changes

res/layout/var_edit.xml

@@ -39,7 +39,6 @@
 		<EditText a:id="@+id/var_edit_value"
 				  a:layout_width="fill_parent"
 				  a:layout_height="wrap_content"
-				  a:inputType="numberDecimal"
 				  style="@style/default_text_size">
 		</EditText>
 

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

@@ -26,6 +26,7 @@ import org.solovyev.common.utils.StringUtils;
 
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Comparator;
 import java.util.List;
 
 /**
@@ -59,7 +60,7 @@ public class CalculatorVarsActivity extends ListActivity {
 			@Override
 			public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {
 				final Var var = (Var) parent.getItemAtPosition(position);
-				createEditVariableDialog(var, var.getName(), var.getValue(), var.getDescription());
+				createEditVariableDialog(var, var.getName(), StringUtils.getNotEmpty(var.getValue(), ""), var.getDescription());
 				return true;
 			}
 		});
@@ -81,6 +82,8 @@ public class CalculatorVarsActivity extends ListActivity {
 			}
 		});
 
+		sort();
+
 		final Intent intent = getIntent();
 		if ( intent != null ) {
 			final String varValue = intent.getStringExtra(CREATE_VAR_EXTRA_STRING);
@@ -206,8 +209,17 @@ public class CalculatorVarsActivity extends ListActivity {
 
 				final AndroidVarsRegistry varsRegistry = CalculatorEngine.instance.getVarsRegister();
 				if (!StringUtils.isEmpty(name)) {
+
+					boolean canBeSaved = false;
+
 					final Var varFromRegister = varsRegistry.get(name);
-					if (varFromRegister == null || varFromRegister == editedInstance) {
+					if ( varFromRegister == null ) {
+						canBeSaved = true;
+					} else if ( editedInstance != null && varFromRegister.getId().equals(editedInstance.getId()) ) {
+						canBeSaved = true;
+					}
+
+					if (canBeSaved) {
 						final MathType.Result mathType = MathType.getType(name, 0);
 
 						if (mathType.getMathType() == MathType.text || mathType.getMathType() == MathType.constant) {
@@ -220,9 +232,9 @@ public class CalculatorVarsActivity extends ListActivity {
 								error = null;
 							} else {
 								// value is not empty => must be a number
-								boolean correctDouble = isValid(value);
+								boolean valid = isValid(value);
 
-								if (correctDouble) {
+								if (valid) {
 									varBuilder.setName(name);
 									varBuilder.setDescription(description);
 									varBuilder.setValue(value);
@@ -248,25 +260,33 @@ public class CalculatorVarsActivity extends ListActivity {
 					if ( editedInstance == null ) {
 						CalculatorVarsActivity.this.adapter.add(varsRegistry.add(null, varBuilder));
 					} else {
-						varsRegistry.add(editedInstance.getName(), varBuilder);
+						final Var newInstance = varsRegistry.add(editedInstance.getName(), varBuilder);
+						CalculatorVarsActivity.this.adapter.remove(editedInstance);
+						CalculatorVarsActivity.this.adapter.add(newInstance);
 					}
 
 					varsRegistry.save(CalculatorVarsActivity.this);
 
-					CalculatorVarsActivity.this.adapter.notifyDataSetChanged();
+					sort();
 				}
 			}
 		}
 	}
 
-	public static boolean isValid(@NotNull String value) {
+	private void sort() {
-		boolean valid = true;
+		CalculatorVarsActivity.this.adapter.sort(new Comparator<Var>() {
-		try {
+			@Override
-			Double.valueOf(value);
+			public int compare(Var var, Var var1) {
-		} catch (NumberFormatException e) {
+				return var.getName().compareTo(var1.getName());
-			valid = false;
 			}
-		return valid;
+		});
+
+		CalculatorVarsActivity.this.adapter.notifyDataSetChanged();
+	}
+
+	public static boolean isValid(@NotNull String value) {
+		// now every string might be constant
+		return true;
 	}
 
 	private class VarsArrayAdapter extends ArrayAdapter<Var> {

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

@@ -71,7 +71,7 @@ public class AndroidFunctionsRegistryImpl implements AndroidFunctionsRegistry {
 	}
 
