Snap for 9550355 from 1da17e8ed45748c16a5c2bade198ae22fb411949 to sdk-releaseplatform-tools-34.0.1platform-tools-34.0.0platform-tools-33.0.4

Change-Id: I03dc468b8c47c17733acd618dc9ef7295e1879d1

49 files changed, 737 insertions, 223 deletions

diff --git a/Android.bp b/Android.bp
index e731a13..345cf74 100644
--- a/Android.bp
+++ b/Android.bp
@@ -4,9 +4,23 @@ package {
 
 java_binary_host {
     name: "xsdc",
-    srcs: ["src/**/*.java"],
+    srcs: [
+        "src/main/java/**/*.java",
+    ],
     static_libs: [
         "commons-cli-1.2",
     ],
     manifest: "MANIFEST.MF"
 }
+
+java_test_host {
+    name: "xsdc-unittest",
+    srcs: [
+        "src/test/java/**/*.java",
+    ],
+    static_libs: [
+        "commons-cli-1.2",
+        "junit",
+        "xsdc",
+    ],
+}
diff --git a/build/xsdc.go b/build/xsdc.go
index f92ba28..c5bc28d 100644
--- a/build/xsdc.go
+++ b/build/xsdc.go
@@ -40,16 +40,23 @@ var (
 	xsdc         = pctx.HostBinToolVariable("xsdcCmd", "xsdc")
 	xsdcJavaRule = pctx.StaticRule("xsdcJavaRule", blueprint.RuleParams{
 		Command: `rm -rf "${out}.temp" && mkdir -p "${out}.temp" && ` +
-			`${xsdcCmd} $in -p $pkgName -o ${out}.temp -j $args && ` +
+			`${xsdcCmd} $in -p $pkgName -o ${out}.temp -j $args -d ${out}.dep && ` +
+			`echo "${out} : \\" > ${out}.d && cat ${out}.dep >> ${out}.d && ` +
 			`${config.SoongZipCmd} -jar -o ${out} -C ${out}.temp -D ${out}.temp && ` +
-			`rm -rf ${out}.temp`,
+			`rm -rf ${out}.temp && rm -rf ${out}.dep`,
+		Depfile:     "${out}.d",
+		Deps:        blueprint.DepsGCC,
 		CommandDeps: []string{"${xsdcCmd}", "${config.SoongZipCmd}"},
 		Description: "xsdc Java ${in} => ${out}",
 	}, "pkgName", "args")
 
 	xsdcCppRule = pctx.StaticRule("xsdcCppRule", blueprint.RuleParams{
 		Command: `rm -rf "${outDir}" && ` +
-			`${xsdcCmd} $in -p $pkgName -o ${outDir} -c $args`,
+			`${xsdcCmd} $in -p $pkgName -o ${outDir} -c $args -d ${out}.dep && ` +
+			`echo "${out} : \\" > ${out}.d && cat ${out}.dep >> ${out}.d && ` +
+			`rm -rf ${out}.dep`,
+		Depfile:     "${out}.d",
+		Deps:        blueprint.DepsGCC,
 		CommandDeps: []string{"${xsdcCmd}", "${config.SoongZipCmd}"},
 		Description: "xsdc C++ ${in} => ${out}",
 	}, "pkgName", "outDir", "args")
@@ -86,6 +93,11 @@ type xsdConfigProperties struct {
 	// ENTITY_REFs.
 	// This can improve memory footprint. Default value is false.
 	Tinyxml *bool
+	// Specify root elements explicitly. If not set, XSDC generates parsers and
+	// writers for all elements which can be root element. When set, XSDC
+	// generates parsers and writers for specified root elements. This can be
+	// used to avoid unnecessary code.
+	Root_elements []string
 }
 
 type xsdConfig struct {
@@ -214,6 +226,10 @@ func (module *xsdConfig) GenerateAndroidBuildActions(ctx android.ModuleContext)
 		args = args + " -t "
 	}
 
+	for _, elem := range module.properties.Root_elements {
+		args = args + " -r " + elem
+	}
+
 	module.genOutputs_j = android.PathForModuleGen(ctx, "java", filenameStem+"_xsdcgen.srcjar")
 
 	ctx.Build(pctx, android.BuildParams{
@@ -246,6 +262,15 @@ func (module *xsdConfig) GenerateAndroidBuildActions(ctx android.ModuleContext)
 			android.PathForModuleGen(ctx, "cpp", "include/"+filenameStem+".h"),
 			android.PathForModuleGen(ctx, "cpp", "include/"+filenameStem+"_enums.h")}
 	}
+
+	output := module.genOutputs_c[0]
+	// Multiple outputs aren't supported by depslog.
+	// So ImplicitOutputs is used for additional generated code.
+	implicitOutputs := module.genOutputs_h
+	if len(module.genOutputs_c) > 1 {
+		implicitOutputs = append(implicitOutputs, module.genOutputs_c[1:]...)
+	}
+
 	module.genOutputDir = android.PathForModuleGen(ctx, "cpp", "include")
 
 	ctx.Build(pctx, android.BuildParams{
@@ -253,8 +278,8 @@ func (module *xsdConfig) GenerateAndroidBuildActions(ctx android.ModuleContext)
 		Description:     "xsdc " + xsdFile.String(),
 		Input:           xsdFile,
 		Implicit:        module.docsPath,
-		Outputs:         module.genOutputs_c,
-		ImplicitOutputs: module.genOutputs_h,
+		Output:          output,
+		ImplicitOutputs: implicitOutputs,
 		Args: map[string]string{
 			"pkgName": pkgName,
 			"outDir":  android.PathForModuleGen(ctx, "cpp").String(),
@@ -330,4 +355,4 @@ func (module *xsdConfig) OutputFiles(tag string) (android.Paths, error) {
 	}
 }
 
-var _ android.OutputFileProducer = (*xsdConfig)(nil);
+var _ android.OutputFileProducer = (*xsdConfig)(nil)
diff --git a/src/com/android/xsdc/CodeWriter.java b/src/main/java/com/android/xsdc/CodeWriter.java
index 489ccdc..489ccdc 100644
--- a/src/com/android/xsdc/CodeWriter.java
+++ b/src/main/java/com/android/xsdc/CodeWriter.java
diff --git a/src/com/android/xsdc/FileSystem.java b/src/main/java/com/android/xsdc/FileSystem.java
index 2d746f3..2d746f3 100644
--- a/src/com/android/xsdc/FileSystem.java
+++ b/src/main/java/com/android/xsdc/FileSystem.java
diff --git a/src/com/android/xsdc/Main.java b/src/main/java/com/android/xsdc/Main.java
index 0f486d0..90e0719 100644
--- a/src/com/android/xsdc/Main.java
+++ b/src/main/java/com/android/xsdc/Main.java
@@ -18,7 +18,11 @@ package com.android.xsdc;
 
 import java.io.File;
 import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.PrintWriter;
 import java.nio.file.Paths;
+import java.util.ArrayList;
+import java.util.List;
 
 import static java.lang.System.exit;
 
@@ -101,6 +105,18 @@ public class Main {
                 .withDescription("Only generate XML parser in Cpp code.")
                 .create("x");
         options.addOption(genParserOnly);
+        Option genDepFile = OptionBuilder
+                .withLongOpt("depfile")
+                .hasArgs(1)
+                .withDescription("Generate depfile for ninja.")
+                .create("d");
+        options.addOption(genDepFile);
+        options.addOption(OptionBuilder
+                .withLongOpt("root")
+                .hasArgs(1)
+                .withDescription("Root element.")
+                .create("r"));
+
         // "Only generate enums" and "Only generate parser" options are mutually exclusive.
         OptionGroup genOnlyGroup = new OptionGroup();
         genOnlyGroup.setRequired(false);
@@ -119,7 +135,6 @@ public class Main {
             return;
         }
 
-        String[] xsdFile = cmd.getArgs();
         String packageName = cmd.getOptionValue('p', null);
         String outDir = cmd.getOptionValue('o', null);
         boolean writer = cmd.hasOption('w');
@@ -129,8 +144,10 @@ public class Main {
         boolean parserOnly = cmd.hasOption('x');
         boolean booleanGetter = cmd.hasOption('b');
         boolean useTinyXml = cmd.hasOption('t');
+        String depFile = cmd.getOptionValue('d', null);
+        String[] rootElements = cmd.getOptionValues('r');
 
-        if (xsdFile.length != 1 || packageName == null) {
+        if (cmd.getArgs().length != 1 || packageName == null) {
             System.err.println("Error: no xsd files or package name");
             help(options);
         }
@@ -139,7 +156,20 @@ public class Main {
             outDir = ".";
         }
 
-        XmlSchema xmlSchema = parse(xsdFile[0]);
+        String xsdFile = cmd.getArgs()[0];
+        List<String> included = new ArrayList<>();
+        included.add(xsdFile);
+        XmlSchema xmlSchema = parse(xsdFile, included);
+
+        // When -r (root element) is specified, then validate if it's defined in schema.
+        if (rootElements != null) {
+            for (String rootElement : rootElements) {
+                if (!xmlSchema.getElementMap().containsKey(rootElement)) {
+                    System.err.println("Invalid root element(-r): " + rootElement);
+                    System.exit(1);
+                }
+            }
+        }
 
         if (cmd.hasOption('j')) {
             File packageDir = new File(Paths.get(outDir, packageName.replace(".", "/")).toString());
@@ -147,7 +177,7 @@ public class Main {
             FileSystem fs = new FileSystem(packageDir);
             JavaCodeGenerator javaCodeGenerator =
                     new JavaCodeGenerator(xmlSchema, packageName, writer, nullability, genHas,
-                                          booleanGetter);
+                                          booleanGetter, rootElements);
             javaCodeGenerator.print(fs);
         } else if (cmd.hasOption('c')) {
             File includeDir = new File(Paths.get(outDir, "include").toString());
@@ -158,12 +188,16 @@ public class Main {
                             CppCodeGenerator.GENERATE_ENUMS | CppCodeGenerator.GENERATE_PARSER);
             CppCodeGenerator cppCodeGenerator =
                     new CppCodeGenerator(xmlSchema, packageName, writer, generators,
-                            booleanGetter, useTinyXml);
+                            booleanGetter, useTinyXml, rootElements);
             cppCodeGenerator.print(fs);
         }
+
+        if (depFile != null) {
+            writeDepFile(depFile, included);
+        }
     }
 
-    private static XmlSchema parse(String xsdFile) throws Exception {
+    private static XmlSchema parse(String xsdFile, List<String> included) throws Exception {
         XmlSchema xmlSchema;
         try (FileInputStream in = new FileInputStream(xsdFile)) {
             SAXParserFactory factory = SAXParserFactory.newInstance();
@@ -174,12 +208,21 @@ public class Main {
             xmlSchema = xsdHandler.getSchema();
         }
         for (String file : xmlSchema.getIncludeList()) {
-            XmlSchema temp = parse(Paths.get(xsdFile).resolveSibling(file).toString());
+            String filePath = Paths.get(xsdFile).resolveSibling(file).toString();
+            included.add(filePath);
+            XmlSchema temp = parse(filePath, included);
             xmlSchema.include(temp);
         }
         return xmlSchema;
     }
 
