[d76c588] | 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 | // TypeEnvironment.cpp -- |
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| 8 | // |
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| 9 | // Author : Aaron B. Moss |
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| 10 | // Created On : Wed May 29 11:00:00 2019 |
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[07de76b] | 11 | // Last Modified By : Peter A. Buhr |
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| 12 | // Last Modified On : Wed Dec 11 21:49:13 2019 |
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| 13 | // Update Count : 4 |
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[d76c588] | 14 | // |
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| 15 | |
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| 16 | #include "TypeEnvironment.hpp" |
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| 17 | |
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| 18 | #include <algorithm> // for copy |
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| 19 | #include <cassert> |
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| 20 | #include <iterator> // for ostream_iterator |
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| 21 | #include <iostream> |
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| 22 | #include <string> |
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| 23 | #include <utility> // for move |
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| 24 | #include <vector> |
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| 25 | |
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| 26 | #include "Decl.hpp" |
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| 27 | #include "Node.hpp" |
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| 28 | #include "Pass.hpp" |
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| 29 | #include "Print.hpp" |
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| 30 | #include "Type.hpp" |
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| 31 | #include "Common/Indenter.h" |
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| 32 | #include "ResolvExpr/typeops.h" // for occurs |
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| 33 | #include "ResolvExpr/WidenMode.h" |
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| 34 | #include "ResolvExpr/Unify.h" // for unifyInexact |
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| 35 | #include "Tuples/Tuples.h" // for isTtype |
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[cd6a6ff] | 36 | #include "CompilationState.h" |
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[d76c588] | 37 | |
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| 38 | using ResolvExpr::WidenMode; |
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| 39 | |
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| 40 | namespace ast { |
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| 41 | |
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| 42 | void print( std::ostream & out, const AssertionSet & assns, Indenter indent ) { |
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| 43 | for ( const auto & i : assns ) { |
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| 44 | print( out, i.first, indent ); |
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| 45 | out << ( i.second.isUsed ? " (used)" : " (not used)" ); |
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| 46 | } |
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| 47 | } |
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| 48 | |
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[f474e91] | 49 | void print( std::ostream & out, const OpenVarSet & open, Indenter indent ) { |
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[d76c588] | 50 | out << indent; |
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| 51 | bool first = true; |
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[f474e91] | 52 | for ( const auto & i : open ) { |
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[d76c588] | 53 | if ( first ) { first = false; } else { out << ' '; } |
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| 54 | out << i.first << "(" << i.second << ")"; |
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| 55 | } |
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| 56 | } |
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| 57 | |
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| 58 | void print( std::ostream & out, const EqvClass & clz, Indenter indent ) { |
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[cd6a6ff] | 59 | out << "("; |
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| 60 | bool first = true; |
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| 61 | for(const auto & var : clz.vars) { |
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| 62 | if(first) first = false; |
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| 63 | else out << " "; |
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| 64 | if( deterministic_output && isUnboundType(var) ) out << "[unbound]"; |
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| 65 | else out << var; |
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| 66 | } |
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[d76c588] | 67 | out << ")"; |
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[7ff3e522] | 68 | |
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[d76c588] | 69 | if ( clz.bound ) { |
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| 70 | out << " -> "; |
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| 71 | print( out, clz.bound, indent+1 ); |
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| 72 | } |
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| 73 | |
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| 74 | if ( ! clz.allowWidening ) { |
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| 75 | out << " (no widening)"; |
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| 76 | } |
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| 77 | |
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| 78 | out << std::endl; |
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| 79 | } |
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| 80 | |
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| 81 | const EqvClass * TypeEnvironment::lookup( const std::string & var ) const { |
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| 82 | for ( ClassList::const_iterator i = env.begin(); i != env.end(); ++i ) { |
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| 83 | if ( i->vars.find( var ) != i->vars.end() ) return &*i; |
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| 84 | } |
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| 85 | return nullptr; |
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| 86 | } |
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| 87 | |
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| 88 | namespace { |
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| 89 | /// Removes any class from env that intersects eqvClass |
