88 lines
3.1 KiB
C++
88 lines
3.1 KiB
C++
/////////////////////////////////////////////////////////////////////////////
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//
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// (C) Copyright Ion Gaztanaga 2007-2013
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//
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// Distributed under the Boost Software License, Version 1.0.
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// (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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//
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// See http://www.boost.org/libs/intrusive for documentation.
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//
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/////////////////////////////////////////////////////////////////////////////
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//[doc_stateful_value_traits
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#include <boost/intrusive/list.hpp>
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using namespace boost::intrusive;
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//This type is not modifiable so we can't store hooks or custom nodes
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typedef int identifier_t;
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//This value traits will associate elements from an array of identifiers with
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//elements of an array of nodes. The element i of the value array will use the
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//node i of the node array:
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struct stateful_value_traits
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{
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typedef list_node_traits<void*> node_traits;
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typedef node_traits::node node;
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typedef node * node_ptr;
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typedef const node * const_node_ptr;
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typedef identifier_t value_type;
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typedef identifier_t * pointer;
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typedef const identifier_t * const_pointer;
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static const link_mode_type link_mode = normal_link;
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stateful_value_traits(pointer ids, node_ptr node_array)
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: ids_(ids), nodes_(node_array)
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{}
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///Note: non static functions!
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node_ptr to_node_ptr (value_type &value) const
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{ return this->nodes_ + (&value - this->ids_); }
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const_node_ptr to_node_ptr (const value_type &value) const
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{ return this->nodes_ + (&value - this->ids_); }
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pointer to_value_ptr(node_ptr n) const
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{ return this->ids_ + (n - this->nodes_); }
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const_pointer to_value_ptr(const_node_ptr n) const
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{ return this->ids_ + (n - this->nodes_); }
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private:
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pointer ids_;
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node_ptr nodes_;
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};
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int main()
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{
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const int NumElements = 100;
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//This is an array of ids that we want to "store"
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identifier_t ids [NumElements];
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//This is an array of nodes that is necessary to form the linked list
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list_node_traits<void*>::node nodes [NumElements];
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//Initialize id objects, each one with a different number
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for(int i = 0; i != NumElements; ++i) ids[i] = i;
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//Define a list that will "link" identifiers using external nodes
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typedef list<identifier_t, value_traits<stateful_value_traits> > List;
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//This list will store ids without modifying identifier_t instances
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//Stateful value traits must be explicitly passed in the constructor.
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List my_list (stateful_value_traits (ids, nodes));
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//Insert ids in reverse order in the list
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for(identifier_t * it(&ids[0]), *itend(&ids[NumElements]); it != itend; ++it)
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my_list.push_front(*it);
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//Now test lists
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List::const_iterator list_it (my_list.cbegin());
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identifier_t *it_val(&ids[NumElements]), *it_rbeg_val(&ids[0]);
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//Test the objects inserted in the base hook list
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for(; it_val != it_rbeg_val; --it_val, ++list_it)
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if(&*list_it != &it_val[-1]) return 1;
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return 0;
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}
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//]
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