+    private static void writeDepFile(String depFile, List<String> files)
+            throws IOException {
+        try (PrintWriter out = new PrintWriter(new File(depFile))) {
+            out.println(String.format("  %s", String.join(" \\\n  ", files)));
+        }
+    }
+
     private static void help(Options options) {
         new HelpFormatter().printHelp(
                 "xsdc path/to/xsd_file.xsd","", options, null, true);
diff --git a/src/com/android/xsdc/XmlSchema.java b/src/main/java/com/android/xsdc/XmlSchema.java
index 4bfa3fd..4bfa3fd 100644
--- a/src/com/android/xsdc/XmlSchema.java
+++ b/src/main/java/com/android/xsdc/XmlSchema.java
diff --git a/src/com/android/xsdc/XsdConstants.java b/src/main/java/com/android/xsdc/XsdConstants.java
index 6c79b9b..6c79b9b 100644
--- a/src/com/android/xsdc/XsdConstants.java
+++ b/src/main/java/com/android/xsdc/XsdConstants.java
diff --git a/src/com/android/xsdc/XsdHandler.java b/src/main/java/com/android/xsdc/XsdHandler.java
index f6a9492..f6a9492 100644
--- a/src/com/android/xsdc/XsdHandler.java
+++ b/src/main/java/com/android/xsdc/XsdHandler.java
diff --git a/src/com/android/xsdc/XsdParserException.java b/src/main/java/com/android/xsdc/XsdParserException.java
index aa755d5..aa755d5 100644
--- a/src/com/android/xsdc/XsdParserException.java
+++ b/src/main/java/com/android/xsdc/XsdParserException.java
diff --git a/src/com/android/xsdc/cpp/CppCodeGenerator.java b/src/main/java/com/android/xsdc/cpp/CppCodeGenerator.java
index e470216..9bfbe56 100644
--- a/src/com/android/xsdc/cpp/CppCodeGenerator.java
+++ b/src/main/java/com/android/xsdc/cpp/CppCodeGenerator.java
@@ -51,17 +51,20 @@ public class CppCodeGenerator {
     private int generators;
     private boolean booleanGetter;
     private boolean useTinyXml;
+    private String[] rootElements;
 
     private static final String UNKNOWN_ENUM = "UNKNOWN";
 
     public CppCodeGenerator(XmlSchema xmlSchema, String pkgName, boolean writer, int generators,
-            boolean booleanGetter, boolean useTinyXml) throws CppCodeGeneratorException {
+            boolean booleanGetter, boolean useTinyXml, String[] rootElements)
+            throws CppCodeGeneratorException {
         this.xmlSchema = xmlSchema;
         this.pkgName = pkgName;
         this.writer = writer;
         this.generators = generators;
         this.booleanGetter = booleanGetter;
         this.useTinyXml = useTinyXml;
+        this.rootElements = rootElements;
 
         // class naming validation
         {
@@ -178,6 +181,14 @@ public class CppCodeGenerator {
         enumsCppFile.printf("#include \"%s\"\n\n", enumsHeaderFileName);
         parserCppFile.printf("#define LOG_TAG \"%s\"\n", pkgName);
         parserCppFile.printf("#include \"%s\"\n\n", parserHeaderFileName);
+        // define _xsdc_assert to abort with message regardless of NDEBUG
+        parserCppFile.println("#include <assert.h>\n"
+                + "#ifndef __BIONIC__\n"
+                + "#define __assert2(f,n,fun,e) do { fprintf(stderr, \"%s:%d: %s: Assertion `%s'"
+                + " failed\", (f), (n), (fun), (e)); abort(); } while (false)\n"
+                + "#endif\n"
+                + "#define _xsdc_assert(e) do if (!(e)) __assert2(__FILE__, __LINE__,"
+                + " __PRETTY_FUNCTION__, #e); while (false)\n");
 
         List<String> namespace = new java.util.ArrayList<>();
         for (String token : pkgName.split("\\.")) {
@@ -322,6 +333,14 @@ public class CppCodeGenerator {
         enumsHeaderFile.printf("};\n");
     }
 
+    /**
+     * Prints forward declarations for complex types.
+     *
+     * Foo.h:
+     *
+     *     class Foo;
+     *
+     */
     private void printPrototype() throws CppCodeGeneratorException {
         for (XsdType type : xmlSchema.getTypeMap().values()) {
             if (type instanceof XsdComplexType) {
@@ -338,6 +357,22 @@ public class CppCodeGenerator {
         }
     }
 
+    /**
+     * Prints class definitions for complex types.
+     *
+     * Foo.h:
+     *
+     *     class Foo {
+     *       printClass(<inner types>)
+     *       <members>
+     *       const optional<> value_;
+     *       args = printConstructor()
+     *       printGetter(<members>)
+     *       printParser( args )
+     *       printWriter()
+     *     };
+     *
+     */
     private void printClass(String name, String nameScope, XsdComplexType complexType)
             throws CppCodeGeneratorException {
         assert name != null;
@@ -379,7 +414,7 @@ public class CppCodeGenerator {
             elementTypes.add(cppType);
         }
         List<CppSimpleType> attributeTypes = new ArrayList<>();
-        List<XsdAttribute> attributes = new ArrayList();
+        List<XsdAttribute> attributes = new ArrayList<>();
         for (XsdAttributeGroup attributeGroup : complexType.getAttributeGroups()) {
             attributes.addAll(getAllAttributes(resolveAttributeGroup(attributeGroup)));
         }
@@ -451,6 +486,27 @@ public class CppCodeGenerator {
         parserHeaderFile.println("};\n");
     }
 
+    /**
+     * Prints read() static member function for complex types.
+     * Note that read() is a non-validating parser.
+     *
+     * Foo.h:
+     *
+     *     static Foo read(XmlNode* root);
+     *
+     * Foo.cpp:
+     *
+     *     Foo Foo::read(XmlNode* root) {
+     *        string _raw;
+     *        for each member m
+     *           _raw = ..
+     *           parsing expressions for each member (read _raw, set _value)
+     *           m = _value;
+     *        Foo instance(args...);
+     *        return instance;
+     *     }
+     *
+     */
     private void printParser(String name, String nameScope, XsdComplexType complexType, String args)
             throws CppCodeGeneratorException {
         CppSimpleType baseValueType = (complexType instanceof XsdSimpleContent) ?
@@ -477,13 +533,13 @@ public class CppCodeGenerator {
         parserHeaderFile.printf("static %s read(%s *root);\n", fullName, nodeType);
         parserCppFile.printf("\n%s %s::read(%s *root) {\n", fullName, fullName, nodeType);
 
-        parserCppFile.print("std::string raw;\n");
+        parserCppFile.print("std::string _raw;\n");
 
         for (int i = 0; i < allAttributes.size(); ++i) {
             CppSimpleType type = allAttributeTypes.get(i);
             XsdAttribute attribute = resolveAttribute(allAttributes.get(i));
             String variableName = Utils.toVariableName(attribute.getName());
-            parserCppFile.printf("raw = getXmlAttribute(root, \"%s\");\n", attribute.getName());
+            parserCppFile.printf("_raw = getXmlAttribute(root, \"%s\");\n", attribute.getName());
             if (attribute.isRequired()) {
                 if (type.isEnum()) {
                     parserCppFile.printf("%s %s = %s::%s;\n",
@@ -495,15 +551,15 @@ public class CppCodeGenerator {
                 parserCppFile.printf("std::optional<%s> %s = std::nullopt;\n", type.getName(),
                         variableName);
             }
-            parserCppFile.printf("if (raw != \"\") {\n");
+            parserCppFile.printf("if (_raw != \"\") {\n");
             parserCppFile.print(type.getParsingExpression());
-            parserCppFile.printf("%s = value;\n}\n", variableName);
+            parserCppFile.printf("%s = _value;\n}\n", variableName);
         }
 
         if (baseValueType != null) {
-            printNodeListGetString("root");
+            printSetRawWithElementText("root");
             parserCppFile.print(baseValueType.getParsingExpression());
-            parserCppFile.printf("instance.setValue(value);\n");
+            parserCppFile.printf("instance.setValue(_value);\n");
             parserCppFile.printf("}\n");
         } else if (!allElements.isEmpty()) {
             for (int i = 0; i < allElements.size(); ++i) {
@@ -515,13 +571,13 @@ public class CppCodeGenerator {
                         element.isMultiple() || type instanceof CppComplexType), variableName);
             }
             if (useTinyXml) {
-                parserCppFile.print("for (auto *child = root->FirstChildElement();"
-                        + " child != nullptr;"
-                        + " child = child->NextSiblingElement()) {\n");
+                parserCppFile.print("for (auto *_child = root->FirstChildElement();"
+                        + " _child != nullptr;"
+                        + " _child = _child->NextSiblingElement()) {\n");
             } else {
-                parserCppFile.print("for (auto *child = root->xmlChildrenNode;"
-                        + " child != nullptr;"
-                        + " child = child->next) {\n");
+                parserCppFile.print("for (auto *_child = root->xmlChildrenNode;"
+                        + " _child != nullptr;"
+                        + " _child = _child->next) {\n");
             }
             for (int i = 0; i < allElements.size(); ++i) {
                 CppType type = allElementTypes.get(i);
@@ -531,24 +587,24 @@ public class CppCodeGenerator {
 
                 if (i != 0) parserCppFile.printf("} else ");
                 if (useTinyXml) {
-                    parserCppFile.printf("if (!strcmp(child->Name(), \"%s\")) {\n",
+                    parserCppFile.printf("if (!strcmp(_child->Name(), \"%s\")) {\n",
                             elementValue.getName());
                 } else {
-                    parserCppFile.printf("if (!xmlStrcmp(child->name,"
+                    parserCppFile.printf("if (!xmlStrcmp(_child->name,"
                             + " reinterpret_cast<const xmlChar*>(\"%s\"))) {\n",
                             elementValue.getName());
                 }
 
                 if (type instanceof CppSimpleType) {
-                    printNodeListGetString("child");
+                    printSetRawWithElementText("_child");
                 }
 
                 parserCppFile.print(type.getParsingExpression());
 
                 if (element.isMultiple() || type instanceof CppComplexType) {
-                    parserCppFile.printf("%s.push_back(std::move(value));\n", variableName);
+                    parserCppFile.printf("%s.push_back(std::move(_value));\n", variableName);
                 } else {
-                    parserCppFile.printf("%s = std::move(value);\n", variableName);
+                    parserCppFile.printf("%s = std::move(_value);\n", variableName);
                 }
             }
             parserCppFile.printf("}\n}\n");
@@ -562,31 +618,45 @@ public class CppCodeGenerator {
         return (useTinyXml ? "tinyxml2::XMLElement" : "xmlNode");
     }
 
-    private void printNodeListGetString(String varName) {
+    private void printSetRawWithElementText(String varName) {
         if (useTinyXml) {
             // The tinyxml version, in contrast to xmlNodeListGetString does not deal
             // with ENTITY_REF nodes
-            parserCppFile.printf("raw = \"\";\n");
+            parserCppFile.printf("_raw = \"\";\n");
             parserCppFile.printf("for (auto *textNode = %s->FirstChild();"
                     + " textNode != nullptr;"
                     + " textNode = textNode->NextSibling()) {\n", varName);
             parserCppFile.printf("if (textNode->ToText() != nullptr) {\n");
-            parserCppFile.printf("raw.append(textNode->Value());\n");
+            parserCppFile.printf("_raw.append(textNode->Value());\n");
             parserCppFile.printf("}\n");
             parserCppFile.printf("}\n");
         } else {
             parserCppFile.printf("auto xmlValue = make_xmlUnique(xmlNodeListGetString(");
             parserCppFile.printf("%s->doc, %s->xmlChildrenNode, 1));\n", varName, varName);
-            parserCppFile.printf("if (xmlValue == nullptr) {\nraw = \"\";\n} else {\n");
-            parserCppFile.printf("raw = reinterpret_cast<const char*>(xmlValue.get());\n}");
+            parserCppFile.printf("if (xmlValue == nullptr) {\n_raw = \"\";\n} else {\n");
+            parserCppFile.printf("_raw = reinterpret_cast<const char*>(xmlValue.get());\n}");
             parserCppFile.printf("\n");
         }
     }
 
