SerializeSTL.h

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* (c) Copyright 1998-2025 CERN for the benefit of the LHCb and ATLAS collaborations *
*                                                                                   *
* This software is distributed under the terms of the Apache version 2 licence,     *
* copied verbatim in the file "LICENSE".                                            *
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#pragma once
 
#include <array>
#include <list>
#include <map>
#include <ostream>
#include <set>
#include <unordered_set>
#include <utility>
#include <vector>
 
namespace GaudiUtils {
  template <class T1, class T2>
  std::ostream& operator<<( std::ostream& s, const std::pair<T1, T2>& p );

  template <typename... Args>
  std::ostream& operator<<( std::ostream& s, const std::tuple<Args...>& tuple );

  template <class T, class ALLOC>
  std::ostream& operator<<( std::ostream& s, const std::vector<T, ALLOC>& v );

  template <class T, std::size_t N>
  std::ostream& operator<<( std::ostream& s, const std::array<T, N>& v );

  template <class T, class ALLOC>
  std::ostream& operator<<( std::ostream& s, const std::list<T, ALLOC>& l );

  template <class T, class ALLOC>
  std::ostream& operator<<( std::ostream& s, const std::set<T, ALLOC>& l );

  template <class T, class ALLOC>
  std::ostream& operator<<( std::ostream& s, const std::unordered_set<T, ALLOC>& l );

  template <class T1, class T2, class COMP, class ALLOC>
  std::ostream& operator<<( std::ostream& s, const std::map<T1, T2, COMP, ALLOC>& m );
 
  namespace details {
 
    struct IdentityOutputter {
      template <typename T>
      std::ostream& operator()( std::ostream& os, T&& t ) const {
        return os << std::forward<T>( t );
      }
    };
 
    template <typename Stream, typename Iterator, typename Separator, typename OutputElement = IdentityOutputter>
    Stream& ostream_joiner( Stream& os, Iterator first, Iterator last, Separator sep,
                            OutputElement output = OutputElement{} ) {
      if ( first != last ) output( os, *first++ );
      while ( first != last ) output( os << sep, *first++ );
      return os;
    }
 
    template <typename Stream, typename Container, typename Separator, typename OutputElement = IdentityOutputter>
    Stream& ostream_joiner( Stream& os, const Container& c, Separator sep, OutputElement output = OutputElement{} ) {
      using std::begin, std::end;
      return ostream_joiner( os, begin( c ), end( c ), sep, output );
    }
  } // namespace details
 
  template <class T1, class T2>
  std::ostream& operator<<( std::ostream& s, const std::pair<T1, T2>& p ) {
    return s << '(' << p.first << ", " << p.second << ')';
  }
 
  template <typename... Args>
  std::ostream& operator<<( std::ostream& s, const std::tuple<Args...>& tup ) {
    return std::apply(
        [&s]( const auto&... a ) -> decltype( auto ) {
          unsigned n = sizeof...( a );
          if ( n == 1 ) n = 2; // special case in python...
          s << " (";
          ( ( s << " " << a << ( --n == 0 ? "" : "," ) ), ... );
          return s << " )";
        },
        tup );
  }
 
  template <class T, class ALLOC>
  std::ostream& operator<<( std::ostream& s, const std::vector<T, ALLOC>& v ) {
    return details::ostream_joiner( s << '[', v, ", " ) << ']';
  }
 
  template <class T, std::size_t N>
  std::ostream& operator<<( std::ostream& s, const std::array<T, N>& v ) {
    return details::ostream_joiner( s << '[', v, ", " ) << ']';
  }
 
  template <class T, class ALLOC>
  std::ostream& operator<<( std::ostream& s, const std::list<T, ALLOC>& l ) {
    return details::ostream_joiner( s << '[', l, ", " ) << ']';
  }
 
  template <class T, class ALLOC>
  std::ostream& operator<<( std::ostream& s, const std::set<T, ALLOC>& l ) {
    return details::ostream_joiner( s << '[', l, ", " ) << ']';
  }
 
  template <class T, class ALLOC>
  std::ostream& operator<<( std::ostream& s, const std::unordered_set<T, ALLOC>& l ) {
    auto ordered = std::set( l.begin(), l.end() ); // ensure reproducible printout
    s << ordered;
    return s;
  }
 
  template <class T1, class T2, class COMP, class ALLOC>
  std::ostream& operator<<( std::ostream& s, const std::map<T1, T2, COMP, ALLOC>& m ) {
    return details::ostream_joiner( s << "{", m, ", ",
                                    []( std::ostream& os, const std::pair<const T1, T2>& p ) -> std::ostream& {
                                      return os << p.first << ": " << p.second;
                                    } )
           << "}";
  }
 
} // namespace GaudiUtils