X-Git-Url: https://git.quassel-irc.org/?a=blobdiff_plain;f=src%2Fcommon%2Ffunchelpers.h;h=f1524ddbc2cc306929376b8dfe8633e24c6f56c6;hb=e868433618defabcbdc078745e6d19dd9573c005;hp=c56cdb94e0b7b51f1eac8f530edbbd6ae5378287;hpb=03ee70025a98912c163155955fe3cc3045f629b9;p=quassel.git

diff --git a/src/common/funchelpers.h b/src/common/funchelpers.h
index c56cdb94..f1524ddb 100644
--- a/src/common/funchelpers.h
+++ b/src/common/funchelpers.h
@@ -20,8 +20,19 @@
 
 #pragma once
 
+#include <array>
 #include <functional>
 #include <tuple>
+#include <type_traits>
+#include <utility>
+
+#include <boost/optional.hpp>
+
+#include <QDebug>
+#include <QVariant>
+#include <QVariantList>
+
+// ---- Function traits --------------------------------------------------------------------------------------------------------------------
 
 namespace detail {
 
@@ -62,3 +73,96 @@ struct FuncHelper<R(C::*)(Args...) const> : public FuncHelper<R(C::*)(Args...)>
  */
 template<typename Callable>
 using FunctionTraits = detail::FuncHelper<Callable>;
+
+// ---- Invoke function with argument list -------------------------------------------------------------------------------------------------
+
+namespace detail {
+
+// Helper for invoking the callable, wrapping its return value in a QVariant (default-constructed if callable returns void).
+// The correct overload is selected via SFINAE.
+template<typename Callable, typename ...Args>
+auto invokeWithArgs(const Callable& c, Args&&... args)
+    -> std::enable_if_t<std::is_void<typename FunctionTraits<Callable>::ReturnType>::value, QVariant>
+{
+    c(std::forward<Args>(args)...);
+    return QVariant{};
+}
+
+template<typename Callable, typename ...Args>
+auto invokeWithArgs(const Callable& c, Args&&... args)
+    -> std::enable_if_t<!std::is_void<typename FunctionTraits<Callable>::ReturnType>::value, QVariant>
+{
+    return QVariant::fromValue(c(std::forward<Args>(args)...));
+}
+
+// Helper for unpacking the argument list via an index sequence
+template<typename Callable, std::size_t ...Is, typename ArgsTuple = typename FunctionTraits<Callable>::ArgsTuple>
+boost::optional<QVariant> invokeWithArgsList(const Callable& c, const QVariantList& args, std::index_sequence<Is...>)
+{
+    // Sanity check that all types can be converted
+    std::array<bool, std::tuple_size<ArgsTuple>::value> convertible{{args[Is].canConvert<std::decay_t<std::tuple_element_t<Is, ArgsTuple>>>()...}};
+    for (size_t i = 0; i < convertible.size(); ++i) {
+        if (!convertible[i]) {
+            qWarning() << "Cannot convert parameter" << i << "from type" << args[static_cast<int>(i)].typeName() << "to expected argument type";
+            return boost::none;
+        }
+    }
+
+    // Invoke callable with unmarshalled arguments
+    return invokeWithArgs(c, args[Is].value<std::decay_t<std::tuple_element_t<Is, ArgsTuple>>>()...);
+}
+
+}  // detail
+
+/**
+ * Invokes the given callable with the arguments contained in the given variant list.
+ *
+ * The types contained in the given QVariantList are converted to the types expected by the callable.
+ * If the invocation is successful, the returned optional contains a QVariant with the return value,
+ * or an invalid QVariant if the callable returns void.
+ * If the conversion fails, or if the argument count does not match, this function returns boost::none
+ * and the callable is not invoked.
+ *
+ * @param c    Callable
+ * @param args Arguments to be given to the callable
+ * @returns An optional containing a QVariant with the return value if the callable could be invoked with
+ *          the given list of arguments; otherwise boost::none
+ */
+template<typename Callable>
+boost::optional<QVariant> invokeWithArgsList(const Callable& c, const QVariantList& args)
+{
+    using ArgsTuple = typename FunctionTraits<Callable>::ArgsTuple;
+    constexpr auto tupleSize = std::tuple_size<ArgsTuple>::value;
+
+    if (tupleSize != args.size()) {
+        qWarning().nospace() << "Argument count mismatch! Expected: " << tupleSize << ", actual: " << args.size();
+        return boost::none;
+    }
+    return detail::invokeWithArgsList(c, args, std::make_index_sequence<tupleSize>{});
+}
+
+/**
+ * Invokes the given member function pointer on the given object with the arguments contained in the given variant list.
+ *
+ * The types contained in the given QVariantList are converted to the types expected by the member function.
+ * If the invocation is successful, the returned optional contains a QVariant with the return value,
+ * or an invalid QVariant if the member function returns void.
+ * If the conversion fails, or if the argument count does not match, this function returns boost::none
+ * and the member function is not invoked.
+ *
+ * @param c    Callable
+ * @param args Arguments to be given to the member function
+ * @returns An optional containing a QVariant with the return value if the member function could be invoked with
+ *          the given list of arguments; otherwise boost::none
+ */
+template<typename R, typename C, typename ...Args>
+boost::optional<QVariant> invokeWithArgsList(C* object, R(C::*func)(Args...), const QVariantList& args)
+{
+    if (sizeof...(Args) != args.size()) {
+        qWarning().nospace() << "Argument count mismatch! Expected: " << sizeof...(Args) << ", actual: " << args.size();
+        return boost::none;
+    }
+    return detail::invokeWithArgsList([object, func](Args&&... args) {
+        return (object->*func)(std::forward<decltype(args)>(args)...);
+    }, args, std::make_index_sequence<sizeof...(Args)>{});
+}