[c671112] | 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 | // TypeSubstitution.cc -- |
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| 8 | // |
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| 9 | // Author : Richard C. Bilson |
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| 10 | // Created On : Mon May 18 07:44:20 2015 |
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[dafe9e1] | 11 | // Last Modified By : Andrew Beach |
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| 12 | // Last Modified On : Mon Jun 3 13:26:00 2017 |
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| 13 | // Update Count : 5 |
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[c671112] | 14 | // |
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| 15 | |
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| 16 | #include "Type.hpp" // for TypeInstType, Type, StructInstType, UnionInstType |
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| 17 | #include "TypeSubstitution.hpp" |
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| 18 | |
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| 19 | namespace ast { |
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| 20 | |
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[c15085d] | 21 | |
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[0d070ca] | 22 | // size_t TypeSubstitution::Substituter::traceId = Stats::Heap::new_stacktrace_id("TypeSubstitution"); |
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[c15085d] | 23 | |
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[c671112] | 24 | TypeSubstitution::TypeSubstitution() { |
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| 25 | } |
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| 26 | |
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| 27 | TypeSubstitution::TypeSubstitution( const TypeSubstitution &other ) : Node() { |
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| 28 | initialize( other, *this ); |
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| 29 | } |
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| 30 | |
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[dafe9e1] | 31 | TypeSubstitution::~TypeSubstitution() {} |
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[c671112] | 32 | |
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| 33 | TypeSubstitution &TypeSubstitution::operator=( const TypeSubstitution &other ) { |
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| 34 | if ( this == &other ) return *this; |
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| 35 | initialize( other, *this ); |
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| 36 | return *this; |
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| 37 | } |
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| 38 | |
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| 39 | void TypeSubstitution::initialize( const TypeSubstitution &src, TypeSubstitution &dest ) { |
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| 40 | dest.typeEnv.clear(); |
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| 41 | dest.add( src ); |
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| 42 | } |
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| 43 | |
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| 44 | void TypeSubstitution::add( const TypeSubstitution &other ) { |
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| 45 | for ( TypeEnvType::const_iterator i = other.typeEnv.begin(); i != other.typeEnv.end(); ++i ) { |
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| 46 | typeEnv[ i->first ] = i->second; |
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| 47 | } // for |
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| 48 | } |
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| 49 | |
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[3e5dd913] | 50 | void TypeSubstitution::add( const TypeInstType * formalType, const Type *actualType ) { |
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| 51 | typeEnv[ *formalType ] = actualType; |
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[c671112] | 52 | } |
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| 53 | |
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[3e5dd913] | 54 | void TypeSubstitution::add( const TypeInstType::TypeEnvKey & key, const Type * actualType) { |
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| 55 | typeEnv[ key ] = actualType; |
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[172d9342] | 56 | } |
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| 57 | |
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[3e5dd913] | 58 | void TypeSubstitution::remove( const TypeInstType * formalType ) { |
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| 59 | TypeEnvType::iterator i = typeEnv.find( *formalType ); |
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[c671112] | 60 | if ( i != typeEnv.end() ) { |
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[3e5dd913] | 61 | typeEnv.erase( *formalType ); |
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[c671112] | 62 | } // if |
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| 63 | } |
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| 64 | |
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[3e5dd913] | 65 | const Type *TypeSubstitution::lookup( const TypeInstType * formalType ) const { |
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| 66 | TypeEnvType::const_iterator i = typeEnv.find( *formalType ); |
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[c671112] | 67 | |
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| 68 | // break on not in substitution set |
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| 69 | if ( i == typeEnv.end() ) return 0; |
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| 70 | |
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| 71 | // attempt to transitively follow TypeInstType links. |
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| 72 | while ( const TypeInstType *actualType = i->second.as<TypeInstType>()) { |
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| 73 | // break cycles in the transitive follow |
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[3e5dd913] | 74 | if ( *formalType == *actualType ) break; |
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[c671112] | 75 | |
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| 76 | // Look for the type this maps to, returning previous mapping if none-such |
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[3e5dd913] | 77 | i = typeEnv.find( *actualType ); |
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[c671112] | 78 | if ( i == typeEnv.end() ) return actualType; |
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| 79 | } |
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| 80 | |
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| 81 | // return type from substitution set |
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| 82 | return i->second; |
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| 83 | } |
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| 84 | |
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| 85 | bool TypeSubstitution::empty() const { |
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[3e5dd913] | 86 | return typeEnv.empty(); |
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[c671112] | 87 | } |
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| 88 | |
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| 89 | namespace { |
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| 90 | struct EnvTrimmer { |
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[55b6476] | 91 | const TypeSubstitution * env; |
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[c671112] | 92 | TypeSubstitution * newEnv; |
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| 93 | EnvTrimmer( const TypeSubstitution * env, TypeSubstitution * newEnv ) : env( env ), newEnv( newEnv ){} |
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[3e5dd913] | 94 | void previsit( FunctionType * ftype ) { |
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[c671112] | 95 | // transfer known bindings for seen type variables |
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[3e5dd913] | 96 | for (auto & formal : ftype->forall) { |
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| 97 | if ( const Type * t = env->lookup( formal ) ) { |
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| 98 | newEnv->add( formal, t ); |
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| 99 | } |
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[c671112] | 100 | } |
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| 101 | } |
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| 102 | }; |
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| 103 | } // namespace |
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| 104 | |
