ah-unique.H

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/*
                          Aleph_w
 
  Data structures & Algorithms
  version 2.0.0b
  https://github.com/lrleon/Aleph-w
 
  This file is part of Aleph-w library
 
  Copyright (c) 2002-2026 Leandro Rabindranath Leon
 
  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:
 
  The above copyright notice and this permission notice shall be included in all
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  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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*/
 
#ifndef AH_UNIQUE_H
#define AH_UNIQUE_H
 
#include <concepts>
#include <set>
#include <ah-concepts.H>
 
namespace Aleph {
 
  template <class Container>
  concept AlephSequential = requires(Container c,
                                     typename Container::Key_Type v,
                                     bool (&op)(typename Container::Key_Type &))
  {
    typename Container::Key_Type;
    { c.traverse(op) } -> std::convertible_to<bool>;
    c.append(v);
    c.swap(c);
    { c.size() } -> std::convertible_to<size_t>;
  };
 
  template <AlephSequential Container,
            class Compare = std::less<typename Container::Key_Type>>
    requires Aleph::StrictWeakOrder<Compare, typename Container::Key_Type>
  void in_place_unique(Container & c, Compare cmp = {})
  {
    using Key = typename Container::Key_Type;
 
    std::set<Key, Compare> seen(cmp);
    Container clean;
 
    // Reserve only for vector-like containers (e.g. Array) where reserve()
    // does not change logical size. DynArray is intentionally excluded.
    if constexpr (requires(Container & x)
                  {
                    { x.capacity() } -> std::convertible_to<size_t>;
                    x.reserve(size_t{});
                  })
      if (clean.capacity() < c.size())
        clean.reserve(c.size());
 
    c.traverse([&](Key & item)
               {
                 if (seen.contains(item))
                   return true; // skip duplicates
 
                 seen.insert(item);
                 clean.append(item);
                 return true;
               });
 
    c.swap(clean);
  }
 
} // namespace Aleph
 
#endif // AH_UNIQUE_H