1 | #pragma once |
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2 | |
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3 | #include "collection.hfa" |
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4 | |
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5 | forall( dtype T ) { |
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6 | struct Queue { |
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7 | inline Collection; // Plan 9 inheritance |
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8 | T * last; // last element, or 0 if queue is empty. |
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9 | }; |
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10 | |
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11 | inline { |
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12 | // wrappers to make Collection have T |
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13 | T * head( Queue(T) & q ) with( q ) { |
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14 | return (T *)head( (Collection &)q ); |
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15 | } // post: empty() & head() == 0 | !empty() & head() in *q |
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16 | |
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17 | bool empty( Queue(T) & q ) with( q ) { // 0 <=> *q contains no elements |
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18 | return empty( (Collection &)q ); |
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19 | } |
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20 | |
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21 | bool listed( T * n ) { |
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22 | return Next( (Colable *)n ) != 0; |
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23 | } |
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24 | |
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25 | T *& Next( T * n ) { |
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26 | return (T *)Next( (Colable *)n ); |
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27 | } |
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28 | |
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29 | T * Root( Queue(T) & q ) with( q ) { |
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30 | return (T *)root; |
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31 | } |
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32 | |
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33 | void ?{}( Queue(T) &, const Queue(T) & ) = void; // no copy |
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34 | Queue(T) & ?=?( const Queue(T) & ) = void; // no assignment |
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35 | |
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36 | void ?{}( Queue(T) & q ) with( q ) { |
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37 | ((Collection &)q){}; |
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38 | last = 0p; |
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39 | } // post: empty() |
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40 | |
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41 | T * tail( Queue(T) & q ) with( q ) { |
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42 | return last; |
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43 | } |
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44 | |
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45 | T * succ( Queue(T) & q, T * n ) with( q ) { // pre: *n in *q |
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46 | #ifdef __CFA_DEBUG__ |
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47 | if ( ! listed( n ) ) abort( "(Queue &)%p.succ( %p ) : Node is not on a list.", &q, n ); |
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48 | #endif // __CFA_DEBUG__ |
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49 | return (Next( n ) == n) ? 0p : Next( n ); |
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50 | } // post: n == tail() & succ(n) == 0 | n != tail() & *succ(n) in *q |
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51 | |
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52 | void addHead( Queue(T) & q, T * n ) with( q ) { |
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53 | #ifdef __CFA_DEBUG__ |
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54 | if ( listed( n ) ) abort( "(Queue &)%p.addHead( %p ) : Node is already on another list.", &q, n ); |
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55 | #endif // __CFA_DEBUG__ |
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56 | if ( last ) { |
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57 | Next( n ) = Root( q ); |
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58 | q.root = n; |
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59 | } else { |
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60 | root = last = n; |
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61 | Next( n ) = n; // last node points to itself |
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62 | } |
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63 | } |
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64 | |
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65 | void addTail( Queue(T) & q, T * n ) with( q ) { |
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66 | #ifdef __CFA_DEBUG__ |
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67 | if ( listed( n ) ) abort( "(Queue &)%p.addTail( %p ) : Node is already on another list.", &q, n ); |
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68 | #endif // __CFA_DEBUG__ |
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69 | if ( last ) Next( last ) = n; |
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70 | else root = n; |
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71 | last = n; |
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72 | Next( n ) = n; // last node points to itself |
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73 | } |
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74 | |
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75 | void add( Queue(T) & q, T * n ) with( q ) { |
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76 | addTail( q, n ); |
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77 | } |
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78 | |
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79 | T * dropHead( Queue(T) & q ) with( q ) { |
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80 | T * t = head( q ); |
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81 | if ( root ) { |
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82 | root = Next( root ); |
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83 | if ( Root( q ) == t ) { |
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84 | root = last = 0p; // only one element |
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85 | } |
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86 | Next( t ) = 0p; |
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87 | } |
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88 | return t; |
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89 | } |
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90 | |
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91 | T * drop( Queue(T) & q ) with( q ) { |
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92 | return dropHead( q ); |
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93 | } |
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94 | |
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95 | void remove( Queue(T) & q, T * n ) with( q ) { // O(n) |
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96 | #ifdef __CFA_DEBUG__ |
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97 | if ( ! listed( (Colable &)(*n) ) ) abort( "(Queue &)%p.remove( %p ) : Node is not on a list.", &q, n ); |
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98 | #endif // __CFA_DEBUG__ |
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99 | T * prev = 0; |
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100 | T * curr = (T *)root; |
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101 | for ( ;; ) { |
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102 | if (n == curr) { // found => remove |
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103 | if ((T *)root == n) { |
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104 | dropHead( q ); |
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105 | } else if (last == n) { |