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| 90 | void filterOverlappingClasses( std::list<EqvClass> & env, const EqvClass & eqvClass ) { |
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| 91 | auto i = env.begin(); |
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| 92 | while ( i != env.end() ) { |
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| 93 | auto next = i; ++next; // save next node in case of erasure |
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| 94 | |
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| 95 | for ( const auto & v : eqvClass.vars ) { |
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| 96 | if ( i->vars.count( v ) ) { |
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| 97 | env.erase( i ); // remove overlapping class |
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| 98 | break; // done with this class |
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| 99 | } |
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| 100 | } |
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[7ff3e522] | 101 | |
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[d76c588] | 102 | i = next; // go to next node even if this removed |
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| 103 | } |
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| 104 | } |
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| 105 | } |
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| 106 | |
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| 107 | void TypeEnvironment::add( const ParameterizedType::ForallList & tyDecls ) { |
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| 108 | for ( const TypeDecl * tyDecl : tyDecls ) { |
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| 109 | env.emplace_back( tyDecl ); |
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| 110 | } |
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| 111 | } |
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| 112 | |
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| 113 | void TypeEnvironment::add( const TypeSubstitution & sub ) { |
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| 114 | for ( const auto p : sub ) { |
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| 115 | add( EqvClass{ p.first, p.second } ); |
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| 116 | } |
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| 117 | } |
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| 118 | |
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| 119 | void TypeEnvironment::writeToSubstitution( TypeSubstitution & sub ) const { |
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| 120 | for ( const auto & clz : env ) { |
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| 121 | std::string clzRep; |
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| 122 | for ( const auto & var : clz.vars ) { |
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| 123 | if ( clz.bound ) { |
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| 124 | sub.add( var, clz.bound ); |
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| 125 | } else if ( clzRep.empty() ) { |
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| 126 | clzRep = var; |
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| 127 | } else { |
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| 128 | sub.add( var, new TypeInstType{ clzRep, clz.data.kind } ); |
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| 129 | } |
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| 130 | } |
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| 131 | } |
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| 132 | sub.normalize(); |
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| 133 | } |
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| 134 | |
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| 135 | void TypeEnvironment::simpleCombine( const TypeEnvironment & o ) { |
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| 136 | env.insert( env.end(), o.env.begin(), o.env.end() ); |
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| 137 | } |
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| 138 | |
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| 139 | namespace { |
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| 140 | /// Implements occurs check by traversing type |
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| 141 | struct Occurs : public ast::WithVisitorRef<Occurs> { |
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| 142 | bool result; |
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| 143 | std::set< std::string > vars; |
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| 144 | const TypeEnvironment & tenv; |
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| 145 | |
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| 146 | Occurs( const std::string & var, const TypeEnvironment & env ) |
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| 147 | : result( false ), vars(), tenv( env ) { |
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| 148 | if ( const EqvClass * clz = tenv.lookup( var ) ) { |
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| 149 | vars = clz->vars; |
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| 150 | } else { |
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| 151 | vars.emplace( var ); |
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| 152 | } |
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| 153 | } |
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| 154 | |
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| 155 | void previsit( const TypeInstType * typeInst ) { |
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| 156 | if ( vars.count( typeInst->name ) ) { |
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| 157 | result = true; |
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| 158 | } else if ( const EqvClass * clz = tenv.lookup( typeInst->name ) ) { |
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| 159 | if ( clz->bound ) { |
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| 160 | clz->bound->accept( *visitor ); |
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| 161 | } |
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| 162 | } |
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| 163 | } |
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| 164 | }; |
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| 165 | |
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| 166 | /// true if `var` occurs in `ty` under `env` |
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| 167 | bool occurs( const Type * ty, const std::string & var, const TypeEnvironment & env ) { |
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| 168 | Pass<Occurs> occur{ var, env }; |
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| 169 | maybe_accept( ty, occur ); |
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[7ff3e522] | 170 | return occur.core.result; |
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[d76c588] | 171 | } |
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| 172 | } |
