1 | // |
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2 | // Cforall Version 1.0.0 Copyright (C) 2021 University of Waterloo |
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3 | // |
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4 | // The contents of this file are covered under the licence agreement in the |
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5 | // file "LICENCE" distributed with Cforall. |
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6 | // |
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7 | // bits/sequence.hfa -- PUBLIC |
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8 | // Intrusive doubly-linked list |
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9 | // |
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10 | // Author : Colby Alexander Parsons & Peter A. Buhr |
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11 | // Created On : Thu Jan 21 19:46:50 2021 |
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12 | // Last Modified By : |
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13 | // Last Modified On : |
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14 | // Update Count : |
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15 | // |
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16 | |
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17 | #pragma once |
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18 | |
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19 | #include "bits/collection.hfa" |
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20 | #include "bits/defs.hfa" |
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21 | |
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22 | struct Seqable { |
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23 | __cfa_anonymous_object(Colable); |
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24 | // pointer to previous node in the list |
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25 | struct Seqable * back; |
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26 | }; |
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27 | |
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28 | #ifdef __cforall |
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29 | static inline { |
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30 | // PUBLIC |
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31 | |
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32 | void ?{}( Seqable & sq ) { |
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33 | ((Colable &)sq){}; |
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34 | sq.back = 0p; |
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35 | } // post: ! listed() |
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36 | |
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37 | Seqable & getBack( Seqable & sq ) with( sq ) { |
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38 | return *back; |
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39 | } |
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40 | |
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41 | // PRIVATE |
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42 | |
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43 | Seqable *& Back( Seqable * sq ) { |
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44 | return sq->back; |
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45 | } |
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46 | } // distribution |
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47 | |
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48 | |
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49 | // A Sequence(T) is a Collection(T) defining the ordering of a uStack and uQueue, and to insert and remove elements |
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50 | // anywhere in the sequence. T must be a public descendant of uSeqable. |
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51 | |
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52 | // The implementation is a typical doubly-linked list, except the next field of the last node points at the first node |
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53 | // and the back field of the last node points at the first node (circular). |
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54 | |
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55 | forall( T & ) { |
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56 | struct Sequence { |
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57 | // Plan 9 inheritance |
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58 | inline Collection; |
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59 | }; |
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60 | |
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61 | static inline { |
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62 | void ?{}( Sequence(T) &, const Sequence(T) & ) = void; // no copy |
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63 | Sequence(T) & ?=?( const Sequence(T) & ) = void; // no assignment |
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64 | |
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65 | void ?{}( Sequence(T) & s ) with( s ) { |
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66 | ((Collection &)s){}; |
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67 | } // post: isEmpty() |
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68 | } |
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69 | |
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70 | static inline forall(| { T *& Back ( T * ); T *& Next ( T * ); }) { |
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71 | // wrappers to make Collection have T |
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72 | T & head( Sequence(T) & s ) with( s ) { |
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73 | return *(T *)head( (Collection &)s ); |
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74 | } // post: empty() & head() == 0 | !empty() & head() in *s |
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75 | |
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76 | // Return a pointer to the last sequence element, without removing it. |
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77 | T & tail( Sequence(T) & s ) with( s ) { |
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78 | return root ? (T &)*Back( &head( s ) ) : *0p; |
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79 | } // post: empty() & tail() == 0 | !empty() & tail() in *s |
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80 | |
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81 | // Return a pointer to the element after *n, or 0p if list empty. |
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82 | T * succ( Sequence(T) & s, T * n ) with( s ) { // pre: *n in *s |
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83 | #ifdef __CFA_DEBUG__ |
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84 | if ( ! listed( n ) ) abort( "(Sequence &)%p.succ( %p ) : Node is not on a list.", &s, n ); |
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85 | #endif // __CFA_DEBUG__ |
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86 | return Next( n ) == &head( s ) ? 0p : Next( n ); |
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87 | } // post: n == tail() & succ(n) == 0 | n != tail() & *succ(n) in *s |