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| 105 | /// reduce environment to just the parts that are referenced in a given expression |
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| 106 | TypeSubstitution * TypeSubstitution::newFromExpr( const Expr * expr, const TypeSubstitution * env ) { |
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| 107 | if ( env ) { |
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| 108 | TypeSubstitution * newEnv = new TypeSubstitution(); |
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| 109 | Pass<EnvTrimmer> trimmer( env, newEnv ); |
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| 110 | expr->accept( trimmer ); |
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| 111 | return newEnv; |
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| 112 | } |
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| 113 | return nullptr; |
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| 114 | } |
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| 115 | |
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| 116 | void TypeSubstitution::normalize() { |
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[55b6476] | 117 | Pass<Substituter> sub( *this, true ); |
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[c671112] | 118 | do { |
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[7ff3e522] | 119 | sub.core.subCount = 0; |
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| 120 | sub.core.freeOnly = true; |
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[c671112] | 121 | for ( TypeEnvType::iterator i = typeEnv.begin(); i != typeEnv.end(); ++i ) { |
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[55b6476] | 122 | i->second = i->second->accept( sub ); |
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[c671112] | 123 | } |
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[7ff3e522] | 124 | } while ( sub.core.subCount ); |
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[c671112] | 125 | } |
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| 126 | |
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[55b6476] | 127 | const Type * TypeSubstitution::Substituter::postvisit( const TypeInstType *inst ) { |
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[3e5dd913] | 128 | BoundVarsType::const_iterator bound = boundVars.find( *inst ); |
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[c671112] | 129 | if ( bound != boundVars.end() ) return inst; |
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| 130 | |
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[3e5dd913] | 131 | TypeEnvType::const_iterator i = sub.typeEnv.find( *inst ); |
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[c671112] | 132 | if ( i == sub.typeEnv.end() ) { |
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| 133 | return inst; |
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| 134 | } else { |
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| 135 | // cut off infinite loop for the case where a type is bound to itself. |
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| 136 | // Note: this does not prevent cycles in the general case, so it may be necessary to do something more sophisticated here. |
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| 137 | // TODO: investigate preventing type variables from being bound to themselves in the first place. |
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[55b6476] | 138 | if ( const TypeInstType * replacement = i->second.as<TypeInstType>() ) { |
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[3e5dd913] | 139 | if ( *inst == *replacement ) { |
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[c671112] | 140 | return inst; |
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| 141 | } |
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| 142 | } |
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| 143 | // std::cerr << "found " << inst->name << ", replacing with " << i->second << std::endl; |
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| 144 | subCount++; |
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[55b6476] | 145 | ptr<Type> newType = i->second; // force clone if needed |
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| 146 | add_qualifiers( newType, inst->qualifiers ); |
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[2890212] | 147 | // Note: need to recursively apply substitution to the new type because normalize does not |
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[55b6476] | 148 | // substitute bound vars, but bound vars must be substituted when not in freeOnly mode. |
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| 149 | newType = newType->accept( *visitor ); |
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| 150 | return newType.release(); |
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[c671112] | 151 | } // if |
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| 152 | } |
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| 153 | |
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[361bf01] | 154 | void TypeSubstitution::Substituter::previsit( const FunctionType * ptype ) { |
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[c671112] | 155 | GuardValue( boundVars ); |
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| 156 | // bind type variables from forall-qualifiers |
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| 157 | if ( freeOnly ) { |
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[3e5dd913] | 158 | for ( auto & tyvar : ptype->forall ) { |
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| 159 | boundVars.insert( *tyvar ); |
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[c671112] | 160 | } // for |
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| 161 | } // if |
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| 162 | } |
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| 163 | |
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[3e5dd913] | 164 | /* |
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[98e8b3b] | 165 | void TypeSubstitution::Substituter::handleAggregateType( const BaseInstType * type ) { |
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[c671112] | 166 | GuardValue( boundVars ); |
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| 167 | // bind type variables from forall-qualifiers |
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| 168 | if ( freeOnly ) { |
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| 169 | // bind type variables from generic type instantiations |
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[55b6476] | 170 | if ( auto decl = type->aggr() ) { |
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[417117e] | 171 | if ( ! type->params.empty() ) { |
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| 172 | for ( const TypeDecl * tyvar : decl->params ) { |
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[3e5dd913] | 173 | boundVars.insert( *tyvar ); |
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[55b6476] | 174 | } // for |
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| 175 | } // if |
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| 176 | } |
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[c671112] | 177 | } // if |
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| 178 | } |
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| 179 | |
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[55b6476] | 180 | void TypeSubstitution::Substituter::previsit( const StructInstType * aggregateUseType ) { |
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[c671112] | 181 | handleAggregateType( aggregateUseType ); |
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| 182 | } |
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| 183 | |
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[55b6476] | 184 | void TypeSubstitution::Substituter::previsit( const UnionInstType *aggregateUseType ) { |
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[c671112] | 185 | handleAggregateType( aggregateUseType ); |
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| 186 | } |
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[3e5dd913] | 187 | */ |
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[c671112] | 188 | |
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| 189 | } // namespace ast |
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| 190 | |
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| 191 | // Local Variables: // |
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| 192 | // tab-width: 4 // |
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| 193 | // mode: c++ // |
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| 194 | // compile-command: "make install" // |
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| 195 | // End: // |
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