AbstractHistoryState{
 
+@Root
+public class CalculatorHistoryState extends AbstractHistoryState {
+
+	@Element
 	@NotNull
 	private EditorHistoryState editorState;
 
+	@Element
 	@NotNull
 	private CalculatorDisplayHistoryState displayState;
 
-	public CalculatorHistoryState(@NotNull EditorHistoryState editorState,
+	private CalculatorHistoryState() {
+		// for xml
+	}
+
+	private CalculatorHistoryState(@NotNull EditorHistoryState editorState,
 								  @NotNull CalculatorDisplayHistoryState displayState) {
 		this.editorState = editorState;
 		this.displayState = displayState;
 	}
 
+	public static CalculatorHistoryState newInstance(@NotNull Editor editor, @NotNull ICalculatorDisplay display) {
+		final EditorHistoryState editorHistoryState = EditorHistoryState.newInstance(editor);
+		final CalculatorDisplayHistoryState displayHistoryState = CalculatorDisplayHistoryState.newInstance(display);
+		return new CalculatorHistoryState(editorHistoryState, displayHistoryState);
+	}
+
 	@NotNull
 	public EditorHistoryState getEditorState() {
 		return editorState;
@@ -71,4 +88,9 @@ public class CalculatorHistoryState extends AbstractHistoryState{
 		result = 31 * result + displayState.hashCode();
 		return result;
 	}
+
+	public void setValuesFromHistory(@NotNull Editor editor, @NotNull ICalculatorDisplay display) {
+		this.getEditorState().setValuesFromHistory(editor);
+		this.getDisplayState().setValuesFromHistory(display);
+	}
 }

src/main/java/org/solovyev/android/calculator/history/Editor.java

@@ -0,0 +1,27 @@
+/*
+ * Copyright (c) 2009-2011. Created by serso aka se.solovyev.
+ * For more information, please, contact se.solovyev@gmail.com
+ * or visit http://se.solovyev.org
+ */
+
+package org.solovyev.android.calculator.history;
+
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * User: serso
+ * Date: 12/17/11
+ * Time: 9:37 PM
+ */
+public interface Editor {
+
+	@Nullable
+	CharSequence getText();
+
+	void setText(@Nullable CharSequence text);
+
+	int  getSelection();
+
+	void setSelection(int selection);
+
+}

src/main/java/org/solovyev/android/calculator/history/EditorHistoryState.java

@@ -3,33 +3,42 @@
  * For more information, please, contact se.solovyev@gmail.com
  */
 
-package org.solovyev.android.calculator;
+package org.solovyev.android.calculator.history;
 
-import android.widget.TextView;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.simpleframework.xml.Element;
+import org.simpleframework.xml.Root;
 
+@Root
 public class EditorHistoryState {
 
+	@Element
 	private int cursorPosition;
 
+	@Element(required = false)
 	@Nullable
 	private String text;
 
 	private EditorHistoryState() {
+		// for xml
 	}
 
-
 	@NotNull
-	public static EditorHistoryState newInstance(@NotNull TextView textView) {
+	public static EditorHistoryState newInstance(@NotNull Editor editor) {
 		final EditorHistoryState result = new EditorHistoryState();
 
-		result.text = String.valueOf(textView.getText());
+		result.text = String.valueOf(editor.getText());
-		result.cursorPosition = textView.getSelectionStart();
+		result.cursorPosition = editor.getSelection();
 
 		return result;
 	}
 
+	public void setValuesFromHistory(@NotNull Editor editor) {
+		editor.setText(this.getText());
+		editor.setSelection(this.getCursorPosition());
+	}
+
 	@Nullable
 	public String getText() {
 		return text;

src/main/java/org/solovyev/android/calculator/history/History.java

@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) 2009-2011. Created by serso aka se.solovyev.
+ * For more information, please, contact se.solovyev@gmail.com
+ * or visit http://se.solovyev.org
+ */
+
+package org.solovyev.android.calculator.history;
+
+import org.simpleframework.xml.ElementList;
+import org.simpleframework.xml.Root;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * User: serso
+ * Date: 12/17/11
+ * Time: 9:30 PM
+ */
+
+@Root
+public class History {
+
+	@ElementList
+	private List<CalculatorHistoryState> historyItems = new ArrayList<CalculatorHistoryState>();
+
+	public History() {
+	}
+
+	public List<CalculatorHistoryState> getHistoryItems() {
+		return historyItems;
+	}
+}