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88 | |
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89 | // Return a pointer to the element before *n, or 0p if list empty. |
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90 | T * pred( Sequence(T) & s, T * n ) with( s ) { // pre: *n in *s |
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91 | #ifdef __CFA_DEBUG__ |
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92 | if ( ! listed( n ) ) abort( "(Sequence &)%p.pred( %p ) : Node is not on a list.", &s, n ); |
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93 | #endif // __CFA_DEBUG__ |
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94 | return n == &head( s ) ? 0p : Back( n ); |
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95 | } // post: n == head() & head(n) == 0 | n != head() & *pred(n) in *s |
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96 | |
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97 | |
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98 | // Insert *n into the sequence before *bef, or at the end if bef == 0p. |
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99 | T & insertBef( Sequence(T) & s, T & n, T & bef ) with( s ) { // pre: !n->listed() & *bef in *s |
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100 | #ifdef __CFA_DEBUG__ |
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101 | if ( listed( &n ) ) abort( "(Sequence &)%p.insertBef( %p, %p ) : Node is already on another list.", &s, n, &bef ); |
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102 | #endif // __CFA_DEBUG__ |
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103 | if ( &bef == &head( s ) ) { // must change root |
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104 | if ( root ) { |
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105 | Next( &n ) = &head( s ); |
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106 | Back( &n ) = Back( &head( s ) ); |
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107 | // inserted node must be consistent before it is seen |
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108 | asm( "" : : : "memory" ); // prevent code movement across barrier |
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109 | Back( &head( s ) ) = &n; |
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110 | Next( Back( &n ) ) = &n; |
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111 | } else { |
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112 | Next( &n ) = &n; |
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113 | Back( &n ) = &n; |
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114 | } // if |
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115 | // inserted node must be consistent before it is seen |
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116 | asm( "" : : : "memory" ); // prevent code movement across barrier |
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117 | root = &n; |
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118 | } else { |
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119 | if ( ! &bef ) &bef = &head( s ); |
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120 | Next( &n ) = &bef; |
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121 | Back( &n ) = Back( &bef ); |
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122 | // inserted node must be consistent before it is seen |
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123 | asm( "" : : : "memory" ); // prevent code movement across barrier |
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124 | Back( &bef ) = &n; |
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125 | Next( Back( &n ) ) = &n; |
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126 | } // if |
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127 | return n; |
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128 | } // post: n->listed() & *n in *s & succ(n) == bef |
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129 | |
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130 | |
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131 | // Insert *n into the sequence after *aft, or at the beginning if aft == 0. |
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132 | T & insertAft( Sequence(T) & s, T & aft, T & n ) with( s ) { // pre: !n->listed() & *aft in *s |
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133 | #ifdef __CFA_DEBUG__ |
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134 | if ( listed( &n ) ) abort( "(Sequence &)%p.insertAft( %p, %p ) : Node is already on another list.", &s, &aft, &n ); |
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135 | #endif // __CFA_DEBUG__ |
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136 | if ( ! &aft ) { // must change root |
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137 | if ( root ) { |
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138 | Next( &n ) = &head( s ); |
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139 | Back( &n ) = Back( &head( s ) ); |
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140 | // inserted node must be consistent before it is seen |
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141 | asm( "" : : : "memory" ); // prevent code movement across barrier |
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142 | Back( &head( s ) ) = &n; |
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143 | Next( Back( &n ) ) = &n; |
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144 | } else { |
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145 | Next( &n ) = &n; |
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146 | Back( &n ) = &n; |
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147 | } // if |
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148 | asm( "" : : : "memory" ); // prevent code movement across barrier |
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149 | root = &n; |
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150 | } else { |
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151 | Next( &n ) = Next( &aft ); |
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152 | Back( &n ) = &aft; |
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153 | // inserted node must be consistent before it is seen |
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154 | asm( "" : : : "memory" ); // prevent code movement across barrier |
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155 | Back( Next( &n ) ) = &n; |
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156 | Next( &aft ) = &n; |
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157 | } // if |
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158 | return n; |
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159 | } // post: n->listed() & *n in *s & succ(n) == bef |
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160 | |
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161 | // pre: n->listed() & *n in *s |
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162 | T & remove( Sequence(T) & s, T & n ) with( s ) { // O(1) |
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163 | #ifdef __CFA_DEBUG__ |
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164 | if ( ! listed( &n ) ) abort( "(Sequence &)%p.remove( %p ) : Node is not on a list.", &s, &n ); |
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165 | #endif // __CFA_DEBUG__ |
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166 | if ( &n == &head( s ) ) { |
