Add skstd::unique_ptr and use it.

include/private/SkUniquePtr.h

+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkUniquePtr_DEFINED
+#define SkUniquePtr_DEFINED
+
+#include "SkTLogic.h"
+#include "SkUtility.h"
+
+namespace skstd {
+
+template <typename T> struct default_delete {
+    /*constexpr*/ default_delete() /*noexcept*/ = default;
+
+    template <typename U, typename = enable_if_t<is_convertible<U*, T*>::value>>
+    default_delete(const default_delete<U>&) /*noexcept*/ {}
+
+    void operator()(T* obj) const {
+        static_assert(sizeof(T) > 0, "Deleting pointer to incomplete type!");
+        delete obj;
+    }
+};
+template <typename T> struct default_delete<T[]> {
+    /*constexpr*/ default_delete() /*noexcept*/ = default;
+
+    void operator()(T* obj) const {
+        static_assert(sizeof(T) > 0, "Deleting pointer to incomplete type!");
+        delete [] obj;
+    }
+};
+
+template <typename T, typename D = default_delete<T>> class unique_ptr {
+    // remove_reference_t<D>::pointer if that type exists, otherwise T*.
+    struct pointer_type_detector {
+        template <typename U> static typename U::pointer detector(typename U::pointer*);
+        template <typename U> static T* detector(...);
+        using type = decltype(detector<remove_reference_t<D>>(0));
+    };
+
+public:
+    using pointer = typename pointer_type_detector::type;
+    using element_type = T;
+    using deleter_type = D;
+
+private:
+    template <typename B, bool = is_empty<B>::value /*&& !is_final<B>::value*/>
+    struct compressed_base : private B {
+        /*constexpr*/ compressed_base() : B() {}
+        /*constexpr*/ compressed_base(const B& b) : B(b) {}
+        /*constexpr*/ compressed_base(const B&& b) : B(move(b)) {}
+        /*constexpr*/ B& get() /*noexcept*/ { return *this; }
+        /*constexpr*/ B const& get() const /*noexcept*/ { return *this; }
+        void swap(compressed_base&) /*noexcept*/ { }
+    };
+
+    template <typename B> struct compressed_base<B, false> {
+        B fb;
+        /*constexpr*/ compressed_base() : B() {}
+        /*constexpr*/ compressed_base(const B& b) : fb(b) {}
+        /*constexpr*/ compressed_base(const B&& b) : fb(move(b)) {}
+        /*constexpr*/ B& get() /*noexcept*/ { return fb; }
+        /*constexpr*/ B const& get() const /*noexcept*/ { return fb; }
+        void swap(compressed_base& that) /*noexcept*/ { SkTSwap(fb, that.fB); }
+    };
+
+    struct compressed_data : private compressed_base<deleter_type> {
+        pointer fPtr;
+        /*constexpr*/ compressed_data() : compressed_base<deleter_type>(), fPtr() {}
+        /*constexpr*/ compressed_data(const pointer& ptr, const deleter_type& d)
+            : compressed_base<deleter_type>(d), fPtr(ptr) {}
+        template <typename U1, typename U2, typename = enable_if_t<
+            is_convertible<U1, pointer>::value && is_convertible<U2, deleter_type>::value
+        >> /*constexpr*/ compressed_data(U1&& ptr, U2&& d)
+            : compressed_base<deleter_type>(skstd::forward<U2>(d)), fPtr(skstd::forward<U1>(ptr)) {}
+        /*constexpr*/ pointer& getPointer() /*noexcept*/ { return fPtr; }
+        /*constexpr*/ pointer const& getPointer() const /*noexcept*/ { return fPtr; }
+        /*constexpr*/ deleter_type& getDeleter() /*noexcept*/ {
+            return compressed_base<deleter_type>::get();
+        }
+        /*constexpr*/ deleter_type const& getDeleter() const /*noexcept*/ {
+            return compressed_base<deleter_type>::get();
+        }
+        void swap(compressed_data& that) /*noexcept*/ {
+            compressed_base<deleter_type>::swap(static_cast<compressed_base<deleter_type>>(that));
+            SkTSwap(fPtr, that.fPtr);