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| 173 | |
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[7ff3e522] | 174 | bool TypeEnvironment::combine( |
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[f474e91] | 175 | const TypeEnvironment & o, OpenVarSet & open, const SymbolTable & symtab ) { |
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[d76c588] | 176 | // short-circuit easy cases |
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| 177 | if ( o.empty() ) return true; |
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| 178 | if ( empty() ) { |
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| 179 | simpleCombine( o ); |
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| 180 | return true; |
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| 181 | } |
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| 182 | |
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| 183 | // merge classes |
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| 184 | for ( const EqvClass & c : o.env ) { |
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| 185 | // index of typeclass in local environment bound to c |
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| 186 | auto rt = env.end(); |
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| 187 | |
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| 188 | // look for first existing bound variable |
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| 189 | auto vt = c.vars.begin(); |
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| 190 | for ( ; vt != c.vars.end(); ++vt ) { |
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| 191 | rt = internal_lookup( *vt ); |
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| 192 | if ( rt != env.end() ) break; |
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| 193 | } |
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| 194 | |
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| 195 | if ( rt != env.end() ) { // c needs to be merged into *rt |
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| 196 | EqvClass & r = *rt; |
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| 197 | // merge bindings |
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[f474e91] | 198 | if ( ! mergeBound( r, c, open, symtab ) ) return false; |
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[d76c588] | 199 | // merge previous unbound variables into this class, checking occurs if needed |
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| 200 | if ( r.bound ) for ( const auto & u : c.vars ) { |
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| 201 | if ( occurs( r.bound, u, *this ) ) return false; |
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| 202 | r.vars.emplace( u ); |
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| 203 | } else { r.vars.insert( c.vars.begin(), vt ); } |
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| 204 | // merge subsequent variables into this class (skipping *vt, already there) |
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| 205 | while ( ++vt != c.vars.end() ) { |
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| 206 | auto st = internal_lookup( *vt ); |
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| 207 | if ( st == env.end() ) { |
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[7ff3e522] | 208 | // unbound, safe to add if occurs |
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[d76c588] | 209 | if ( r.bound && occurs( r.bound, *vt, *this ) ) return false; |
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| 210 | r.vars.emplace( *vt ); |
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| 211 | } else if ( st != rt ) { |
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| 212 | // bound, but not to the same class |
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[f474e91] | 213 | if ( ! mergeClasses( rt, st, open, symtab ) ) return false; |
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[d76c588] | 214 | } // ignore bound into the same class |
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| 215 | } |
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| 216 | } else { // no variables in c bound; just copy up |
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| 217 | env.emplace_back( c ); |
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| 218 | } |
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| 219 | } |
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| 220 | |
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| 221 | // merged all classes |
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| 222 | return true; |
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| 223 | } |
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| 224 | |
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[f474e91] | 225 | void TypeEnvironment::extractOpenVars( OpenVarSet & open ) const { |
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[d76c588] | 226 | for ( const auto & clz : env ) { |
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| 227 | for ( const auto & var : clz.vars ) { |
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[f474e91] | 228 | open[ var ] = clz.data; |
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[d76c588] | 229 | } |
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| 230 | } |
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| 231 | } |
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| 232 | |
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[f474e91] | 233 | void TypeEnvironment::addActual( const TypeEnvironment & actualEnv, OpenVarSet & open ) { |
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[d76c588] | 234 | for ( const auto & clz : actualEnv ) { |
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| 235 | EqvClass c = clz; |
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| 236 | c.allowWidening = false; |
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| 237 | for ( const auto & var : c.vars ) { |
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[f474e91] | 238 | open[ var ] = c.data; |
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[d76c588] | 239 | } |
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| 240 | env.emplace_back( std::move(c) ); |
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| 241 | } |
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| 242 | } |
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| 243 | |
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[ee574a2] | 244 | /// true if a type is a function type |
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| 245 | bool isFtype( const Type * type ) { |
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| 246 | if ( dynamic_cast< const FunctionType * >( type ) ) { |
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| 247 | return true; |
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| 248 | } else if ( auto typeInst = dynamic_cast< const TypeInstType * >( type ) ) { |
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[07de76b] | 249 | return typeInst->kind == TypeDecl::Ftype; |
