使用Boost ICL查找範圍包含點的所有對象

Question

我給出了一個包含添加時間，刪除時間，名稱和其他字段的對象列表L。給定一個時間T，我想返回一個只包含L的對象的列表，其中T落在對象的時間加上和時間刪除之間（另外，我想同時搜索特定名稱的所有對象，但它不是如果它使事情複雜化，則是必要的）我將如何使用Boost的ICL來做這件事？

Answer 1

比方說，你的對象看起來像

struct record { 
    std::string name; 

    using ptime = boost::posix_time::ptime; 
    ptime added, removed; 
}; 

現在，讓我們添加一個便捷的方法，所以我們可以用時間間隔工作更輕鬆：

icl::interval<ptime>::interval_type validity() const { 
     icl::interval<ptime> x; 
     return x.right_open(added, removed); 
    } 

一個簡單的測試程序是這樣的：

int main() 
{ 
    ptime const start(day_clock::local_day(), { }); 

    std::vector<record> L { 
     { "long"  , start + hours(77) , start + days(7) } , 
     { "medium" , start + hours(200), start + hours(236) }, 
     { "short" , start + hours(220), start + hours(226) }, 
     { "ephemeral", start + hours(100), start + hours(101) }, 
    }; 

    for (ptime T = start; T <= (start + days(10)); T += hours(6)) 
    { 
     std::cout << "\nT:" << T << "\t"; 
     std::ostream_iterator<record> out(std::cout, ";"); 
     std::copy_if(L.begin(), L.end(), out, [T](record const& r) { return icl::contains(r.validity(), T); }); 
    } 
} 

它重複了一個時間點T在10天的範圍s 6小時TEPS，並從L打印匹配對象，看它Live On Coliru

T:2014-Jun-06 00:00:00 
T:2014-Jun-06 06:00:00 
T:2014-Jun-06 12:00:00 
T:2014-Jun-06 18:00:00 
T:2014-Jun-07 00:00:00 
T:2014-Jun-07 06:00:00 
T:2014-Jun-07 12:00:00 
T:2014-Jun-07 18:00:00 
T:2014-Jun-08 00:00:00 
T:2014-Jun-08 06:00:00 
T:2014-Jun-08 12:00:00 
T:2014-Jun-08 18:00:00 
T:2014-Jun-09 00:00:00 
T:2014-Jun-09 06:00:00 {long, 2014-Jun-09 05:00:00, 2014-Jun-13 00:00:00}; 
T:2014-Jun-09 12:00:00 {long, 2014-Jun-09 05:00:00, 2014-Jun-13 00:00:00}; 
T:2014-Jun-09 18:00:00 {long, 2014-Jun-09 05:00:00, 2014-Jun-13 00:00:00}; 
T:2014-Jun-10 00:00:00 {long, 2014-Jun-09 05:00:00, 2014-Jun-13 00:00:00}; 
T:2014-Jun-10 06:00:00 {long, 2014-Jun-09 05:00:00, 2014-Jun-13 00:00:00}; 
T:2014-Jun-10 12:00:00 {long, 2014-Jun-09 05:00:00, 2014-Jun-13 00:00:00}; 
T:2014-Jun-10 18:00:00 {long, 2014-Jun-09 05:00:00, 2014-Jun-13 00:00:00}; 
T:2014-Jun-11 00:00:00 {long, 2014-Jun-09 05:00:00, 2014-Jun-13 00:00:00}; 
T:2014-Jun-11 06:00:00 {long, 2014-Jun-09 05:00:00, 2014-Jun-13 00:00:00}; 
T:2014-Jun-11 12:00:00 {long, 2014-Jun-09 05:00:00, 2014-Jun-13 00:00:00}; 
T:2014-Jun-11 18:00:00 {long, 2014-Jun-09 05:00:00, 2014-Jun-13 00:00:00}; 
T:2014-Jun-12 00:00:00 {long, 2014-Jun-09 05:00:00, 2014-Jun-13 00:00:00}; 
T:2014-Jun-12 06:00:00 {long, 2014-Jun-09 05:00:00, 2014-Jun-13 00:00:00}; 
T:2014-Jun-12 12:00:00 {long, 2014-Jun-09 05:00:00, 2014-Jun-13 00:00:00}; 
T:2014-Jun-12 18:00:00 {long, 2014-Jun-09 05:00:00, 2014-Jun-13 00:00:00}; 
T:2014-Jun-13 00:00:00 
T:2014-Jun-13 06:00:00 
T:2014-Jun-13 12:00:00 
T:2014-Jun-13 18:00:00 
T:2014-Jun-14 00:00:00 
T:2014-Jun-14 06:00:00 
T:2014-Jun-14 12:00:00 {medium, 2014-Jun-14 08:00:00, 2014-Jun-15 20:00:00}; 
T:2014-Jun-14 18:00:00 {medium, 2014-Jun-14 08:00:00, 2014-Jun-15 20:00:00}; 
T:2014-Jun-15 00:00:00 {medium, 2014-Jun-14 08:00:00, 2014-Jun-15 20:00:00}; 
T:2014-Jun-15 06:00:00 {medium, 2014-Jun-14 08:00:00, 2014-Jun-15 20:00:00};{short, 2014-Jun-15 04:00:00, 2014-Jun-15 10:00:00}; 
T:2014-Jun-15 12:00:00 {medium, 2014-Jun-14 08:00:00, 2014-Jun-15 20:00:00}; 
T:2014-Jun-15 18:00:00 {medium, 2014-Jun-14 08:00:00, 2014-Jun-15 20:00:00}; 
T:2014-Jun-16 00:00:00 

正如你所看到的，"ephemeral"是如此短暫，它就會被完全使用這種方法錯過！您可能要穿越時間插槽，而不是時間點逐步：

for (auto Slot = icl::interval<ptime>::right_open(start, start + hours(6)); 
    Slot.lower() <= (start + days(10)); 
    Slot = icl::interval<ptime>::right_open(Slot.upper(), Slot.upper() + hours(6))) 
{ 
    std::cout << "\nSlot:" << Slot << "\t"; 
    std::ostream_iterator<record> out(std::cout, ";"); 
    std::copy_if(L.begin(), L.end(), out, [Slot](record const& r) { return icl::intersects(Slot, r.validity()); }); 
} 

請參閱Live On Coliru過，並觀察"ephemeral"如何不再錯過：

... 
Slot:[2014-Jun-09 18:00:00,2014-Jun-10 00:00:00) {long, 2014-Jun-09 05:00:00, 2014-Jun-13 00:00:00}; 
Slot:[2014-Jun-10 00:00:00,2014-Jun-10 06:00:00) {long, 2014-Jun-09 05:00:00, 2014-Jun-13 00:00:00};{ephemeral, 2014-Jun-10 04:00:00, 2014-Jun-10 05:00:00}; 
Slot:[2014-Jun-10 06:00:00,2014-Jun-10 12:00:00) {long, 2014-Jun-09 05:00:00, 2014-Jun-13 00:00:00}; 
...