1 | //
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2 | // Copyright (C) 2004 Tanguy Fautré.
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3 | // For conditions of distribution and use,
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4 | // see copyright notice in tri_stripper.h
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5 | //
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6 | //////////////////////////////////////////////////////////////////////
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7 | // SVN: $Id: heap_array.h 86 2005-06-08 17:47:27Z gpsnoopy $
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8 | //////////////////////////////////////////////////////////////////////
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9 |
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10 | #ifndef TRI_STRIPPER_HEADER_GUARD_HEAP_ARRAY_H
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11 | #define TRI_STRIPPER_HEADER_GUARD_HEAP_ARRAY_H
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12 |
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13 | #include <vector>
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14 |
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15 |
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16 |
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17 |
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18 | namespace triangle_stripper {
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19 |
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20 | namespace detail {
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21 |
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22 |
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23 |
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24 |
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25 | // mutable heap
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26 | // can be interfaced pretty muck like an array
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27 | template <class T, class CmpT = std::less<T> >
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28 | class heap_array
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29 | {
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30 | public:
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31 |
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32 | // Pre = PreCondition, Post = PostCondition
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33 |
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34 | heap_array() : m_Locked(false) { } // Post: ((size() == 0) && ! locked())
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35 |
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36 | void clear(); // Post: ((size() == 0) && ! locked())
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37 |
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38 | void reserve(size_t Size);
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39 | size_t size() const;
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40 |
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41 | bool empty() const;
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42 | bool locked() const;
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43 | bool removed(size_t i) const; // Pre: (valid(i))
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44 | bool valid(size_t i) const;
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45 |
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46 | size_t position(size_t i) const; // Pre: (valid(i))
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47 |
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48 | const T & top() const; // Pre: (! empty())
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49 | const T & peek(size_t i) const; // Pre: (! removed(i))
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50 | const T & operator [] (size_t i) const; // Pre: (! removed(i))
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51 |
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52 | void lock(); // Pre: (! locked()) Post: (locked())
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53 | size_t push(const T & Elem); // Pre: (! locked())
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54 |
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55 | void pop(); // Pre: (locked() && ! empty())
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56 | void erase(size_t i); // Pre: (locked() && ! removed(i))
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57 | void update(size_t i, const T & Elem); // Pre: (locked() && ! removed(i))
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58 |
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59 | protected:
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60 |
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61 | heap_array(const heap_array &);
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62 | heap_array & operator = (const heap_array &);
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63 |
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64 | class linker
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65 | {
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66 | public:
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67 | linker(const T & Elem, size_t i)
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68 | : m_Elem(Elem), m_Index(i) { }
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69 |
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70 | T m_Elem;
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71 | size_t m_Index;
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72 | };
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73 |
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74 | typedef std::vector<linker> linked_heap;
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75 | typedef std::vector<size_t> finder;
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76 |
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77 | void Adjust(size_t i);
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78 | void Swap(size_t a, size_t b);
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79 | bool Less(const linker & a, const linker & b) const;
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80 |
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81 | linked_heap m_Heap;
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82 | finder m_Finder;
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83 | CmpT m_Compare;
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84 | bool m_Locked;
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85 | };
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86 |
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87 |
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88 |
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89 |
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90 |
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91 | //////////////////////////////////////////////////////////////////////////
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92 | // heap_indexed inline functions
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93 | //////////////////////////////////////////////////////////////////////////
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94 |
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95 | template <class T, class CmpT>
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96 | inline void heap_array<T, CmpT>::clear()
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97 | {
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98 | m_Heap.clear();
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99 | m_Finder.clear();
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100 | m_Locked = false;
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101 | }
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102 |
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103 |
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104 | template <class T, class CmpT>
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105 | inline bool heap_array<T, CmpT>::empty() const
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106 | {
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107 | return m_Heap.empty();
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108 | }
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109 |
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110 |
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111 | template <class T, class CmpT>
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112 | inline bool heap_array<T, CmpT>::locked() const
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113 | {
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114 | return m_Locked;
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115 | }
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116 |
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117 |
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118 | template <class T, class CmpT>
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119 | inline void heap_array<T, CmpT>::reserve(const size_t Size)
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120 | {
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121 | m_Heap.reserve(Size);
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122 | m_Finder.reserve(Size);
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123 | }
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124 |
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125 |
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126 | template <class T, class CmpT>
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127 | inline size_t heap_array<T, CmpT>::size() const
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128 | {
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129 | return m_Heap.size();
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130 | }
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131 |
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132 |
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133 | template <class T, class CmpT>
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134 | inline const T & heap_array<T, CmpT>::top() const
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135 | {
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136 | assert(! empty());
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137 |
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138 | return m_Heap.front().m_Elem;
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139 | }
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140 |
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141 |
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142 | template <class T, class CmpT>
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143 | inline const T & heap_array<T, CmpT>::peek(const size_t i) const
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144 | {
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145 | assert(! removed(i));
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146 |
