lnav/src/auto_mem.hh

/**
 * Copyright (c) 2007-2012, Timothy Stack
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 * * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * * Neither the name of Timothy Stack nor the names of its contributors
 * may be used to endorse or promote products derived from this software
 * without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ''AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * @file auto_mem.hh
 */

#ifndef __auto_mem_hh
#define __auto_mem_hh

#include <string.h>
#include <unistd.h>
#include <stdlib.h>

#include <exception>

typedef void (*free_func_t)(void *);

/**
 * Resource management class for memory allocated by a custom allocator.
 *
 * @param T The object type.
 * @param auto_free The function to call to free the managed object.
 */
template<class T, free_func_t default_free = free>
class auto_mem {
public:
    auto_mem(T *ptr = NULL) : am_ptr(ptr), am_free_func(default_free) { };

    auto_mem(auto_mem & am)
        : am_ptr(am.release()), am_free_func(am.am_free_func)
    {};

    template<typename F>
    auto_mem(F free_func)
        : am_ptr(NULL), am_free_func((free_func_t)free_func) { };

    auto_mem(auto_mem &&other) : am_ptr(nullptr) {
        this->reset(other.release());
        this->am_free_func = other.am_free_func;
    };

    ~auto_mem()
    {
        this->reset();
    };

    operator T *(void) const { return this->am_ptr; };

    auto_mem &operator =(T *ptr)
    {
        this->reset(ptr);
        return *this;
    };

    auto_mem &operator =(auto_mem & am)
    {
        this->reset(am.release());
        this->am_free_func = am.am_free_func;
        return *this;
    };

    T *release(void)
    {
        T *retval = this->am_ptr;

        this->am_ptr = NULL;
        return retval;
    };

    T *in(void) const
    {
        return this->am_ptr;
    };

    T **out(void)
    {
        this->reset();
        return &this->am_ptr;
    };

    void reset(T *ptr = NULL)
    {
        if (this->am_ptr != ptr) {
            if (this->am_ptr != NULL) {
                this->am_free_func((void *)this->am_ptr);
            }
            this->am_ptr = ptr;
        }
    };

private:
    T *  am_ptr;
    void (*am_free_func)(void *);
};

template<typename T, void(*free_func) (T *)>
class static_root_mem {
public:
    static_root_mem()
    {
        memset(&this->srm_value, 0, sizeof(T));
    };

    ~static_root_mem() { free_func(&this->srm_value); };

    const T *operator->(void) const { return &this->srm_value; };

    const T &in(void) const { return this->srm_value; };

    T *inout(void) {
        free_func(&this->srm_value);
        memset(&this->srm_value, 0, sizeof(T));
        return &this->srm_value;
    };

private:
    static_root_mem &operator =(T &) { return *this; };

    static_root_mem &operator =(static_root_mem &) { return *this; };

    T srm_value;
};
#endif