+        }
+    };
+    compressed_data data;
+
+public:
+    /*constexpr*/ unique_ptr() /*noexcept*/ : data() {
+        static_assert(!is_pointer<deleter_type>::value, "Deleter is nullptr function pointer!");
+    }
+
+    /*constexpr*/ unique_ptr(skstd::nullptr_t) /*noexcept*/ : unique_ptr() { }
+
+    explicit unique_ptr(pointer ptr) /*noexcept*/ : data(ptr, deleter_type()) {
+        static_assert(!is_pointer<deleter_type>::value, "Deleter is nullptr function pointer!");
+    }
+
+    unique_ptr(pointer ptr,
+               conditional_t<is_reference<deleter_type>::value, deleter_type,const deleter_type&> d)
+    /*noexcept*/ : data(ptr, d)
+    {}
+
+    unique_ptr(pointer ptr, remove_reference_t<deleter_type>&& d) /*noexcept*/
+        : data(move(ptr), move(d))
+    {
+        static_assert(!is_reference<deleter_type>::value,
+            "Binding an rvalue reference deleter as an lvalue reference deleter is not allowed.");
+    }
+
+
+    unique_ptr(unique_ptr&& that) /*noexcept*/
+        : data(that.release(), forward<deleter_type>(that.get_deleter()))
+    {}
+
+    template <typename U, typename ThatD, typename = enable_if_t<
+        is_convertible<typename unique_ptr<U, ThatD>::pointer, pointer>::value &&
+        !is_array<U>::value &&
+        conditional_t<is_reference<D>::value, is_same<ThatD, D>, is_convertible<ThatD, D>>::value>>
+    unique_ptr(unique_ptr<U, ThatD>&& that) /*noexcept*/
+        : data(that.release(), forward<ThatD>(that.get_deleter()))
+    {}
+
+    ~unique_ptr() /*noexcept*/ {
+        pointer& ptr = data.getPointer();
+        if (ptr != nullptr) {
+            get_deleter()(ptr);
+        }
+        ptr = pointer();
+    }
+
+    unique_ptr& operator=(unique_ptr&& that) /*noexcept*/ {
+        reset(that.release());
+        get_deleter() = forward<deleter_type>(that.get_deleter());
+        return *this;
+    }
+
+    template <typename U, typename ThatD> enable_if_t<
+        is_convertible<typename unique_ptr<U, ThatD>::pointer, pointer>::value &&
+        !is_array<U>::value,
+    unique_ptr&> operator=(unique_ptr<U, ThatD>&& that) /*noexcept*/ {
+        reset(that.release());
+        get_deleter() = forward<ThatD>(that.get_deleter());
+        return *this;
+    }
+
+    unique_ptr& operator=(skstd::nullptr_t) /*noexcept*/ {
+        reset();
+        return *this;
+    }
+
+    add_lvalue_reference_t<element_type> operator*() const {
+        SkASSERT(get() != pointer());
+        return *get();
+    }
+
+    pointer operator->() const /*noexcept*/ {
+        SkASSERT(get() != pointer());
+        return get();
+    }
+
+    pointer get() const /*noexcept*/ {
+        return data.getPointer();
+    }
+
+    deleter_type& get_deleter() /*noexcept*/ {
+        return data.getDeleter();
+    }
+
+    const deleter_type& get_deleter() const /*noexcept*/ {
+        return data.getDeleter();
+    }
+
+    //explicit operator bool() const noexcept {
+    bool is_attached() const /*noexcept*/ {
+        return get() == pointer() ? false : true;
+    }
+
+    pointer release() /*noexcept*/ {
+        pointer ptr = get();
+        data.getPointer() = pointer();
+        return ptr;
+    }
+
+    void reset(pointer ptr = pointer()) /*noexcept*/ {
+        SkTSwap(data.getPointer(), ptr);
+        if (ptr != pointer()) {
+            get_deleter()(ptr);
+        }
+    }
+
+    void swap(unique_ptr& that) /*noexcept*/ {
+        SkTSwap(data, that.data);
+    }
+
+    unique_ptr(const unique_ptr&) = delete;
+    unique_ptr& operator=(const unique_ptr&) = delete;
+};
+
+template <typename T, typename D> class unique_ptr<T[], D> {
+    // remove_reference_t<D>::pointer if that type exists, otherwise T*.
