localpointer.h

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// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
/*
*******************************************************************************
*
*   Copyright (C) 2009-2016, International Business Machines
*   Corporation and others.  All Rights Reserved.
*
*******************************************************************************
*   file name:  localpointer.h
*   encoding:   UTF-8
*   tab size:   8 (not used)
*   indentation:4
*
*   created on: 2009nov13
*   created by: Markus W. Scherer
*/

#ifndef __LOCALPOINTER_H__
#define __LOCALPOINTER_H__

#include "unicode/utypes.h"

#if U_SHOW_CPLUSPLUS_API

#include <memory>

U_NAMESPACE_BEGIN

template<typename T>
class LocalPointerBase {
public:
    // No heap allocation. Use only on the stack.
    static void* U_EXPORT2 operator new(size_t) = delete;
    static void* U_EXPORT2 operator new[](size_t) = delete;
#if U_HAVE_PLACEMENT_NEW
    static void* U_EXPORT2 operator new(size_t, void*) = delete;
#endif

    explicit LocalPointerBase(T *p=nullptr) : ptr(p) {}
    ~LocalPointerBase() { /* delete ptr; */ }
    UBool isNull() const { return ptr==nullptr; }
    UBool isValid() const { return ptr!=nullptr; }
    bool operator==(const T *other) const { return ptr==other; }
    bool operator!=(const T *other) const { return ptr!=other; }
    T *getAlias() const { return ptr; }
    T &operator*() const { return *ptr; }
    T *operator->() const { return ptr; }
    T *orphan() {
        T *p=ptr;
        ptr=nullptr;
        return p;
    }
    void adoptInstead(T *p) {
        // delete ptr;
        ptr=p;
    }
protected:
    T *ptr;
private:
    // No comparison operators with other LocalPointerBases.
    bool operator==(const LocalPointerBase<T> &other);
    bool operator!=(const LocalPointerBase<T> &other);
    // No ownership sharing: No copy constructor, no assignment operator.
    LocalPointerBase(const LocalPointerBase<T> &other);
    void operator=(const LocalPointerBase<T> &other);
};

template<typename T>
class LocalPointer : public LocalPointerBase<T> {
public:
    using LocalPointerBase<T>::operator*;
    using LocalPointerBase<T>::operator->;
    explicit LocalPointer(T *p=nullptr) : LocalPointerBase<T>(p) {}
    LocalPointer(T *p, UErrorCode &errorCode) : LocalPointerBase<T>(p) {
        if(p==nullptr && U_SUCCESS(errorCode)) {
            errorCode=U_MEMORY_ALLOCATION_ERROR;
        }
    }
    LocalPointer(LocalPointer<T> &&src) noexcept : LocalPointerBase<T>(src.ptr) {
        src.ptr=nullptr;
    }

    explicit LocalPointer(std::unique_ptr<T> &&p)
        : LocalPointerBase<T>(p.release()) {}

    ~LocalPointer() {
        delete LocalPointerBase<T>::ptr;
    }
    LocalPointer<T> &operator=(LocalPointer<T> &&src) noexcept {
        delete LocalPointerBase<T>::ptr;
        LocalPointerBase<T>::ptr=src.ptr;
        src.ptr=nullptr;
        return *this;
    }

    LocalPointer<T> &operator=(std::unique_ptr<T> &&p) noexcept {
        adoptInstead(p.release());
        return *this;
    }

    void swap(LocalPointer<T> &other) noexcept {
        T *temp=LocalPointerBase<T>::ptr;
        LocalPointerBase<T>::ptr=other.ptr;
        other.ptr=temp;
    }
    friend inline void swap(LocalPointer<T> &p1, LocalPointer<T> &p2) noexcept {
        p1.swap(p2);
    }
    void adoptInstead(T *p) {
        delete LocalPointerBase<T>::ptr;
        LocalPointerBase<T>::ptr=p;
    }
    void adoptInsteadAndCheckErrorCode(T *p, UErrorCode &errorCode) {
        if(U_SUCCESS(errorCode)) {
            delete LocalPointerBase<T>::ptr;
            LocalPointerBase<T>::ptr=p;
            if(p==nullptr) {
                errorCode=U_MEMORY_ALLOCATION_ERROR;
            }
        } else {
            delete p;
        }
    }

    operator std::unique_ptr<T> () && {
        return std::unique_ptr<T>(LocalPointerBase<T>::orphan());
    }
};

template<typename T>
class LocalArray : public LocalPointerBase<T> {
public:
    using LocalPointerBase<T>::operator*;
    using LocalPointerBase<T>::operator->;
    explicit LocalArray(T *p=nullptr) : LocalPointerBase<T>(p) {}
    LocalArray(T *p, UErrorCode &errorCode) : LocalPointerBase<T>(p) {
        if(p==nullptr && U_SUCCESS(errorCode)) {
            errorCode=U_MEMORY_ALLOCATION_ERROR;
        }
    }
    LocalArray(LocalArray<T> &&src) noexcept : LocalPointerBase<T>(src.ptr) {
        src.ptr=nullptr;
    }

    explicit LocalArray(std::unique_ptr<T[]> &&p)
        : LocalPointerBase<T>(p.release()) {}

