[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.varEnv.clear(); |
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| 42 | dest.add( src ); |
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| 43 | } |
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| 44 | |
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| 45 | void TypeSubstitution::add( const TypeSubstitution &other ) { |
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| 46 | for ( TypeEnvType::const_iterator i = other.typeEnv.begin(); i != other.typeEnv.end(); ++i ) { |
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| 47 | typeEnv[ i->first ] = i->second; |
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| 48 | } // for |
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| 49 | for ( VarEnvType::const_iterator i = other.varEnv.begin(); i != other.varEnv.end(); ++i ) { |
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| 50 | varEnv[ i->first ] = i->second; |
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| 51 | } // for |
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| 52 | } |
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| 53 | |
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| 54 | void TypeSubstitution::add( std::string formalType, const Type *actualType ) { |
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| 55 | typeEnv[ formalType ] = actualType; |
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| 56 | } |
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| 57 | |
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[172d9342] | 58 | void TypeSubstitution::addVar( std::string formalExpr, const Expr *actualExpr ) { |
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| 59 | varEnv[ formalExpr ] = actualExpr; |
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| 60 | } |
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| 61 | |
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[c671112] | 62 | void TypeSubstitution::remove( std::string formalType ) { |
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| 63 | TypeEnvType::iterator i = typeEnv.find( formalType ); |
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| 64 | if ( i != typeEnv.end() ) { |
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| 65 | typeEnv.erase( formalType ); |
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| 66 | } // if |
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| 67 | } |
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| 68 | |
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| 69 | const Type *TypeSubstitution::lookup( std::string formalType ) const { |
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| 70 | TypeEnvType::const_iterator i = typeEnv.find( formalType ); |
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| 71 | |
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| 72 | // break on not in substitution set |
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| 73 | if ( i == typeEnv.end() ) return 0; |
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| 74 | |
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| 75 | // attempt to transitively follow TypeInstType links. |
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| 76 | while ( const TypeInstType *actualType = i->second.as<TypeInstType>()) { |
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| 77 | const std::string& typeName = actualType->name; |
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| 78 | |
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| 79 | // break cycles in the transitive follow |
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| 80 | if ( formalType == typeName ) break; |
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| 81 | |
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| 82 | // Look for the type this maps to, returning previous mapping if none-such |
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| 83 | i = typeEnv.find( typeName ); |
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| 84 | if ( i == typeEnv.end() ) return actualType; |
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| 85 | } |
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| 86 | |
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| 87 | // return type from substitution set |
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| 88 | return i->second; |
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| 89 | } |
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| 90 | |
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| 91 | bool TypeSubstitution::empty() const { |
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| 92 | return typeEnv.empty() && varEnv.empty(); |
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| 93 | } |
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| 94 | |
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| 95 | namespace { |
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| 96 | struct EnvTrimmer { |
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[55b6476] | 97 | const TypeSubstitution * env; |
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[c671112] | 98 | TypeSubstitution * newEnv; |
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| 99 | EnvTrimmer( const TypeSubstitution * env, TypeSubstitution * newEnv ) : env( env ), newEnv( newEnv ){} |
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| 100 | void previsit( TypeDecl * tyDecl ) { |
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| 101 | // transfer known bindings for seen type variables |
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| 102 | if ( const Type * t = env->lookup( tyDecl->name ) ) { |
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| 103 | newEnv->add( tyDecl->name, t ); |
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| 104 | } |
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| 105 | } |
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| 106 | }; |
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| 107 | } // namespace |
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| 108 | |
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| 109 | /// reduce environment to just the parts that are referenced in a given expression |
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| 110 | TypeSubstitution * TypeSubstitution::newFromExpr( const Expr * expr, const TypeSubstitution * env ) { |
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| 111 | if ( env ) { |
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| 112 | TypeSubstitution * newEnv = new TypeSubstitution(); |
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| 113 | Pass<EnvTrimmer> trimmer( env, newEnv ); |
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| 114 | expr->accept( trimmer ); |
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| 115 | return newEnv; |
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| 116 | } |
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| 117 | return nullptr; |
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| 118 | } |
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| 119 | |
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| 120 | void TypeSubstitution::normalize() { |
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[55b6476] | 121 | Pass<Substituter> sub( *this, true ); |
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[c671112] | 122 | do { |
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[7ff3e522] | 123 | sub.core.subCount = 0; |
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| 124 | sub.core.freeOnly = true; |
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[c671112] | 125 | for ( TypeEnvType::iterator i = typeEnv.begin(); i != typeEnv.end(); ++i ) { |
