// Test case.

const std::map<int, int> result{

{-1, -1},

{ 0, 0},

{ 1, 0},

{ 2, 2},

{ 3, 2},

{ 4, 2},

{ 5, 5},

{ 6, 5},

{ 7, 7},

};

// Raw lambda map.

{

int x;

const std::map<int,std::function<void()>> m{

{0, [&](){

x = -1;

}},

{2, [&](){

x = 0;

}},

{5, [&](){

x = 2;

}},

{7, [&](){

x = 5;

}}

};

const auto end = m.end();

for (auto i = -1; i < 8; ++i) {

auto it = m.upper_bound(i);

if (it == end) {

x = 7;

} else {

it->second();

}

assert(x == result.at(i));

}

}

// How to use the range pattern from a method.

// The key is to static initialize the lambda map.

{

struct RangeSwitch {

int method(int x) {

static const std::map<int,std::function<void(int&)>> m{

{0, [&](int &x){

x = -1;

}},

{2, [&](int &x){

x = 0;

}},

{5, [&](int &x){

x = 2;

}},

{7, [&](int &x){

x = 5;

}}

};

static const auto end = m.end();

auto it = m.upper_bound(x);

if (it == end) {

x = 7;

} else {

it->second(x);

}

return x;

}

};

RangeSwitch rangeSwitch;

for (auto i = -1; i < 8; ++i) {

assert(rangeSwitch.method(i) == result.at(i));

}

}