Reflection is a powerful programming feature that enables a program to examine and modify its own structure and behavior at runtime. In the context of C++, reflection is not a built-in feature, but it can be emulated using techniques such as template metaprogramming.
Jsonifier leverages reflection to dynamically parse JSON data into C++ structures without requiring excessive explicit manual parsing code for each structure. This allows for more flexible and maintainable code, as changes to the structure do not necessitate corresponding changes to the parsing logic.
Consider the following usage example:
// Define the structure to be registered
struct available_tag {
jsonifier::string name;
bool moderated;
int32_t id;
};
// Register the structure using reflection
template<> struct jsonifier::core<available_tag> {
using value_type = available_tag;
constexpr decltype(auto) parseValue = createValue<&value_type::name, &value_type::moderated, &value_type::id>();
};
// Define JSON data and the structure instance
jsonifier::string testData{};
available_tag tagsTest{};
jsonifier::jsonifier_core parser{};
// Parse JSON data to populate the structure
parser.parseJson(tagsTest, testData);
In this example:
- We define a structure named
available_tag
with membersname
,moderated
, andid
. - We then specialize the
jsonifier::core
template for this structure, providing reflection capabilities to parse JSON data into the structure. - Finally, we demonstrate how to parse JSON data into an instance of
available_tag
using thejsonifier_core
instance'sparseJson
method.
Define the structure you want to register with Jsonifier, ensuring it contains the necessary members.
struct available_tag {
jsonifier::string name;
bool moderated;
int32_t id;
};
Specialize the jsonifier::core
template for the structure, providing the necessary reflection information for parsing.
template<> struct jsonifier::core<available_tag> {
using value_type = available_tag;
constexpr decltype(auto) parseValue = createValue<&value_type::name, &value_type::moderated, &value_type::id>();
};
Instantiate a jsonifier_core
object and use its parseJson
method to populate the structure from JSON data.
jsonifier::string testData{};
available_tag tagsTest{};
jsonifier::jsonifier_core parser{};
parser.parseJson(tagsTest, testData);
This completes the process of registering a structure using reflection with Jsonifier and parsing JSON data into the structure. Reflection empowers Jsonifier to dynamically adapt to changes in structure, enhancing code flexibility and maintainability.