src/main/java/org/solovyev/android/calculator/history/HistoryUtils.java

@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2009-2011. Created by serso aka se.solovyev.
+ * For more information, please, contact se.solovyev@gmail.com
+ * or visit http://se.solovyev.org
+ */
+
+package org.solovyev.android.calculator.history;
+
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+import org.simpleframework.xml.Serializer;
+import org.simpleframework.xml.core.Persister;
+import org.solovyev.common.utils.history.HistoryHelper;
+
+import java.io.StringWriter;
+
+/**
+ * User: serso
+ * Date: 12/17/11
+ * Time: 9:59 PM
+ */
+class HistoryUtils {
+
+	// not intended for instantiation
+	private HistoryUtils() {
+		throw new AssertionError();
+	}
+
+	public static void fromXml(@Nullable String xml, @NotNull HistoryHelper<CalculatorHistoryState> calculatorHistory) {
+		if (xml != null) {
+			final Serializer serializer = new Persister();
+			try {
+				final History history = serializer.read(History.class, xml);
+				for (CalculatorHistoryState historyItem : history.getHistoryItems()) {
+					calculatorHistory.addState(historyItem);
+				}
+			} catch (Exception e) {
+				throw new RuntimeException(e);
+			}
+		}
+	}
+
+	@NotNull
+	public static String toXml(@NotNull HistoryHelper<CalculatorHistoryState> calculatorHistory) {
+		final History history = new History();
+		for (CalculatorHistoryState historyState : calculatorHistory.getStates()) {
+			if (historyState.isSaved()) {
+				history.getHistoryItems().add(historyState);
+			}
+		}
+
+		final StringWriter xml = new StringWriter();
+		final Serializer serializer = new Persister();
+		try {
+			serializer.write(history, xml);
+		} catch (Exception e) {
+			throw new RuntimeException(e);
+		}
+		return xml.toString();
+	}
+}

src/main/java/org/solovyev/android/calculator/history/TextViewEditorAdapter.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2009-2011. Created by serso aka se.solovyev.
+ * For more information, please, contact se.solovyev@gmail.com
+ * or visit http://se.solovyev.org
+ */
+
+package org.solovyev.android.calculator.history;
+
+import android.widget.EditText;
+import android.widget.TextView;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * User: serso
+ * Date: 12/17/11
+ * Time: 9:39 PM
+ */
+public class TextViewEditorAdapter implements Editor {
+
+	@NotNull
+	private final TextView textView;
+
+	public TextViewEditorAdapter(@NotNull TextView textView) {
+		this.textView = textView;
+	}
+
+	@Override
+	public CharSequence getText() {
+		return textView.getText().toString();
+	}
+
+	@Override
+	public void setText(@Nullable CharSequence text) {
+		textView.setText(text);
+	}
+
+	@Override
+	public int getSelection() {
+		return textView.getSelectionStart();
+	}
+
+	@Override
+	public void setSelection(int selection) {
+		if ( textView instanceof EditText ) {
+			((EditText) textView).setSelection(selection);
+		}
+	}
+}

src/main/java/org/solovyev/android/calculator/jscl/FromJsclNumericTextProcessor.java

@@ -18,6 +18,8 @@ import org.solovyev.android.calculator.model.TextProcessor;
  */
 class FromJsclNumericTextProcessor implements TextProcessor<String, Generic> {
 
+	public static final FromJsclNumericTextProcessor instance = new FromJsclNumericTextProcessor();
+
 	@NotNull
 	@Override
 	public String process(@NotNull Generic numeric) throws CalculatorParseException {

src/main/java/org/solovyev/android/calculator/jscl/JsclOperation.java

@@ -16,66 +16,55 @@ import org.solovyev.android.calculator.model.TextProcessor;
 
 public enum JsclOperation {
 
-	simplify(new FromJsclSimplifyTextProcessor()) {
+	simplify,
-		@NotNull
+	elementary,
-		@Override
+	numeric;
-		public String evaluate(@NotNull String expression) throws ParseException {
-			return CalculatorEngine.instance.getEngine().simplify(expression);
-		}
 
