allocator-test.cc

/*
 * allocator-test.cc
 * Copyright (C) 2013 Adrian Perez <[email protected]>
 *
 * Distributed under terms of the MIT license.
 */

#include <cstdlib>
#include <cstdio>


struct Allocator
{
    void* (*alloc) (void*, size_t);
    void  (*free ) (void*, void*);
    void* userdata;

    static Allocator Default;
};


template <typename T>
void Delete(Allocator& alloc, T*& obj)
{
    obj->~T();
    (*alloc.free) (alloc.userdata, obj);
    obj = 0; // Clean up the pointer
}


static void*
std_alloc(void*, size_t size)
{
    void* p = malloc(size);
    printf("%s: allocated %p, %lu bytes\n", __func__, p, size);
    return p;
}

static void
std_free(void*, void* p)
{
    free(p);
    printf("%s: freed %p\n", __func__, p);
}


Allocator Allocator::Default =
{
    std_alloc,
    std_free,
    NULL,
};


class Malloced {
public:
    void* operator new(size_t size, Allocator& alloc) {
        return (*alloc.alloc) (alloc.userdata, size);
    }
    void operator delete(void* p, Allocator& alloc) {
        // Used when the above throws exceptions
        return (*alloc.free) (alloc.userdata, p);
    }
    void operator delete(void*) {
        printf("%s <-- SHOULD NOT HAPPEN\n", __PRETTY_FUNCTION__);
    }
};


class Foo : public Malloced {
public:
    Foo() {
        printf("%s\n", __PRETTY_FUNCTION__);
    }
    virtual ~Foo() {
        printf("%s\n", __PRETTY_FUNCTION__);
    }
};


class Bar : public Foo
{
public:
    Bar(int x): Foo() {
        printf("%s (x=%i)\n", __PRETTY_FUNCTION__, x);
    }
    virtual ~Bar() {
        printf("%s\n", __PRETTY_FUNCTION__);
    }
};


int main()
{
    Foo *f = new(Allocator::Default) Foo();
    Delete(Allocator::Default, f);

    f = new(Allocator::Default) Bar(42);
    Delete(Allocator::Default, f);

    f = new(Allocator::Default) Bar(666);
    delete f; // Whoops, would print "SHOULD NOT HAPPEN"
}