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Integrated compile time type checking and error detection for data structure parsing. #12

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a1a80f7
Integrated compile type checking for JSON structure data extraction.
nathan-disguise Jul 7, 2026
f2caa8a
Added missing source file.
nathan-disguise Jul 7, 2026
e757fb2
Added missing template entries.
nathan-disguise Jul 7, 2026
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2 changes: 1 addition & 1 deletion CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,7 @@ set (

src/OpenTrackIOProperties.cpp
src/OpenTrackIOSample.cpp
src/OpenTrackIOTypes.cpp
)

list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake")
Expand Down Expand Up @@ -78,7 +79,6 @@ target_include_directories(
PUBLIC
$<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
$<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>

)

target_link_libraries(${PROJECT_NAME} PUBLIC nlohmann_json::nlohmann_json)
Expand Down
126 changes: 107 additions & 19 deletions include/opentrackio-cpp/OpenTrackIOHelper.h
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Original file line number Diff line number Diff line change
Expand Up @@ -14,8 +14,16 @@
#pragma once
#include <format>
#include <regex>
#include <string>
#include <type_traits>
#include <nlohmann/json.hpp>

#define TYPE_COVERSION_ASSERT(JsonConcept, CppType) \
static_assert(JsonConcept<CppType>, "Type is not compatible!");

#define TYPE_NON_COVERSION_ASSERT(JsonConcept, CppType) \
static_assert(!JsonConcept<CppType>, "Type is unexpectedly compatible!");

namespace opentrackio
{
template<typename T>
Expand All @@ -32,6 +40,36 @@ namespace opentrackio
{ t.iris } -> std::convertible_to<std::optional<uint16_t>>;
{ t.zoom } -> std::convertible_to<std::optional<uint16_t>>;
};

template<typename T>
concept JsonBool = std::is_same_v<T, bool>;
template<typename T>
concept JsonString = std::is_same_v<T, std::string>;
template<typename T>
concept JsonNumber = std::is_integral_v<T> && !JsonBool<T>;
template<typename T>
concept JsonFloatDouble = std::is_floating_point_v<T> && !JsonNumber<T>;

// Basic type conversion checks to ensure compatability with json library.
TYPE_COVERSION_ASSERT(JsonBool, bool);
TYPE_NON_COVERSION_ASSERT(JsonBool, int);
TYPE_NON_COVERSION_ASSERT(JsonBool, short);
TYPE_NON_COVERSION_ASSERT(JsonBool, long);

TYPE_COVERSION_ASSERT(JsonString, std::string);
TYPE_NON_COVERSION_ASSERT(JsonString, const char*);

TYPE_COVERSION_ASSERT(JsonNumber, int);
TYPE_COVERSION_ASSERT(JsonNumber, long);
TYPE_COVERSION_ASSERT(JsonNumber, short);
TYPE_NON_COVERSION_ASSERT(JsonNumber, float);
TYPE_NON_COVERSION_ASSERT(JsonNumber, double);

TYPE_COVERSION_ASSERT(JsonFloatDouble, float);
TYPE_COVERSION_ASSERT(JsonFloatDouble, double);
TYPE_NON_COVERSION_ASSERT(JsonFloatDouble, int);
TYPE_NON_COVERSION_ASSERT(JsonFloatDouble, long);
TYPE_NON_COVERSION_ASSERT(JsonFloatDouble, short);

class OpenTrackIOHelpers
{
Expand Down Expand Up @@ -83,18 +121,44 @@ namespace opentrackio

template<typename T>
static void assignField(nlohmann::json &json, std::string_view fieldStr, std::optional<T> &field,
std::string_view typeStr, std::vector<std::string> &errors)
std::vector<std::string> &errors)
{
if (json.contains(fieldStr))
{
if (!checkJsonTypeMatch<T>(json[fieldStr], fieldStr, errors))
return;

getFieldFromJson(json[fieldStr], field);
json.erase(fieldStr);
}
}

template<typename T>
static void assignFieldArray(nlohmann::json& json, std::string_view fieldStr, std::optional<std::vector<T>>& field,
std::vector<std::string>& errors)
{
if (json.contains(fieldStr))
{
if (!json[fieldStr].is_array())
{
errors.emplace_back(std::format("field: {0} isn't an array:", fieldStr));
return;
}

for (const auto& jsonValue : json[fieldStr])
{
if (!checkJsonTypeMatch<T>(jsonValue, fieldStr, errors))
return;
}

getFieldFromJson(json[fieldStr], field);
json.erase(fieldStr);
}
}

template<Encoder T>
static void assignField(nlohmann::json &json, std::string_view fieldStr, std::optional<T> &field,
std::string_view typeStr, std::vector<std::string> &errors)
std::vector<std::string> &errors)
{
if (!json.contains(fieldStr))
{
Expand All @@ -104,9 +168,9 @@ namespace opentrackio

