time_cache.h

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#ifndef ED_TIME_CACHE_H_
#define ED_TIME_CACHE_H_
 
#include "ed/time.h"
#include <map>
 
namespace ed
{
 
template<typename T>
class TimeCache
{
 
public:
 
    typedef typename std::map<Time, T>::const_iterator const_iterator;
 
    TimeCache() : max_size_(0) {}
 
    ~TimeCache() {}
 
    void insert(const Time& t, const T& value)
    {
        if (max_size_ > 0 && cache_.size() == max_size_)
            cache_.erase(cache_.begin());
        cache_[t] = value;
    }
 
    void getLowerUpper(const Time& t, const_iterator& lower, const_iterator& upper) const
    {
        if (cache_.empty())
        {
            lower = cache_.end();
            upper = cache_.end();
            return;
        }
 
        // std::map::upper_bound returns first iterator after key
        upper = cache_.upper_bound(t);
 
        if (upper == cache_.begin())
        {
            lower = cache_.end();
        }
        else
        {
            lower = upper;
            --lower;
        }
    }
 
    inline const_iterator begin() const { return cache_.begin(); }
    inline const_iterator end() const { return cache_.end(); }
 
    inline unsigned int size() const { return cache_.size(); }
 
    void setMaxSize(unsigned int n) { max_size_ = n; }
 
private:
 
    // Cache with items ordered in time
    std::map<Time, T> cache_;
 
    unsigned int max_size_;
 
};
 
} // end namespace ed
 
#endif