-		@NotNull
+	JsclOperation() {
-		@Override
-		public Generic evaluateGeneric(@NotNull String expression) throws ParseException {
-			return CalculatorEngine.instance.getEngine().simplifyGeneric(expression);
-		}
-	},
-
-	elementary(DummyTextProcessor.instance) {
-		@NotNull
-		@Override
-		public String evaluate(@NotNull String expression) throws ParseException {
-			return CalculatorEngine.instance.getEngine().elementary(expression);
-
-		}
-
-		@NotNull
-		@Override
-		public Generic evaluateGeneric(@NotNull String expression) throws ParseException {
-			return CalculatorEngine.instance.getEngine().elementaryGeneric(expression);
-		}
-	},
-
-	numeric(new FromJsclNumericTextProcessor()) {
-		@NotNull
-		@Override
-		public String evaluate(@NotNull String expression) throws ParseException {
-			return CalculatorEngine.instance.getEngine().evaluate(expression);
-		}
-
-		@NotNull
-		@Override
-		public Generic evaluateGeneric(@NotNull String expression) throws ParseException {
-			return CalculatorEngine.instance.getEngine().evaluateGeneric(expression);
-		}
-	};
-
-	@NotNull
-	private final TextProcessor<String, Generic> fromProcessor;
-
-	JsclOperation(@NotNull TextProcessor<String, Generic> fromProcessor) {
-		this.fromProcessor = fromProcessor;
 	}
 
+
 	@NotNull
 	public TextProcessor<String, Generic> getFromProcessor() {
-		return fromProcessor;
+		switch (this) {
+			case simplify:
+				return FromJsclSimplifyTextProcessor.instance;
+			case elementary:
+				return DummyTextProcessor.instance;
+			case numeric:
+				return FromJsclNumericTextProcessor.instance;
+			default:
+				throw new UnsupportedOperationException();
+		}
 	}
 
 	@NotNull
-	public abstract String evaluate(@NotNull String expression) throws ParseException;
+	public final String evaluate(@NotNull String expression) throws ParseException {
+		switch (this) {
+			case simplify:
+				return CalculatorEngine.instance.getEngine().simplify(expression);
+			case elementary:
+				return CalculatorEngine.instance.getEngine().elementary(expression);
+			case numeric:
+				return CalculatorEngine.instance.getEngine().evaluate(expression);
+			default:
+				throw new UnsupportedOperationException();
+		}
+	}
 
 	@NotNull
-	public abstract Generic evaluateGeneric(@NotNull String expression) throws ParseException;
+	public final Generic evaluateGeneric(@NotNull String expression) throws ParseException {
+		switch (this) {
+			case simplify:
+				return CalculatorEngine.instance.getEngine().simplifyGeneric(expression);
+			case elementary:
+				return CalculatorEngine.instance.getEngine().elementaryGeneric(expression);
+			case numeric:
+				return CalculatorEngine.instance.getEngine().evaluateGeneric(expression);
+			default:
+				throw new UnsupportedOperationException();
+		}
+	}
 
 
 }

src/main/java/org/solovyev/android/calculator/model/AndroidVarsRegistry.java

@@ -19,7 +19,7 @@ import org.solovyev.common.math.MathRegistry;
  */
 public interface AndroidVarsRegistry extends MathRegistry<Var>{
 
-	void init(@Nullable Context context, @Nullable SharedPreferences preferences);
+	void load(@Nullable Context context, @Nullable SharedPreferences preferences);
 
 	void save(@NotNull Context context);
 }

src/main/java/org/solovyev/android/calculator/model/AndroidVarsRegistryImpl.java

@@ -37,7 +37,7 @@ class AndroidVarsRegistryImpl implements AndroidVarsRegistry {
 		this.mathRegistry = mathRegistry;
 	}
 
