| 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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