+    /**
+     * Prints write() member function for complex types.
+     *
+     * Foo.h:
+     *
+     *     void write(ostream& _out, string name) const;
+     *
+     * Foo.cpp:
+     *
+     *     void Foo::write(ostream& _out, string name) const {
+     *        <FooElement attrs....>
+     *          value_
+     *        </Fooelement>
+     *     }
+     *
+     */
     private void printWriter(String name, String nameScope, XsdComplexType complexType)
             throws CppCodeGeneratorException {
-        CppSimpleType baseValueType = (complexType instanceof XsdSimpleContent) ?
-                getValueType((XsdSimpleContent) complexType, true) : null;
         List<XsdElement> allElements = new ArrayList<>();
         List<XsdAttribute> allAttributes = new ArrayList<>();
         stackComponents(complexType, allElements, allAttributes);
@@ -605,24 +675,24 @@ public class CppCodeGenerator {
         }
 
         String fullName = nameScope + name;
-        parserHeaderFile.printf("void write(std::ostream& out, const std::string& name) const;\n");
+        parserHeaderFile.printf("void write(std::ostream& _out, const std::string& _name) const;\n");
         parserCppFile.printf(
-                "\nvoid %s::write(std::ostream& out, const std::string& name) const {\n",
+                "\nvoid %s::write(std::ostream& _out, const std::string& _name) const {\n",
                 fullName);
 
-        parserCppFile.printf("out << printIndent() << \"<\" << name;\n");
+        parserCppFile.printf("_out << printIndent() << \"<\" << _name;\n");
         for (int i = 0; i < allAttributes.size(); ++i) {
             CppType type = allAttributeTypes.get(i);
             XsdAttribute attribute = resolveAttribute(allAttributes.get(i));
             String variableName = Utils.toVariableName(attribute.getName());
             parserCppFile.printf("if (has%s()) {\n", Utils.capitalize(variableName));
-            parserCppFile.printf("out << \" %s=\\\"\";\n", attribute.getName());
+            parserCppFile.printf("_out << \" %s=\\\"\";\n", attribute.getName());
             parserCppFile.print(type.getWritingExpression(String.format("%s%s()",
                     getterName(type.getName()), Utils.capitalize(variableName)),
                     attribute.getName()));
-            parserCppFile.printf("out << \"\\\"\";\n}\n");
+            parserCppFile.printf("_out << \"\\\"\";\n}\n");
         }
-        parserCppFile.print("out << \">\" << std::endl;\n");
+        parserCppFile.print("_out << \">\" << std::endl;\n");
         parserCppFile.print("++indentIndex;\n");
 
         if (!allElements.isEmpty()) {
@@ -634,30 +704,30 @@ public class CppCodeGenerator {
                 String variableName = Utils.toVariableName(elementName);
 
                 if (type instanceof CppComplexType || element.isMultiple()) {
-                    parserCppFile.printf("for (auto& value : get%s()) {\n",
+                    parserCppFile.printf("for (auto& _value : get%s()) {\n",
                             Utils.capitalize(variableName));
                     if (type instanceof CppSimpleType) {
-                        parserCppFile.printf("out << printIndent() << \"<%s>\";\n",
+                        parserCppFile.printf("_out << printIndent() << \"<%s>\";\n",
                                 elementValue.getName());
                     }
                     parserCppFile.printf(
-                            type.getWritingExpression("value", elementValue.getName()));
+                            type.getWritingExpression("_value", elementValue.getName()));
                     if (type instanceof CppSimpleType) {
-                        parserCppFile.printf("out << \"</%s>\" << std::endl;\n",
+                        parserCppFile.printf("_out << \"</%s>\" << std::endl;\n",
                                 elementValue.getName());
                     }
                     parserCppFile.printf("}\n");
                 } else {
                     parserCppFile.printf("if (has%s()) {\n", Utils.capitalize(variableName));
                     if (type instanceof CppSimpleType) {
-                        parserCppFile.printf("out << printIndent() << \"<%s>\";\n",
+                        parserCppFile.printf("_out << printIndent() << \"<%s>\";\n",
                                 elementValue.getName());
                     }
                     parserCppFile.print(type.getWritingExpression(String.format("%s%s()",
                               getterName(type.getName()), Utils.capitalize(variableName)),
                               elementValue.getName()));
                     if (type instanceof CppSimpleType) {
-                        parserCppFile.printf("out << \"</%s>\" << std::endl;\n",
+                        parserCppFile.printf("_out << \"</%s>\" << std::endl;\n",
                                 elementValue.getName());
                     }
                     parserCppFile.print("}\n");
@@ -665,24 +735,56 @@ public class CppCodeGenerator {
             }
         }
         parserCppFile.print("--indentIndex;\n");
-        parserCppFile.printf("out << printIndent() << \"</\" << name << \">\" << std::endl;\n");
+        parserCppFile.printf("_out << printIndent() << \"</\" << _name << \">\" << std::endl;\n");
         parserCppFile.printf("}\n");
     }
 
+    /**
+     * Prints hasAttr() and getAttr() member functions for each member field.
+     *
+     * Foo.h:
+     *
+     *     const Attr& getAttr() const;
+     *     bool hasAttr() const;
+     *     const Item* getFirstItem() const; // for multi-value member
+     *
+     * Foo.cpp:
+     *
+     *     const Attr& Foo::getAttr() const {
+     *       return attr_;
+     *     }
+     *     bool Foo::hasAttr() const {
+     *       return true;
+     *     }
+     *     const Item* Foo::getFirstItem() const {
+     *       if (item_.empty()) {
+     *          return nullptr;
+     *       }
+     *       return &item_[0];
+     *     }
+     *
+     */
     private void printGetter(String name, CppType type, String variableName,
             boolean isMultiple, boolean isMultipleType, boolean isRequired) {
         String typeName = isMultiple ? String.format("std::vector<%s>",
                 type.getName()) : type.getName();
+        String assertHasValue = String.format("_xsdc_assert(has%s());\n",
+                Utils.capitalize(variableName));
 
         parserHeaderFile.printf("const %s& %s%s() const;\n", typeName, getterName(typeName),
                 Utils.capitalize(variableName));
 
         parserCppFile.println();
-        parserCppFile.printf("const %s& %s::%s%s() const {\n"
-                + "return %s;\n}\n\n",
-                typeName, name, getterName(typeName), Utils.capitalize(variableName),
-                isMultiple || isRequired ?
-                variableName + "_" : String.format("%s_.value()", variableName));
+        parserCppFile.printf("const %s& %s::%s%s() const {\n", typeName, name,
+                getterName(typeName), Utils.capitalize(variableName));
+        if (isMultiple || isRequired) {
+            parserCppFile.printf("return %s_;\n", variableName);
+        } else {
+            // Before accessing an optional::value(), we need to ensure that it has a value.
+            parserCppFile.print(assertHasValue);
+            parserCppFile.printf("return %s_.value();\n", variableName);
+        }
+        parserCppFile.printf("}\n\n");
 
         parserHeaderFile.printf("bool has%s() const;\n", Utils.capitalize(variableName));
         parserCppFile.printf("bool %s::has%s() const {\n", name, Utils.capitalize(variableName));
@@ -694,6 +796,7 @@ public class CppCodeGenerator {
             parserCppFile.printf("return %s_.has_value();\n}\n", variableName);
         }
 
+        // For elements that may occur multiple types or have a list of simple types
         if (isMultiple || isMultipleType) {
             String elementTypeName = type instanceof CppComplexType ? type.getName() :
                     ((CppSimpleType)type).getTypeName();
@@ -702,12 +805,15 @@ public class CppCodeGenerator {
                         elementTypeName, Utils.capitalize(variableName));
                 parserCppFile.println();
                 parserCppFile.printf("%s %s::getFirst%s() const {\n"
+                        + "%s"
                         + "if (%s_%sempty()) {\n"
                         + "return false;\n"
                         + "}\n"
                         + "return %s;\n"
                         + "}\n",
-                        elementTypeName, name, Utils.capitalize(variableName), variableName,
+                        elementTypeName, name, Utils.capitalize(variableName),
+                        isMultiple ? "" : assertHasValue,
+                        variableName,
                         isMultiple ? "." : "->",
                         isMultiple ? String.format("%s_[0]", variableName) :
                         String.format("%s_.value()[0]", variableName));
@@ -716,12 +822,15 @@ public class CppCodeGenerator {
                         elementTypeName, Utils.capitalize(variableName));
                 parserCppFile.println();
                 parserCppFile.printf("const %s* %s::getFirst%s() const {\n"
+                        + "%s"
                         + "if (%s_%sempty()) {\n"
                         + "return nullptr;\n"
                         + "}\n"
                         + "return &%s;\n"
                         + "}\n",
-                        elementTypeName, name, Utils.capitalize(variableName), variableName,
+                        elementTypeName, name, Utils.capitalize(variableName),
+                        isMultiple ? "" : assertHasValue,
+                        variableName,
                         isMultiple ? "." : "->",
                         isMultiple ? String.format("%s_[0]", variableName) :
                         String.format("%s_.value()[0]", variableName));
@@ -729,6 +838,18 @@ public class CppCodeGenerator {
         }
     }
 
+    /**
+     * Prints constructor for complex types
+     *
+     * Foo.h:
+     *
+     *     Foo(args...);
+     *
+     * Foo.cpp:
+     *
+     *     Foo::Foo(args...): initializer... {}
+     *
+     */
     private String printConstructor(String name, String nameScope, XsdComplexType complexType,
             List<XsdElement> elements, List<XsdAttribute> attributes, String baseName)
             throws CppCodeGeneratorException {
@@ -742,7 +863,6 @@ public class CppCodeGenerator {
         List<XsdAttribute> allAttributes = new ArrayList<>();
         stackComponents(complexType, allElements, allAttributes);
 
-        List<CppType> allElementTypes = new ArrayList<>();
         for (XsdElement element : allElements) {
             XsdElement elementValue = resolveElement(element);
             CppType type = parseType(elementValue.getType(), elementValue.getName());
@@ -766,7 +886,6 @@ public class CppCodeGenerator {
                 parentArgs.append(String.format(", %s", variableName));
             }
         }
-        List<CppSimpleType> allAttributeTypes = new ArrayList<>();
         for (XsdAttribute attribute : allAttributes) {
             CppType type = parseSimpleType(resolveAttribute(attribute).getType(), false);
             String variableName = Utils.toVariableName(resolveAttribute(attribute).getName());
@@ -817,6 +936,22 @@ public class CppCodeGenerator {
         return argsString;
     }
 
+    /**
+     * Prints reader functions for each top-level types.
+     *
+     * Foo.h:
+     *
+     *     optional<Foo> readFoo(const char* filename);
+     *
+     * Foo.cpp:
+     *
+     *     std::optional<Foo> readFoo(const char* filename) {
+     *        ...
+     *        Foo _value = Foo::read(root);
+     *        return _value;
+     *     }
+     *
+     */
     private void printXmlParser() throws CppCodeGeneratorException {
         if (useTinyXml) {
             // Nothing to do for libtinyxml2
@@ -853,75 +988,122 @@ public class CppCodeGenerator {
             parserCppFile.printf("}\n\n");
         }
 