-	public synchronized void init(@Nullable Context context, @Nullable SharedPreferences preferences) {
+	public synchronized void load(@Nullable Context context, @Nullable SharedPreferences preferences) {
 
 		if (context != null && preferences != null) {
 			final String value = preferences.getString(context.getString(R.string.p_calc_vars), null);

src/main/java/org/solovyev/android/calculator/model/CalculatorEngine.java

@@ -283,7 +283,7 @@ public enum CalculatorEngine {
 				}
 			}
 
-			varsRegister.init(context, preferences);
+			varsRegister.load(context, preferences);
 		}
 	}
 

src/main/java/org/solovyev/android/calculator/model/FromJsclSimplifyTextProcessor.java

@@ -15,6 +15,8 @@ import java.util.List;
  */
 public class FromJsclSimplifyTextProcessor implements TextProcessor<String, Generic> {
 
+	public static final FromJsclSimplifyTextProcessor instance = new FromJsclSimplifyTextProcessor();
+
 	public FromJsclSimplifyTextProcessor() {
 	}
 

src/main/java/org/solovyev/common/SameEqualizer.java

@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 2009-2011. Created by serso aka se.solovyev.
+ * For more information, please, contact se.solovyev@gmail.com
+ * or visit http://se.solovyev.org
+ */
+
+package org.solovyev.common;
+
+
+import org.jetbrains.annotations.Nullable;
+import org.solovyev.common.utils.Equalizer;
+
+/**
+ * User: serso
+ * Date: 12/17/11
+ * Time: 11:11 PM
+ */
+public enum SameEqualizer implements Equalizer {
+
+	instance;
+
+	private SameEqualizer() {
+	}
+
+	@Override
+	public boolean equals(@Nullable Object first, @Nullable Object second) {
+		return first == second;
+	}
+}