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147 | return (m_Heap[m_Finder[i]].m_Elem);
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148 | }
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149 |
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150 |
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151 | template <class T, class CmpT>
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152 | inline const T & heap_array<T, CmpT>::operator [] (const size_t i) const
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153 | {
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154 | return peek(i);
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155 | }
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156 |
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157 |
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158 | template <class T, class CmpT>
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159 | inline void heap_array<T, CmpT>::pop()
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160 | {
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161 | assert(locked());
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162 | assert(! empty());
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163 |
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164 | Swap(0, size() - 1);
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165 | m_Heap.pop_back();
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166 |
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167 | if (! empty())
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168 | Adjust(0);
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169 | }
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170 |
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171 |
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172 | template <class T, class CmpT>
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173 | inline void heap_array<T, CmpT>::lock()
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174 | {
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175 | assert(! locked());
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176 |
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177 | m_Locked =true;
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178 | }
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179 |
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180 |
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181 | template <class T, class CmpT>
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182 | inline size_t heap_array<T, CmpT>::push(const T & Elem)
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183 | {
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184 | assert(! locked());
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185 |
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186 | const size_t Id = size();
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187 | m_Finder.push_back(Id);
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188 | m_Heap.push_back(linker(Elem, Id));
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189 | Adjust(Id);
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190 |
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191 | return Id;
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192 | }
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193 |
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194 |
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195 | template <class T, class CmpT>
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196 | inline void heap_array<T, CmpT>::erase(const size_t i)
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197 | {
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198 | assert(locked());
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199 | assert(! removed(i));
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200 |
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201 | const size_t j = m_Finder[i];
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202 | Swap(j, size() - 1);
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203 | m_Heap.pop_back();
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204 |
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205 | if (j != size())
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206 | Adjust(j);
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207 | }
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208 |
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209 |
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210 | template <class T, class CmpT>
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211 | inline bool heap_array<T, CmpT>::removed(const size_t i) const
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212 | {
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213 | assert(valid(i));
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214 |
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215 | return (m_Finder[i] >= m_Heap.size());
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216 | }
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217 |
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218 |
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219 | template <class T, class CmpT>
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220 | inline bool heap_array<T, CmpT>::valid(const size_t i) const
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221 | {
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222 | return (i < m_Finder.size());
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223 | }
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224 |
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225 |
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226 | template <class T, class CmpT>
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227 | inline size_t heap_array<T, CmpT>::position(const size_t i) const
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228 | {
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229 | assert(valid(i));
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230 |
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231 | return (m_Heap[i].m_Index);
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232 | }
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233 |
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234 |
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235 | template <class T, class CmpT>
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236 | inline void heap_array<T, CmpT>::update(const size_t i, const T & Elem)
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237 | {
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238 | assert(locked());
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239 | assert(! removed(i));
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240 |
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241 | const size_t j = m_Finder[i];
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242 | m_Heap[j].m_Elem = Elem;
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243 | Adjust(j);
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244 | }
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245 |
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246 |
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247 | template <class T, class CmpT>
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248 | inline void heap_array<T, CmpT>::Adjust(size_t i)
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249 | {
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250 | assert(i < m_Heap.size());
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251 |
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252 | size_t j;
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253 |
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254 | // Check the upper part of the heap
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255 | for (j = i; (j > 0) && (Less(m_Heap[(j - 1) / 2], m_Heap[j])); j = ((j - 1) / 2))
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256 | Swap(j, (j - 1) / 2);
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257 |
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258 | // Check the lower part of the heap
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259 | for (i = j; (j = 2 * i + 1) < size(); i = j) {
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260 | if ((j + 1 < size()) && (Less(m_Heap[j], m_Heap[j + 1])))
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261 | ++j;
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262 |
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263 | if (Less(m_Heap[j], m_Heap[i]))
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264 | return;
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265 |
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266 | Swap(i, j);
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267 | }
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268 | }
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269 |
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270 |
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271 | template <class T, class CmpT>
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272 | inline void heap_array<T, CmpT>::Swap(const size_t a, const size_t b)
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273 | {
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274 | std::swap(m_Heap[a], m_Heap[b]);
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275 |
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276 | m_Finder[(m_Heap[a].m_Index)] = a;
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277 | m_Finder[(m_Heap[b].m_Index)] = b;
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278 | }
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279 |
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280 |
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281 | template <class T, class CmpT>
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282 | inline bool heap_array<T, CmpT>::Less(const linker & a, const linker & b) const
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283 | {
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284 | return m_Compare(a.m_Elem, b.m_Elem);
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285 | }
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286 |
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287 |
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288 |
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289 |
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290 | } // namespace detail
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291 |
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292 | } // namespace triangle_stripper
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293 |
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294 |
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295 |
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296 |
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297 | #endif // TRI_STRIPPER_HEADER_GUARD_HEAP_ARRAY_H
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