+    struct pointer_type_detector {
+        template <typename U> static typename U::pointer detector(typename U::pointer*);
+        template <typename U> static T* detector(...);
+        using type = decltype(detector<remove_reference_t<D>>(0));
+    };
+
+public:
+    using pointer = typename pointer_type_detector::type;
+    using element_type = T;
+    using deleter_type = D;
+
+private:
+    template <typename B, bool = is_empty<B>::value /*&& !is_final<B>::value*/>
+    struct compressed_base : private B {
+        /*constexpr*/ compressed_base() : B() {}
+        /*constexpr*/ compressed_base(const B& b) : B(b) {}
+        /*constexpr*/ compressed_base(const B&& b) : B(move(b)) {}
+        /*constexpr*/ B& get() /*noexcept*/ { return *this; }
+        /*constexpr*/ B const& get() const /*noexcept*/ { return *this; }
+        void swap(compressed_base&) /*noexcept*/ { }
+    };
+
+    template <typename B> struct compressed_base<B, false> {
+        B fb;
+        /*constexpr*/ compressed_base() : B() {}
+        /*constexpr*/ compressed_base(const B& b) : fb(b) {}
+        /*constexpr*/ compressed_base(const B&& b) : fb(move(b)) {}
+        /*constexpr*/ B& get() /*noexcept*/ { return fb; }
+        /*constexpr*/ B const& get() const /*noexcept*/ { return fb; }
+        void swap(compressed_base& that) /*noexcept*/ { SkTSwap(fb, that.fB); }
+    };
+
+    struct compressed_data : private compressed_base<deleter_type> {
+        pointer fPtr;
+        /*constexpr*/ compressed_data() : compressed_base<deleter_type>(), fPtr() {}
+        /*constexpr*/ compressed_data(const pointer& ptr, const deleter_type& d)
+            : compressed_base<deleter_type>(d), fPtr(ptr) {}
+        template <typename U1, typename U2, typename = enable_if_t<
+            is_convertible<U1, pointer>::value && is_convertible<U2, deleter_type>::value
+        >> /*constexpr*/ compressed_data(U1&& ptr, U2&& d)
+            : compressed_base<deleter_type>(skstd::forward<U2>(d)), fPtr(skstd::forward<U1>(ptr)) {}
+        /*constexpr*/ pointer& getPointer() /*noexcept*/ { return fPtr; }
+        /*constexpr*/ pointer const& getPointer() const /*noexcept*/ { return fPtr; }
+        /*constexpr*/ deleter_type& getDeleter() /*noexcept*/ {
+            return compressed_base<deleter_type>::get();
+        }
+        /*constexpr*/ deleter_type const& getDeleter() const /*noexcept*/ {
+            return compressed_base<deleter_type>::get();
+        }
+        void swap(compressed_data& that) /*noexcept*/ {
+            compressed_base<deleter_type>::swap(static_cast<compressed_base<deleter_type>>(that));
+            SkTSwap(fPtr, that.fPtr);
+        }
+    };
+    compressed_data data;
+
+public:
+    /*constexpr*/ unique_ptr() /*noexcept*/ : data() {
+        static_assert(!is_pointer<deleter_type>::value, "Deleter is nullptr function pointer!");
+    }
+
+    /*constexpr*/ unique_ptr(skstd::nullptr_t) /*noexcept*/ : unique_ptr() { }
+
+    explicit unique_ptr(pointer ptr) /*noexcept*/ : data(ptr, deleter_type()) {
+        static_assert(!is_pointer<deleter_type>::value, "Deleter is nullptr function pointer!");
+    }
+
+    unique_ptr(pointer ptr,
+               conditional_t<is_reference<deleter_type>::value, deleter_type,const deleter_type&> d)