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167 | if ( Next( &head( s ) ) == &head( s ) ) root = 0p; |
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168 | else root = Next( &head( s ) ); |
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169 | } // if |
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170 | Back( Next( &n ) ) = Back( &n ); |
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171 | Next( Back( &n ) ) = Next( &n ); |
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172 | Next( &n ) = Back( &n ) = 0p; |
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173 | return n; |
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174 | } // post: !n->listed() |
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175 | |
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176 | // Add an element to the head of the sequence. |
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177 | T & addHead( Sequence(T) & s, T & n ) { // pre: !n->listed(); post: n->listed() & head() == n |
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178 | return insertAft( s, *0p, n ); |
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179 | } |
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180 | |
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181 | // Add an element to the tail of the sequence. |
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182 | T & addTail( Sequence(T) & s, T & n ) { // pre: !n->listed(); post: n->listed() & head() == n |
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183 | return insertBef( s, n, *0p ); |
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184 | } |
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185 | |
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186 | // Add an element to the tail of the sequence. |
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187 | T & add( Sequence(T) & s, T & n ) { // pre: !n->listed(); post: n->listed() & head() == n |
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188 | return addTail( s, n ); |
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189 | } |
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190 | |
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191 | // Remove and return the head element in the sequence. |
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192 | T & dropHead( Sequence(T) & s ) { |
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193 | T & n = head( s ); |
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194 | return &n ? remove( s, n ), n : *0p; |
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195 | } |
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196 | |
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197 | // Remove and return the head element in the sequence. |
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198 | T & drop( Sequence(T) & s ) { |
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199 | return dropHead( s ); |
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200 | } |
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201 | |
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202 | // Remove and return the tail element in the sequence. |
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203 | T & dropTail( Sequence(T) & s ) { |
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204 | T & n = tail( s ); |
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205 | return &n ? remove( s, n ), n : *0p; |
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206 | } |
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207 | |
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208 | // Transfer the "from" list to the end of s sequence; the "from" list is empty after the transfer. |
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209 | void transfer( Sequence(T) & s, Sequence(T) & from ) with( s ) { |
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210 | if ( empty( from ) ) return; // "from" list empty ? |
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211 | if ( empty( s ) ) { // "to" list empty ? |
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212 | root = from.root; |
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213 | } else { // "to" list not empty |
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214 | T * toEnd = Back( &head( s ) ); |
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215 | T * fromEnd = Back( &head( from ) ); |
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216 | Back( (T *)root ) = fromEnd; |
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217 | Next( fromEnd ) = &head( s ); |
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218 | Back( (T *)from.root ) = toEnd; |
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219 | Next( toEnd ) = &head( from ); |
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220 | } // if |
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221 | from.root = 0p; // mark "from" list empty |
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222 | } |
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223 | |
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224 | // Transfer the "from" list up to node "n" to the end of s list; the "from" list becomes the sequence after node "n". |
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225 | // Node "n" must be in the "from" list. |
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226 | void split( Sequence(T) & s, Sequence(T) & from, T & n ) with( s ) { |
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227 | #ifdef __CFA_DEBUG__ |
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228 | if ( ! listed( &n ) ) abort( "(Sequence &)%p.split( %p ) : Node is not on a list.", &s, &n ); |
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229 | #endif // __CFA_DEBUG__ |
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230 | Sequence(T) to; |
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231 | to.root = from.root; // start of "to" list |
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232 | from.root = Next( &n ); // start of "from" list |
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233 | if ( to.root == from.root ) { // last node in list ? |
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234 | from.root = 0p; // mark "from" list empty |
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235 | } else { |
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236 | Back( &head( from ) ) = Back( &head( to ) ); // fix "from" list |
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237 | Next( Back( &head( to ) ) ) = &head( from ); |
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238 | Next( &n ) = &head( to ); // fix "to" list |
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239 | Back( &head( to ) ) = &n; |
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240 | } // if |
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241 | transfer( s, to ); |
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242 | } |
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243 | } // distribution |
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244 | } // distribution |
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245 | |
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246 | forall( T & | { T *& Back ( T * ); T *& Next ( T * ); } ) { |
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247 | // SeqIter(T) is used to iterate over a Sequence(T) in head-to-tail order. |
