Let Group be copyable.

Storage is still uncopyable. But I give Storage the ability to
create a default JSON object. Here is an example:

Storage has_JObj; ///< this will create a default JSON object
EXPECT_TRUE(has_JObj.isValid());

Storage has_no_JObj(Storage::Empty); ///< it's waiting for read/open
EXPECT_FALSE(has_JObj.isValid());
has_no_JObj.read("{ }");

include/onnc/JSON/Group.h

@@ -80,10 +80,17 @@ class Group
   typedef GroupIterator iterator;
 
 public:
+  /// default constructor is a Null group.
+  Group();
+
   Group(Storage& pParent, StringRef pName);
 
+  Group(const Group& pOther);
+
   ~Group() { }
 
+  Group& operator=(const Group& pOther);
+
   /// group - Return the sub-group @ref pName.
   /// This function is unsafe. If there is no sub-group named @ref pKey, then
   /// the function behavior is undefined.

include/onnc/JSON/Storage.h

@@ -45,6 +45,14 @@ namespace json {
  *  a parent group. @ref Storage::group and @ref Group::group returns child
  *  group.
  *
+ *  In case that you uses storage as a member variable, you might want the
+ *  storage object is invalid and can postpone open/read calls. You can add
+ *  a dummy integer in the constructor parameter. Here is the example:
+ *  \code
+ *  json::Storage storage(0);
+ *  storage.read("{ }");
+ *  \endcode
+ *
  *  An entry is a key-value pair.
  *  A key must be a string, used to identify an entry. A value can be multiple
  *  types:
@@ -66,10 +74,19 @@ class Storage : private Uncopyable
     kReadWrite ///< Opened, and will write back to JSON file in destructor.
   };
 
+  enum {
+    Empty
+  };
+
 public:
-  /// Default constructor. A invalid storage, because we didn't read any thing.
+  /// Default constructor. It is equivalent to Storage("{ }")
   Storage();
 
+  /// Constructor with dummy integer. This is a invalid storage (not read
+  /// anything).
+  /// This constructor is used to postpone open/read calls.
+  explicit Storage(int);
+
   /// Read the JSON object from string @ref pContent
   /// 
   /// @param[in] pContent The content of a configuration file

lib/Analysis/Statistics.cpp

@@ -21,8 +21,7 @@ using namespace onnc;
 // It is reduced to an adapter of StatisticsPrivate.
 //===----------------------------------------------------------------------===//
 Statistics::Statistics()
-  : json::Storage() {
-  // read nothing
+  : json::Storage(json::Storage::Empty) {
 }
 
 Statistics::Statistics(StringRef pContent)

lib/JSON/Group.cpp

@@ -109,6 +109,10 @@ Group Group::ValueIterator::group()
 //===----------------------------------------------------------------------===//
 // Group
 //===----------------------------------------------------------------------===//
+Group::Group()
+  : m_pObject(&*g_NullObject) {
+}
+
 Group::Group(Storage& pParent, StringRef pName)
   : m_pObject(pParent.group(pName).m_pObject) {
 }
@@ -117,6 +121,16 @@ Group::Group(json::Object& pObject)
   : m_pObject(&pObject) {
 }
 
+Group::Group(const Group& pOther)
+  : m_pObject(pOther.m_pObject) {
+}
+
+Group& Group::operator=(const Group& pOther)
+{
+  m_pObject = pOther.m_pObject;
+  return *this;
+}
+
 Group Group::group(StringRef pName)
 {
   if (hasGroup(pName))

lib/JSON/Storage.cpp

@@ -24,7 +24,11 @@ namespace json {
 //===----------------------------------------------------------------------===//
 Storage::Storage()
   : m_pGroup(NULL), m_AccessMode(kReadOnly), m_FilePath(), m_Value() {
-  // read nothing
+  read("{ }");
+}
+
+Storage::Storage(int)
+  : m_pGroup(NULL), m_AccessMode(kReadOnly), m_FilePath(), m_Value() {
 }
 
 Storage::Storage(StringRef pContent)

tools/unittests/CMakeLists.txt

@@ -32,7 +32,7 @@ add_onnc_test(Any AnyTest.cpp)
 add_onnc_test(BinaryTree BinaryTreeTest.cpp)
 add_onnc_test(StringSwitch StringSwitchTest.cpp)
 add_onnc_test(StringMap StringMapTest.cpp)
-add_onnc_test(Json JsonValueTest.cpp JsonObjectTest.cpp)
+add_onnc_test(Json JsonValueTest.cpp JsonObjectTest.cpp StorageTest.cpp)
 add_onnc_test(ComputeIR ComputeIRTest.cpp)
 add_onnc_test(TensorSel TensorSelTest.cpp)
 add_onnc_test(MemAllocTest MemAllocTest.cpp)

tools/unittests/Makefile.am

@@ -9,6 +9,7 @@ TEST_SOURCES = DigraphTest.cpp \
 	BinaryTreeTest.cpp \
 	StringSwitchTest.cpp \
 	StringMapTest.cpp \
+	StorageTest.cpp \
 	JsonValueTest.cpp \
 	JsonObjectTest.cpp \
 	ComputeIRTest.cpp \

tools/unittests/StorageTest.cpp

@@ -0,0 +1,29 @@
+//===- StorageTest.cpp ----------------------------------------------------===//
+//
+//                             The ONNC Project
+//
+// See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+#include <skypat/skypat.h>
+#include <onnc/JSON/Storage.h>
+#include <onnc/JSON/Group.h>
+#include <onnc/Support/IOStream.h>
+
+using namespace onnc;
+
+//===----------------------------------------------------------------------===//
+// Storage Test
+//===----------------------------------------------------------------------===//
+SKYPAT_F(GroupTest, constructor)
+{
+  json::Group group;
+  EXPECT_TRUE(group.isNull());
+
+  json::Storage storage;
+  json::Group g1 = storage.addGroup("group 1");
+  outs() << storage << std::endl;
+//  group = g1;
+//  EXPECT_FALSE(group.isNull());
+//  EXPECT_TRUE(group.isEmpty());
+}