| 1 | //
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| 2 | // Cforall Version 1.0.0 Copyright (C) 2015 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 | // Cost.h --
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| 8 | //
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| 9 | // Author           : Peter Buhr and Aaron Moss
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| 10 | // Created On       : Sun May 17 09:39:50 2015
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| 11 | // Last Modified By : Peter A. Buhr
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| 12 | // Last Modified On : Fri Jun 21 11:39:13 2019
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| 13 | // Update Count     : 63
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| 14 | //
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| 15 | 
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| 16 | #pragma once
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| 17 | 
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| 18 | #include <iostream>
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| 19 | #include <cassert>
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| 20 | #include <climits>
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| 21 | 
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| 22 | namespace ResolvExpr {
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| 23 |         // To maximize performance and space, the 7 resolution costs are packed into a single 64-bit word. However, the
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| 24 |         // specialization cost is a negative value so a correction is needed is a few places.
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| 25 | 
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| 26 |         class Cost {
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| 27 |                 union {
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| 28 |                         struct {
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| 29 |                         #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
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| 30 |                                 // Little-endian => first value is low priority and last is high priority.
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| 31 |                                 unsigned char padding;                                  ///< unused
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| 32 |                                 unsigned char referenceCost;                    ///< reference conversions
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| 33 |                                 unsigned char specCost;                                 ///< Polymorphic type specializations (type assertions), negative cost
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| 34 |                                 unsigned char varCost;                                  ///< Count of polymorphic type variables
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| 35 |                                 unsigned char signCost;                                 ///< Count of safe sign conversions
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| 36 |                                 unsigned char safeCost;                                 ///< Safe (widening) conversions
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| 37 |                                 unsigned char polyCost;                                 ///< Count of parameters and return values bound to some poly type
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| 38 |                                 unsigned char unsafeCost;                               ///< Unsafe (narrowing) conversions
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| 39 |                         #else
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| 40 |                                 #error Cost BIG_ENDIAN unsupported
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| 41 |                         #endif
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| 42 |                         } v;
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| 43 |                         uint64_t all;
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| 44 |                 };
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| 45 |                 static const unsigned char correctb = 0xff;             // byte correction for negative spec cost
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| 46 |                 static const uint64_t correctw = 0x00'00'00'00'00'ff'00'00; //' word correction for negative spec cost
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| 47 |           public:
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| 48 |                 // Compiler adjusts constants for correct endian.
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| 49 |                 enum : uint64_t {
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| 50 |                         zero      = 0x00'00'00'00'00'ff'00'00,
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| 51 |                         infinity  = 0xff'ff'ff'ff'ff'00'ff'ff,
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| 52 |                         unsafe    = 0x01'00'00'00'00'ff'00'00,
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| 53 |                         poly      = 0x00'01'00'00'00'ff'00'00,
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| 54 |                         safe      = 0x00'00'01'00'00'ff'00'00,
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| 55 |                         sign      = 0x00'00'00'01'00'ff'00'00,
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| 56 |                         var       = 0x00'00'00'00'01'ff'00'00,
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| 57 |                         spec      = 0x00'00'00'00'00'fe'00'00,
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| 58 |                         reference = 0x00'00'00'00'00'ff'01'00,
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| 59 |                 }; //'
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| 60 | 
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| 61 |                 Cost( uint64_t all ) { Cost::all = all; }
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| 62 |                 Cost( int unsafeCost, int polyCost, int safeCost, int signCost, int varCost, int specCost, int referenceCost ) {
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| 63 |                         // Assume little-endian => first value is low priority and last is high priority.
