[core] Replace unique_any with peer from mapbox-bindgen

4 files changed, 115 insertions, 275 deletions

diff --git a/include/mbgl/style/layer.hpp b/include/mbgl/style/layer.hpp
index 12494f5387..b5a4b63d2e 100644
--- a/include/mbgl/style/layer.hpp
+++ b/include/mbgl/style/layer.hpp
@@ -1,7 +1,7 @@
 #pragma once
 
 #include <mbgl/util/noncopyable.hpp>
-#include <mbgl/util/unique_any.hpp>
+#include <mbgl/util/peer.hpp>
 #include <mbgl/util/immutable.hpp>
 #include <mbgl/style/layer_type.hpp>
 #include <mbgl/style/types.hpp>
@@ -132,7 +132,7 @@ public:
     // For use in SDK bindings, which store a reference to a platform-native peer
     // object here, so that separately-obtained references to this object share
     // identical platform-native peers.
-    util::unique_any peer;
+    util::peer peer;
 };
 
 } // namespace style
diff --git a/include/mbgl/style/source.hpp b/include/mbgl/style/source.hpp
index 2f2838ade8..dc3a8d73fb 100644
--- a/include/mbgl/style/source.hpp
+++ b/include/mbgl/style/source.hpp
@@ -2,7 +2,7 @@
 
 #include <mbgl/util/noncopyable.hpp>
 #include <mbgl/util/optional.hpp>
-#include <mbgl/util/unique_any.hpp>
+#include <mbgl/util/peer.hpp>
 #include <mbgl/util/immutable.hpp>
 #include <mbgl/style/types.hpp>
 
@@ -77,7 +77,7 @@ public:
     // For use in SDK bindings, which store a reference to a platform-native peer
     // object here, so that separately-obtained references to this object share
     // identical platform-native peers.
-    util::unique_any peer;
+    util::peer peer;
 };
 