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106 | last = prev; |
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107 | Next( last ) = last; |
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108 | } else { |
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109 | Next( prev ) = Next( curr ); |
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110 | } |
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111 | Next( n ) = 0p; |
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112 | break; |
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113 | } |
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114 | #ifdef __CFA_DEBUG__ |
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115 | // not found => error |
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116 | if (curr == last) abort( "(Queue &)%p.remove( %p ) : Node is not in list.", &q, n ); |
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117 | #endif // __CFA_DEBUG__ |
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118 | prev = curr; |
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119 | curr = Next( curr ); |
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120 | } |
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121 | } // post: ! listed( n ) |
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122 | |
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123 | T * dropTail( Queue(T) & q ) with( q ) { // O(n) |
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124 | T * n = tail( q ); |
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125 | return n ? remove( q, n ), n : 0p; |
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126 | } |
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127 | |
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128 | // Transfer the "from" list to the end of queue sequence; the "from" list is empty after the transfer. |
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129 | void transfer( Queue(T) & q, Queue(T) & from ) with( q ) { |
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130 | if ( empty( from ) ) return; // "from" list empty ? |
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131 | if ( empty( q ) ) { // "to" list empty ? |
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132 | root = from.root; |
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133 | } else { // "to" list not empty |
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134 | Next( last ) = Root( from ); |
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135 | } |
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136 | last = from.last; |
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137 | from.root = from.last = 0p; // mark "from" list empty |
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138 | } |
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139 | |
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140 | // Transfer the "from" list up to node "n" to the end of queue list; the "from" list becomes the list after node "n". |
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141 | // Node "n" must be in the "from" list. |
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142 | void split( Queue(T) & q, Queue(T) & from, T * n ) with( q ) { |
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143 | #ifdef __CFA_DEBUG__ |
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144 | if ( ! listed( (Colable &)(*n) ) ) abort( "(Queue &)%p.split( %p ) : Node is not on a list.", &q, n ); |
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145 | #endif // __CFA_DEBUG__ |
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146 | Queue(T) to; |
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147 | to.root = from.root; // start of "to" list |
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148 | to.last = n; // end of "to" list |
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149 | from.root = Next( n ); // start of "from" list |
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150 | if ( n == Root( from ) ) { // last node in list ? |
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151 | from.root = from.last = 0p; // mark "from" list empty |
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152 | } else { |
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153 | Next( n ) = n; // fix end of "to" list |
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154 | } |
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155 | transfer( q, to ); |
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156 | } |
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157 | } // distribution |
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158 | } // distribution |
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159 | |
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160 | forall( dtype T ) { |
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161 | struct QueueIter { |
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162 | inline ColIter; // Plan 9 inheritance |
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163 | }; |
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164 | |
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165 | inline { |
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166 | // wrappers to make ColIter have T |
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167 | T * Curr( QueueIter(T) & qi ) with( qi ) { |
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168 | return (T *)curr; |
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169 | } |
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170 | |
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171 | void ?{}( QueueIter(T) & qi ) with( qi ) { |
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172 | ((ColIter &)qi){}; |
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173 | } // post: curr == 0p |
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174 | |
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175 | // create an iterator active in Queue q |
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176 | void ?{}( QueueIter(T) & qi, Queue(T) & q ) with( qi ) { |
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177 | curr = head( q ); |
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178 | } // post: curr = {e in q} |
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179 | |
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180 | void ?{}( QueueIter(T) & qi, T * start ) with( qi ) { |
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181 | curr = start; |
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182 | } // post: curr = {e in q} |
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183 | |
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184 | // make existing iterator active in Queue q |
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185 | void over( QueueIter(T) & qi, Queue(T) & q ) with( qi ) { |
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186 | curr = head( q ); |
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187 | } // post: curr = {e in q} |
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188 | |
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189 | bool ?>>?( QueueIter(T) & qi, T && tp ) with( qi ) { |
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190 | if ( curr ) { |
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191 | &tp = Curr( qi ); |
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192 | T * n = Next( Curr( qi ) ); |
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193 | curr = (n == Curr( qi ) ) ? 0p : n; |
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194 | } else &tp = 0p; |
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195 | return &tp != 0p; |
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196 | } |
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197 | // post: elts == null & !operator>>(tp) | elts != null & *tp' in elts & elts' == elts - *tp & operator>>(tp) |
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198 | } // distribution |
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199 | } // distribution |
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200 | |
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201 | // Local Variables: // |
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202 | // compile-command: "make install" // |
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203 | // End: // |
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