// Eggs.FlatMap

//

// Copyright Agustin K-ballo Berge, Fusion Fenix 2026

//

// Distributed under the Boost Software License, Version 1.0. (See accompanying

// file LICENSE.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

// Example: game entity database

//

// A flat_map<uint32_t(Vec3, float, std::string)> used as a cache-friendly SoA

// entity store keyed by entity ID, demonstrating the primary use cases:

//

// - brace-init insertion

// - structured bindings over rows

// - per-element value access via value<I>()

// - cache-friendly column iteration via values<I>()

// - cross-column access via find + distance

#include <eggs/flat_map.hpp>

#include <algorithm>

#include <cstdint>

#include <iostream>

#include <string>

using namespace eggs;

struct Vec3

{

float x, y, z;

};

int main()

{

// entities keyed by ID: position, health, name

flat_map<uint32_t(Vec3, float, std::string)> entities;

// insert via brace init — {key, v0, v1, v2}

entities.insert({1u, Vec3{0.f, 0.f, 0.f}, 100.f, "Goblin"});

entities.insert({2u, Vec3{5.f, 0.f, 3.f}, 80.f, "Troll"});

entities.insert({3u, Vec3{1.f, 0.f, 1.f}, 60.f, "Orc"});

// iterate all rows — use as_const to get const_iterator (proxy ref semantics)

std::cout << "--- All entities ---\n";

for (const auto& [id, pos, hp, name] : std::as_const(entities))

std::cout << id << ": " << name << " hp=" << hp << "\n";

// find one entity, mutate a single value column

if (auto it = entities.find(2); it != entities.end())

it->value<1>() -= 25.f; // deal damage to Troll

// regen tick — iterate health column directly, no key/name touched

for (float& hp : entities.values<1>()) hp = std::min(hp + 5.f, 100.f);

// find + distance: one lookup, then O(1) direct column writes

auto it = entities.find(1);

auto idx = std::distance(entities.begin(), it);

entities.values<0>()[idx] = Vec3{2.f, 0.f, 2.f}; // reposition Goblin

entities.values<2>()[idx] = "Goblin Chief"; // promote

std::cout << "\n--- After updates ---\n";

for (const auto& [id, pos, hp, name] : std::as_const(entities))

std::cout << id << ": " << name << " hp=" << hp << "\n";

}