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| author | graehl <graehl@ec762483-ff6d-05da-a07a-a48fb63a330f> | 2010-08-21 00:39:39 +0000 | 
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| committer | graehl <graehl@ec762483-ff6d-05da-a07a-a48fb63a330f> | 2010-08-21 00:39:39 +0000 | 
| commit | bb480adcc7177a76e2f3d2e1c428fa729ce067d3 (patch) | |
| tree | 938c4193b4bfa38e6abe3594037dedede6366621 /utils/d_ary_heap.hpp | |
| parent | 35d409935c9085ed481ec5b7cf17fde4ac6e8afc (diff) | |
rename
git-svn-id: https://ws10smt.googlecode.com/svn/trunk@607 ec762483-ff6d-05da-a07a-a48fb63a330f
Diffstat (limited to 'utils/d_ary_heap.hpp')
| -rw-r--r-- | utils/d_ary_heap.hpp | 305 | 
1 files changed, 0 insertions, 305 deletions
diff --git a/utils/d_ary_heap.hpp b/utils/d_ary_heap.hpp deleted file mode 100644 index 2ec716d3..00000000 --- a/utils/d_ary_heap.hpp +++ /dev/null @@ -1,305 +0,0 @@ -// -//======================================================================= -// Copyright 2009 Trustees of Indiana University -// Authors: Jeremiah J. Willcock, Andrew Lumsdaine -// -// 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) -//======================================================================= -// -#ifndef BOOST_D_ARY_HEAP_HPP -#define BOOST_D_ARY_HEAP_HPP - -#include <vector> -#include <cstddef> -#include <algorithm> -#include <utility> -#include <cassert> -#include <boost/static_assert.hpp> -#include <boost/shared_array.hpp> -#include <boost/property_map/property_map.hpp> - -namespace boost { - -  // Swap two elements in a property map without assuming they model -  // LvaluePropertyMap -- currently not used -  template <typename PropMap> -  inline void property_map_swap( -         PropMap prop_map, -         const typename boost::property_traits<PropMap>::key_type& ka,  -         const typename boost::property_traits<PropMap>::key_type& kb) { -    typename boost::property_traits<PropMap>::value_type va = get(prop_map, ka); -    put(prop_map, ka, get(prop_map, kb)); -    put(prop_map, kb, va); -  } - -  namespace detail { -    template <typename Value> -    class fixed_max_size_vector { -      boost::shared_array<Value> m_data; -      std::size_t m_size; - -      public: -      typedef std::size_t size_type; -      fixed_max_size_vector(std::size_t max_size) -        : m_data(new Value[max_size]), m_size(0) {} -      std::size_t size() const {return m_size;} -      bool empty() const {return m_size == 0;} -      Value& operator[](std::size_t i) {return m_data[i];} -      const Value& operator[](std::size_t i) const {return m_data[i];} -      void push_back(Value v) {m_data[m_size++] = v;} -      void pop_back() {--m_size;} -      Value& back() {return m_data[m_size - 1];} -      const Value& back() const {return m_data[m_size - 1];} -    }; -  } - -  // D-ary heap using an indirect compare operator (use identity_property_map -  // as DistanceMap to get a direct compare operator).  This heap appears to be -  // commonly used for Dijkstra's algorithm for its good practical performance -  // on some platforms; asymptotically, it has an O(lg N) decrease-key -  // operation while that can be done in constant time on a relaxed heap.  The -  // implementation is mostly based on the binary heap page on Wikipedia and -  // online sources that state that the operations are the same for d-ary -  // heaps.  This code is not based on the old Boost d-ary heap code. -  // -  // - d_ary_heap_indirect is a model of UpdatableQueue as is needed for -  //   dijkstra_shortest_paths. -  // -  // - Value must model Assignable. -  // - Arity must be at least 2 (optimal value appears to be 4, both in my and -  //   third-party experiments). -  // - IndexInHeapMap must be a ReadWritePropertyMap from Value to -  //   Container::size_type (to store the index of each stored value within the -  //   heap for decrease-key aka update). -  // - DistanceMap must be a ReadablePropertyMap from Value to something -  //   (typedef'ed as distance_type). -  // - Compare must be a BinaryPredicate used as a less-than operator on -  //   distance_type. -  // - Container must be a random-access, contiguous container (in practice, -  //   the operations used probably require that it is std::vector<Value>). -  // -  template <typename Value, -            std::size_t Arity, -            typename IndexInHeapPropertyMap, -            typename DistanceMap, -            typename Compare = std::less<Value>, -            typename Container = std::vector<Value> > -  class d_ary_heap_indirect { -    BOOST_STATIC_ASSERT (Arity >= 2); - -    public: -    typedef typename Container::size_type size_type; -    typedef Value value_type; - -    d_ary_heap_indirect(DistanceMap distance, -                        IndexInHeapPropertyMap index_in_heap, -                        const Compare& compare = Compare(), -                        const Container& data = Container()) -      : compare(compare), data(data), distance(distance), -        index_in_heap(index_in_heap) {} -    /* Implicit copy constructor */ -    /* Implicit assignment operator */ - -    size_type size() const { -      return data.size(); -    } - -    bool empty() const { -      return data.empty(); -    } - -    void push(const Value& v) { -      size_type index = data.size(); -      data.push_back(v); -      put(index_in_heap, v, index); -      preserve_heap_property_up(index); -      verify_heap(); -    } - -    Value& top() { -      return data[0]; -    } - -    const Value& top() const { -      return data[0]; -    } - -    void pop() { -      put(index_in_heap, data[0], (size_type)(-1)); -      if (data.size() != 1) { -        data[0] = data.back(); -        put(index_in_heap, data[0], 0); -        data.pop_back(); -        preserve_heap_property_down(); -        verify_heap(); -      } else { -        data.pop_back(); -      } -    } - -    // This function assumes the key has been updated (using an external write -    // to the distance map or such) -    // See http://coding.derkeiler.com/Archive/General/comp.theory/2007-05/msg00043.html -    void update(const Value& v) { /* decrease-key */ -      size_type index = get(index_in_heap, v); -      preserve_heap_property_up(index); -      verify_heap(); -    } - -    bool contains(const Value& v) const { -      size_type index = get(index_in_heap, v); -      return (index != (size_type)(-1)); -    } - -    void push_or_update(const Value& v) { /* insert if not present, else update */ -      size_type index = get(index_in_heap, v); -      if (index == (size_type)(-1)) { -        index = data.size(); -        data.push_back(v); -        put(index_in_heap, v, index); -      } -      preserve_heap_property_up(index); -      verify_heap(); -    } - -    private: -    Compare compare; -    Container data; -    DistanceMap distance; -    IndexInHeapPropertyMap index_in_heap; - -    // The distances being compared using compare and that are stored in the -    // distance map -    typedef typename boost::property_traits<DistanceMap>::value_type distance_type; - -    // Get the parent of a given node in the heap -    static size_type parent(size_type index) { -      return (index - 1) / Arity; -    } - -    // Get the child_idx'th child of a given node; 0 <= child_idx < Arity -    static size_type child(size_type index, std::size_t child_idx) { -      return index * Arity + child_idx + 1; -    } - -    // Swap two elements in the heap by index, updating index_in_heap -    void swap_heap_elements(size_type index_a, size_type index_b) { -      using std::swap; -      Value value_a = data[index_a]; -      Value value_b = data[index_b]; -      data[index_a] = value_b; -      data[index_b] = value_a; -      put(index_in_heap, value_a, index_b); -      put(index_in_heap, value_b, index_a); -    } - -    // Emulate the indirect_cmp that is now folded into this heap class -    bool compare_indirect(const Value& a, const Value& b) const { -      return compare(get(distance, a), get(distance, b)); -    } - -    // Verify that the array forms a heap; commented out by default -    void verify_heap() const { -      // This is a very expensive test so it should be disabled even when -      // NDEBUG is not defined -#if 0 -      for (size_t i = 1; i < data.size(); ++i) { -        if (compare_indirect(data[i], data[parent(i)])) { -          assert (!"Element is smaller than its parent"); -        } -      } -#endif -    } - -    // Starting at a node, move up the tree swapping elements to preserve the -    // heap property -    void preserve_heap_property_up(size_type index) { -      size_type orig_index = index; -      size_type num_levels_moved = 0; -      // The first loop just saves swaps that need to be done in order to avoid -      // aliasing issues in its search; there is a second loop that does the -      // necessary swap operations -      if (index == 0) return; // Do nothing on root -      Value currently_being_moved = data[index]; -      distance_type currently_being_moved_dist = -        get(distance, currently_being_moved); -      for (;;) { -        if (index == 0) break; // Stop at root -        size_type parent_index = parent(index); -        Value parent_value = data[parent_index]; -        if (compare(currently_being_moved_dist, get(distance, parent_value))) { -          ++num_levels_moved; -          index = parent_index; -          continue; -        } else { -          break; // Heap property satisfied -        } -      } -      // Actually do the moves -- move num_levels_moved elements down in the -      // tree, then put currently_being_moved at the top -      index = orig_index; -      for (size_type i = 0; i < num_levels_moved; ++i) { -        size_type parent_index = parent(index); -        Value parent_value = data[parent_index]; -        put(index_in_heap, parent_value, index); -        data[index] = parent_value; -        index = parent_index; -      } -      data[index] = currently_being_moved; -      put(index_in_heap, currently_being_moved, index); -      verify_heap(); -    } - -    // From the root, swap elements (each one with its smallest child) if there -    // are any parent-child pairs that violate the heap property -    void preserve_heap_property_down() { -      if (data.empty()) return; -      size_type index = 0; -      Value currently_being_moved = data[0]; -      distance_type currently_being_moved_dist = -        get(distance, currently_being_moved); -      size_type heap_size = data.size(); -      Value* data_ptr = &data[0]; -      for (;;) { -        size_type first_child_index = child(index, 0); -        if (first_child_index >= heap_size) break; /* No children */ -        Value* child_base_ptr = data_ptr + first_child_index; -        size_type smallest_child_index = 0; -        distance_type smallest_child_dist = get(distance, child_base_ptr[smallest_child_index]); -        if (first_child_index + Arity <= heap_size) { -          // Special case for a statically known loop count (common case) -          for (size_t i = 1; i < Arity; ++i) { -            Value i_value = child_base_ptr[i]; -            distance_type i_dist = get(distance, i_value); -            if (compare(i_dist, smallest_child_dist)) { -              smallest_child_index = i; -              smallest_child_dist = i_dist; -            } -          } -        } else { -          for (size_t i = 1; i < heap_size - first_child_index; ++i) { -            distance_type i_dist = get(distance, child_base_ptr[i]); -            if (compare(i_dist, smallest_child_dist)) { -              smallest_child_index = i; -              smallest_child_dist = i_dist; -            } -          } -        } -        if (compare(smallest_child_dist, currently_being_moved_dist)) { -          swap_heap_elements(smallest_child_index + first_child_index, index); -          index = smallest_child_index + first_child_index; -          continue; -        } else { -          break; // Heap property satisfied -        } -      } -      verify_heap(); -    } - -  }; - -} // namespace boost - -#endif // BOOST_D_ARY_HEAP_HPP  | 