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[ee574a2] | 250 | } else return false; |
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| 251 | } |
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[d76c588] | 252 | |
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[ee574a2] | 253 | namespace { |
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[d76c588] | 254 | /// true if the given type can be bound to the given type variable |
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| 255 | bool tyVarCompatible( const TypeDecl::Data & data, const Type * type ) { |
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| 256 | switch ( data.kind ) { |
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[07de76b] | 257 | case TypeDecl::Dtype: |
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[d76c588] | 258 | // to bind to an object type variable, the type must not be a function type. |
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| 259 | // if the type variable is specified to be a complete type then the incoming |
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| 260 | // type must also be complete |
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| 261 | // xxx - should this also check that type is not a tuple type and that it's not a ttype? |
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| 262 | return ! isFtype( type ) && ( ! data.isComplete || type->isComplete() ); |
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[07de76b] | 263 | case TypeDecl::Ftype: |
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[d76c588] | 264 | return isFtype( type ); |
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[07de76b] | 265 | case TypeDecl::Ttype: |
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[d76c588] | 266 | // ttype unifies with any tuple type |
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| 267 | return dynamic_cast< const TupleType * >( type ) || Tuples::isTtype( type ); |
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| 268 | default: |
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| 269 | assertf(false, "Unhandled tyvar kind: %d", data.kind); |
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| 270 | return false; |
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| 271 | } |
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| 272 | } |
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| 273 | } |
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| 274 | |
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[7ff3e522] | 275 | bool TypeEnvironment::bindVar( |
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| 276 | const TypeInstType * typeInst, const Type * bindTo, const TypeDecl::Data & data, |
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| 277 | AssertionSet & need, AssertionSet & have, const OpenVarSet & open, WidenMode widen, |
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| 278 | const SymbolTable & symtab |
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[f474e91] | 279 | ) { |
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[d76c588] | 280 | // remove references from bound type, so that type variables can only bind to value types |
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[f474e91] | 281 | ptr<Type> target = bindTo->stripReferences(); |
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| 282 | auto tyvar = open.find( typeInst->name ); |
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| 283 | assert( tyvar != open.end() ); |
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| 284 | if ( ! tyVarCompatible( tyvar->second, target ) ) return false; |
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| 285 | if ( occurs( target, typeInst->name, *this ) ) return false; |
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[d76c588] | 286 | |
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| 287 | auto it = internal_lookup( typeInst->name ); |
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| 288 | if ( it != env.end() ) { |
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| 289 | if ( it->bound ) { |
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| 290 | // attempt to unify equivalence class type with type to bind to. |
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| 291 | // equivalence class type has stripped qualifiers which must be restored |
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[f474e91] | 292 | ptr<Type> common; |
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[d76c588] | 293 | ptr<Type> newType = it->bound; |
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[ee574a2] | 294 | reset_qualifiers( newType, typeInst->qualifiers ); |
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[7ff3e522] | 295 | if ( unifyInexact( |
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| 296 | newType, target, *this, need, have, open, |
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[f474e91] | 297 | widen & WidenMode{ it->allowWidening, true }, symtab, common ) ) { |
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[d76c588] | 298 | if ( common ) { |
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[f474e91] | 299 | it->bound = std::move(common); |
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[ee574a2] | 300 | reset_qualifiers( it->bound ); |
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[d76c588] | 301 | } |
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| 302 | } else return false; |
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| 303 | } else { |
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[f474e91] | 304 | it->bound = std::move(target); |
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[ee574a2] | 305 | reset_qualifiers( it->bound ); |
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[f474e91] | 306 | it->allowWidening = widen.first && widen.second; |
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[d76c588] | 307 | } |
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| 308 | } else { |
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[7ff3e522] | 309 | env.emplace_back( |
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[f474e91] | 310 | typeInst->name, target, widen.first && widen.second, data ); |
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[d76c588] | 311 | } |
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| 312 | return true; |
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| 313 | } |
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| 314 | |
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[7ff3e522] | 315 | bool TypeEnvironment::bindVarToVar( |
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| 316 | const TypeInstType * var1, const TypeInstType * var2, TypeDecl::Data && data, |
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| 317 | AssertionSet & need, AssertionSet & have, const OpenVarSet & open, |
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| 318 | WidenMode widen, const SymbolTable & symtab |
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[f474e91] | 319 | ) { |
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[d76c588] | 320 | auto c1 = internal_lookup( var1->name ); |
