Key-value flyweights reference

flyweight reference

Boost.Flyweight reference

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Contents

• Key extractors
• Header "boost/flyweight/key_value_fwd.hpp" synopsis
• Header "boost/flyweight/key_value.hpp" synopsis
  • Class template key_value

Key extractors

Let Key be a type with some implicit equivalence relationship and Value a type constructible from Key. A Default Constructible type KeyFromValue is said to be a key extractor from Value to Key if

1. kfv(cv) is defined and have type const Key&,
2. kfv(cv) is equivalent to kfv(Value(cv)),
3. kfv(Value(k)) is equivalent to k,

Header "boost/flyweight/key_value_fwd.hpp" synopsis

namespace boost{

namespace flyweights{

struct no_key_from_value;

template<
  typename Key,typename Value,
  typename KeyFromValue=no_key_from_value
>
struct key_value;

} // namespace boost::flyweights

} // namespace boost

Header "boost/flyweight/key_value.hpp" synopsis

Class template key_value

In flyweight instantiations of the form flyweight<T,...>, the associated key_type and value_type are both equal to T. Instantiations of the form flyweight<key_value<Key,Value[,KeyFromValue]>,...> allow to specify these types separately. Key and Value must be different types. When provided, KeyFromValue must be a Key Extractor from Value to Key.

flyweight reference

Boost.Flyweight reference

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Revised April 24th 2019

© Copyright 2006-2019 Joaquín M López Muñoz. Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)