 } // namespace style
diff --git a/include/mbgl/util/peer.hpp b/include/mbgl/util/peer.hpp
new file mode 100644
index 0000000000..a4abea0e88
--- /dev/null
+++ b/include/mbgl/util/peer.hpp
@@ -0,0 +1,111 @@
+#pragma once
+
+#include <type_traits>
+#include <utility>
+
+namespace mbgl {
+namespace util {
+
+class peer {
+public:
+    peer() = default;
+    peer(const peer&) = delete;
+
+    peer(peer&& other)
+        : vtable(other.vtable)
+    {
+        if (vtable) {
+            vtable->move(other.storage, storage);
+        }
+        other.vtable = nullptr;
+    }
+
+    template <class T>
+    peer(T&& value) {
+        using _Vt = std::decay_t<T>;
+        vtable = get_vtable<_Vt>();
+        new (&storage) _Vt(std::forward<T>(value));
+    }
+
+    ~peer() {
+        reset();
+    }
+
+    peer& operator=(peer&& rhs) {
+        peer(std::move(rhs)).swap(*this);
+        return *this;
+    }
+
+    void reset()  {
+        if (vtable) {
+            vtable->destroy(storage);
+            vtable = nullptr;
+        }
+    }
+
+    void swap(peer& rhs)  {
+        if (this == &rhs) {
+            return;
+        } else {
+            peer tmp(std::move(rhs));
+            rhs.vtable = vtable;
+            if (rhs.vtable) {
+                rhs.vtable->move(storage, rhs.storage);
+            }
+            vtable = tmp.vtable;
+            if (vtable) {
+                vtable->move(tmp.storage, storage);
+            }
+        }
+    }
+
+    bool has_value() const {
+        return vtable != nullptr;
+    }
+
+    template <class T>
+    T& get() {
+        return reinterpret_cast<T&>(storage);
+    }
+
+    template <class T>
+    T&& take() {
+        reset();
+        return std::move(get<T>());
+    }
+
+private:
+    using storage_t = std::aligned_storage_t<2*sizeof(void*), alignof(void*)>;
+
+    struct vtable {
+        virtual ~vtable() = default;
+        virtual void move(storage_t&, storage_t&) = 0;
+        virtual void destroy(storage_t&) = 0;
+    };
+
+    template <class T>
+    struct vtable_impl : public vtable {
+        static_assert(sizeof(T) <= sizeof(storage_t), "peer object is too big");
+
+        void move(storage_t& src, storage_t& dst) override {
+            new (&dst) T(std::move(reinterpret_cast<T&>(src)));
+            destroy(src);
+        }
+
+        void destroy(storage_t& s) override {
+            reinterpret_cast<T&>(s).~T();
+        }
+    };
+
+    template <class T>
+    static vtable* get_vtable() {
+        static vtable_impl<T> vtable;
+        return &vtable;
+    }
+
+    vtable* vtable = nullptr;
+    storage_t storage;
+};
+
+} // namespace util
+} // namespace mbgl
diff --git a/include/mbgl/util/unique_any.hpp b/include/mbgl/util/unique_any.hpp
deleted file mode 100644
index c7dc8b38ea..0000000000
--- a/include/mbgl/util/unique_any.hpp
+++ /dev/null
@@ -1,271 +0,0 @@
-#pragma once
-
-#include <typeinfo>
-#include <type_traits>
-#include <stdexcept>
-namespace mbgl {
-namespace util {
-
-class bad_any_cast : public std::bad_cast {
-public:
-    const char* what() const noexcept override {
-        return "bad any_cast<>()";
-    }
-};
-/**
- * A variant of `std::any` for non-copyable types.
- *
- * Use `unique_any` for non-copyable types (e.g. `std::unique_ptr<T>`)
- * or to ensure that no copies are made of copyable types that are
- * moved in.
- *
- * `uniqe_any` differs from `std::any` in that it does not support copy construction
- * or copy assignment. It also does not require the contained type to be copy
- * constructible.
- *
- * The `any_cast<T>()` methods work similar to `std::any_cast<T>()` except that
- * non-copyable types may only be cast to references.
- *
- * Example usage:
- *  unique_any u1(3);
- *  auto u2 = unique_any(std::move(u1)); // u1 is moved from
- *  int i = any_cast<int>(u2);
- *
- *  unique_any u2;
- *  u2 = std::unique_ptr<int>(new int);
- *  std::unique_ptr<int> iPtr = any_cast<std::unique_ptr<int>>(std::move(u2));
- *
- * Inspired by linb::any (https://github.com/thelink2012/any) and the
- * libc++ implementation (https://github.com/llvm-mirror/libcxx).
- */
-class unique_any final
-{
-public:
-    unique_any() = default;
-
-    //Copy constructor (deleted)
-    unique_any(const unique_any& rhs) = delete;
-
-    unique_any(unique_any&& rhs)  : vtable(rhs.vtable) {
-        if (vtable) {
-            vtable->move(std::move(rhs.storage), storage);
-        }
-        rhs.vtable = nullptr;
-    }
-
-    // Constructs with a direct-initilizated object of type ValueType
-    template <typename ValueType,
-        typename _Vt = std::decay_t<ValueType>,
-        typename = std::enable_if_t<!std::is_same<_Vt, unique_any>::value> >
-    unique_any(ValueType&& value) {
-        create(std::forward<ValueType>(value));
-    }
-
-    ~unique_any() {
-        reset();
-    }
-
-    unique_any& operator=(unique_any&& rhs)  {
-        unique_any(std::move(rhs)).swap(*this);
-        return *this;
-    }
-
-    template <class ValueType,
-        typename = std::enable_if_t<!std::is_same<std::decay_t<ValueType>, unique_any>::value> >
-    unique_any& operator=(ValueType&& rhs) {
-        unique_any(std::forward<ValueType>(rhs)).swap(*this);
-        return *this;
-    }
-
-    void reset()  {
-        if (vtable) {
-            vtable->destroy(storage);
-            vtable = nullptr;
-        }
-    }
-
-    void swap(unique_any& rhs)  {
-        if (this == &rhs) {
-            return;