-        String className = Utils.toClassName(pkgName);
-
         boolean isMultiRootElement = xmlSchema.getElementMap().values().size() > 1;
         for (XsdElement element : xmlSchema.getElementMap().values()) {
-            CppType cppType = parseType(element.getType(), element.getName());
-            String elementName = element.getName();
-            String VariableName = Utils.toVariableName(elementName);
-            String typeName = cppType instanceof CppSimpleType ? cppType.getName() :
-                    Utils.toClassName(cppType.getName());
-
-            parserHeaderFile.printf("std::optional<%s> read%s(const char* configFile);\n\n",
-                    typeName, isMultiRootElement ? Utils.capitalize(typeName) : "");
-            parserCppFile.printf("std::optional<%s> read%s(const char* configFile) {\n",
-                    typeName, isMultiRootElement ? Utils.capitalize(typeName) : "");
-            if (useTinyXml) {
-                parserCppFile.printf("tinyxml2::XMLDocument doc;\n"
-                        + "if (doc.LoadFile(configFile) != tinyxml2::XML_SUCCESS) {\n"
-                        + "return std::nullopt;\n"
-                        + "}\n"
-                        + "auto child = doc.FirstChildElement();\n"
-                        + "if (child == nullptr) {\n"
-                        + "return std::nullopt;\n"
-                        + "}\n\n"
-                        + "if (strcmp(child->Name(), \"%s\") == 0) {\n",
-                        elementName);
-            } else {
-                parserCppFile.printf("auto doc = make_xmlUnique(xmlParseFile(configFile));\n"
-                        + "if (doc == nullptr) {\n"
-                        + "return std::nullopt;\n"
-                        + "}\n"
-                        + "xmlNodePtr child = xmlDocGetRootElement(doc.get());\n"
-                        + "if (child == nullptr) {\n"
-                        + "return std::nullopt;\n"
-                        + "}\n"
-                        + "if (xmlXIncludeProcess(doc.get()) < 0) {\n"
-                        + "return std::nullopt;\n"
-                        + "}\n\n"
-                        + "if (!xmlStrcmp(child->name, reinterpret_cast<const xmlChar*>"
-                        + "(\"%s\"))) {\n",
-                        elementName);
-            }
-
-            if (cppType instanceof CppSimpleType) {
-                parserCppFile.printf("%s value = getXmlAttribute(child, \"%s\");\n",
-                        elementName, elementName);
-            } else {
-                parserCppFile.printf(cppType.getParsingExpression());
-            }
-            parserCppFile.printf("return value;\n}\n");
-            parserCppFile.printf("return std::nullopt;\n");
-            parserCppFile.printf("}\n\n");
+            // Skip parser if not specified as root.
+            if (rootElements != null
+                    && Arrays.asList(rootElements).indexOf(element.getName()) == -1) continue;
+            printXmlParserFor(element, /*loadFile=*/true, isMultiRootElement);
+            printXmlParserFor(element, /*loadFile=*/false, isMultiRootElement);
         }
     }
 
+    /**
+     * Prints readType(const char* configFile) if loadFile is true.
+     * Otherwise, prints parseType(const char* xml).
+     */
+    private void printXmlParserFor(XsdElement element, boolean loadFile, boolean isMultiRootElement)
+            throws CppCodeGeneratorException {
+        CppType cppType = parseType(element.getType(), element.getName());
+        String elementName = element.getName();
+        String typeName = cppType.getName();
+        String readerName =
+                cppType instanceof CppSimpleType ? Utils.toClassName(elementName) : typeName;
+        String methodName = loadFile ? "read" : "parse";
+        String argName = loadFile ? "configFile" : "xml";
+        parserHeaderFile.printf("std::optional<%s> %s%s(const char* %s);\n\n",
+                typeName,
+                methodName,
+                isMultiRootElement ? readerName : "",
+                argName);
+        parserCppFile.printf("std::optional<%s> %s%s(const char* %s) {\n",
+                typeName,
+                methodName,
+                isMultiRootElement ? readerName : "",
+                argName);
+        if (useTinyXml) {
+            String innerParser = loadFile ? "LoadFile(configFile)" : "Parse(xml)";
+            parserCppFile.printf("tinyxml2::XMLDocument doc;\n"
+                    + "if (doc.%s != tinyxml2::XML_SUCCESS) {\n"
+                    + "return std::nullopt;\n"
+                    + "}\n"
+                    + "auto _child = doc.FirstChildElement();\n"
+                    + "if (_child == nullptr) {\n"
+                    + "return std::nullopt;\n"
+                    + "}\n\n"
+                    + "if (strcmp(_child->Name(), \"%s\") == 0) {\n",
+                    innerParser,
+                    elementName);
+        } else {
+            String innerParser = loadFile
+                    ? "xmlParseFile(configFile)"
+                    : "xmlParseDoc(reinterpret_cast<const xmlChar*>(xml))";
+            parserCppFile.printf("auto doc = make_xmlUnique(%s);\n"
+                    + "if (doc == nullptr) {\n"
+                    + "return std::nullopt;\n"
+                    + "}\n"
+                    + "xmlNodePtr _child = xmlDocGetRootElement(doc.get());\n"
+                    + "if (_child == nullptr) {\n"
+                    + "return std::nullopt;\n"
+                    + "}\n"
+                    + "if (xmlXIncludeProcess(doc.get()) < 0) {\n"
+                    + "return std::nullopt;\n"
+                    + "}\n\n"
+                    + "if (!xmlStrcmp(_child->name, reinterpret_cast<const xmlChar*>"
+                    + "(\"%s\"))) {\n",
+                    innerParser,
+                    elementName);
+        }
+
+        if (cppType instanceof CppSimpleType) {
+            parserCppFile.print("std::string _raw;\n");
+            printSetRawWithElementText("_child");
+        }
+        parserCppFile.printf(cppType.getParsingExpression());
+        parserCppFile.printf("return _value;\n}\n");
+        parserCppFile.printf("return std::nullopt;\n");
+        parserCppFile.printf("}\n\n");
+    }
+
+    /**
+     * Prints writer functions for each top-level types
+     *
+     * Foo.h:
+     *
+     *     void write(ostream&, const Foo& foo);
+     *
+     * Foo.cpp:
+     *
+     *     void write(ostream& _out, const Foo& foo) {
+     *        ... <?xml ... ?>
+     *        foo.write(_out, "FooElementName");
+     *     }
+     *
+     */
     private void printXmlWriter() throws CppCodeGeneratorException {
         for (XsdElement element : xmlSchema.getElementMap().values()) {
+            // Skip writer if not specified as root.
+            if (rootElements != null
+                    && Arrays.asList(rootElements).indexOf(element.getName()) == -1) continue;
             CppType cppType = parseType(element.getType(), element.getName());
             String elementName = element.getName();
-            String VariableName = Utils.toVariableName(elementName);
-            String typeName = cppType instanceof CppSimpleType ? cppType.getName() :
-                    Utils.toClassName(cppType.getName());
-            parserHeaderFile.printf("void write(std::ostream& out, %s& %s);\n\n",
-                    typeName, VariableName);
-            parserCppFile.printf("void write(std::ostream& out, %s& %s) {\n",
-                    typeName, VariableName);
-
+            String variableName = Utils.toVariableName(elementName);
+            String typeName = cppType.getName();
+            String writerName =
+                    cppType instanceof CppSimpleType ? Utils.toClassName(elementName) : "";
+            parserHeaderFile.printf("void write%s(std::ostream& _out, const %s& %s);\n\n",
+                    writerName, typeName, variableName);
+            parserCppFile.printf("void write%s(std::ostream& _out, const %s& %s) {\n",
+                    writerName, typeName, variableName);
             parserCppFile.print(
-                    "out << \"<?xml version=\\\"1.0\\\" encoding=\\\"utf-8\\\"?>\\n\";\n");
-            parserCppFile.printf("%s.write(out, \"%s\");\n", VariableName, elementName);
+                    "_out << \"<?xml version=\\\"1.0\\\" encoding=\\\"utf-8\\\"?>\\n\";\n");
+            if (cppType instanceof CppSimpleType) {
+                parserCppFile.printf("_out << \"<%s>\";\n", elementName);
+                parserCppFile.print(cppType.getWritingExpression(variableName, ""));
+                parserCppFile.printf("_out << \"</%s>\" << std::endl;\n", elementName);
+            } else {
+                parserCppFile.printf("%s.write(_out, \"%s\");\n", variableName, elementName);
+            }
             parserCppFile.printf("}\n\n");
         }
 
@@ -1157,7 +1339,6 @@ public class CppCodeGenerator {
         }
         boolean results = false;
         for (XsdElement element : complexType.getElements()) {
-            XsdElement elementValue = resolveElement(element);
             if (element.getRef() == null && element.getType().getRef() == null
                     && element.getType() instanceof XsdComplexType) {
                 results = hasAttribute((XsdComplexType) element.getType());
diff --git a/src/com/android/xsdc/cpp/CppCodeGeneratorException.java b/src/main/java/com/android/xsdc/cpp/CppCodeGeneratorException.java
index a6ccf2a..a6ccf2a 100644
--- a/src/com/android/xsdc/cpp/CppCodeGeneratorException.java
+++ b/src/main/java/com/android/xsdc/cpp/CppCodeGeneratorException.java
diff --git a/src/com/android/xsdc/cpp/CppComplexType.java b/src/main/java/com/android/xsdc/cpp/CppComplexType.java
index 64d735d..4a87afa 100644
--- a/src/com/android/xsdc/cpp/CppComplexType.java
+++ b/src/main/java/com/android/xsdc/cpp/CppComplexType.java
@@ -30,11 +30,11 @@ class CppComplexType implements CppType {
 
     @Override
     public String getParsingExpression() {
-        return String.format("%s value = %s::read(child);\n", name, name);
+        return String.format("%s _value = %s::read(_child);\n", name, name);
     }
 
