我正在尝试重构我使用指针不使用指针的路径查找算法的一部分。不幸的是,我对参考文献并不了解。我收到错误:Invalid operands to binary expression ('std::__1::reference_wrapper<Tile>' and 'const std::__1::reference_wrapper<Tile>')
我也不知道这意味着什么。我的代码在下面,我可以收集它来自行openList.erase(std::find(openList.begin(), openList.end(), current));
,但我不知道如何解决这个问题。
bool TileMap::tilesBetween(Tile& p_start, Tile& p_end)
{
std::vector<std::reference_wrapper<Tile>> openList;
std::vector<std::reference_wrapper<Tile>> closedList;
openList.push_back(p_start);
do
{
std::sort(openList.begin(), openList.end(), sortF());
Tile& current = openList[0];
closedList.push_back(current);
openList.erase(std::find(openList.begin(), openList.end(), current));
if(std::find(closedList.begin(), closedList.end(), p_end) != closedList.end())
{
return true;
}
std::vector<std::reference_wrapper<Tile>> adjacentTiles;
if (current.m_coordinates.x > 0)
{
adjacentTiles.push_back(m_tiles[current.m_coordinates.y * m_width + (current.m_coordinates.x - 1)]);
}
if (current.m_coordinates.x < m_width)
{
adjacentTiles.push_back(m_tiles[current.m_coordinates.y * m_width + (current.m_coordinates.x + 1)]);
}
if (current.m_coordinates.y > 0)
{
adjacentTiles.push_back(m_tiles[(current.m_coordinates.y - 1) * m_width + current.m_coordinates.x]);
}
if (current.m_coordinates.y < m_height)
{
adjacentTiles.push_back(m_tiles[(current.m_coordinates.y + 1) * m_width + current.m_coordinates.x]);
}
for(auto t : adjacentTiles)
{
if(std::find(closedList.begin(), closedList.end(), t) != closedList.end())
{
continue;
}
if(std::find(openList.begin(), openList.end(), t) == closedList.end())
{
openList.push_back(t);
}
}
}
while(!openList.empty());
return false;
}
编辑:发布了sortF
struct sortF
{
bool operator()(const Tile* p_a, const Tile* p_b) const
{
return p_a->f < p_b->f;
}
};
更新:根据建议,我已将函数更改为使用指针而不是引用。它看起来很有效,但在完成之前我还有更多工作要做。
bool TileMap::tilesBetween(Tile* p_start, Tile* p_end)
{
std::vector<Tile*> openList;
std::vector<Tile*> closedList;
std::cout << p_start << ", ";
openList.push_back(p_start);
do
{
std::sort(openList.begin(), openList.end(), sortF());
Tile* current = openList[0];
closedList.push_back(current);
openList.erase(std::find(openList.begin(), openList.end(), current));
if(std::find(closedList.begin(), closedList.end(), p_end) != closedList.end())
{
return true;
}
std::vector<Tile*> adjacentTiles;
if (current->m_coordinates.x > 0)
{
adjacentTiles.push_back(&m_tiles[current->m_coordinates.y * m_width + (current->m_coordinates.x - 1)]);
}
if (current->m_coordinates.x < m_width)
{
std::cout << &m_tiles[current->m_coordinates.y * m_width + (current->m_coordinates.x + 1)] << std::endl;
adjacentTiles.push_back(&m_tiles[current->m_coordinates.y * m_width + (current->m_coordinates.x + 1)]);
}
if (current->m_coordinates.y > 0)
{
adjacentTiles.push_back(&m_tiles[(current->m_coordinates.y - 1) * m_width + current->m_coordinates.x]);
}
if (current->m_coordinates.y < m_height)
{
adjacentTiles.push_back(&m_tiles[(current->m_coordinates.y + 1) * m_width + current->m_coordinates.x]);
}
for(auto t : adjacentTiles)
{
if(std::find(closedList.begin(), closedList.end(), t) != closedList.end())
{
continue;
}
if(std::find(openList.begin(), openList.end(), t) == openList.end())
{
openList.push_back(t);
}
}
}
while(!openList.empty());
return false;
}
答案 0 :(得分:4)
我可以收集它来自行:openList.erase(std :: find(openList.begin(),openList.end(),current));但我不确定如何解决这个问题。
std::find
遍历std::reference_wrapper<Tile>
而非Tile&
本身。因此
Tile& current = openList[0];
openList.erase(std::find(openList.begin(), openList.end(), current));
不正确。将其更改为
openList.erase(std::find_if(openList.begin(), openList.end(), [&](const std::reference_wrapper<Tile> &i)
{
return i.get() == current;
}));
std::reference_wrapper::get
返回基础参考。
一个简单的working example来证明这个
#include <algorithm>
#include <list>
#include <vector>
#include <iostream>
#include <functional>
struct S
{
int val;
S(int i) : val(i) {}
};
int main()
{
std::list<S> l = {-4, -3, -2, -1, 0, 1, 2, 3, 4};
std::vector<std::reference_wrapper<S>> v(l.begin(), l.end());
auto& x = l.front();
v.erase(std::find_if(v.cbegin(), v.cend(), [&](const std::reference_wrapper<S> &i)
{
return i.get().val == x.val;
}));
std::cout << v[0].get().val;
}
答案 1 :(得分:0)
你的问题在这里:
std::sort(openList.begin(), openList.end(), sortF());
您的sortF
是无效的比较对象。 operator()
必须如下所示:
bool operator()(const Tile& lhs, const Tile& rhs) const
// ^^^ ref ^^^ ^^^ ref ^^^
{
return lhs.f < rhs.f;
}
而不是:
bool operator()(const Tile* p_a, const Tile* p_b) const
// ^^^ ptr ^^^ ^^^ ptr ^^^
您有reference_wrapper<Tile>
的向量,而不是Tile*
的向量。