field = T{};
auto &encoderJson = json[fieldStr];
assignField(encoderJson, "focus", field->focus, typeStr, errors);
assignField(encoderJson, "iris", field->iris, typeStr, errors);
assignField(encoderJson, "zoom", field->zoom, typeStr, errors);
assignField(encoderJson, "focus", field->focus, errors);
assignField(encoderJson, "iris", field->iris, errors);
assignField(encoderJson, "zoom", field->zoom, errors);

if (!(field->focus.has_value() && field->iris.has_value() && field->zoom.has_value()))
{
Expand Down Expand Up @@ -140,23 +204,47 @@ namespace opentrackio
json.erase(fieldStr);
}
}
};

template<>
inline void OpenTrackIOHelpers::assignField<std::vector<std::string>>(nlohmann::json &json, std::string_view fieldStr,
std::optional<std::vector<std::string>> &field,
std::string_view typeStr, std::vector<std::string> &errors)
{
if (!json.contains(fieldStr) || !json[fieldStr].is_array())
static inline void assignStringArray(nlohmann::json& json, std::string_view fieldStr,
std::optional<std::vector<std::string>>& field,
std::vector<std::string>& errors)
{
field = std::nullopt;
return;
if (!json.contains(fieldStr) || !json[fieldStr].is_array())
{
field = std::nullopt;
return;
}

std::vector<std::string> vec{};
iterateJsonArrayAndPopulateVector<std::string>(json[fieldStr], vec);

field = std::move(vec);
json.erase(fieldStr);
}

std::vector<std::string> vec{};
iterateJsonArrayAndPopulateVector(json[fieldStr], vec);
private:
template<typename FieldT>
static inline constexpr nlohmann::json::value_t getJsonTypeValue()
requires JsonBool<FieldT> || JsonFloatDouble<FieldT> || JsonNumber<FieldT> || JsonString<FieldT>
{
if constexpr (JsonString<FieldT>) { return nlohmann::json::value_t::string; }
else if constexpr (JsonBool<FieldT>) { return nlohmann::json::value_t::boolean; }
else if constexpr (JsonFloatDouble<FieldT>) { return nlohmann::json::value_t::number_float; }
else if constexpr (JsonNumber<FieldT>) { return nlohmann::json::value_t::number_unsigned; }
}

template<typename FieldT>
static inline bool constexpr checkJsonTypeMatch(const nlohmann::json& json, const std::string_view& fieldStr, std::vector<std::string>& errors)
{
nlohmann::json::value_t cppToJsonType = getJsonTypeValue<FieldT>();
if (json.type() != cppToJsonType)
{
errors.emplace_back(std::format("field: {0} of type {1} isn't compatible with {2}.", fieldStr, json.type_name(), typeid(FieldT).name()));
return false;
}

return true;
}

field = std::move(vec);
json.erase(fieldStr);
}
};
} // namespace opentrackio
4 changes: 2 additions & 2 deletions include/opentrackio-cpp/OpenTrackIOProperties.h
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Original file line number Diff line number Diff line change
Expand Up @@ -315,8 +315,8 @@ namespace opentrackio::opentrackioproperties
struct SourceNumber
{
/**
* Number that identifies the index of the stream from a source from which data is being transported.
* This is most important in the case where a source is producing multiple streams of samples. */
* Number that identifies the index of the stream from a source from which data is being transported.
* This is most important in the case where a source is producing multiple streams of samples. */
Comment on lines +318 to +319

@nathan-disguise nathan-disguise Jul 7, 2026

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Suggested change
* Number that identifies the index of the stream from a source from which data is being transported.
* This is most important in the case where a source is producing multiple streams of samples. */
* Number that identifies the index of the stream from a source from which data is being transported.
* This is most important in the case where a source is producing multiple streams of samples. */

uint32_t value;

static std::optional<SourceNumber> parse(nlohmann::json& json, std::vector<std::string>& errors);
Expand Down
7 changes: 4 additions & 3 deletions include/opentrackio-cpp/OpenTrackIOSample.h
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Original file line number Diff line number Diff line change
Expand Up @@ -38,10 +38,11 @@ namespace opentrackio
bool initialise(const nlohmann::json& json);
bool initialise(const std::string_view jsonString);
bool initialise(std::span<const uint8_t> cbor);
const std::vector<std::string>& getErrors() { return m_errorMessages; };
const std::vector<std::string>& getWarnings() { return m_warningMessages; };

const std::vector<std::string>& getErrors() const { return m_errorMessages; };
const std::vector<std::string>& getWarnings() const { return m_warningMessages; };
const nlohmann::json& getJson();

private:
void generateJson();
void parseCameraToJson(nlohmann::json& baseJson);
Expand Down
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