     @Override
     public String getWritingExpression(String getValue, String name) {
-        return String.format("%s.write(out, \"%s\");\n", getValue, name);
+        return String.format("%s.write(_out, \"%s\");\n", getValue, name);
     }
 }
diff --git a/src/com/android/xsdc/cpp/CppSimpleType.java b/src/main/java/com/android/xsdc/cpp/CppSimpleType.java
index d063ebe..5168329 100644
--- a/src/com/android/xsdc/cpp/CppSimpleType.java
+++ b/src/main/java/com/android/xsdc/cpp/CppSimpleType.java
@@ -62,19 +62,19 @@ class CppSimpleType implements CppType {
         StringBuilder expression = new StringBuilder();
         if (list) {
             expression.append(
-                    String.format("%s value;\n", getName()));
+                    String.format("%s _value;\n", getName()));
             expression.append(String.format("{\n"
-                    + "std::istringstream stream(raw);\n"
-                    + "for(std::string str; stream >> str; ) {\n"
-                    + "    value.push_back(%s);\n"
+                    + "std::istringstream _stream(_raw);\n"
+                    + "for(std::string str; _stream >> str; ) {\n"
+                    + "    _value.push_back(%s);\n"
                     + "}\n",
                     String.format(rawParsingExpression, "str")));
             expression.append("}\n");
         } else {
             expression.append(
-                    String.format("%s %svalue = %s;\n", getName(),
+                    String.format("%s %s_value = %s;\n", getName(),
                             this.name.equals("std::string") ? "&" : "",
-                            String.format(rawParsingExpression, "raw")));
+                            String.format(rawParsingExpression, "_raw")));
         }
         return expression.toString();
     }
@@ -83,31 +83,31 @@ class CppSimpleType implements CppType {
     public String getWritingExpression(String getValue, String name) {
         StringBuilder expression = new StringBuilder();
         if (list) {
-            expression.append("{\nint count = 0;\n");
-            expression.append(String.format("for (const auto& v : %s) {\n", getValue));
+            expression.append("{\nint _count = 0;\n");
+            expression.append(String.format("for (const auto& _v : %s) {\n", getValue));
             String value;
             if (isEnum) {
-                value = String.format("%sToString(v)", this.name);
+                value = String.format("%sToString(_v)", this.name);
             } else if (this.name.equals("char") || this.name.equals("unsigned char")) {
-                value = "(int)v";
+                value = "(int)_v";
             } else if (this.name.equals("bool")) {
-                value = "(v ? \"true\" : \"false\")";
+                value = "(_v ? \"true\" : \"false\")";
             } else {
-                value = "v";
+                value = "_v";
             }
-            expression.append("if (count != 0) {\n"
-                    + "out << \" \";\n}\n"
-                    + "++count;\n");
-            expression.append(String.format("out << %s;\n}\n}\n", value));
+            expression.append("if (_count != 0) {\n"
+                    + "_out << \" \";\n}\n"
+                    + "++_count;\n");
+            expression.append(String.format("_out << %s;\n}\n}\n", value));
         } else {
             if (isEnum) {
-                expression.append(String.format("out << toString(%s);\n", getValue));
+                expression.append(String.format("_out << toString(%s);\n", getValue));
             } else if (this.name.equals("char") || this.name.equals("unsigned char")) {
-                expression.append(String.format("out << (int)%s;\n", getValue));
+                expression.append(String.format("_out << (int)%s;\n", getValue));
             } else if (this.name.equals("bool")) {
-                expression.append(String.format("out << (%s ? \"true\" : \"false\");\n", getValue));
+                expression.append(String.format("_out << (%s ? \"true\" : \"false\");\n", getValue));
             } else {
-                expression.append(String.format("out << %s;\n", getValue));
+                expression.append(String.format("_out << %s;\n", getValue));
             }
         }
         return expression.toString();
diff --git a/src/com/android/xsdc/cpp/CppType.java b/src/main/java/com/android/xsdc/cpp/CppType.java
index 05d4da9..1c72d3f 100644
--- a/src/com/android/xsdc/cpp/CppType.java
+++ b/src/main/java/com/android/xsdc/cpp/CppType.java
@@ -19,6 +19,13 @@ package com.android.xsdc.cpp;
 interface CppType {
     String getName();
 
+    /**
+     * Statements to parse the input to this type. For simple types,
+     * `_raw(std::string)` should be available. For complex types,
+     * `_child(T)` should be available.
+     *
+     * @return statements declaring `_value` for this type from input
+     */
     String getParsingExpression();
 
     public String getWritingExpression(String getValue, String name);
diff --git a/src/com/android/xsdc/cpp/Utils.java b/src/main/java/com/android/xsdc/cpp/Utils.java
index d54a9aa..d54a9aa 100644
--- a/src/com/android/xsdc/cpp/Utils.java
+++ b/src/main/java/com/android/xsdc/cpp/Utils.java
diff --git a/src/com/android/xsdc/java/JavaCodeGenerator.java b/src/main/java/com/android/xsdc/java/JavaCodeGenerator.java
index 0025896..0fc2b7c 100644
--- a/src/com/android/xsdc/java/JavaCodeGenerator.java
+++ b/src/main/java/com/android/xsdc/java/JavaCodeGenerator.java
@@ -23,6 +23,7 @@ import com.android.xsdc.XsdConstants;
 import com.android.xsdc.tag.*;
 
 import java.io.IOException;
+import java.util.Arrays;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.HashSet;
@@ -41,9 +42,11 @@ public class JavaCodeGenerator {
     private boolean generateHasMethod;
     private boolean useHexBinary;
     private boolean booleanGetter;
+    private String[] rootElements;
 
     public JavaCodeGenerator(XmlSchema xmlSchema, String packageName, boolean writer,
-            boolean showNullability, boolean generateHasMethod, boolean booleanGetter)
+            boolean showNullability, boolean generateHasMethod, boolean booleanGetter,
+            String[] rootElements)
             throws JavaCodeGeneratorException {
         this.xmlSchema = xmlSchema;
         this.packageName = packageName;
@@ -51,6 +54,7 @@ public class JavaCodeGenerator {
         this.showNullability = showNullability;
         this.generateHasMethod = generateHasMethod;
         this.booleanGetter = booleanGetter;
+        this.rootElements = rootElements;
         useHexBinary = false;
 
         // class naming validation
@@ -306,69 +310,69 @@ public class JavaCodeGenerator {
             allAttributeTypes.add(parseSimpleType(type, false));
         }
 
-        out.printf("static %s%s read(%sorg.xmlpull.v1.XmlPullParser parser) " +
+        out.printf("static %s%s read(%sorg.xmlpull.v1.XmlPullParser _parser) " +
                 "throws org.xmlpull.v1.XmlPullParserException, java.io.IOException, " +
                 "javax.xml.datatype.DatatypeConfigurationException {\n",
                 getDefaultNullability(Nullability.NON_NULL), name,
                 getDefaultNullability(Nullability.NON_NULL));
 
-        out.printf("%s instance = new %s();\n"
-                + "String raw = null;\n", name, name);
+        out.printf("%s _instance = new %s();\n"
+                + "String _raw = null;\n", name, name);
         for (int i = 0; i < allAttributes.size(); ++i) {
             JavaType type = allAttributeTypes.get(i);
             XsdAttribute attribute = resolveAttribute(allAttributes.get(i));
             String variableName = Utils.toVariableName(attribute.getName());
-            out.printf("raw = parser.getAttributeValue(null, \"%s\");\n"
-                    + "if (raw != null) {\n", attribute.getName());
+            out.printf("_raw = _parser.getAttributeValue(null, \"%s\");\n"
+                    + "if (_raw != null) {\n", attribute.getName());
             out.print(type.getParsingExpression());
-            out.printf("instance.set%s(value);\n"
+            out.printf("_instance.set%s(_value);\n"
                     + "}\n", Utils.capitalize(variableName));
         }
 
         if (baseValueType != null) {
-            out.print("raw = XmlParser.readText(parser);\n"
-                    + "if (raw != null) {\n");
+            out.print("_raw = XmlParser.readText(_parser);\n"
+                    + "if (_raw != null) {\n");
             out.print(baseValueType.getParsingExpression());
-            out.print("instance.setValue(value);\n"
+            out.print("_instance.setValue(_value);\n"
                     + "}\n");
         } else if (!allElements.isEmpty()) {
-            out.print("int outerDepth = parser.getDepth();\n"
+            out.print("int outerDepth = _parser.getDepth();\n"
                     + "int type;\n"
-                    + "while ((type=parser.next()) != org.xmlpull.v1.XmlPullParser.END_DOCUMENT\n"
+                    + "while ((type=_parser.next()) != org.xmlpull.v1.XmlPullParser.END_DOCUMENT\n"
                     + "        && type != org.xmlpull.v1.XmlPullParser.END_TAG) {\n"
-                    + "if (parser.getEventType() != org.xmlpull.v1.XmlPullParser.START_TAG) "
+                    + "if (_parser.getEventType() != org.xmlpull.v1.XmlPullParser.START_TAG) "
                     + "continue;\n"
-                    + "String tagName = parser.getName();\n");
+                    + "String _tagName = _parser.getName();\n");
             for (int i = 0; i < allElements.size(); ++i) {
                 JavaType type = allElementTypes.get(i);
                 XsdElement element = allElements.get(i);
                 XsdElement elementValue = resolveElement(element);
                 String variableName = Utils.toVariableName(getElementName(elementValue));
-                out.printf("if (tagName.equals(\"%s\")) {\n", elementValue.getName());
+                out.printf("if (_tagName.equals(\"%s\")) {\n", elementValue.getName());
                 if (type instanceof JavaSimpleType) {
-                    out.print("raw = XmlParser.readText(parser);\n");
+                    out.print("_raw = XmlParser.readText(_parser);\n");
                 }
                 out.print(type.getParsingExpression());
                 if (element.isMultiple()) {
-                    out.printf("instance.get%s().add(value);\n",
+                    out.printf("_instance.get%s().add(_value);\n",
                             Utils.capitalize(variableName));
                 } else {
-                    out.printf("instance.set%s(value);\n",
+                    out.printf("_instance.set%s(_value);\n",
                             Utils.capitalize(variableName));
                 }
                 out.printf("} else ");
             }
             out.print("{\n"
-                    + "XmlParser.skip(parser);\n"
+                    + "XmlParser.skip(_parser);\n"
                     + "}\n"
                     + "}\n");
             out.printf("if (type != org.xmlpull.v1.XmlPullParser.END_TAG) {\n"
                     + "throw new javax.xml.datatype.DatatypeConfigurationException(\"%s is not closed\");\n"
                     + "}\n", name);
         } else {
-            out.print("XmlParser.skip(parser);\n");
+            out.print("XmlParser.skip(_parser);\n");
         }
-        out.print("return instance;\n"
+        out.print("return _instance;\n"
                 + "}\n");
     }
 
@@ -393,27 +397,27 @@ public class JavaCodeGenerator {
             allAttributeTypes.add(parseSimpleType(type, false));
         }
 
-        out.printf("\nvoid write(%sXmlWriter out, %sString name) " +
+        out.printf("\nvoid write(%sXmlWriter _out, %sString _name) " +
                 "throws java.io.IOException {\n", getDefaultNullability(Nullability.NON_NULL),
                 getDefaultNullability(Nullability.NON_NULL));
 
-        out.print("out.print(\"<\" + name);\n");
+        out.print("_out.print(\"<\" + _name);\n");
         for (int i = 0; i < allAttributes.size(); ++i) {
             JavaType type = allAttributeTypes.get(i);
             boolean isList = allAttributeTypes.get(i).isList();
             XsdAttribute attribute = resolveAttribute(allAttributes.get(i));
             String variableName = Utils.toVariableName(attribute.getName());
             out.printf("if (has%s()) {\n", Utils.capitalize(variableName));
-            out.printf("out.print(\" %s=\\\"\");\n", attribute.getName());
+            out.printf("_out.print(\" %s=\\\"\");\n", attribute.getName());
             out.print(type.getWritingExpression(String.format("%s%s()",
                     getterName(type.getName()), Utils.capitalize(variableName)),
                     attribute.getName()));
-            out.printf("out.print(\"\\\"\");\n}\n");
+            out.printf("_out.print(\"\\\"\");\n}\n");
         }
-        out.printf("out.print(\">\\n\");\n");
+        out.printf("_out.print(\">\\n\");\n");
 
         if (!allElements.isEmpty()) {
-            out.printf("out.increaseIndent();\n");
+            out.printf("_out.increaseIndent();\n");
             for (int i = 0; i < allElements.size(); ++i) {
                 JavaType type = allElementTypes.get(i);
                 XsdElement element = allElements.get(i);
@@ -425,31 +429,31 @@ public class JavaCodeGenerator {
                     out.printf("for (%s value : get%s()) {\n", type.getName(),
                             Utils.capitalize(variableName));
                     if (type instanceof JavaSimpleType) {
-                        out.printf("out.print(\"<%s>\");\n", elementValue.getName());
+                        out.printf("_out.print(\"<%s>\");\n", elementValue.getName());
                     }
                     out.print(type.getWritingExpression("value", elementValue.getName()));
                     if (type instanceof JavaSimpleType) {
-                        out.printf("out.print(\"</%s>\\n\");\n", elementValue.getName());
+                        out.printf("_out.print(\"</%s>\\n\");\n", elementValue.getName());
                     }
                     out.print("}\n");
                 } else {
                     out.printf("if (has%s()) {\n", Utils.capitalize(variableName));
                     if (type instanceof JavaSimpleType) {
-                        out.printf("out.print(\"<%s>\");\n", elementValue.getName());
+                        out.printf("_out.print(\"<%s>\");\n", elementValue.getName());
                     }
                     out.print(type.getWritingExpression(String.format("%s%s()",
                               getterName(type.getName()), Utils.capitalize(variableName)),
                               elementValue.getName()));
                     if (type instanceof JavaSimpleType) {
-                        out.printf("out.print(\"</%s>\\n\");\n", elementValue.getName());
+                        out.printf("_out.print(\"</%s>\\n\");\n", elementValue.getName());
                     }
                     out.printf("}\n");
                 }
 
