diff options
Diffstat (limited to 'lib/converters.h')
| -rw-r--r-- | lib/converters.h | 126 |
1 files changed, 59 insertions, 67 deletions
diff --git a/lib/converters.h b/lib/converters.h index 84fab798..90349019 100644 --- a/lib/converters.h +++ b/lib/converters.h @@ -24,6 +24,21 @@ struct JsonObjectConverter { static void fillFrom(const QJsonObject& jo, T& pod) { pod = T(jo); } }; +//! \brief The switchboard for extra conversion algorithms behind from/toJson +//! +//! This template is mainly intended for partial conversion specialisations +//! since from/toJson are functions and cannot be partially specialised; +//! another case for JsonConverter is to insulate types that can be constructed +//! from basic types - namely, QVariant and QUrl can be directly constructed +//! from QString and having an overload or specialisation for those leads to +//! ambiguity between these and QJsonValue. For trivial (converting +//! QJsonObject/QJsonValue) and most simple cases such as primitive types or +//! QString this class is not needed. +//! +//! Do NOT call the functions of this class directly unless you know what you're +//! doing; and do not try to specialise basic things unless you're really sure +//! that they are not supported and it's not feasible to support those by means +//! of overloading toJson() and specialising fromJson(). template <typename T> struct JsonConverter { static QJsonObject dump(const T& pod) @@ -42,13 +57,17 @@ struct JsonConverter { static T load(const QJsonDocument& jd) { return doLoad(jd.object()); } }; -template <typename T> +template <typename T, + typename = std::enable_if_t<!std::is_constructible_v<QJsonValue, T>>> inline auto toJson(const T& pod) +// -> can return anything from which QJsonValue or, in some cases, QJsonDocument +// is constructible { return JsonConverter<T>::dump(pod); } inline auto toJson(const QJsonObject& jo) { return jo; } +inline auto toJson(const QJsonValue& jv) { return jv; } template <typename T> inline void fillJson(QJsonObject& json, const T& data) @@ -98,80 +117,64 @@ inline void fillFromJson(const QJsonValue& jv, T& pod) // JsonConverter<> specialisations -template <typename T> -struct TrivialJsonDumper { - // Works for: QJsonValue (and all things it can consume), - // QJsonObject, QJsonArray - static auto dump(const T& val) { return val; } -}; +template<> +inline bool fromJson(const QJsonValue& jv) { return jv.toBool(); } template <> -struct JsonConverter<bool> : public TrivialJsonDumper<bool> { - static auto load(const QJsonValue& jv) { return jv.toBool(); } -}; +inline int fromJson(const QJsonValue& jv) { return jv.toInt(); } template <> -struct JsonConverter<int> : public TrivialJsonDumper<int> { - static auto load(const QJsonValue& jv) { return jv.toInt(); } -}; +inline double fromJson(const QJsonValue& jv) { return jv.toDouble(); } template <> -struct JsonConverter<double> : public TrivialJsonDumper<double> { - static auto load(const QJsonValue& jv) { return jv.toDouble(); } -}; +inline float fromJson(const QJsonValue& jv) { return float(jv.toDouble()); } template <> -struct JsonConverter<float> : public TrivialJsonDumper<float> { - static auto load(const QJsonValue& jv) { return float(jv.toDouble()); } -}; +inline qint64 fromJson(const QJsonValue& jv) { return qint64(jv.toDouble()); } template <> -struct JsonConverter<qint64> : public TrivialJsonDumper<qint64> { - static auto load(const QJsonValue& jv) { return qint64(jv.toDouble()); } -}; +inline QString fromJson(const QJsonValue& jv) { return jv.toString(); } template <> -struct JsonConverter<QString> : public TrivialJsonDumper<QString> { - static auto load(const QJsonValue& jv) { return jv.toString(); } -}; +inline QJsonArray fromJson(const QJsonValue& jv) { return jv.toArray(); } template <> -struct JsonConverter<QDateTime> { - static auto dump(const QDateTime& val) - { - return val.isValid() ? val.toMSecsSinceEpoch() : QJsonValue(); - } - static auto load(const QJsonValue& jv) - { - return QDateTime::fromMSecsSinceEpoch(fromJson<qint64>(jv), Qt::UTC); - } -}; +inline QJsonArray fromJson(const QJsonDocument& jd) { return jd.array(); } +inline QJsonValue toJson(const QDateTime& val) +{ + return val.isValid() ? val.toMSecsSinceEpoch() : QJsonValue(); +} template <> -struct JsonConverter<QDate> { - static auto dump(const QDate& val) { - return toJson( +inline QDateTime fromJson(const QJsonValue& jv) +{ + return QDateTime::fromMSecsSinceEpoch(fromJson<qint64>(jv), Qt::UTC); +} + +inline QJsonValue toJson(const QDate& val) { + return toJson( #if QT_VERSION < QT_VERSION_CHECK(5, 14, 0) - QDateTime(val) + QDateTime(val) #else - val.startOfDay() + val.startOfDay() #endif - ); - } - static auto load(const QJsonValue& jv) - { - return fromJson<QDateTime>(jv).date(); - } -}; + ); +} +template <> +inline QDate fromJson(const QJsonValue& jv) +{ + return fromJson<QDateTime>(jv).date(); +} + +// Insulate QVariant and QUrl conversions into JsonConverter so that they don't +// interfere with toJson(const QJsonValue&) over QString, since both types are +// constructible from QString (even if QUrl requires explicit construction). template <> struct JsonConverter<QUrl> { static auto load(const QJsonValue& jv) { - // QT_NO_URL_CAST_FROM_STRING makes this a bit more verbose - QUrl url; - url.setUrl(jv.toString()); - return url; + return QUrl(jv.toString()); } static auto dump(const QUrl& url) { @@ -180,11 +183,6 @@ struct JsonConverter<QUrl> { }; template <> -struct JsonConverter<QJsonArray> : public TrivialJsonDumper<QJsonArray> { - static auto load(const QJsonValue& jv) { return jv.toArray(); } -}; - -template <> struct JsonConverter<QVariant> { static QJsonValue dump(const QVariant& v); static QVariant load(const QJsonValue& jv); @@ -206,15 +204,11 @@ struct JsonConverter<Omittable<T>> { template <typename VectorT, typename T = typename VectorT::value_type> struct JsonArrayConverter { - static void dumpTo(QJsonArray& ar, const VectorT& vals) - { - for (const auto& v : vals) - ar.push_back(toJson(v)); - } static auto dump(const VectorT& vals) { QJsonArray ja; - dumpTo(ja, vals); + for (const auto& v : vals) + ja.push_back(toJson(v)); return ja; } static auto load(const QJsonArray& ja) @@ -254,7 +248,7 @@ struct JsonObjectConverter<QSet<QString>> { static void dumpTo(QJsonObject& json, const QSet<QString>& s) { for (const auto& e : s) - json.insert(toJson(e), QJsonObject {}); + json.insert(e, QJsonObject {}); } static void fillFrom(const QJsonObject& json, QSet<QString>& s) { @@ -287,11 +281,9 @@ template <typename T> struct JsonObjectConverter<QHash<QString, T>> : public HashMapFromJson<QHash<QString, T>> {}; +QJsonObject toJson(const QVariantHash& vh); template <> -struct JsonConverter<QVariantHash> { - static QJsonObject dump(const QVariantHash& vh); - static QVariantHash load(const QJsonValue& jv); -}; +QVariantHash fromJson(const QJsonValue& jv); // Conditional insertion into a QJsonObject |