Rewrite of the main function of http://codereview.stackexchange.com/q/62493/308

LoadFromFile.cpp

Tile LoadFromFile(std::string filename) {
    std::ifstream ifs{filename};

    std::string line;
    if (not getline(ifs, line))
        throw "foo";

    std::string name{line};
    int numBoxes{};
    int numTargets{};
    Point playerStart{};
    bool playerStartSet{};
    std::vector<Tile> tiles(TileCount, Tile::Free);
    int y{};

    while (getline(ifs, line)) {
        if (y > Level::MaxRows)
            throw "foo";

        int x{};

        for (char c : line) {
            if (x > Level::MaxCols)
                throw "foo";

            if (! validTile(c))  // TODO: implement `validTile`.
                throw "foo";

            auto tile = static_cast<Tile>(c);

            switch (tile) {
                case Tile::Free:
                    break;
                case Tile::Box:
                    ++numBoxes;
                    break;
                case Tile::BoxOnTarget:
                    ++numBoxes;
                    ++numTargets;
                    break;
                case Tile::Target:
                    ++numTargets;
                    break;
                case Tile::Wall:
                    break;
                case Tile::PlayerStart:
                    if (playerStartSet)
                        throw "foo";

                    playerStartSet = true;
                    playerStart = Point{x, y};
                    tile = Tile::Free;
                    break;
            }

            tiles[indexof(x, y)] = tile;
            ++x;
        }
        ++y;
    }

    if (numBoxes != numTargets)
        throw "foo";
    if (not playerStart)
        throw "foo";

    return Level{tiles, name, playerStart};
}