 	@Override
-	public Function add(@Nullable String name, @NotNull IBuilder<Function> IBuilder) {
+	public Function add(@Nullable String name, @NotNull IBuilder<? extends Function> IBuilder) {
 		return functionsRegistry.add(name, IBuilder);
 	}
 
@@ -95,4 +95,9 @@ public class AndroidFunctionsRegistryImpl implements AndroidFunctionsRegistry {
 	public Function get(@NotNull String name) {
 		return functionsRegistry.get(name);
 	}
+
+	@Override
+	public Function getById(@NotNull Integer id) {
+		return functionsRegistry.getById(id);
+	}
 }

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

@@ -9,43 +9,39 @@ package org.solovyev.android.calculator.model;
 import android.content.Context;
 import android.content.SharedPreferences;
 import android.preference.PreferenceManager;
+import jscl.math.function.IConstant;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.simpleframework.xml.Serializer;
 import org.simpleframework.xml.core.Persister;
 import org.solovyev.android.calculator.R;
 import org.solovyev.android.calculator.math.MathType;
-import org.solovyev.common.math.AbstractMathRegistry;
+import org.solovyev.common.definitions.IBuilder;
+import org.solovyev.common.math.MathRegistry;
 
 import java.io.StringWriter;
+import java.util.ArrayList;
+import java.util.List;
 
 /**
  * User: serso
  * Date: 9/29/11
  * Time: 4:57 PM
  */
-class AndroidVarsRegistryImpl extends AbstractMathRegistry<Var> implements AndroidVarsRegistry {
+class AndroidVarsRegistryImpl implements AndroidVarsRegistry {
 
-	protected AndroidVarsRegistryImpl() {
+	@NotNull
+	private final MathRegistry<IConstant> mathRegistry;
+
+	protected AndroidVarsRegistryImpl(@NotNull MathRegistry<IConstant> mathRegistry) {
+		this.mathRegistry = mathRegistry;
 	}
 
-/*	public void merge(@NotNull final List<Var> varsParam) {
+	private boolean initialized = false;
-		final Set<Var> result = new HashSet<Var>(varsParam);
-
-		for (Var systemVar : systemEntities) {
-			if (!result.contains(systemVar)) {
-				result.add(systemVar);
-			}
-		}
-
-		entities.clear();
-		entities.addAll(result);
-	}*/
 
 	public synchronized void init(@Nullable Context context, @Nullable SharedPreferences preferences) {
 
-		this.entities.clear();
+		if (!initialized) {
-		this.systemEntities.clear();
 
 			if (context != null && preferences != null) {
 				final String value = preferences.getString(context.getString(R.string.p_calc_vars), null);
@@ -53,7 +49,11 @@ class AndroidVarsRegistryImpl extends AbstractMathRegistry<Var> implements Andro
 					final Serializer serializer = new Persister();
 					try {
 						final Vars vars = serializer.read(Vars.class, value);
-					this.entities.addAll(vars.getVars());
+						for (Var var : vars.getVars()) {
+							if (!contains(var.getName())) {
+								add(null, new Var.Builder(var));
+							}
+						}
 					} catch (Exception e) {
 						throw new RuntimeException(e);
 					}
@@ -78,7 +78,7 @@ class AndroidVarsRegistryImpl extends AbstractMathRegistry<Var> implements Andro
 				} else if (systemVarName.equals(MathType.G)) {
 					builder = new Var.Builder(systemVarName, MathType.G_VALUE);
 					varDescription = R.string.c_g_description;
-/*			} else if (systemVarName.equals(MathType.H)) {
+					/*			} else if (systemVarName.equals(MathType.H)) {
 										builder = new Var.Builder(systemVarName, MathType.H_VALUE);
 										varDescription = R.string.c_h_description;*/
 				} else if (systemVarName.equals(MathType.H_REDUCED)) {
@@ -103,13 +103,13 @@ class AndroidVarsRegistryImpl extends AbstractMathRegistry<Var> implements Andro
 					builder.setDescription(context.getString(varDescription));
 				}
 
-			final Var systemVar = builder.create();
+				if (!contains(systemVarName)) {
+					add(null, builder);
+				}
+			}
+		}
 
-			systemEntities.add(systemVar);
+		initialized = true;
-			if (!entities.contains(systemVar)) {
-				entities.add(systemVar);
-			}
-		}
 
