DescriptorSet.h

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/*
 * Copyright (C) 1996-2023 The Squid Software Foundation and contributors
 *
 * Squid software is distributed under GPLv2+ license and includes
 * contributions from numerous individuals and organizations.
 * Please see the COPYING and CONTRIBUTORS files for details.
 */
 
#ifndef SQUID_DESCRIPTOR_SET_H
#define SQUID_DESCRIPTOR_SET_H
 
#include <iosfwd>
 
/* TODO: Should we use std::set<int> with its flexibility? Our implementation
    has constant overhead, which is smaller than log(n) of std::set.
*/
class DescriptorSet
{
public:
    // for STL compatibility, should we decide to switch to std::set or similar
    typedef const int *const_iterator;
 
    DescriptorSet();
    ~DescriptorSet();
 
    bool has(const int fd) const {
        return 0 <= fd && fd < capacity_ &&
               index_[fd] >= 0;
    }
 
    bool add(int fd); 
    bool del(int fd); 
    int pop(); 
 
    bool empty() const { return !size_; } 
 
    const_iterator begin() const { return descriptors_; }
    const_iterator end() const { return begin() + size_; }
 
    void print(std::ostream &os) const;
 
private:
    // these would be easy to support when needed; prohibit for now
    DescriptorSet(const DescriptorSet &s); // declared but undefined
    DescriptorSet &operator =(const DescriptorSet &s); // declared, undefined
 
    int *descriptors_; 
    int *index_; 
    int capacity_; 
    int size_; 
};
 
inline std::ostream &
operator <<(std::ostream &os, const DescriptorSet &ds)
{
    ds.print(os);
    return os;
}
 
#endif /* SQUID_DESCRIPTOR_SET_H */