src/test/java/org/solovyev/android/calculator/history/HistoryUtilsTest.java

@@ -0,0 +1,306 @@
+/*
+ * Copyright (c) 2009-2011. Created by serso aka se.solovyev.
+ * For more information, please, contact se.solovyev@gmail.com
+ * or visit http://se.solovyev.org
+ */
+
+package org.solovyev.android.calculator.history;
+
+import jscl.math.Generic;
+import junit.framework.Assert;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+import org.junit.Test;
+import org.solovyev.android.calculator.ICalculatorDisplay;
+import org.solovyev.android.calculator.jscl.JsclOperation;
+import org.solovyev.common.utils.CollectionEqualizer;
+import org.solovyev.common.utils.EqualsTool;
+import org.solovyev.common.utils.history.HistoryHelper;
+import org.solovyev.common.utils.history.SimpleHistoryHelper;
+
+import java.util.Date;
+
+/**
+ * User: serso
+ * Date: 12/17/11
+ * Time: 10:01 PM
+ */
+public class HistoryUtilsTest {
+
+	@Test
+	public void testFromXml() throws Exception {
+
+	}
+
+	private static final String emptyHistory = "<history>\n" +
+			"   <historyItems class=\"java.util.ArrayList\"/>\n" +
+			"</history>";
+
+	private static final String toXml1 = "<history>\n" +
+			"   <historyItems class=\"java.util.ArrayList\">\n" +
+			"      <calculatorHistoryState>\n" +
+			"         <time>1970-01-02 06:46:40.0 MSK</time>\n" +
+			"         <editorState>\n" +
+			"            <cursorPosition>3</cursorPosition>\n" +
+			"            <text>1+1</text>\n" +
+			"         </editorState>\n" +
+			"         <displayState>\n" +
+			"            <editorState>\n" +
+			"               <cursorPosition>1</cursorPosition>\n" +
+			"               <text>Error</text>\n" +
+			"            </editorState>\n" +
+			"            <jsclOperation>simplify</jsclOperation>\n" +
+			"         </displayState>\n" +
+			"      </calculatorHistoryState>\n" +
+			"   </historyItems>\n" +
+			"</history>";
+
+	private static final String toXml2 = "<history>\n" +
+			"   <historyItems class=\"java.util.ArrayList\">\n" +
+			"      <calculatorHistoryState>\n" +
+			"         <time>1970-01-02 06:46:40.0 MSK</time>\n" +
+			"         <editorState>\n" +
+			"            <cursorPosition>3</cursorPosition>\n" +
+			"            <text>1+1</text>\n" +
+			"         </editorState>\n" +
+			"         <displayState>\n" +
+			"            <editorState>\n" +
+			"               <cursorPosition>1</cursorPosition>\n" +
+			"               <text>Error</text>\n" +
+			"            </editorState>\n" +
+			"            <jsclOperation>simplify</jsclOperation>\n" +
+			"         </displayState>\n" +
+			"      </calculatorHistoryState>\n" +
+			"      <calculatorHistoryState>\n" +
+			"         <time>1970-01-02 06:46:40.0 MSK</time>\n" +
+			"         <editorState>\n" +
+			"            <cursorPosition>2</cursorPosition>\n" +
+			"            <text>5/6</text>\n" +
+			"         </editorState>\n" +
+			"         <displayState>\n" +
+			"            <editorState>\n" +
+			"               <cursorPosition>3</cursorPosition>\n" +
+			"               <text>5/6</text>\n" +
+			"            </editorState>\n" +
+			"            <jsclOperation>numeric</jsclOperation>\n" +
+			"         </displayState>\n" +
+			"      </calculatorHistoryState>\n" +
+			"      <calculatorHistoryState>\n" +
+			"         <time>1970-01-02 06:46:40.0 MSK</time>\n" +
+			"         <editorState>\n" +
+			"            <cursorPosition>1</cursorPosition>\n" +
+			"            <text>null</text>\n" +
+			"         </editorState>\n" +
+			"         <displayState>\n" +
+			"            <editorState>\n" +
+			"               <cursorPosition>1</cursorPosition>\n" +
+			"               <text>Error</text>\n" +
+			"            </editorState>\n" +
+			"            <jsclOperation>elementary</jsclOperation>\n" +
+			"         </displayState>\n" +
+			"      </calculatorHistoryState>\n" +
+			"      <calculatorHistoryState>\n" +
+			"         <time>1970-01-02 06:46:40.0 MSK</time>\n" +
+			"         <editorState>\n" +
+			"            <cursorPosition>0</cursorPosition>\n" +
+			"            <text>4+5/35sin(41)+dfdsfsdfs</text>\n" +
+			"         </editorState>\n" +
+			"         <displayState>\n" +
+			"            <editorState>\n" +
+			"               <cursorPosition>1</cursorPosition>\n" +
+			"               <text>4+5/35sin(41)+dfdsfsdfs</text>\n" +
+			"            </editorState>\n" +
+			"            <jsclOperation>numeric</jsclOperation>\n" +
+			"         </displayState>\n" +
+			"      </calculatorHistoryState>\n" +
+			"   </historyItems>\n" +
+			"</history>";
+
+	@Test
+	public void testToXml() throws Exception {
+		final Date date = new Date(100000000);
+
+		HistoryHelper<CalculatorHistoryState> history = new SimpleHistoryHelper<CalculatorHistoryState>();
+
