Ans variable

calculatorpp-core/src/main/java/org/solovyev/android/calculator/CalculatorImpl.java

@@ -13,6 +13,7 @@ import org.jetbrains.annotations.Nullable;
 import org.solovyev.android.calculator.history.CalculatorHistory;
 import org.solovyev.android.calculator.history.CalculatorHistoryState;
 import org.solovyev.android.calculator.jscl.JsclOperation;
+import org.solovyev.android.calculator.model.Var;
 import org.solovyev.android.calculator.text.TextProcessor;
 import org.solovyev.android.calculator.units.CalculatorNumeralBase;
 import org.solovyev.common.history.HistoryAction;
@@ -388,16 +389,20 @@ public class CalculatorImpl implements Calculator, CalculatorEventListener {
 
         switch (calculatorEventType) {
             case editor_state_changed:
-                final CalculatorEditorChangeEventData changeEventData = (CalculatorEditorChangeEventData) data;
+                final CalculatorEditorChangeEventData editorChangeEventData = (CalculatorEditorChangeEventData) data;
 
-                final String newText = changeEventData.getNewValue().getText();
+                final String newText = editorChangeEventData.getNewValue().getText();
-                final String oldText = changeEventData.getOldValue().getText();
+                final String oldText = editorChangeEventData.getOldValue().getText();
 
                 if (!newText.equals(oldText)) {
-                    evaluate(JsclOperation.numeric, changeEventData.getNewValue().getText(), calculatorEventData.getSequenceId());
+                    evaluate(JsclOperation.numeric, editorChangeEventData.getNewValue().getText(), calculatorEventData.getSequenceId());
                 }
                 break;
 
+            case display_state_changed:
+                onDisplayStateChanged((CalculatorDisplayChangeEventData) data);
+                break;
+
             case engine_preferences_changed:
                 evaluate(calculatorEventData.getSequenceId());
                 break;
@@ -420,6 +425,30 @@ public class CalculatorImpl implements Calculator, CalculatorEventListener {
         }
     }
 
+    private void onDisplayStateChanged(@NotNull CalculatorDisplayChangeEventData displayChangeEventData) {
+        final CalculatorDisplayViewState newState = displayChangeEventData.getNewValue();
+        if (newState.isValid()) {
+            final String result = newState.getStringResult();
+            if ( !StringUtils.isEmpty(result) ) {
+                final CalculatorMathRegistry<IConstant> varsRegistry = CalculatorLocatorImpl.getInstance().getEngine().getVarsRegistry();
+                final IConstant ansVar = varsRegistry.get(CalculatorVarsRegistry.ANS);
+
+                final Var.Builder varBuilder;
+                if (ansVar != null) {
+                    varBuilder = new Var.Builder(ansVar);
+                } else {
+                    varBuilder = new Var.Builder();
+                }
+
+                varBuilder.setName(CalculatorVarsRegistry.ANS);
+                varBuilder.setValue(result);
+                varBuilder.setDescription(CalculatorMessages.getBundle().getString("ans_description"));
+
+                varsRegistry.add(varBuilder);
+            }
+        }
+    }
+
     /*
     **********************************************************************
     *

calculatorpp-core/src/main/java/org/solovyev/android/calculator/CalculatorVarsRegistry.java

@@ -23,6 +23,9 @@ import java.util.Map;
  */
 public class CalculatorVarsRegistry extends AbstractCalculatorMathRegistry<IConstant, Var> {
 
+    @NotNull
+    public static final String ANS = "ans";
+
 	@NotNull
 	private static final Map<String, String> substitutes = new HashMap<String, String>();
 	static {

calculatorpp-core/src/main/resources/org/solovyev/android/calculator/messages.properties

@@ -7,3 +7,4 @@ msg_6=Infinite loop is detected in expression
 
 syntax_error=Error
 result_copied=Result copied to clipboard!
+ans_description=Last calculated value

calculatorpp-core/src/main/resources/org/solovyev/android/calculator/messages_ru.properties

@@ -7,3 +7,4 @@ msg_6=В выражении найден Бесконечный цикл - пр
 
 syntax_error=Ошибка
 result_copied=Результат скопирован в буфер!
+ans_description=Последний посчитанный результат

calculatorpp-core/src/test/java/org/solovyev/android/calculator/CalculatorImplTest.java

@@ -0,0 +1,33 @@
+package org.solovyev.android.calculator;
+
+import org.junit.Before;
+import org.junit.Test;
+
+/**
+ * User: Solovyev_S
+ * Date: 15.10.12
+ * Time: 12:30
+ */
+public class CalculatorImplTest extends AbstractCalculatorTest {
+
+    @Before
+    public void setUp() throws Exception {
+        super.setUp();
+    }
+
+    @Test
+    public void testAnsVariable() throws Exception {
+        CalculatorTestUtils.assertError("ans");
+        CalculatorTestUtils.assertError("ans");
+        CalculatorTestUtils.assertEval("2", "2");
+        CalculatorTestUtils.assertEval("2", "ans");
+        CalculatorTestUtils.assertEval("4", "ans^2");
+        CalculatorTestUtils.assertEval("16", "ans^2");
+        CalculatorTestUtils.assertEval("0", "0");
+        CalculatorTestUtils.assertEval("0", "ans");
+        CalculatorTestUtils.assertEval("3", "3");
+        CalculatorTestUtils.assertEval("9", "ans*ans");
+        CalculatorTestUtils.assertError("ans*an");
+        CalculatorTestUtils.assertEval("81", "ans*ans");
+    }
+}