 		/*Log.d(AndroidVarsRegistry.class.getName(), vars.size() + " variables registered!");
 		for (Var var : vars) {
@@ -123,7 +123,7 @@ class AndroidVarsRegistryImpl extends AbstractMathRegistry<Var> implements Andro
 		final SharedPreferences.Editor editor = settings.edit();
 
 		final Vars vars = new Vars();
-		for (Var var : this.entities) {
+		for (Var var : this.getEntities()) {
 			if (!var.isSystem()) {
 				vars.getVars().add(var);
 			}
@@ -141,4 +141,81 @@ class AndroidVarsRegistryImpl extends AbstractMathRegistry<Var> implements Andro
 
 		editor.commit();
 	}
+
+	@NotNull
+	@Override
+	public List<Var> getEntities() {
+		final List<Var> result = new ArrayList<Var>();
+		for (IConstant iConstant : mathRegistry.getEntities()) {
+			result.add(transform(iConstant));
+		}
+		return result;
+	}
+
+	@NotNull
+	@Override
+	public List<Var> getSystemEntities() {
+		final List<Var> result = new ArrayList<Var>();
+		for (IConstant iConstant : mathRegistry.getSystemEntities()) {
+			result.add(transform(iConstant));
+		}
+		return result;
+	}
+
+	@Override
+	public Var add(@Nullable String name, @NotNull IBuilder<? extends Var> IBuilder) {
+		IConstant result = mathRegistry.add(name, IBuilder);
+		if (result instanceof Var) {
+			return (Var) result;
+		} else if (result != null) {
+			return transform(result);
+		} else {
+			return null;
+		}
+	}
+
+	@NotNull
+	private Var transform(@NotNull IConstant result) {
+		return new Var.Builder(result).create();
+	}
+
+	@Override
+	public void remove(@NotNull Var var) {
+		mathRegistry.remove(var);
+	}
+
+	@NotNull
+	@Override
+	public List<String> getNames() {
+		return mathRegistry.getNames();
+	}
+
+	@Override
+	public boolean contains(@NotNull String name) {
+		return mathRegistry.contains(name);
+	}
+
+	@Override
+	public Var get(@NotNull String name) {
+		IConstant result = mathRegistry.get(name);
+		if (result instanceof Var) {
+			return (Var) result;
+		} else if (result != null) {
+			return transform(result);
+		} else {
+			return null;
+		}
+	}
+
+	@Override
+	public Var getById(@NotNull Integer id) {
+		final IConstant result = mathRegistry.getById(id);
+		if (result instanceof Var) {
+			return (Var) result;
+		} else if (result != null) {
+			return transform(result);
+		} else {
+			return null;
+		}
+	}
 }

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

@@ -67,7 +67,7 @@ public enum CalculatorEngine {
 	public final TextProcessor<PreparedExpression> preprocessor = new ToJsclTextProcessor();
 
 	@NotNull
-	private final AndroidVarsRegistry varsRegister = new AndroidVarsRegistryImpl();
+	private final AndroidVarsRegistry varsRegister = new AndroidVarsRegistryImpl(engine.getConstantsRegistry());
 
 	@NotNull
 	private final AndroidFunctionsRegistry functionsRegistry = new AndroidFunctionsRegistryImpl(engine.getFunctionsRegistry());

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

@@ -17,10 +17,21 @@ import java.util.List;
 
 class ToJsclTextProcessor implements TextProcessor<PreparedExpression> {
 
+	@NotNull
+	private static final Integer MAX_DEPTH = 10;
+
 	@Override
 	@NotNull
 	public PreparedExpression process(@NotNull String s) throws ParseException {
+		return processWithDepth(s, 0, new ArrayList<Var>());
+	}
 
+	private static PreparedExpression processWithDepth(@NotNull String s, int depth, @NotNull List<Var> undefinedVars) throws ParseException {
+		return replaceVariables(processExpression(s).toString(), depth, undefinedVars);
+	}
+
+	@NotNull
+	private static StringBuilder processExpression(@NotNull String s) throws ParseException {
 		final StartsWithFinder startsWithFinder = new StartsWithFinder(s, 0);
 		final StringBuilder result = new StringBuilder();
 
@@ -49,15 +60,18 @@ class ToJsclTextProcessor implements TextProcessor<PreparedExpression> {
 
 			i = mathTypeResult.processToJscl(result, i);
 		}
-
+		return result;
-		return replaceVariables(result.toString());
 	}
 
