diff options
Diffstat (limited to 'lib/util.h')
| -rw-r--r-- | lib/util.h | 41 |
1 files changed, 41 insertions, 0 deletions
@@ -245,6 +245,47 @@ inline std::pair<InputIt, ForwardIt> findFirstOf(InputIt first, InputIt last, return std::make_pair(last, sLast); } +//! \brief An owning implementation pointer +//! +//! This is basically std::unique_ptr<> to hold your pimpl's but without having +//! to define default constructors/operator=() out of line. +//! Thanks to https://oliora.github.io/2015/12/29/pimpl-and-rule-of-zero.html +//! for inspiration +template <typename ImplType> +using ImplPtr = std::unique_ptr<ImplType, void (*)(ImplType*)>; + +// Why this works (see also the link above): because this defers the moment +// of requiring sizeof of ImplType to the place where makeImpl is invoked +// (which is located, necessarily, in the .cpp file after ImplType definition). +// The stock unique_ptr deleter (std::default_delete) normally needs sizeof +// at the same spot - as long as you defer definition of the owning type +// constructors and operator='s to the .cpp file as well. Which means you +// have to explicitly declare and define them (even if with = default), +// formally breaking the rule of zero; informally, just adding boilerplate code. +// The custom deleter itself is instantiated at makeImpl invocation - there's +// no way earlier to even know how ImplType will be deleted and whether that +// will need sizeof(ImplType) earlier. In theory it's a tad slower because +// the deleter is called by the pointer; however, the difference will not +// be noticeable (if exist at all) for any class with non-trivial contents. + +//! \brief make_unique for ImplPtr +//! +//! Since std::make_unique is not compatible with ImplPtr, this should be used +//! in constructors of frontend classes to create implementation instances. +template <typename ImplType, typename DeleterType = void (*)(ImplType*), + typename... ArgTs> +inline ImplPtr<ImplType> makeImpl(ArgTs&&... args) +{ + return ImplPtr<ImplType> { new ImplType(std::forward<ArgTs>(args)...), + [](ImplType* impl) { delete impl; } }; +} + +template <typename ImplType> +const inline ImplPtr<ImplType> ZeroImpl() +{ + return { nullptr, [](ImplType*) {} }; +} + /** Convert what looks like a URL or a Matrix ID to an HTML hyperlink */ QUOTIENT_API void linkifyUrls(QString& htmlEscapedText); |