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| 321 | auto c2 = internal_lookup( var2->name ); |
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[7ff3e522] | 322 | |
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[d76c588] | 323 | // exit early if variables already bound together |
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| 324 | if ( c1 != env.end() && c1 == c2 ) { |
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[f474e91] | 325 | c1->allowWidening &= widen; |
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[d76c588] | 326 | return true; |
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| 327 | } |
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| 328 | |
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| 329 | bool widen1 = false, widen2 = false; |
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| 330 | const Type * type1 = nullptr, * type2 = nullptr; |
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| 331 | |
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| 332 | // check for existing bindings, perform occurs check |
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| 333 | if ( c1 != env.end() ) { |
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| 334 | if ( c1->bound ) { |
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| 335 | if ( occurs( c1->bound, var2->name, *this ) ) return false; |
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| 336 | type1 = c1->bound; |
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| 337 | } |
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[f474e91] | 338 | widen1 = widen.first && c1->allowWidening; |
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[d76c588] | 339 | } |
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| 340 | if ( c2 != env.end() ) { |
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| 341 | if ( c2->bound ) { |
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| 342 | if ( occurs( c2->bound, var1->name, *this ) ) return false; |
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| 343 | type2 = c2->bound; |
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| 344 | } |
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[f474e91] | 345 | widen2 = widen.second && c2->allowWidening; |
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[d76c588] | 346 | } |
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| 347 | |
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| 348 | if ( type1 && type2 ) { |
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| 349 | // both classes bound, merge if bound types can be unified |
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| 350 | ptr<Type> newType1{ type1 }, newType2{ type2 }; |
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| 351 | WidenMode newWidenMode{ widen1, widen2 }; |
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[f474e91] | 352 | ptr<Type> common; |
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[d76c588] | 353 | |
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| 354 | if ( unifyInexact( |
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[f474e91] | 355 | newType1, newType2, *this, need, have, open, newWidenMode, symtab, common ) ) { |
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[d76c588] | 356 | c1->vars.insert( c2->vars.begin(), c2->vars.end() ); |
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| 357 | c1->allowWidening = widen1 && widen2; |
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| 358 | if ( common ) { |
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[f474e91] | 359 | c1->bound = std::move(common); |
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[ee574a2] | 360 | reset_qualifiers( c1->bound ); |
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[d76c588] | 361 | } |
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| 362 | c1->data.isComplete |= data.isComplete; |
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| 363 | env.erase( c2 ); |
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| 364 | } else return false; |
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| 365 | } else if ( c1 != env.end() && c2 != env.end() ) { |
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| 366 | // both classes exist, at least one unbound, merge unconditionally |
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| 367 | if ( type1 ) { |
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| 368 | c1->vars.insert( c2->vars.begin(), c2->vars.end() ); |
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| 369 | c1->allowWidening = widen1; |
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| 370 | c1->data.isComplete |= data.isComplete; |
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| 371 | env.erase( c2 ); |
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| 372 | } else { |
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| 373 | c2->vars.insert( c1->vars.begin(), c1->vars.end() ); |
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| 374 | c2->allowWidening = widen2; |
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| 375 | c2->data.isComplete |= data.isComplete; |
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| 376 | env.erase( c1 ); |
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| 377 | } |
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| 378 | } else if ( c1 != env.end() ) { |
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| 379 | // var2 unbound, add to env[c1] |
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| 380 | c1->vars.emplace( var2->name ); |
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| 381 | c1->allowWidening = widen1; |
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| 382 | c1->data.isComplete |= data.isComplete; |
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| 383 | } else if ( c2 != env.end() ) { |
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| 384 | // var1 unbound, add to env[c2] |
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| 385 | c2->vars.emplace( var1->name ); |
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| 386 | c2->allowWidening = widen2; |
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| 387 | c2->data.isComplete |= data.isComplete; |
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| 388 | } else { |
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| 389 | // neither var bound, create new class |
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| 390 | env.emplace_back( var1->name, var2->name, widen1 && widen2, data ); |
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| 391 | } |
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| 392 | |
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| 393 | return true; |
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| 394 | } |
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| 395 | |
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| 396 | void TypeEnvironment::forbidWidening() { |
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| 397 | for ( EqvClass& c : env ) c.allowWidening = false; |
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| 398 | } |