 	@NotNull
-	private PreparedExpression replaceVariables(@NotNull final String s) {
+	private static PreparedExpression replaceVariables(@NotNull final String s, int depth, @NotNull List<Var> undefinedVars) throws ParseException {
-		final StartsWithFinder startsWithFinder = new StartsWithFinder(s, 0);
+		if (depth >= MAX_DEPTH) {
+			throw new ParseException("Infinite loop in expression: " + s);
+		} else {
+			depth++;
+		}
 
-		final List<Var> undefinedVars = new ArrayList<Var>();
+		final StartsWithFinder startsWithFinder = new StartsWithFinder(s, 0);
 
 		final StringBuilder result = new StringBuilder();
 		for (int i = 0; i < s.length(); i++) {
@@ -70,12 +84,19 @@ class ToJsclTextProcessor implements TextProcessor<PreparedExpression> {
 				if (varName != null) {
 					final Var var = CalculatorEngine.instance.getVarsRegister().get(varName);
 					if (var != null) {
-						if (var.isUndefined()) {
+						if (!var.isDefined()) {
 							undefinedVars.add(var);
 							result.append(varName);
 							offset = varName.length();
 						} else {
-							result.append(var.getValue());
+							final String value = var.getValue();
+							assert value != null;
+
+							if ( var.getDoubleValue() != null ) {
+								result.append(value);
+							} else {
+								result.append("(").append(processWithDepth(value, depth, undefinedVars)).append(")");
+							}
 							offset = varName.length();
 						}
 					}

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

@@ -6,10 +6,13 @@
 
 package org.solovyev.android.calculator.model;
 
+import jscl.math.function.Constant;
+import jscl.math.function.IConstant;
 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.common.definitions.IBuilder;
 import org.solovyev.common.math.MathEntity;
 import org.solovyev.common.utils.StringUtils;
@@ -21,7 +24,11 @@ import org.solovyev.common.utils.StringUtils;
  */
 
 @Root
-public class Var implements MathEntity{
+public class Var implements IConstant {
+
+	@NotNull
+	@Transient
+	private Integer id;
 
 	@Element
 	@NotNull
@@ -38,7 +45,10 @@ public class Var implements MathEntity{
 	@Nullable
 	private String description;
 
-	public static class Builder implements IBuilder<Var>{
+	@Transient
+	private Constant constant;
+
+	public static class Builder implements IBuilder<Var> {
 
 		@NotNull
 		private String name;
@@ -51,6 +61,9 @@ public class Var implements MathEntity{
 		@Nullable
 		private String description;
 
+		@Nullable
+		private Integer id;
+
 		public Builder() {
 		}
 
@@ -59,6 +72,17 @@ public class Var implements MathEntity{
 			this.value = var.value;
 			this.system = var.system;
 			this.description = var.description;
+			this.id = var.id;
+		}
+
+		public Builder(@NotNull IConstant iConstant) {
+			this.name = iConstant.getName();
+
+			this.value = iConstant.getValue();
+
+			this.system = iConstant.isSystem();
+			this.description = iConstant.getDescription();
+			this.id = iConstant.getId();
 		}
 
 		public Builder(@NotNull String name, @NotNull Double value) {
@@ -70,6 +94,7 @@ public class Var implements MathEntity{
 			this.value = value;
 		}
 
+
 		public void setName(@NotNull String name) {
 			this.name = name;
 		}
@@ -89,49 +114,103 @@ public class Var implements MathEntity{
 		}
 
 		@NotNull
-		public Var create () {
+		public Var create() {
-			final Var var = new Var();
+			final Var result;
+			if (id != null) {
+				result = new Var(id);
+			} else {
+				result = new Var();
+			}
 
-			var.name = name;
+			result.name = name;
-			var.value = value;
+			result.value = value;
-			var.system = system;
+			result.system = system;
-			var.description = description;
+			result.description = description;
 
