add a new method to insert a new value in an array at specific index.

include/json/value.h

@@ -464,6 +464,9 @@ Json::Value obj_value(Json::objectValue); // {}
   /// Equivalent to jsonvalue[jsonvalue.size()] = value;
   Value& append(const Value& value);
   Value& append(Value&& value);
+  /// \brief Insert value in array at specific index
+  bool insert(ArrayIndex index, const Value& newValue);
+  bool insert(ArrayIndex index, Value&& newValue);
 
   /// Access an object value by name, create a null member if it does not exist.
   /// \note Because of our implementation, keys are limited to 2^30 -1 chars.

src/lib_json/json_value.cpp

@@ -1168,13 +1168,35 @@ Value const& Value::operator[](CppTL::ConstString const& key) const {
   return *found;
 }
 #endif
-
 Value& Value::append(const Value& value) { return (*this)[size()] = value; }
 
 Value& Value::append(Value&& value) {
   return (*this)[size()] = std::move(value);
 }
 
+/// \brief Insert value in array at specific index
+bool Value::insert(ArrayIndex index, const Value& newValue) {
+  JSON_ASSERT_MESSAGE(type() == nullValue || type() == arrayValue,
+                      "in Json::Value::insert(ArrayIndex index, const Value& "
+                      "newValue): requires arrayValue");
+  return insert(index, Value(newValue));
+}
+bool Value::insert(ArrayIndex index, Value&& newValue) {
+  JSON_ASSERT_MESSAGE(type() == nullValue || type() == arrayValue,
+                      "in Json::Value::insert(ArrayIndex index, Value&& "
+                      "newValue): requires arrayValue");
+  ArrayIndex length = size();
+  if (index > length) {
+    append(std::move(newValue));
+    return true;
+  } else {
+    for (ArrayIndex i = length; i > index; i--) {
+      (*this)[i] = std::move((*this)[i - 1]);
+    }
+    (*this)[index] = std::move(newValue);
+    return true;
+  }
+}
 Value Value::get(char const* begin,
                  char const* end,
                  Value const& defaultValue) const {
@@ -1436,8 +1458,7 @@ bool Value::isObject() const { return type() == objectValue; }
 Value::Comments::Comments(const Comments& that)
     : ptr_{cloneUnique(that.ptr_)} {}
 
-Value::Comments::Comments(Comments&& that)
-    : ptr_{std::move(that.ptr_)} {}
+Value::Comments::Comments(Comments&& that) : ptr_{std::move(that.ptr_)} {}
 
 Value::Comments& Value::Comments::operator=(const Comments& that) {
   ptr_ = cloneUnique(that.ptr_);

src/test_lib_json/jsontest.cpp

@@ -378,8 +378,8 @@ void Runner::preventDialogOnCrash() {
   _CrtSetReportHook(&msvcrtSilentReportHook);
 #endif // if defined(_MSC_VER)
 
-  // @todo investigate this handler (for buffer overflow)
-  // _set_security_error_handler
+// @todo investigate this handler (for buffer overflow)
+// _set_security_error_handler
 
 #if defined(_WIN32)
   // Prevents the system from popping a dialog for debugging if the

src/test_lib_json/main.cpp

@@ -211,14 +211,17 @@ JSONTEST_FIXTURE(ValueTest, objects) {
   JSONTEST_ASSERT_EQUAL(Json::Value(1234), *foundId);
 
   const char unknownIdKey[] = "unknown id";
-  const Json::Value* foundUnknownId = object1_.find(unknownIdKey, unknownIdKey + strlen(unknownIdKey));
+  const Json::Value* foundUnknownId =
+      object1_.find(unknownIdKey, unknownIdKey + strlen(unknownIdKey));
   JSONTEST_ASSERT_EQUAL(nullptr, foundUnknownId);
 
   // Access through demand()
   const char yetAnotherIdKey[] = "yet another id";
-  const Json::Value* foundYetAnotherId = object1_.find(yetAnotherIdKey, yetAnotherIdKey + strlen(yetAnotherIdKey));
+  const Json::Value* foundYetAnotherId =
+      object1_.find(yetAnotherIdKey, yetAnotherIdKey + strlen(yetAnotherIdKey));
   JSONTEST_ASSERT_EQUAL(nullptr, foundYetAnotherId);
-  Json::Value* demandedYetAnotherId = object1_.demand(yetAnotherIdKey, yetAnotherIdKey + strlen(yetAnotherIdKey));
+  Json::Value* demandedYetAnotherId = object1_.demand(
+      yetAnotherIdKey, yetAnotherIdKey + strlen(yetAnotherIdKey));
   JSONTEST_ASSERT(demandedYetAnotherId != nullptr);
   *demandedYetAnotherId = "baz";
 
@@ -308,6 +311,72 @@ JSONTEST_FIXTURE(ValueTest, arrayIssue252) {
   // JSONTEST_ASSERT_EQUAL(5, root["array"].size());
 }
 