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248 | struct SeqIter { |
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249 | inline ColIter; |
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250 | // The Sequence must be passed to pred and succ to check for the end of the Sequence and return 0p. Without |
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251 | // passing the sequence, traversing would require its length. Thus the iterator needs a pointer to the sequence |
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252 | // to pass to succ/pred. Both stack and queue just encounter 0p since the lists are not circular. |
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253 | Sequence(T) * seq; // FIX ME: cannot be reference |
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254 | }; |
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255 | |
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256 | static inline { |
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257 | void ?{}( SeqIter(T) & si ) with( si ) { |
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258 | ((ColIter &)si){}; |
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259 | seq = 0p; |
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260 | } // post: elts = null |
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261 | |
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262 | // Create a iterator active in sequence s. |
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263 | void ?{}( SeqIter(T) & si, Sequence(T) & s ) with( si ) { |
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264 | ((ColIter &)si){}; |
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265 | seq = &s; |
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266 | curr = &head( s ); |
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267 | } // post: elts = null |
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268 | |
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269 | void ?{}( SeqIter(T) & si, Sequence(T) & s, T & start ) with( si ) { |
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270 | ((ColIter &)si){}; |
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271 | seq = &s; |
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272 | curr = &start; |
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273 | } // post: elts = null |
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274 | |
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275 | // Make the iterator active in sequence s. |
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276 | void over( SeqIter(T) & si, Sequence(T) & s ) with( si ) { |
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277 | seq = &s; |
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278 | curr = &head( s ); |
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279 | } // post: elts = {e in s} |
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280 | |
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281 | bool ?|?( SeqIter(T) & si, T && tp ) with( si ) { |
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282 | if ( curr ) { |
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283 | &tp = Curr( si ); |
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284 | T * n = succ( *seq, Curr( si ) ); |
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285 | curr = n == &head( *seq ) ? 0p : n; |
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286 | } else &tp = 0p; |
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287 | return &tp != 0p; |
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288 | } |
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289 | } // distribution |
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290 | |
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291 | |
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292 | // A SeqIterRev(T) is used to iterate over a Sequence(T) in tail-to-head order. |
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293 | struct SeqIterRev { |
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294 | inline ColIter; |
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295 | // See above for explanation. |
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296 | Sequence(T) * seq; // FIX ME: cannot be reference |
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297 | }; |
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298 | |
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299 | static inline { |
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300 | void ?{}( SeqIterRev(T) & si ) with( si ) { |
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301 | ((ColIter &)si){}; |
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302 | seq = 0p; |
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303 | } // post: elts = null |
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304 | |
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305 | // Create a iterator active in sequence s. |
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306 | void ?{}( SeqIterRev(T) & si, Sequence(T) & s ) with( si ) { |
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307 | ((ColIter &)si){}; |
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308 | seq = &s; |
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309 | curr = &tail( s ); |
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310 | } // post: elts = null |
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311 | |
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312 | void ?{}( SeqIterRev(T) & si, Sequence(T) & s, T & start ) with( si ) { |
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313 | ((ColIter &)si){}; |
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314 | seq = &s; |
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315 | curr = &start; |
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316 | } // post: elts = null |
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317 | |
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318 | // Make the iterator active in sequence s. |
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319 | void over( SeqIterRev(T) & si, Sequence(T) & s ) with( si ) { |
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320 | seq = &s; |
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321 | curr = &tail( s ); |
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322 | } // post: elts = {e in s} |
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323 | |
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324 | bool ?|?( SeqIterRev(T) & si, T && tp ) with( si ) { |
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325 | if ( curr ) { |
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326 | &tp = Curr( si ); |
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327 | T * n = pred( *seq, Curr( si ) ); |
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328 | curr = n == &tail( *seq ) ? 0p : n; |
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329 | } else &tp = 0p; |
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330 | return &tp != 0p; |
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331 | } |
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332 | } // distribution |
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333 | } // distribution |
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334 | |
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335 | #endif |
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