urho3d/Source/Engine/Container/ForEach.h

#pragma once

#include "Vector.h"

namespace Urho3D {

template<typename T>
struct false_wrapper {
    false_wrapper(const T& value) : value(value) { }
    operator bool() const { return false; }
    T value;
};

template<typename T>
false_wrapper<T> make_false_wrapper(const T& value) {
    return false_wrapper<T>(value);
}

// vector support functions

template <class T>
Urho3D::RandomAccessIterator<T> Begin(Urho3D::Vector<T> &v) {
    return v.Begin();
}
template <class T>
Urho3D::RandomAccessIterator<T> Begin(Urho3D::Vector<T> *v) {
    return v->Begin();
}

template <class T>
Urho3D::RandomAccessConstIterator<T> Begin(const Urho3D::Vector<T> &v) {
    return v.Begin();
}
template <class T>
Urho3D::RandomAccessConstIterator<T> Begin(const Urho3D::Vector<T> *v) {
    return v->Begin();
}

template <class T>
Urho3D::RandomAccessIterator<T> End(Urho3D::Vector<T> &v) {
    return v.End();
}
template <class T>
Urho3D::RandomAccessIterator<T> End(Urho3D::Vector<T> *v) {
    return v->End();
}

template <class T>
Urho3D::RandomAccessConstIterator<T> End(const Urho3D::Vector<T> &v) {
    return v.End();
}
template <class T>
Urho3D::RandomAccessConstIterator<T> End(const Urho3D::Vector<T> *v) {
    return v->End();
}

// podvector support functions

template <class T>
Urho3D::RandomAccessIterator<T> Begin(Urho3D::PODVector<T> &v) {
    return v.Begin();
}
template <class T>
Urho3D::RandomAccessIterator<T> Begin(Urho3D::PODVector<T> *v) {
    return v->Begin();
}

template <class T>
Urho3D::RandomAccessConstIterator<T> Begin(const Urho3D::PODVector<T> &v) {
    return v.Begin();
}
template <class T>
Urho3D::RandomAccessConstIterator<T> Begin(const Urho3D::PODVector<T> *v) {
    return v->Begin();
}

template <class T>
Urho3D::RandomAccessIterator<T> End(Urho3D::PODVector<T> &v) {
    return v.End();
}
template <class T>
Urho3D::RandomAccessIterator<T> End(Urho3D::PODVector<T> *v) {
    return v->End();
}

template <class T>
Urho3D::RandomAccessConstIterator<T> End(const Urho3D::PODVector<T> &v) {
    return v.End();
}
template <class T>
Urho3D::RandomAccessConstIterator<T> End(const Urho3D::PODVector<T> *v) {
    return v->End();
}

} // namespace Urho3D

#define foreach(VAL, VALS) \
    if (const auto& _foreach_begin = Urho3D::make_false_wrapper(Urho3D::Begin(VALS))) { } else \
    if (const auto& _foreach_end = Urho3D::make_false_wrapper(Urho3D::End(VALS))) { } else \
    for (auto it = _foreach_begin.value; it != _foreach_end.value; ++it) \
    if (bool _foreach_flag = false) { } else \
    for (VAL = *it; !_foreach_flag; _foreach_flag = true)

#define foreachv(ITER, VAL, VALS) \
    if (const auto& _foreach_begin = Urho3D::make_false_wrapper(Urho3D::Begin(VALS))) { } else \
    if (const auto& _foreach_end = Urho3D::make_false_wrapper(Urho3D::End(VALS))) { } else \
    if (int ITER = 0) { } else \
    for (auto it = _foreach_begin.value; it != _foreach_end.value; ++it) \
    if (bool _foreach_flag = false) { } else \
    for (VAL = *it; !_foreach_flag; ITER++, _foreach_flag = true)