    ~LocalArray() {
        delete[] LocalPointerBase<T>::ptr;
    }
    LocalArray<T> &operator=(LocalArray<T> &&src) noexcept {
        delete[] LocalPointerBase<T>::ptr;
        LocalPointerBase<T>::ptr=src.ptr;
        src.ptr=nullptr;
        return *this;
    }

    LocalArray<T> &operator=(std::unique_ptr<T[]> &&p) noexcept {
        adoptInstead(p.release());
        return *this;
    }

    void swap(LocalArray<T> &other) noexcept {
        T *temp=LocalPointerBase<T>::ptr;
        LocalPointerBase<T>::ptr=other.ptr;
        other.ptr=temp;
    }
    friend inline void swap(LocalArray<T> &p1, LocalArray<T> &p2) noexcept {
        p1.swap(p2);
    }
    void adoptInstead(T *p) {
        delete[] LocalPointerBase<T>::ptr;
        LocalPointerBase<T>::ptr=p;
    }
    void adoptInsteadAndCheckErrorCode(T *p, UErrorCode &errorCode) {
        if(U_SUCCESS(errorCode)) {
            delete[] LocalPointerBase<T>::ptr;
            LocalPointerBase<T>::ptr=p;
            if(p==nullptr) {
                errorCode=U_MEMORY_ALLOCATION_ERROR;
            }
        } else {
            delete[] p;
        }
    }
    T &operator[](ptrdiff_t i) const { return LocalPointerBase<T>::ptr[i]; }

    operator std::unique_ptr<T[]> () && {
        return std::unique_ptr<T[]>(LocalPointerBase<T>::orphan());
    }
};

#define U_DEFINE_LOCAL_OPEN_POINTER(LocalPointerClassName, Type, closeFunction) \
    class LocalPointerClassName : public LocalPointerBase<Type> { \
    public: \
        using LocalPointerBase<Type>::operator*; \
        using LocalPointerBase<Type>::operator->; \
        explicit LocalPointerClassName(Type *p=nullptr) : LocalPointerBase<Type>(p) {} \
        LocalPointerClassName(LocalPointerClassName &&src) noexcept \
                : LocalPointerBase<Type>(src.ptr) { \
            src.ptr=nullptr; \
        } \
        /* TODO: Be agnostic of the deleter function signature from the user-provided std::unique_ptr? */ \
        explicit LocalPointerClassName(std::unique_ptr<Type, decltype(&closeFunction)> &&p) \
                : LocalPointerBase<Type>(p.release()) {} \
        ~LocalPointerClassName() { if (ptr != nullptr) { closeFunction(ptr); } } \
        LocalPointerClassName &operator=(LocalPointerClassName &&src) noexcept { \
            if (ptr != nullptr) { closeFunction(ptr); } \
            LocalPointerBase<Type>::ptr=src.ptr; \
            src.ptr=nullptr; \
            return *this; \
        } \
        /* TODO: Be agnostic of the deleter function signature from the user-provided std::unique_ptr? */ \
        LocalPointerClassName &operator=(std::unique_ptr<Type, decltype(&closeFunction)> &&p) { \
            adoptInstead(p.release()); \
            return *this; \
        } \
        void swap(LocalPointerClassName &other) noexcept { \
            Type *temp=LocalPointerBase<Type>::ptr; \
            LocalPointerBase<Type>::ptr=other.ptr; \
            other.ptr=temp; \
        } \
        friend inline void swap(LocalPointerClassName &p1, LocalPointerClassName &p2) noexcept { \
            p1.swap(p2); \
        } \
        void adoptInstead(Type *p) { \
            if (ptr != nullptr) { closeFunction(ptr); } \
            ptr=p; \
        } \
        operator std::unique_ptr<Type, decltype(&closeFunction)> () && { \
            return std::unique_ptr<Type, decltype(&closeFunction)>(LocalPointerBase<Type>::orphan(), closeFunction); \
        } \
    }

U_NAMESPACE_END

#endif  /* U_SHOW_CPLUSPLUS_API */
#endif  /* __LOCALPOINTER_H__ */