+JSONTEST_FIXTURE(ValueTest, arrayInsertAtRandomIndex) {
+  Json::Value array;
+  Json::Value str0("index2");
+  Json::Value str1("index3");
+  array.append("index0"); // append rvalue
+  array.append("index1");
+  array.append(str0); // append lvalue
+
+  std::vector<Json::Value*> vec; // storage value address for checking
+  for (int i = 0; i < 3; i++) {
+    vec.push_back(&array[i]);
+  }
+  JSONTEST_ASSERT_EQUAL(Json::Value("index0"), array[0]); // check append
+  JSONTEST_ASSERT_EQUAL(Json::Value("index1"), array[1]);
+  JSONTEST_ASSERT_EQUAL(Json::Value("index2"), array[2]);
+
+  // insert lvalue at the head
+  array.insert(0, str1);
+  JSONTEST_ASSERT_EQUAL(Json::Value("index3"), array[0]);
+  JSONTEST_ASSERT_EQUAL(Json::Value("index0"), array[1]);
+  JSONTEST_ASSERT_EQUAL(Json::Value("index1"), array[2]);
+  JSONTEST_ASSERT_EQUAL(Json::Value("index2"), array[3]);
+  // checking address
+  for (int i = 0; i < 3; i++) {
+    JSONTEST_ASSERT_EQUAL(vec[i], &array[i]);
+  }
+  vec.push_back(&array[3]);
+  // insert rvalue at middle
+  array.insert(2, "index4");
+  JSONTEST_ASSERT_EQUAL(Json::Value("index3"), array[0]);
+  JSONTEST_ASSERT_EQUAL(Json::Value("index0"), array[1]);
+  JSONTEST_ASSERT_EQUAL(Json::Value("index4"), array[2]);
+  JSONTEST_ASSERT_EQUAL(Json::Value("index1"), array[3]);
+  JSONTEST_ASSERT_EQUAL(Json::Value("index2"), array[4]);
+  // checking address
+  for (int i = 0; i < 4; i++) {
+    JSONTEST_ASSERT_EQUAL(vec[i], &array[i]);
+  }
+  vec.push_back(&array[4]);
+  // insert rvalue at the tail
+  array.insert(5, "index5");
+  JSONTEST_ASSERT_EQUAL(Json::Value("index3"), array[0]);
+  JSONTEST_ASSERT_EQUAL(Json::Value("index0"), array[1]);
+  JSONTEST_ASSERT_EQUAL(Json::Value("index4"), array[2]);
+  JSONTEST_ASSERT_EQUAL(Json::Value("index1"), array[3]);
+  JSONTEST_ASSERT_EQUAL(Json::Value("index2"), array[4]);
+  JSONTEST_ASSERT_EQUAL(Json::Value("index5"), array[5]);
+  // checking address
+  for (int i = 0; i < 5; i++) {
+    JSONTEST_ASSERT_EQUAL(vec[i], &array[i]);
+  }
+  vec.push_back(&array[5]);
+  // beyond max array size, it should be allowed to insert into its tail
+  array.insert(10, "index10");
+  JSONTEST_ASSERT_EQUAL(Json::Value("index3"), array[0]);
+  JSONTEST_ASSERT_EQUAL(Json::Value("index0"), array[1]);
+  JSONTEST_ASSERT_EQUAL(Json::Value("index4"), array[2]);
+  JSONTEST_ASSERT_EQUAL(Json::Value("index1"), array[3]);
+  JSONTEST_ASSERT_EQUAL(Json::Value("index2"), array[4]);
+  JSONTEST_ASSERT_EQUAL(Json::Value("index5"), array[5]);
+  JSONTEST_ASSERT_EQUAL(Json::Value("index10"), array[6]);
+  // checking address
+  for (int i = 0; i < 6; i++) {
+    JSONTEST_ASSERT_EQUAL(vec[i], &array[i]);
+  }
+}
 JSONTEST_FIXTURE(ValueTest, null) {
   JSONTEST_ASSERT_EQUAL(Json::nullValue, null_.type());
 
@@ -2535,6 +2604,7 @@ int main(int argc, const char* argv[]) {
   JSONTEST_REGISTER_FIXTURE(runner, ValueTest, objects);
   JSONTEST_REGISTER_FIXTURE(runner, ValueTest, arrays);
   JSONTEST_REGISTER_FIXTURE(runner, ValueTest, arrayIssue252);
+  JSONTEST_REGISTER_FIXTURE(runner, ValueTest, arrayInsertAtRandomIndex);
   JSONTEST_REGISTER_FIXTURE(runner, ValueTest, null);
   JSONTEST_REGISTER_FIXTURE(runner, ValueTest, strings);
   JSONTEST_REGISTER_FIXTURE(runner, ValueTest, bools);