+    /*noexcept*/ : data(ptr, d)
+    {}
+
+    unique_ptr(pointer ptr, remove_reference_t<deleter_type>&& d) /*noexcept*/
+        : data(move(ptr), move(d))
+    {
+        static_assert(!is_reference<deleter_type>::value,
+            "Binding an rvalue reference deleter as an lvalue reference deleter is not allowed.");
+    }
+
+    unique_ptr(unique_ptr&& that) /*noexcept*/
+        : data(that.release(), forward<deleter_type>(that.get_deleter()))
+    {}
+
+    ~unique_ptr() {
+        pointer& ptr = data.getPointer();
+        if (ptr != nullptr) {
+          get_deleter()(ptr);
+        }
+        ptr = pointer();
+    }
+
+    unique_ptr& operator=(unique_ptr&& that) /*noexcept*/ {
+        reset(that.release());
+        get_deleter() = forward<deleter_type>(that.get_deleter());
+        return *this;
+    }
+
+    unique_ptr& operator=(skstd::nullptr_t) /*noexcept*/ {
+        reset();
+        return *this;
+    }
+
+    add_lvalue_reference_t<element_type> operator[](size_t i) const {
+        SkASSERT(get() != pointer());
+        return get()[i];
+    }
+
+    pointer get() const /*noexcept*/ {
+        return data.getPointer();
+    }
+
+    deleter_type& get_deleter() /*noexcept*/ {
+        return data.getDeleter();
+    }
+
+    const deleter_type& get_deleter() const /*noexcept*/ {
+        return data.getDeleter();
+    }
+
+    //explicit operator bool() const noexcept {
+    bool is_attached() const /*noexcept*/ {
+        return get() == pointer() ? false : true;
+    }
+
+    pointer release() /*noexcept*/ {
+        pointer ptr = get();
+        data.getPointer() = pointer();
+        return ptr;
+    }
+
+    void reset(pointer ptr = pointer()) /*noexcept*/ {
+        SkTSwap(data.getPointer(), ptr);
+        if (ptr != pointer()) {
+            get_deleter()(ptr);
+        }
+    }
+
+    template <typename U> void reset(U*) = delete;
+
+    void swap(unique_ptr& that) /*noexcept*/ {
+        data.swap(that.data);
+    }
+
+    unique_ptr(const unique_ptr&) = delete;
+    unique_ptr& operator=(const unique_ptr&) = delete;
+};
+
+template <typename T, typename D>
+inline void swap(unique_ptr<T, D>& a, unique_ptr<T, D>& b) /*noexcept*/ {
+    a.swap(b);
+}
+
+template <typename T, typename D, typename U, typename ThatD>
+inline bool operator==(const unique_ptr<T, D>& a, const unique_ptr<U, ThatD>& b) {
+    return a.get() == b.get();
+}
+
+template <typename T, typename D>
+inline bool operator==(const unique_ptr<T, D>& a, skstd::nullptr_t) /*noexcept*/ {
+    //return !a;
+    return !a.is_attached();
+}
+
+template <typename T, typename D>
+inline bool operator==(skstd::nullptr_t, const unique_ptr<T, D>& b) /*noexcept*/ {
+    //return !b;
+    return !b.is_attached();
+}
+
+template <typename T, typename D, typename U, typename ThatD>
+inline bool operator!=(const unique_ptr<T, D>& a, const unique_ptr<U, ThatD>& b) {
+    return a.get() != b.get();
+}
+
+template <typename T, typename D>
+inline bool operator!=(const unique_ptr<T, D>& a, skstd::nullptr_t) /*noexcept*/ {
+    //return (bool)a;
+    return a.is_attached();
+}
+
+template <typename T, typename D>
+inline bool operator!=(skstd::nullptr_t, const unique_ptr<T, D>& b) /*noexcept*/ {
+    //return (bool)b;
+    return b.is_attached();
+}
+
+}  // namespace skstd
+
+#endif