             }
-            out.printf("out.decreaseIndent();\n");
+            out.printf("_out.decreaseIndent();\n");
         }
-        out.print("out.print(\"</\" + name + \">\\n\");\n");
+        out.print("_out.print(\"</\" + _name + \">\\n\");\n");
         out.print("}\n");
     }
 
@@ -509,26 +513,33 @@ public class JavaCodeGenerator {
 
         boolean isMultiRootElement = xmlSchema.getElementMap().values().size() > 1;
         for (XsdElement element : xmlSchema.getElementMap().values()) {
+            // Skip parser if not specified as root.
+            if (rootElements != null
+                    && Arrays.asList(rootElements).indexOf(element.getName()) == -1) continue;
             JavaType javaType = parseType(element.getType(), element.getName());
+            String elementName = element.getName();
+            String typeName = javaType.getName();
+            String readerName =
+                    javaType instanceof JavaSimpleType ? Utils.toClassName(elementName) : typeName;
             out.printf("public static %s%s read%s(%sjava.io.InputStream in)"
-                + " throws org.xmlpull.v1.XmlPullParserException, java.io.IOException, "
-                + "javax.xml.datatype.DatatypeConfigurationException {\n"
-                + "org.xmlpull.v1.XmlPullParser parser = org.xmlpull.v1.XmlPullParserFactory"
-                + ".newInstance().newPullParser();\n"
-                + "parser.setFeature(org.xmlpull.v1.XmlPullParser.FEATURE_PROCESS_NAMESPACES, "
-                + "true);\n"
-                + "parser.setInput(in, null);\n"
-                + "parser.nextTag();\n"
-                + "String tagName = parser.getName();\n"
-                + "String raw = null;\n", getDefaultNullability(Nullability.NULLABLE),
-                javaType.getName(), isMultiRootElement ? Utils.capitalize(javaType.getName()) : "",
-                getDefaultNullability(Nullability.NON_NULL));
-            out.printf("if (tagName.equals(\"%s\")) {\n", element.getName());
+                    + " throws org.xmlpull.v1.XmlPullParserException, java.io.IOException, "
+                    + "javax.xml.datatype.DatatypeConfigurationException {\n"
+                    + "org.xmlpull.v1.XmlPullParser _parser = org.xmlpull.v1.XmlPullParserFactory"
+                    + ".newInstance().newPullParser();\n"
+                    + "_parser.setFeature(org.xmlpull.v1.XmlPullParser.FEATURE_PROCESS_NAMESPACES, "
+                    + "true);\n"
+                    + "_parser.setInput(in, null);\n"
+                    + "_parser.nextTag();\n"
+                    + "String _tagName = _parser.getName();\n"
+                    + "String _raw = null;\n", getDefaultNullability(Nullability.NULLABLE),
+                    typeName, isMultiRootElement ? readerName : "",
+                    getDefaultNullability(Nullability.NON_NULL));
+            out.printf("if (_tagName.equals(\"%s\")) {\n", elementName);
             if (javaType instanceof JavaSimpleType) {
-                out.print("raw = XmlParser.readText(parser);\n");
+                out.print("_raw = XmlParser.readText(_parser);\n");
             }
             out.print(javaType.getParsingExpression());
-            out.print("return value;\n"
+            out.print("return _value;\n"
                     + "}\n"
                     + "return null;\n"
                     + "}\n");
@@ -536,12 +547,12 @@ public class JavaCodeGenerator {
         }
 
         out.printf(
-                "public static %sjava.lang.String readText(%sorg.xmlpull.v1.XmlPullParser parser)"
+                "public static %sjava.lang.String readText(%sorg.xmlpull.v1.XmlPullParser _parser)"
                         + " throws org.xmlpull.v1.XmlPullParserException, java.io.IOException {\n"
                         + "String result = \"\";\n"
-                        + "if (parser.next() == org.xmlpull.v1.XmlPullParser.TEXT) {\n"
-                        + "    result = parser.getText();\n"
-                        + "    parser.nextTag();\n"
+                        + "if (_parser.next() == org.xmlpull.v1.XmlPullParser.TEXT) {\n"
+                        + "    result = _parser.getText();\n"
+                        + "    _parser.nextTag();\n"
                         + "}\n"
                         + "return result;\n"
                         + "}\n", getDefaultNullability(Nullability.NULLABLE),
@@ -549,14 +560,14 @@ public class JavaCodeGenerator {
         out.println();
 
         out.printf(
-                "public static void skip(%sorg.xmlpull.v1.XmlPullParser parser)"
+                "public static void skip(%sorg.xmlpull.v1.XmlPullParser _parser)"
                         + " throws org.xmlpull.v1.XmlPullParserException, java.io.IOException {\n"
-                        + "if (parser.getEventType() != org.xmlpull.v1.XmlPullParser.START_TAG) {\n"
+                        + "if (_parser.getEventType() != org.xmlpull.v1.XmlPullParser.START_TAG) {\n"
                         + "    throw new IllegalStateException();\n"
                         + "}\n"
                         + "int depth = 1;\n"
                         + "while (depth != 0) {\n"
-                        + "    switch (parser.next()) {\n"
+                        + "    switch (_parser.next()) {\n"
                         + "        case org.xmlpull.v1.XmlPullParser.END_TAG:\n"
                         + "            depth--;\n"
                         + "            break;\n"
@@ -622,18 +633,31 @@ public class JavaCodeGenerator {
 
 
         for (XsdElement element : xmlSchema.getElementMap().values()) {
+            // Skip writer if not specified as root.
+            if (rootElements != null
+                    && Arrays.asList(rootElements).indexOf(element.getName()) == -1) continue;
             JavaType javaType = parseType(element.getType(), element.getName());
             String elementName = element.getName();
-            String VariableName = Utils.toVariableName(elementName);
-            String typeName = javaType instanceof JavaSimpleType ? javaType.getName() :
-                    Utils.toClassName(javaType.getName());
-            out.printf("public static void write(%sXmlWriter out, %s%s %s) "
-                    + "throws java.io.IOException {", getDefaultNullability(Nullability.NON_NULL),
-                    getDefaultNullability(Nullability.NON_NULL), typeName, VariableName);
-            out.print("\nout.print(\"<?xml version=\\\"1.0\\\" encoding=\\\"utf-8\\\"?>\\n\");\n");
-            out.printf("if (%s != null) {\n", VariableName);
-            out.printf("%s.write(out, \"%s\");\n}\n", VariableName, elementName);
-            out.print("out.printXml();\n}\n\n");
+            String variableName = Utils.toVariableName(elementName);
+            String typeName = javaType.getName();
+            String writerName
+                    = javaType instanceof JavaSimpleType ? Utils.toClassName(elementName) : "";
+            out.printf("public static void write%s(%sXmlWriter _out, %s%s %s) "
+                    + "throws java.io.IOException {",
+                    writerName,
+                    getDefaultNullability(Nullability.NON_NULL),
+                    getDefaultNullability(Nullability.NON_NULL), typeName, variableName);
+            out.print("\n_out.print(\"<?xml version=\\\"1.0\\\" encoding=\\\"utf-8\\\"?>\\n\");\n");
+            out.printf("if (%s != null) {\n", variableName);
+            if (javaType instanceof JavaSimpleType) {
+                out.printf("_out.print(\"<%s>\");\n", elementName);
+                out.print(javaType.getWritingExpression(variableName, ""));
+                out.printf("_out.print(\"</%s>\\n\");\n", elementName);
+            } else {
+                out.printf("%s.write(_out, \"%s\");\n", variableName, elementName);
+            }
+            out.print("}\n");
+            out.print("_out.printXml();\n}\n\n");
         }
         out.printf("}\n");
     }
diff --git a/src/com/android/xsdc/java/JavaCodeGeneratorException.java b/src/main/java/com/android/xsdc/java/JavaCodeGeneratorException.java
index b37a284..b37a284 100644
--- a/src/com/android/xsdc/java/JavaCodeGeneratorException.java
+++ b/src/main/java/com/android/xsdc/java/JavaCodeGeneratorException.java
diff --git a/src/com/android/xsdc/java/JavaComplexType.java b/src/main/java/com/android/xsdc/java/JavaComplexType.java
index 1a66794..e25acd7 100644
--- a/src/com/android/xsdc/java/JavaComplexType.java
+++ b/src/main/java/com/android/xsdc/java/JavaComplexType.java
@@ -40,11 +40,11 @@ class JavaComplexType implements JavaType {
 
     @Override
     public String getParsingExpression() {
-        return String.format("%s value = %s.read(parser);\n", name, name);
+        return String.format("%s _value = %s.read(_parser);\n", name, name);
     }
 