-        } else {
-            unique_any tmp(std::move(rhs));
-            rhs.vtable = vtable;
-            if (rhs.vtable) {
-                rhs.vtable->move(std::move(storage), rhs.storage);
-            }
-            vtable = tmp.vtable;
-            if (vtable) {
-                vtable->move(std::move(tmp.storage), storage);
-            }
-        }
-    }
-
-    const std::type_info& type() const  {
-      return !has_value()? typeid(void) : vtable->type();
-    }
-
-    bool has_value() const  {
-        return vtable != nullptr;
-    }
-
-private:
-
-    union Storage {
-        using StackStorage = std::aligned_storage_t<3*sizeof(void*), std::alignment_of<void*>::value>;
-        Storage() = default;
-
-        void * dynamic { nullptr };
-        StackStorage stack;
-    };
-
-    template<typename T>
-    struct AllocateOnStack : std::integral_constant<bool,
-        sizeof(T) <= sizeof(Storage::stack)
-        && std::alignment_of<T>::value <= std::alignment_of<Storage::StackStorage>::value
-        && std::is_nothrow_move_constructible<T>::value> {
-    };
-
-    struct VTable {
-        virtual ~VTable() = default;
-        virtual void move(Storage&& src, Storage& dest) = 0;
-        virtual void destroy(Storage&) = 0;
-        virtual const std::type_info& type() = 0;
-    };
-  
-    template <typename ValueType>
-    struct VTableHeap : public VTable {
-        void move(Storage&& src, Storage& dest) override {
-            dest.dynamic = src.dynamic;
-            src.dynamic = nullptr;
-        }
-
-        void destroy(Storage& s) override {
-            delete reinterpret_cast<ValueType*>(s.dynamic);
-        }
-
-        const std::type_info& type() override {
-            return typeid(ValueType);
-        }
-    };
-
-    template <typename ValueType>
-    struct VTableStack : public VTable {
-        void move(Storage&& src, Storage& dest) override {
-            new (&dest.stack) ValueType(std::move(reinterpret_cast<ValueType&>(src.stack)));
-            destroy(src);
-        }
-
-        void destroy(Storage& s) override {
-            reinterpret_cast<ValueType&>(s.stack).~ValueType();
-        }
-
-        const std::type_info& type() override {
-            return typeid(ValueType);
-        }
-    };
-
-    template <typename ValueType>
-    static VTable* vtableForType() {
-        using VTableType = std::conditional_t<AllocateOnStack<ValueType>::value, VTableStack<ValueType>, VTableHeap<ValueType> >;
-        static VTableType vtable;
-        return &vtable;
-    }
-
-    template <typename ValueType, typename _Vt>
-    std::enable_if_t<AllocateOnStack<_Vt>::value>
-    createStorage(ValueType&& value) {
-        new (&storage.stack) _Vt(std::forward<ValueType>(value));
-    }
-
-    template <typename ValueType, typename _Vt>
-    std::enable_if_t<!AllocateOnStack<_Vt>::value>
-    createStorage(ValueType&& value) {
-        storage.dynamic = new _Vt(std::forward<ValueType>(value));
-    }
-
-    template <typename ValueType>
-    void create(ValueType&& value) {
-        using _Vt = std::decay_t<ValueType>;
-        vtable = vtableForType<_Vt>();
-        createStorage<ValueType, _Vt>(std::forward<ValueType>(value));
-    }
-
-    VTable* vtable { nullptr };
-    Storage storage;
-
-protected:
-    template<class ValueType>
-    friend const ValueType* any_cast(const unique_any* operand) ;
-
-    template<class ValueType>
-    friend ValueType* any_cast(unique_any* operand) ;
-
-    template<typename ValueType, typename _Vt = std::decay_t<ValueType> >
-    ValueType* cast()
-    {
-        return reinterpret_cast<ValueType *>(
-            AllocateOnStack<_Vt>::value ? &storage.stack : storage.dynamic);
-    }
-};
-
-template<typename ValueType>
-inline const ValueType* any_cast(const unique_any* any)
-{
-    return any_cast<ValueType>(const_cast<unique_any *>(any));
-}
-
-template<typename ValueType>
-inline ValueType* any_cast(unique_any* any)
-{
-    if(any == nullptr || any->type() != typeid(ValueType))
-        return nullptr;
-    else
-        return any->cast<ValueType>();
-}
-
-template<typename ValueType, typename _Vt = std::decay_t<ValueType> >
-inline ValueType any_cast(const unique_any& any)
-{
-    static_assert(std::is_constructible<ValueType, const _Vt&>::value,
-        "any_cast type can't construct copy of contained object");
-    auto temp = any_cast<_Vt>(&any);
-    if (temp == nullptr) {
-        throw bad_any_cast();
-    }
-    return static_cast<ValueType>(*temp);
-}
-
-template<typename ValueType, typename _Vt = std::decay_t<ValueType> >
-inline ValueType any_cast(unique_any& any)
-{
-    static_assert(std::is_constructible<ValueType, const _Vt&>::value,
-        "any_cast type can't construct copy of contained object");
-    auto temp = any_cast<_Vt>(&any);
-    if (temp == nullptr) {
-        throw bad_any_cast();
-    }
-    return static_cast<ValueType>(*temp);
-}
-
-template<typename ValueType, typename _Vt = std::remove_cv_t<ValueType> >
-inline ValueType any_cast(unique_any&& any)
-{
-    auto temp = any_cast<_Vt>(&any);
-    if (temp == nullptr) {
-        throw bad_any_cast();
-    }
-    auto retValue = static_cast<ValueType>(std::move(*temp));
-    any.reset();
-    return std::move(retValue);
-}
-
-} // namespace util
-} // namespace mbgl
-
-namespace std {
-
-inline void swap(mbgl::util::unique_any& lhs, mbgl::util::unique_any& rhs)  {
-    lhs.swap(rhs);
-}
-
-} // namespace std