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| 64 |                         v = {
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| 65 |                         #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
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| 66 |                                 (unsigned char)0,                                               // padding
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| 67 |                                 (unsigned char)referenceCost,                   // low priority
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| 68 |                                 (unsigned char)(specCost + correctb),   // correct for signedness
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| 69 |                                 (unsigned char)varCost, 
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| 70 |                                 (unsigned char)signCost, 
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| 71 |                                 (unsigned char)safeCost, 
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| 72 |                                 (unsigned char)polyCost, 
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| 73 |                                 (unsigned char)unsafeCost,                              // high priority
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| 74 |                         #else
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| 75 |                                 #error Cost BIG_ENDIAN unsupported
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| 76 |                         #endif
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| 77 |                         };
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| 78 |                 }
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| 79 | 
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| 80 |                 int get_unsafeCost() const { return v.unsafeCost; }
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| 81 |                 int get_polyCost() const { return v.polyCost; }
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| 82 |                 int get_safeCost() const { return v.safeCost; }
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| 83 |                 int get_signCost() const { return v.signCost; }
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| 84 |                 int get_varCost() const { return v.varCost; }
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| 85 |                 int get_specCost() const { return -(correctb - v.specCost); }
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| 86 |                 int get_referenceCost() const { return v.referenceCost; }
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| 87 | 
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| 88 |                 friend bool operator==( const Cost, const Cost );
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| 89 |                 friend bool operator!=( const Cost lhs, const Cost rhs );
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| 90 |                 // returns negative for *this < rhs, 0 for *this == rhs, positive for *this > rhs
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| 91 |                 int compare( const Cost rhs ) const {
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| 92 |                         if ( all == infinity ) return 1;
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| 93 |                         if ( rhs.all == infinity ) return -1;
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| 94 |                         return all > rhs.all ? 1 : all == rhs.all ? 0 : -1;
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| 95 |                 }
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| 96 |                 friend bool operator<( const Cost lhs, const Cost rhs );
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| 97 | 
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| 98 |                 friend Cost operator+( const Cost lhs, const Cost rhs );
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| 99 |  
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| 100 |                 Cost operator+=( const Cost rhs ) {
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| 101 |                         if ( all == infinity ) return *this;
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| 102 |                         if ( rhs.all == infinity ) {
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| 103 |                                 all = infinity;
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| 104 |                                 return *this;
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| 105 |                         }
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| 106 |                         all += rhs.all - correctw;                                      // correct for negative spec cost
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| 107 |                         return *this;
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| 108 |                 }
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| 109 | 
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| 110 |                 Cost incUnsafe( int inc = 1 ) {
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| 111 |                         if ( all != infinity ) { assert( v.unsafeCost + inc <= UCHAR_MAX ); v.unsafeCost += inc; }
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| 112 |                         return *this;
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| 113 |                 }
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| 114 | 
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| 115 |                 Cost incPoly( int inc = 1 ) {
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| 116 |                         if ( all != infinity ) { assert( v.polyCost + inc <= UCHAR_MAX ); v.polyCost += inc; }
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| 117 |                         return *this;
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| 118 |                 }
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| 119 | 
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| 120 |                 Cost incSafe( int inc = 1 ) {
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| 121 |                         if ( all != infinity ) { assert( v.safeCost + inc <= UCHAR_MAX ); v.safeCost += inc; }
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| 122 |                         return *this;
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| 123 |                 }
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| 124 | 
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| 125 |                 Cost incSign( int inc = 1 ) {
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| 126 |                         if ( all != infinity ) { assert( v.signCost + inc <= UCHAR_MAX ); v.signCost += inc; }
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| 127 |                         return *this;
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| 128 |                 }
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| 129 | 
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| 130 |                 Cost incVar( int inc = 1 ) {
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| 131 |                         if ( all != infinity ) { assert( v.varCost + inc <= UCHAR_MAX ); v.varCost += inc; }
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| 132 |                         return *this;
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| 133 |                 }
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| 134 | 
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| 135 |                 Cost decSpec( int dec = 1 ) {
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| 136 |                         if ( all != infinity ) { assert( v.specCost - dec >= 0 ); v.specCost -= dec; }
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| 137 |                         return *this;
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| 138 |                 }
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| 139 | 
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| 140 |                 Cost incReference( int inc = 1 ) {
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| 141 |                         if ( all != infinity ) { assert( v.referenceCost + inc <= UCHAR_MAX ); v.referenceCost += inc; }
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| 142 |                         return *this;
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| 143 |                 }
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| 144 | 
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| 145 |                 friend std::ostream & operator<<( std::ostream & os, const Cost cost );
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| 146 |         };
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| 147 | 
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| 148 |         inline bool operator==( const Cost lhs, const Cost rhs ) {
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| 149 |                 return lhs.all == rhs.all;
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| 150 |         }
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| 151 | 
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| 152 |         inline bool operator!=( const Cost lhs, const Cost rhs ) {
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| 153 |                 return !( lhs.all == rhs.all );
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| 154 |         }
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| 155 | 
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| 156 |         inline bool operator<( const Cost lhs, const Cost rhs ) {
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| 157 |                 if ( lhs.all == Cost::infinity ) return false;
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| 158 |                 if ( rhs.all == Cost::infinity ) return true;
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| 159 |                 return lhs.all < rhs.all;
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| 160 |         }
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| 161 | 
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| 162 |         inline Cost operator+( const Cost lhs, const Cost rhs ) {
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| 163 |                 if ( lhs.all == Cost::infinity || rhs.all == Cost::infinity ) return Cost{ Cost::infinity };
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| 164 |                 return Cost{ lhs.all + rhs.all - Cost::correctw }; // correct for negative spec cost
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| 165 |         }
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| 166 | 
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| 167 |         inline std::ostream & operator<<( std::ostream & os, const Cost cost ) {
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| 168 |                 return os << "( " << cost.get_unsafeCost() << ", " << cost.get_polyCost() << ", " << cost.get_safeCost()
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| 169 |                                   << ", " << cost.get_signCost() << ", " << cost.get_varCost() << ", " << cost.get_specCost()
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| 170 |                                   << ", " << cost.get_referenceCost() << " )";
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| 171 |         }
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| 172 | } // namespace ResolvExpr
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| 173 | 
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| 174 | // Local Variables: //
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| 175 | // tab-width: 4 //
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| 176 | // mode: c++ //
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| 177 | // compile-command: "make install" //
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| 178 | // End: //
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