     @Override
     public String getWritingExpression(String getValue, String name) {
-        return String.format("%s.write(out, \"%s\");\n", getValue, name);
+        return String.format("%s.write(_out, \"%s\");\n", getValue, name);
     }
 }
diff --git a/src/com/android/xsdc/java/JavaSimpleType.java b/src/main/java/com/android/xsdc/java/JavaSimpleType.java
index 5c73466..5ad905f 100644
--- a/src/com/android/xsdc/java/JavaSimpleType.java
+++ b/src/main/java/com/android/xsdc/java/JavaSimpleType.java
@@ -74,15 +74,15 @@ class JavaSimpleType implements JavaType {
         StringBuilder expression = new StringBuilder();
         if (list) {
             expression.append(
-                    String.format("%s value = new java.util.ArrayList<>();\n", getName()));
-            expression.append("for (String token : raw.split(\"\\\\s+\")) {\n");
-            expression.append(String.format("value.add(%s);\n",
-                    String.format(rawParsingExpression, "token")));
+                    String.format("%s _value = new java.util.ArrayList<>();\n", getName()));
+            expression.append("for (String _token : _raw.split(\"\\\\s+\")) {\n");
+            expression.append(String.format("_value.add(%s);\n",
+                    String.format(rawParsingExpression, "_token")));
             expression.append("}\n");
         } else {
             expression.append(
-                    String.format("%s value = %s;\n", getName(),
-                            String.format(rawParsingExpression, "raw")));
+                    String.format("%s _value = %s;\n", getName(),
+                            String.format(rawParsingExpression, "_raw")));
         }
         return expression.toString();
     }
@@ -91,16 +91,16 @@ class JavaSimpleType implements JavaType {
     public String getWritingExpression(String getValue, String name) {
         StringBuilder expression = new StringBuilder();
         if (list) {
-            expression.append("{\nint count = 0;\n");
+            expression.append("{\nint _count = 0;\n");
             expression.append(String.format("for (%s v : %s) {\n", this.name, getValue));
-            expression.append("if (count != 0) {\n"
-                    + "out.print(\" \");\n}\n"
-                    + "++count;\n");
-            expression.append(String.format("out.print(%s);\n}\n",
+            expression.append("if (_count != 0) {\n"
+                    + "_out.print(\" \");\n}\n"
+                    + "++_count;\n");
+            expression.append(String.format("_out.print(%s);\n}\n",
                     String.format(rawWritingExpression, "v")));
             expression.append("}\n");
         } else {
-            expression.append(String.format("out.print(%s);\n",
+            expression.append(String.format("_out.print(%s);\n",
                     String.format(rawWritingExpression, getValue)));
         }
         return expression.toString();
diff --git a/src/com/android/xsdc/java/JavaType.java b/src/main/java/com/android/xsdc/java/JavaType.java
index 8605f5d..8605f5d 100644
--- a/src/com/android/xsdc/java/JavaType.java
+++ b/src/main/java/com/android/xsdc/java/JavaType.java
diff --git a/src/com/android/xsdc/java/Utils.java b/src/main/java/com/android/xsdc/java/Utils.java
index 5a7a92a..5a7a92a 100644
--- a/src/com/android/xsdc/java/Utils.java
+++ b/src/main/java/com/android/xsdc/java/Utils.java
diff --git a/src/com/android/xsdc/tag/Nullability.java b/src/main/java/com/android/xsdc/tag/Nullability.java
index 9e81635..9e81635 100644
--- a/src/com/android/xsdc/tag/Nullability.java
+++ b/src/main/java/com/android/xsdc/tag/Nullability.java
diff --git a/src/com/android/xsdc/tag/XsdAll.java b/src/main/java/com/android/xsdc/tag/XsdAll.java
index 39c2562..39c2562 100644
--- a/src/com/android/xsdc/tag/XsdAll.java
+++ b/src/main/java/com/android/xsdc/tag/XsdAll.java
diff --git a/src/com/android/xsdc/tag/XsdAttribute.java b/src/main/java/com/android/xsdc/tag/XsdAttribute.java
index 0c46eb0..0c46eb0 100644
--- a/src/com/android/xsdc/tag/XsdAttribute.java
+++ b/src/main/java/com/android/xsdc/tag/XsdAttribute.java
diff --git a/src/com/android/xsdc/tag/XsdAttributeGroup.java b/src/main/java/com/android/xsdc/tag/XsdAttributeGroup.java
index 6c8f853..6c8f853 100644
--- a/src/com/android/xsdc/tag/XsdAttributeGroup.java
+++ b/src/main/java/com/android/xsdc/tag/XsdAttributeGroup.java
diff --git a/src/com/android/xsdc/tag/XsdChoice.java b/src/main/java/com/android/xsdc/tag/XsdChoice.java
index 223bb44..223bb44 100644
--- a/src/com/android/xsdc/tag/XsdChoice.java
+++ b/src/main/java/com/android/xsdc/tag/XsdChoice.java
diff --git a/src/com/android/xsdc/tag/XsdComplexContent.java b/src/main/java/com/android/xsdc/tag/XsdComplexContent.java
index aa9de87..aa9de87 100644
--- a/src/com/android/xsdc/tag/XsdComplexContent.java
+++ b/src/main/java/com/android/xsdc/tag/XsdComplexContent.java
diff --git a/src/com/android/xsdc/tag/XsdComplexType.java b/src/main/java/com/android/xsdc/tag/XsdComplexType.java
index a7e0311..a7e0311 100644
--- a/src/com/android/xsdc/tag/XsdComplexType.java
+++ b/src/main/java/com/android/xsdc/tag/XsdComplexType.java
diff --git a/src/com/android/xsdc/tag/XsdElement.java b/src/main/java/com/android/xsdc/tag/XsdElement.java
index 40a6695..40a6695 100644
--- a/src/com/android/xsdc/tag/XsdElement.java
+++ b/src/main/java/com/android/xsdc/tag/XsdElement.java
diff --git a/src/com/android/xsdc/tag/XsdEnumRestriction.java b/src/main/java/com/android/xsdc/tag/XsdEnumRestriction.java
index 3ae7ae0..3ae7ae0 100644
--- a/src/com/android/xsdc/tag/XsdEnumRestriction.java
+++ b/src/main/java/com/android/xsdc/tag/XsdEnumRestriction.java
diff --git a/src/com/android/xsdc/tag/XsdEnumeration.java b/src/main/java/com/android/xsdc/tag/XsdEnumeration.java
index 2f9fdc0..2f9fdc0 100644
--- a/src/com/android/xsdc/tag/XsdEnumeration.java
+++ b/src/main/java/com/android/xsdc/tag/XsdEnumeration.java
diff --git a/src/com/android/xsdc/tag/XsdGeneralExtension.java b/src/main/java/com/android/xsdc/tag/XsdGeneralExtension.java
index 24043e4..24043e4 100644
--- a/src/com/android/xsdc/tag/XsdGeneralExtension.java
+++ b/src/main/java/com/android/xsdc/tag/XsdGeneralExtension.java
diff --git a/src/com/android/xsdc/tag/XsdGeneralRestriction.java b/src/main/java/com/android/xsdc/tag/XsdGeneralRestriction.java
index 6583622..6583622 100644
--- a/src/com/android/xsdc/tag/XsdGeneralRestriction.java
+++ b/src/main/java/com/android/xsdc/tag/XsdGeneralRestriction.java
diff --git a/src/com/android/xsdc/tag/XsdGroup.java b/src/main/java/com/android/xsdc/tag/XsdGroup.java
index dd8f008..dd8f008 100644
--- a/src/com/android/xsdc/tag/XsdGroup.java
+++ b/src/main/java/com/android/xsdc/tag/XsdGroup.java
diff --git a/src/com/android/xsdc/tag/XsdList.java b/src/main/java/com/android/xsdc/tag/XsdList.java
index 70023c8..70023c8 100644
--- a/src/com/android/xsdc/tag/XsdList.java
+++ b/src/main/java/com/android/xsdc/tag/XsdList.java
diff --git a/src/com/android/xsdc/tag/XsdRestriction.java b/src/main/java/com/android/xsdc/tag/XsdRestriction.java
index 17dfdd5..17dfdd5 100644
--- a/src/com/android/xsdc/tag/XsdRestriction.java
+++ b/src/main/java/com/android/xsdc/tag/XsdRestriction.java
diff --git a/src/com/android/xsdc/tag/XsdSimpleContent.java b/src/main/java/com/android/xsdc/tag/XsdSimpleContent.java
index cefa60e..cefa60e 100644
--- a/src/com/android/xsdc/tag/XsdSimpleContent.java
+++ b/src/main/java/com/android/xsdc/tag/XsdSimpleContent.java
diff --git a/src/com/android/xsdc/tag/XsdSimpleType.java b/src/main/java/com/android/xsdc/tag/XsdSimpleType.java
index c7d7e37..c7d7e37 100644
--- a/src/com/android/xsdc/tag/XsdSimpleType.java
+++ b/src/main/java/com/android/xsdc/tag/XsdSimpleType.java
diff --git a/src/com/android/xsdc/tag/XsdTag.java b/src/main/java/com/android/xsdc/tag/XsdTag.java
index 3397267..3397267 100644
--- a/src/com/android/xsdc/tag/XsdTag.java
+++ b/src/main/java/com/android/xsdc/tag/XsdTag.java
diff --git a/src/com/android/xsdc/tag/XsdType.java b/src/main/java/com/android/xsdc/tag/XsdType.java
index a7e41a0..a7e41a0 100644
--- a/src/com/android/xsdc/tag/XsdType.java
+++ b/src/main/java/com/android/xsdc/tag/XsdType.java
diff --git a/src/com/android/xsdc/tag/XsdUnion.java b/src/main/java/com/android/xsdc/tag/XsdUnion.java
index f738330..f738330 100644
--- a/src/com/android/xsdc/tag/XsdUnion.java
+++ b/src/main/java/com/android/xsdc/tag/XsdUnion.java
diff --git a/src/test/java/com/android/xsdc/cpp/TestCppCodeGenerator.java b/src/test/java/com/android/xsdc/cpp/TestCppCodeGenerator.java
new file mode 100644
index 0000000..6106696
--- /dev/null
+++ b/src/test/java/com/android/xsdc/cpp/TestCppCodeGenerator.java
@@ -0,0 +1,150 @@
+/*
+ * Copyright (C) 2022, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.xsdc.cpp;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import com.android.xsdc.FileSystem;
+import com.android.xsdc.XmlSchema;
+import com.android.xsdc.XsdHandler;
+
+import org.junit.Test;
+
+import java.io.ByteArrayInputStream;
+import java.nio.charset.StandardCharsets;
+import java.util.Map;
+import java.util.Set;
+import java.util.TreeMap;
+
+import javax.xml.parsers.SAXParser;
+import javax.xml.parsers.SAXParserFactory;
+
+public class TestCppCodeGenerator {
+    public static final String SCHEMA = "<xs:schema xmlns:xs=\"http://www.w3.org/2001/XMLSchema\">\n"
+            + "  <xs:element name=\"class\" type=\"xs:string\" />\n"
+            + "</xs:schema>";
+
+    @Test
+    public void testParseSchema() throws Exception {
+        XmlSchema schema = parseSchema(SCHEMA);
+        assertEquals(schema.getElementMap().keySet(), Set.of("class"));
+    }
+
+    @Test
+    public void testSimpleTypeRootParser() throws Exception {
+        // We need two root elements to generate reader with element name.
+        String schema = "<xs:schema xmlns:xs=\"http://www.w3.org/2001/XMLSchema\">\n"
+                + "  <xs:element name=\"simple-type-element\" type=\"xs:string\" />\n"
+                + "  <xs:element name=\"another-root\" type=\"xs:string\" />\n"
+                + "</xs:schema>";
+        Map<String, StringBuffer> files = new TreeMap<>();
+        CppCodeGenerator gen =
+                new CppCodeGenerator(
+                        parseSchema(schema),
+                        "com.abc",
+                        /*writer=*/ true,
+                        CppCodeGenerator.GENERATE_PARSER,
+                        false,
+                        false,
+                        null);
+
+        FileSystem fs = new FileSystem(files);
+        gen.print(fs);
+        assertTrue(files.get("com_abc.cpp").toString().contains("readSimpleTypeElement"));
+        assertTrue(files.get("com_abc.cpp").toString().contains("writeSimpleTypeElement"));
+    }
+
+    @Test
+    public void testPrintWithoutEnumOutput() throws Exception {
+        Map<String, StringBuffer> files = new TreeMap<>();
+        CppCodeGenerator gen =
+                new CppCodeGenerator(
+                        parseSchema(SCHEMA),
+                        "com.abc",
+                        false,
+                        CppCodeGenerator.GENERATE_PARSER,
+                        false,
+                        false,
+                        null);
+
+        FileSystem fs = new FileSystem(files);
+        gen.print(fs);
+
+        assertEquals(files.keySet(), Set.of("com_abc.cpp", "include/com_abc.h"));
+    }
+
+    @Test
+    public void printWithEnumOutput() throws Exception {
+        Map<String, StringBuffer> files = new TreeMap<>();
+
+        CppCodeGenerator gen =
+                new CppCodeGenerator(
+                        parseSchema(SCHEMA),
+                        "com.abc",
+                        false,
+                        CppCodeGenerator.GENERATE_PARSER | CppCodeGenerator.GENERATE_ENUMS,
+                        false,
+                        false,
+                        null);
+
+        FileSystem fs = new FileSystem(files);
+        gen.print(fs);
+
+        assertEquals(
+                files.keySet(),
+                Set.of(
+                        "com_abc.cpp",
+                        "include/com_abc.h",
+                        "com_abc_enums.cpp",
+                        "include/com_abc_enums.h"));
+    }
+
+    private XmlSchema parseSchema(String contents) throws Exception {
+        byte[] bytes = contents.getBytes(StandardCharsets.UTF_8);
+        SAXParserFactory factory = SAXParserFactory.newInstance();
+        factory.setNamespaceAware(true);
+        SAXParser parser = factory.newSAXParser();
+        XsdHandler xsdHandler = new XsdHandler();
+        parser.parse(new ByteArrayInputStream(bytes), xsdHandler);
+        return xsdHandler.getSchema();
+    }
+
+    @Test
+    public void generateParsersForSpecifiedRoot() throws Exception {
+        Map<String, StringBuffer> files = new TreeMap<>();
+        String schema = "<xs:schema xmlns:xs=\"http://www.w3.org/2001/XMLSchema\">\n"
+                + "  <xs:element name=\"root1\" type=\"xs:string\" />\n"
+                + "  <xs:element name=\"root2\" type=\"xs:string\" />\n"
+                + "</xs:schema>";
+        CppCodeGenerator gen =
+                new CppCodeGenerator(
+                        parseSchema(schema),
+                        "com.abc",
+                        false,
+                        CppCodeGenerator.GENERATE_PARSER | CppCodeGenerator.GENERATE_ENUMS,
+                        false,
+                        false,
+                        new String[]{"root1"});
+
+        FileSystem fs = new FileSystem(files);
+        gen.print(fs);
+        assertTrue(files.get("com_abc.cpp").toString().contains("readRoot1"));
+        assertFalse(files.get("com_abc.cpp").toString().contains("readRoot2"));
+    }
+}
diff --git a/tests/resources/simple_complex_content/api/current.txt b/tests/resources/simple_complex_content/api/current.txt
index 043fb50..785e014 100644
--- a/tests/resources/simple_complex_content/api/current.txt
+++ b/tests/resources/simple_complex_content/api/current.txt
@@ -24,14 +24,17 @@ package simple.complex.content {
     method public String getName();
     method public simple.complex.content.SubAddress getSubAddress();
     method public simple.complex.content.USAddressP getUSAddressP();
+    method public simple.complex.content.KRAddress getValue();
     method public boolean hasKRAddress();
     method public boolean hasName();
     method public boolean hasSubAddress();
     method public boolean hasUSAddressP();
+    method public boolean hasValue();
     method public void setKRAddress(simple.complex.content.KRAddress);
     method public void setName(String);
     method public void setSubAddress(simple.complex.content.SubAddress);
     method public void setUSAddressP(simple.complex.content.USAddressP);
+    method public void setValue(simple.complex.content.KRAddress);
   }
 