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| 399 | |
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| 400 | void TypeEnvironment::add( EqvClass && eqvClass ) { |
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| 401 | filterOverlappingClasses( env, eqvClass ); |
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| 402 | env.emplace_back( std::move(eqvClass) ); |
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| 403 | } |
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| 404 | |
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[7ff3e522] | 405 | bool TypeEnvironment::mergeBound( |
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[f474e91] | 406 | EqvClass & to, const EqvClass & from, OpenVarSet & open, const SymbolTable & symtab ) { |
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[d76c588] | 407 | if ( from.bound ) { |
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| 408 | if ( to.bound ) { |
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| 409 | // attempt to unify bound types |
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| 410 | ptr<Type> toType{ to.bound }, fromType{ from.bound }; |
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[f474e91] | 411 | WidenMode widen{ to.allowWidening, from.allowWidening }; |
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| 412 | ptr<Type> common; |
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[d76c588] | 413 | AssertionSet need, have; |
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| 414 | |
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[7ff3e522] | 415 | if ( unifyInexact( |
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[f474e91] | 416 | toType, fromType, *this, need, have, open, widen, symtab, common ) ) { |
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[d76c588] | 417 | // unifies, set common type if necessary |
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| 418 | if ( common ) { |
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[f474e91] | 419 | to.bound = std::move(common); |
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[ee574a2] | 420 | reset_qualifiers( to.bound ); |
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[d76c588] | 421 | } |
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| 422 | } else return false; // cannot unify |
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| 423 | } else { |
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| 424 | to.bound = from.bound; |
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| 425 | } |
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| 426 | } |
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| 427 | |
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| 428 | // unify widening if matches |
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| 429 | to.allowWidening &= from.allowWidening; |
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| 430 | return true; |
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| 431 | } |
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| 432 | |
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[7ff3e522] | 433 | bool TypeEnvironment::mergeClasses( |
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[f474e91] | 434 | ClassList::iterator to, ClassList::iterator from, OpenVarSet & open, const SymbolTable & symtab |
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| 435 | ) { |
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[d76c588] | 436 | EqvClass & r = *to, & s = *from; |
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| 437 | |
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| 438 | // ensure bounds match |
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[f474e91] | 439 | if ( ! mergeBound( r, s, open, symtab ) ) return false; |
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[d76c588] | 440 | |
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| 441 | // check safely bindable |
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| 442 | if ( r.bound ) { |
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| 443 | for ( const auto & v : s.vars ) if ( occurs( r.bound, v, *this ) ) return false; |
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| 444 | } |
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| 445 | |
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| 446 | // merge classes |
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| 447 | r.vars.insert( s.vars.begin(), s.vars.end() ); |
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| 448 | r.allowWidening &= s.allowWidening; |
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| 449 | env.erase( from ); |
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| 450 | |
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| 451 | return true; |
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| 452 | } |
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| 453 | |
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| 454 | TypeEnvironment::ClassList::iterator TypeEnvironment::internal_lookup( const std::string & var ) { |
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| 455 | for ( ClassList::iterator i = env.begin(); i != env.end(); ++i ) { |
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| 456 | if ( i->vars.count( var ) ) return i; |
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| 457 | } |
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| 458 | return env.end(); |
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| 459 | } |
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| 460 | |
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| 461 | void print( std::ostream & out, const TypeEnvironment & env, Indenter indent ) { |
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| 462 | for ( const auto & clz : env ) { |
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| 463 | print( out, clz, indent ); |
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| 464 | } |
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| 465 | } |
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| 466 | |
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| 467 | std::ostream & operator<<( std::ostream & out, const TypeEnvironment & env ) { |
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| 468 | print( out, env ); |
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| 469 | return out; |
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| 470 | } |
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| 471 | |
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| 472 | } |
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| 473 | |
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| 474 | // Local Variables: // |
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| 475 | // tab-width: 4 // |
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| 476 | // mode: c++ // |
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| 477 | // compile-command: "make install" // |
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[07de76b] | 478 | // End: // |
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