Add Class.class as an accept data type in TypedOption

pom.xml

@@ -6,7 +6,7 @@
 
     <groupId>com.baidu.hugegraph</groupId>
     <artifactId>hugegraph-common</artifactId>
-    <version>1.8.4</version>
+    <version>1.8.5</version>
 
     <name>hugegraph-common</name>
     <url>https://github.com/hugegraph/hugegraph-common</url>
@@ -266,7 +266,7 @@
                         <manifestEntries>
                             <!-- Must be on one line, otherwise the automatic
                                  upgrade script cannot replace the version number -->
-                            <Implementation-Version>1.8.4.0</Implementation-Version>
+                            <Implementation-Version>1.8.5.0</Implementation-Version>
                         </manifestEntries>
                     </archive>
                 </configuration>

src/main/java/com/baidu/hugegraph/config/ConfigListConvOption.java

@@ -60,7 +60,7 @@ protected boolean forList() {
     }
 
     @Override
-    protected List<T> parse(Object value) {
+    protected List<T> parse(String value) {
         return ConfigListOption.convert(value, part -> {
             return this.parse(part, this.elemClass);
         });

src/main/java/com/baidu/hugegraph/config/ConfigListOption.java

@@ -56,7 +56,7 @@ protected boolean forList() {
     }
 
     @Override
-    protected List<T> parse(Object value) {
+    protected List<T> parse(String value) {
         return convert(value, part -> this.parse(part, this.elemClass));
     }
 

src/main/java/com/baidu/hugegraph/config/HugeConfig.java

@@ -151,7 +151,7 @@ private Object validateOption(String key, Object value) {
                         "Invalid value for key '%s': %s", key, value);
 
         TypedOption<?, ?> option = OptionSpace.get(key);
-        return option.parseConvert(value);
+        return option.parseConvert((String) value);
     }
 
     private void checkRequiredOptions() {

src/main/java/com/baidu/hugegraph/config/TypedOption.java

@@ -50,6 +50,7 @@ public class TypedOption<T, R> {
                 Double.class,
                 String.class,
                 String[].class,
+                Class.class,
                 List.class
         );
 
@@ -112,20 +113,27 @@ public R defaultValue() {
         return this.convert(this.defaultValue);
     }
 
-    public R parseConvert(Object value) {
+    public R parseConvert(String value) {
         T parsed = this.parse(value);
         this.check(parsed);
         return this.convert(parsed);
     }
 
     @SuppressWarnings("unchecked")
-    protected T parse(Object value) {
+    protected T parse(String value) {
         return (T) this.parse(value, this.dataType);
     }
 
-    protected Object parse(Object value, Class<?> dataType) {
+    protected Object parse(String value, Class<?> dataType) {
         if (dataType.equals(String.class)) {
             return value;
+        } else if (dataType.equals(Class.class)) {
+            try {
+                return Class.forName(value);
+            } catch (ClassNotFoundException e) {
+                throw new ConfigException(
+                          "Failed to parse Class from String '%s'", e, value);
+            }
         } else if (List.class.isAssignableFrom(dataType)) {
             E.checkState(this.forList(),
                          "List option can't be registered with class %s",

src/main/java/com/baidu/hugegraph/version/CommonVersion.java

@@ -27,5 +27,5 @@ public class CommonVersion {
 
     // The second parameter of Version.of() is for all-in-one JAR
     public static final Version VERSION = Version.of(CommonVersion.class,
-                                                     "1.8.4");
+                                                     "1.8.5");
 }

src/test/java/com/baidu/hugegraph/unit/config/HugeConfigTest.java

@@ -75,6 +75,8 @@ public void testOptionDataType() {
         Assert.assertEquals(Double.class, TestOptions.double1.dataType());
         Assert.assertEquals(Boolean.class, TestOptions.bool.dataType());
 
+        Assert.assertEquals(Class.class, TestOptions.clazz.dataType());
+
         Assert.assertEquals(List.class, TestOptions.list.dataType());
         Assert.assertEquals(List.class, TestOptions.map.dataType());
 
@@ -110,6 +112,8 @@ public void testOptionsToString() {
                             TestOptions.double1.toString());
         Assert.assertEquals("[Boolean]group1.bool=true",
                             TestOptions.bool.toString());
+        Assert.assertEquals("[Class]group1.class=class java.lang.Object",
+                            TestOptions.clazz.toString());
         Assert.assertEquals("[List]group1.list=[list-value1, list-value2]",
                             TestOptions.list.toString());
         Assert.assertEquals("[List]group1.map=[key1:value1, key2:value2]",
@@ -208,6 +212,15 @@ public void testOptionWithError() {
             );
         });
 
+        Assert.assertThrows(ConfigException.class, () -> {
+            new ConfigOption<>(
+                    "group1.class",
+                    "description of group1.class",
+                    input -> input != null && input.equals(Long.class),
+                    Integer.class
+            );
+        });
+
         Assert.assertThrows(ConfigException.class, () -> {
             new ConfigListOption<>(
                     "group1.list",
@@ -265,6 +278,14 @@ public void testHugeConfig() throws Exception {
 
         Assert.assertEquals(true, config.get(TestOptions.bool));
 
+        Assert.assertEquals(Object.class, config.get(TestOptions.clazz));
+        Assert.assertThrows(ConfigException.class, () -> {
+            config.setProperty(TestOptions.clazz.name(),
+                               "com.baidu.hugegraph.HugeGraph");
+        }, e -> {
+            Assert.assertTrue(e.getCause() instanceof ClassNotFoundException);
+        });
+
         Assert.assertEquals(Arrays.asList("list-value1", "list-value2"),
                             config.get(TestOptions.list));
 
@@ -299,6 +320,8 @@ public void testHugeConfigWithFile() throws Exception {
 
         Assert.assertEquals(false, config.get(TestOptions.bool));
 
+        Assert.assertEquals(String.class, config.get(TestOptions.clazz));
+
         Assert.assertEquals(Arrays.asList("file-v1", "file-v2", "file-v3"),
                             config.get(TestOptions.list));
 
@@ -477,6 +500,14 @@ public static synchronized TestOptions instance() {
                         true
                 );
 
+        public static final ConfigOption<Class<?>> clazz =
+                new ConfigOption<>(
+                        "group1.class",
+                        "description of group1.class",
+                        disallowEmpty(),
+                        Object.class
+                );
+
         public static final ConfigConvOption<String, WeekDay> weekday =
                 new ConfigConvOption<>(
                         "group1.weekday",

src/test/java/com/baidu/hugegraph/unit/config/test.conf

@@ -12,6 +12,8 @@ group1.double1=66
 
 group1.bool=false
 
+group1.class=java.lang.String
+
 group1.list=[file-v1, file-v2, file-v3]
 group1.map=[key1:value1, key3:value3]