-			return var;
+			return result;
 		}
 	}
 
 	private Var() {
 	}
 
+	private Var(@NotNull Integer id) {
+		this.id = id;
+	}
+
 	public void copy(@NotNull MathEntity o) {
-		if (o instanceof Var) {
+		if (o instanceof IConstant) {
-			final Var that = ((Var) o);
+			final IConstant that = ((IConstant) o);
-			this.name = that.name;
+			this.name = that.getName();
-			this.value = that.value;
+			this.value = that.getValue();
-			this.description = that.description;
+			this.description = that.getDescription();
-			this.system = that.system;
+			this.system = that.isSystem();
 		} else {
 			throw new IllegalArgumentException("Trying to make a copy of unsupported type: " + o.getClass());
 		}
 	}
 
+	@Nullable
+	public Double getDoubleValue() {
+		Double result = null;
+		if (value != null) {
+			try {
+				result = Double.valueOf(value);
+			} catch (NumberFormatException e) {
+				// do nothing - string is not a double
+			}
+		}
+		return result;
+	}
+
 	@Nullable
 	public String getValue() {
 		return value;
 	}
 
+	@NotNull
+	@Override
+	public String toJava() {
+		return String.valueOf(value);
+	}
+
 	public boolean isSystem() {
 		return system;
 	}
 
+	@NotNull
+	@Override
+	public Integer getId() {
+		return this.id;
+	}
+
+	@Override
+	public void setId(@NotNull Integer id) {
+		this.id = id;
+	}
+
+	@Override
+	public boolean same(@Nullable MathEntity mathEntity) {
+		if (mathEntity instanceof IConstant) {
+			if (mathEntity.getId().equals(this.getId())) {
+				return true;
+			}
+		}
+		return false;
+	}
+
 	@NotNull
 	public String getName() {
 		return name;
 	}
 
-	public boolean isUndefined() {
+	@NotNull
-		return StringUtils.isEmpty(this.value);
+	@Override
+	public Constant getConstant() {
+		if (constant == null) {
+			constant = new Constant(this.name);
+		}
+		return constant;
 	}
 
 	@Nullable
@@ -139,10 +218,16 @@ public class Var implements MathEntity{
 		return description;
 	}
 
+	@Override
+	public boolean isDefined() {
+		return !StringUtils.isEmpty(value);
+	}
+
 	@Override
 	public String toString() {
-		if (value != null) {
+		final String stringValue = getValue();
-			return getName() + " = " + value;
+		if (!StringUtils.isEmpty(stringValue)) {
+			return getName() + " = " + stringValue;
 		} else {
 			return getName();
 		}

src/test/java/org/solovyev/android/calculator/model/FromJsclSimplifyTextProcessorTest.java

@@ -38,8 +38,8 @@ public class FromJsclSimplifyTextProcessorTest {
 		Assert.assertEquals("ee", tp.process("2.718281828459045*2.718281828459045"));
 		Assert.assertEquals("t×", tp.process("t*"));
 		Assert.assertEquals("×t", tp.process("*t"));
-		Assert.assertEquals("t×2", tp.process("t*2"));
+		Assert.assertEquals("t2", tp.process("t*2"));
-		Assert.assertEquals("2×t", tp.process("2*t"));
+		Assert.assertEquals("2t", tp.process("2*t"));
 		CalculatorEngine.instance.getVarsRegister().add(null, new Var.Builder("t", (String) null));
 		Assert.assertEquals("t×", tp.process("t*"));
 		Assert.assertEquals("×t", tp.process("*t"));