+		ICalculatorDisplay calculatorDisplay = new TestCalculatorDisplay();
+		calculatorDisplay.setErrorMessage("error_msg1");
+		calculatorDisplay.setText("Error");
+		calculatorDisplay.setSelection(1);
+		calculatorDisplay.setJsclOperation(JsclOperation.simplify);
+
+		Editor calculatorEditor = new TestEditor();
+		calculatorEditor.setSelection(3);
+		calculatorEditor.setText("1+1");
+
+		CalculatorHistoryState state = CalculatorHistoryState.newInstance(calculatorEditor, calculatorDisplay);
+		state.setTime(date);
+		history.addState(state);
+
+		Assert.assertEquals(emptyHistory, HistoryUtils.toXml(history));
+
+
+		state.setSaved(true);
+
+		Assert.assertEquals(toXml1, HistoryUtils.toXml(history));
+
+		calculatorDisplay = new TestCalculatorDisplay();
+		calculatorDisplay.setErrorMessage(null);
+		calculatorDisplay.setText("5/6");
+		calculatorDisplay.setSelection(3);
+		calculatorDisplay.setJsclOperation(JsclOperation.numeric);
+
+		calculatorEditor = new TestEditor();
+		calculatorEditor.setSelection(2);
+		calculatorEditor.setText("5/6");
+
+		state = CalculatorHistoryState.newInstance(calculatorEditor, calculatorDisplay);
+		state.setSaved(true);
+		state.setTime(date);
+		history.addState(state);
+
+		calculatorDisplay = new TestCalculatorDisplay();
+		calculatorDisplay.setErrorMessage("error_msg2");
+		calculatorDisplay.setText("Error");
+		calculatorDisplay.setSelection(1);
+		calculatorDisplay.setJsclOperation(JsclOperation.elementary);
+
+		calculatorEditor = new TestEditor();
+		calculatorEditor.setSelection(1);
+		calculatorEditor.setText(null);
+
+		state = CalculatorHistoryState.newInstance(calculatorEditor, calculatorDisplay);
+		state.setSaved(true);
+		state.setTime(date);
+		history.addState(state);
+
+		calculatorDisplay = new TestCalculatorDisplay();
+		calculatorDisplay.setErrorMessage(null);
+		calculatorDisplay.setText("4+5/35sin(41)+dfdsfsdfs");
+		calculatorDisplay.setSelection(1);
+		calculatorDisplay.setJsclOperation(JsclOperation.numeric);
+
+		calculatorEditor = new TestEditor();
+		calculatorEditor.setSelection(0);
+		calculatorEditor.setText("4+5/35sin(41)+dfdsfsdfs");
+
+		state = CalculatorHistoryState.newInstance(calculatorEditor, calculatorDisplay);
+		state.setSaved(true);
+		state.setTime(date);
+		history.addState(state);
+
+		String xml = HistoryUtils.toXml(history);
+		Assert.assertEquals(toXml2, xml);
+
+		final HistoryHelper<CalculatorHistoryState> historyFromXml = new SimpleHistoryHelper<CalculatorHistoryState>();
+		HistoryUtils.fromXml(xml, historyFromXml);
+
+		Assert.assertEquals(history.getStates().size(), historyFromXml.getStates().size());
+
+		Assert.assertTrue(EqualsTool.areEqual(history.getStates(), historyFromXml.getStates(), new CollectionEqualizer<CalculatorHistoryState>(null)));
+	}
+
+
+	private static class TestCalculatorDisplay implements ICalculatorDisplay {
+
+		@NotNull
+		private final TestEditor testEditor = new TestEditor();
+
+		private boolean valid;
+
+		private String errorMessage;
+
+		private JsclOperation operation;
+
+		private Generic genericResult;
+
+		@Override
+		public boolean isValid() {
+			return this.valid;
+		}
+
+		@Override
+		public void setValid(boolean valid) {
+			this.valid = valid;
+		}
+
+		@Override
+		public String getErrorMessage() {
+			return this.errorMessage;
+		}
+
+		@Override
+		public void setErrorMessage(@Nullable String errorMessage) {
+			this.errorMessage = errorMessage;
+		}
+
+		@Override
+		public void setJsclOperation(@NotNull JsclOperation jsclOperation) {
+			this.operation = jsclOperation;
+		}
+
+		@NotNull
+		@Override
+		public JsclOperation getJsclOperation() {
+			return this.operation;
+		}
+
+		@Override
+		public void setGenericResult(@Nullable Generic genericResult) {
+			this.genericResult = genericResult;
+		}
+
+		@Override
+		public Generic getGenericResult() {
+			return this.genericResult;
+		}
+
+		@Override
+		public CharSequence getText() {
+			return this.testEditor.getText();
+		}
+
+		@Override
+		public void setText(@Nullable CharSequence text) {
+			this.testEditor.setText(text);
+		}
+
+		@Override
+		public int getSelection() {
+			return this.testEditor.getSelection();
+		}
+
+		@Override
+		public void setSelection(int selection) {
+			this.testEditor.setSelection(selection);
+		}
+	}
+
+	private static class TestEditor implements Editor {
+
+		@Nullable
+		private CharSequence text;
+
+		private int selection;
+
+		@Nullable
+		@Override
+		public CharSequence getText() {
+			return this.text;
+		}
+
+		@Override
+		public void setText(@Nullable CharSequence text) {
+			this.text = text;
+		}
+
+		@Override
+		public int getSelection() {
+			return this.selection;
+		}
+
+		@Override
+		public void setSelection(int selection) {
+			this.selection = selection;
+		}
+	}
+}