   public class Person2 {
@@ -40,14 +43,17 @@ package simple.complex.content {
     method public String getName();
     method @NonNull public simple.complex.content.SubAddress getSubAddress();
     method public simple.complex.content.USAddressP getUSAddressP();
+    method public String getValue();
     method public boolean hasKRAddress();
     method public boolean hasName();
     method public boolean hasSubAddress();
     method public boolean hasUSAddressP();
+    method public boolean hasValue();
     method public void setKRAddress(simple.complex.content.KRAddress);
     method public void setName(String);
     method public void setSubAddress(@NonNull simple.complex.content.SubAddress);
     method public void setUSAddressP(simple.complex.content.USAddressP);
+    method public void setValue(String);
   }
 
   public class SubAddress {
diff --git a/tests/resources/simple_complex_content/simple_complex_content.xsd b/tests/resources/simple_complex_content/simple_complex_content.xsd
index 62a6497..7bb57b5 100644
--- a/tests/resources/simple_complex_content/simple_complex_content.xsd
+++ b/tests/resources/simple_complex_content/simple_complex_content.xsd
@@ -50,6 +50,7 @@
                 <xs:element name="USAddressP" type="USAddressP"/>
                 <xs:element name="KRAddress" type="KRAddress"/>
                 <xs:element name="subAddress" type="subAddress"/>
+                <xs:element name="value" type="KRAddress" minOccurs="0"/>
             </xs:sequence>
         </xs:complexType>
     </xs:element>
@@ -62,6 +63,7 @@
                 <xs:element name="subAddress" type="subAddress">
                     <xs:annotation name="nonnull"/>
                 </xs:element>
+                <xs:element name="value" type="xs:string" minOccurs="0"/>
             </xs:sequence>
         </xs:complexType>
     </xs:element>
diff --git a/tests/resources/simple_type/api/current.txt b/tests/resources/simple_type/api/current.txt
index 0b163a5..8368c23 100644
--- a/tests/resources/simple_type/api/current.txt
+++ b/tests/resources/simple_type/api/current.txt
@@ -18,16 +18,20 @@ package simple.type {
   public class SimpleTypes {
     ctor public SimpleTypes();
     method public java.util.List<java.lang.Integer> getListInt();
+    method public java.util.List<java.lang.Integer> getOptionalIntList();
     method public java.util.List<java.lang.String> getUnionTest();
     method public java.util.List<simple.type.EnumType> getYesOrNo();
     method public boolean isExample1();
     method public boolean isExample2();
     method public boolean isExample3();
+    method public boolean isValue();
     method public void setExample1(boolean);
     method public void setExample2(boolean);
     method public void setExample3(boolean);
     method public void setListInt(java.util.List<java.lang.Integer>);
+    method public void setOptionalIntList(java.util.List<java.lang.Integer>);
     method public void setUnionTest(java.util.List<java.lang.String>);
+    method public void setValue(boolean);
   }
 
   public class SingleChoice {
@@ -43,6 +47,7 @@ package simple.type {
   public class XmlParser {
     ctor public XmlParser();
     method public static simple.type.MultiChoice readMultiChoice(java.io.InputStream) throws javax.xml.datatype.DatatypeConfigurationException, java.io.IOException, org.xmlpull.v1.XmlPullParserException;
+    method public static java.math.BigInteger readPercent(java.io.InputStream) throws javax.xml.datatype.DatatypeConfigurationException, java.io.IOException, org.xmlpull.v1.XmlPullParserException;
     method public static simple.type.SimpleTypes readSimpleTypes(java.io.InputStream) throws javax.xml.datatype.DatatypeConfigurationException, java.io.IOException, org.xmlpull.v1.XmlPullParserException;
     method public static simple.type.SingleChoice readSingleChoice(java.io.InputStream) throws javax.xml.datatype.DatatypeConfigurationException, java.io.IOException, org.xmlpull.v1.XmlPullParserException;
     method public static String readText(org.xmlpull.v1.XmlPullParser) throws java.io.IOException, org.xmlpull.v1.XmlPullParserException;
@@ -55,6 +60,7 @@ package simple.type {
     method public static void write(simple.type.XmlWriter, simple.type.SimpleTypes) throws java.io.IOException;
     method public static void write(simple.type.XmlWriter, simple.type.MultiChoice) throws java.io.IOException;
     method public static void write(simple.type.XmlWriter, simple.type.SingleChoice) throws java.io.IOException;
+    method public static void writePercent(simple.type.XmlWriter, java.math.BigInteger) throws java.io.IOException;
   }
 
 }
diff --git a/tests/resources/simple_type/simple_type.xsd b/tests/resources/simple_type/simple_type.xsd
index 481c476..9bbd283 100644
--- a/tests/resources/simple_type/simple_type.xsd
+++ b/tests/resources/simple_type/simple_type.xsd
@@ -33,8 +33,10 @@
                 <xs:element name="yesOrNo" type="enumType" maxOccurs="2"/>
                 <xs:element name="example1" type="xs:boolean"/>
                 <xs:element name="example2" type="xs:boolean"/>
+                <xs:element name="optional-int-list" maxOccurs="1" type="ints"/>
             </xs:sequence>
             <xs:attribute name="example3" type="xs:boolean"/>
+            <xs:attribute name="value" type="xs:boolean"/>
         </xs:complexType>
     </xs:element>
     <xs:element name="multi-choice">
@@ -55,4 +57,5 @@
             </xs:choice>
         </xs:complexType>
     </xs:element>
+    <xs:element name="percent" type="percent" />
 </xs:schema>
diff --git a/tests/resources/simple_type_root.xml b/tests/resources/simple_type_root.xml
new file mode 100644
index 0000000..a6fed4f
--- /dev/null
+++ b/tests/resources/simple_type_root.xml
@@ -0,0 +1,2 @@
+<?xml version="1.0" encoding="utf-8"?>
+<percent>100</percent>
diff --git a/tests/simple_type.cpp b/tests/simple_type.cpp
index 5162c6d..3f1b2de 100644
--- a/tests/simple_type.cpp
+++ b/tests/simple_type.cpp
@@ -16,6 +16,7 @@
 
 #include <iostream>
 #include <fstream>
+#include <sstream>
 
 #include <android-base/macros.h>
 
@@ -50,3 +51,28 @@ TEST_F(XmlTest, Simpletype) {
   EXPECT_EQ(simple.getYesOrNo()[0], simple2.getYesOrNo()[0]);
   EXPECT_EQ(simple.getYesOrNo()[1], simple2.getYesOrNo()[1]);
 }
+
+TEST_F(XmlTest, Simpletype_AccessingEmptyOptionalAbortsWithMessage) {
+  using namespace simple::type;
+
+  string file_name = Resource("simple_type.xml");
+  SimpleTypes simple = *readSimpleTypes(file_name.c_str());
+
+  // trying to get the value for optional attribute
+  ASSERT_DEATH(simple.isExample3(), "hasExample3()");
+  // trying to get the value for optional element
+  ASSERT_DEATH(simple.getOptionalIntList(), "hasOptionalIntList()");
+  // trying to get the first value from optional element of list of simple values
+  ASSERT_DEATH(simple.getFirstOptionalIntList(), "hasOptionalIntList()");
+}
+
+TEST_F(XmlTest, SimpleTypeRoot) {
+  using namespace simple::type;
+
+  string file_name = Resource("simple_type_root.xml");
+  ASSERT_EQ(*readPercent(file_name.c_str()), 100);
+
+  ostringstream out;
+  writePercent(out, 100);
+  ASSERT_EQ(out.str(), "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n<percent>100</percent>\n");
+}
diff --git a/tests/src/com/android/xsdc/tests/XmlParserTest.java b/tests/src/com/android/xsdc/tests/XmlParserTest.java
index f3b5eaf..bb54099 100644
--- a/tests/src/com/android/xsdc/tests/XmlParserTest.java
+++ b/tests/src/com/android/xsdc/tests/XmlParserTest.java
@@ -248,6 +248,31 @@ public class XmlParserTest {
     }
 
     @Test
+    public void testSimpleTypeRoot() throws Exception {
+        BigInteger percent;
+        try (InputStream str = this.getClass().getClassLoader().getResourceAsStream(
+                "simple_type_root.xml")) {
+            percent = simple.type.XmlParser.readPercent(str);
+        }
+
+        assertThat(percent, is(BigInteger.valueOf(100)));
+
+        String actualStr, expectedStr;
+        try (InputStream str = this.getClass().getClassLoader().getResourceAsStream(
+            "simple_type_root.xml")) {
+            expectedStr = new String(str.readAllBytes());
+        }
+        try (ByteArrayOutputStream baos = new ByteArrayOutputStream()) {
+            try(simple.type.XmlWriter writer = new simple.type.XmlWriter(new PrintWriter(baos))) {
+                simple.type.XmlWriter.writePercent(writer, percent);
+            }
+            actualStr = new String(baos.toByteArray());
+        }
+
+        assertThat(new String(actualStr), is(expectedStr));
+    }
+
+    @Test
     public void testReference() throws Exception {
         reference.Class _class;
         try (InputStream str = this.getClass().getClassLoader().getResourceAsStream(