src/test/java/org/solovyev/android/calculator/model/ToJsclTextProcessorTest.java

@@ -47,11 +47,11 @@ public class ToJsclTextProcessorTest {
 		Assert.assertEquals( "sin(4)*cos(5)", preprocessor.process("sin(4)cos(5)").toString());
 		Assert.assertEquals( "3.141592653589793*sin(4)*3.141592653589793*cos(√(5))", preprocessor.process("πsin(4)πcos(√(5))").toString());
 		Assert.assertEquals( "3.141592653589793*sin(4)+3.141592653589793*cos(√(5))", preprocessor.process("πsin(4)+πcos(√(5))").toString());
-		Assert.assertEquals( "3.141592653589793*sin(4)+3.141592653589793*cos(√(5+√(-1)))", preprocessor.process("πsin(4)+πcos(√(5+i))").toString());
+		Assert.assertEquals( "3.141592653589793*sin(4)+3.141592653589793*cos(√(5+(√(-1))))", preprocessor.process("πsin(4)+πcos(√(5+i))").toString());
-		Assert.assertEquals( "3.141592653589793*sin(4.01)+3.141592653589793*cos(√(5+√(-1)))", preprocessor.process("πsin(4.01)+πcos(√(5+i))").toString());
+		Assert.assertEquals( "3.141592653589793*sin(4.01)+3.141592653589793*cos(√(5+(√(-1))))", preprocessor.process("πsin(4.01)+πcos(√(5+i))").toString());
-		Assert.assertEquals( "2.718281828459045^3.141592653589793*sin(4.01)+3.141592653589793*cos(√(5+√(-1)))", preprocessor.process("e^πsin(4.01)+πcos(√(5+i))").toString());
+		Assert.assertEquals( "2.718281828459045^3.141592653589793*sin(4.01)+3.141592653589793*cos(√(5+(√(-1))))", preprocessor.process("e^πsin(4.01)+πcos(√(5+i))").toString());
-		Assert.assertEquals( "2.718281828459045^3.141592653589793*sin(4.01)+3.141592653589793*cos(√(5+√(-1)))*10^2", preprocessor.process("e^πsin(4.01)+πcos(√(5+i))E2").toString());
+		Assert.assertEquals( "2.718281828459045^3.141592653589793*sin(4.01)+3.141592653589793*cos(√(5+(√(-1))))*10^2", preprocessor.process("e^πsin(4.01)+πcos(√(5+i))E2").toString());
-		Assert.assertEquals( "2.718281828459045^3.141592653589793*sin(4.01)+3.141592653589793*cos(√(5+√(-1)))*10^-2", preprocessor.process("e^πsin(4.01)+πcos(√(5+i))E-2").toString());
+		Assert.assertEquals( "2.718281828459045^3.141592653589793*sin(4.01)+3.141592653589793*cos(√(5+(√(-1))))*10^-2", preprocessor.process("e^πsin(4.01)+πcos(√(5+i))E-2").toString());
 		Assert.assertEquals( "10^2", preprocessor.process("E2").toString());
 		Assert.assertEquals( "10^-2", preprocessor.process("E-2").toString());
 		Assert.assertEquals( "10^-1/2", preprocessor.process("E-1/2").toString());

src/test/java/org/solovyev/android/calculator/model/VarTest.java

@@ -0,0 +1,68 @@
+/*
+ * 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.model;
+
+import junit.framework.Assert;
+import org.junit.Test;
+import org.simpleframework.xml.Serializer;
+import org.simpleframework.xml.core.Persister;
+
+import java.io.StringWriter;
+
+/**
+ * User: serso
+ * Date: 11/7/11
+ * Time: 7:52 PM
+ */
+public class VarTest {
+
+	private static final String xml = "<vars>\n" +
+			"   <vars class=\"java.util.ArrayList\">\n" +
+			"      <var>\n" +
+			"         <name>e</name>\n" +
+			"         <value>2.718281828459045</value>\n" +
+			"         <system>true</system>\n" +
+			"         <description>description</description>\n" +
+			"      </var>\n" +
+			"      <var>\n" +
+			"         <name>;</name>\n" +
+			"         <value>3.0</value>\n" +
+			"         <system>true</system>\n" +
+			"      </var>\n" +
+			"   </vars>\n" +
+			"</vars>";
+
+	@Test
+	public void testXml() throws Exception {
+		final Vars vars = new Vars();
+		Var first = new Var.Builder("e", Math.E).setDescription("description").setSystem(true).create();
+		vars.getVars().add(first);
+		Var second = new Var.Builder(";", 3d).setSystem(true).create();
+		vars.getVars().add(second);
+
+		final StringWriter sw = new StringWriter();
+		final Serializer serializer = new Persister();
+		serializer.write(vars, sw);
+
+		Assert.assertEquals(xml, sw.toString());
+
+
+		final Vars result = serializer.read(Vars.class, xml);
+		final Var actualFirst = result.getVars().get(0);
+		final Var actualSecond = result.getVars().get(1);
+
+		areEqual(first, actualFirst);
+		areEqual(second, actualSecond);
+
+	}
+
+	private void areEqual(Var expected, Var actual) {
+		Assert.assertEquals(expected.getName(), actual.getName());
+		Assert.assertEquals(expected.getDescription(), actual.getDescription());
+		Assert.assertEquals(expected.getValue(), actual.getValue());
+	}
+}