Image.h - An reinterpreted container library in C++17

Image.h reinterprets a vector which means memory layout. Images have reference of a vector, they reinterpret it as a vector of other trivially copyable objects and users can read and change them.

To start using image.h

Download image.h from this repository and put this file on an include directory of your project.

reference

class template

aslib:: image

namespace aslib {
    template <TImage>
    class image;
}

Overview

image produced in <image.h> reinterprets a std::byte vector as other trivially copyable objects. Like vector, their size can change dynamically, with their storage being handled automatically by the container. But unlike vector, images use reference of a vector instead of contiguous storage locations for their elements. If images change, reference of their vector also change. In short, This class is an extension of pointer reinterpretation.

Operating cost is the same as a vector.

Template parameter's meaning is:

• TImage: this parameter expresses object as which std::bytes is reinterpreted. the object should be a trivially copyable.

Member functions

Construction / Destruction

name	explanation	version
(constructor)	construct image	C++17

Iterator

name	explanation	version
begin()	Return iterator to beginning
end()	Return iterator to end

Capacity

name	explanation	version
size()	Return size
empty()	Test whether image is empty
occupation()	Return occupied bytes count
start()	Return a position where occupation starts in memory

Element access

name	explanation	version
at()	access specified element with bounds chcking
operator[]()	access specified element

Modifiers

name	explanation	version
push_back()	Add an element at the end	C++11
pop_back()	Remove an element at the end	C++11
insert()	insert elements	C++14
erase()	erase elements	C++11

Deleted functions

This class contains reference of an object so you must avoid life extension of it. You can find wrong life extension in compiling owing to deleting functions involved in construction of pointer.

name	explanation	version
operator=()		C++11
operator&()		C++11
operator new()		C++11
operator delete()		C++11
operator new[]()		C++11
operator delete[]()		C++11

Member type

name	explanation	version
iterator		C++11
const_iterator		C++11

Example

Basic usage(C++17)

#include <cstdint>
#include <iostream>
#include <vector>
#include "image.h"

struct object {
    std::uint32_t id;
    float value;
};

int main(void) {
    std::vector<std::byte> v { std::byte{0}, std::byte{0} };
    aslib::image<object> im(v, 2, 0); //if image reinterpret a range larger than referring vector size, vector will be extended.
    
    im.push_back(object { 2, 1.2f });
    std::vector<object> os {
        object { 0, 0.4f },
        object { 1, 1.5f }
    };
    im.insert(im.begin(), os.begin(), os. end());
    im.erase(im.begin() + 1);

    std::cout << "image" << std::endl;

    for(auto&& x : im) {
        std::cout << x.id << " " << x.value << std::endl;
    }

    std::cout << "reinterpret" << std::endl;
    object* o = reinterpret_cast<object*>(v.data() + im.start());
    for(auto i = 0; i < im.size(); i++) {
        std::cout << o[i].id << " " << o[i].value << std::endl;
    }

    return 0;
}

Output

image
0 0.4
2 1.2
reinterpret
0 0.4
2 1.2