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[55b6476] | 126 | i->second = i->second->accept( sub ); |
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[c671112] | 127 | } |
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[7ff3e522] | 128 | } while ( sub.core.subCount ); |
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[c671112] | 129 | } |
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| 130 | |
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[55b6476] | 131 | const Type * TypeSubstitution::Substituter::postvisit( const TypeInstType *inst ) { |
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[c671112] | 132 | BoundVarsType::const_iterator bound = boundVars.find( inst->name ); |
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| 133 | if ( bound != boundVars.end() ) return inst; |
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| 134 | |
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| 135 | TypeEnvType::const_iterator i = sub.typeEnv.find( inst->name ); |
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| 136 | if ( i == sub.typeEnv.end() ) { |
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| 137 | return inst; |
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| 138 | } else { |
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| 139 | // cut off infinite loop for the case where a type is bound to itself. |
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| 140 | // 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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| 141 | // TODO: investigate preventing type variables from being bound to themselves in the first place. |
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[55b6476] | 142 | if ( const TypeInstType * replacement = i->second.as<TypeInstType>() ) { |
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[c671112] | 143 | if ( inst->name == replacement->name ) { |
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| 144 | return inst; |
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| 145 | } |
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| 146 | } |
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| 147 | // std::cerr << "found " << inst->name << ", replacing with " << i->second << std::endl; |
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| 148 | subCount++; |
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[55b6476] | 149 | ptr<Type> newType = i->second; // force clone if needed |
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| 150 | add_qualifiers( newType, inst->qualifiers ); |
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[2890212] | 151 | // Note: need to recursively apply substitution to the new type because normalize does not |
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[55b6476] | 152 | // substitute bound vars, but bound vars must be substituted when not in freeOnly mode. |
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| 153 | newType = newType->accept( *visitor ); |
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| 154 | return newType.release(); |
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[c671112] | 155 | } // if |
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| 156 | } |
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| 157 | |
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[55b6476] | 158 | const Expr * TypeSubstitution::Substituter::postvisit( const NameExpr * nameExpr ) { |
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[c671112] | 159 | VarEnvType::const_iterator i = sub.varEnv.find( nameExpr->name ); |
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| 160 | if ( i == sub.varEnv.end() ) { |
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| 161 | return nameExpr; |
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| 162 | } else { |
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| 163 | subCount++; |
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[55b6476] | 164 | return i->second; |
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[c671112] | 165 | } // if |
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| 166 | } |
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| 167 | |
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[55b6476] | 168 | void TypeSubstitution::Substituter::previsit( const ParameterizedType * ptype ) { |
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[c671112] | 169 | GuardValue( boundVars ); |
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| 170 | // bind type variables from forall-qualifiers |
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| 171 | if ( freeOnly ) { |
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[55b6476] | 172 | for ( const TypeDecl * tyvar : ptype->forall ) { |
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| 173 | boundVars.insert( tyvar->name ); |
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[c671112] | 174 | } // for |
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| 175 | } // if |
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| 176 | } |
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| 177 | |
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[98e8b3b] | 178 | void TypeSubstitution::Substituter::handleAggregateType( const BaseInstType * type ) { |
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[c671112] | 179 | GuardValue( boundVars ); |
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| 180 | // bind type variables from forall-qualifiers |
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| 181 | if ( freeOnly ) { |
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[55b6476] | 182 | for ( const TypeDecl * tyvar : type->forall ) { |
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| 183 | boundVars.insert( tyvar->name ); |
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[c671112] | 184 | } // for |
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| 185 | // bind type variables from generic type instantiations |
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[55b6476] | 186 | if ( auto decl = type->aggr() ) { |
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[417117e] | 187 | if ( ! type->params.empty() ) { |
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| 188 | for ( const TypeDecl * tyvar : decl->params ) { |
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[55b6476] | 189 | boundVars.insert( tyvar->name ); |
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| 190 | } // for |
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| 191 | } // if |
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| 192 | } |
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[c671112] | 193 | } // if |
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| 194 | } |
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| 195 | |
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[55b6476] | 196 | void TypeSubstitution::Substituter::previsit( const StructInstType * aggregateUseType ) { |
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[c671112] | 197 | handleAggregateType( aggregateUseType ); |
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| 198 | } |
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| 199 | |
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[55b6476] | 200 | void TypeSubstitution::Substituter::previsit( const UnionInstType *aggregateUseType ) { |
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[c671112] | 201 | handleAggregateType( aggregateUseType ); |
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| 202 | } |
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| 203 | |
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| 204 | } // namespace ast |
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| 205 | |
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| 206 | // Local Variables: // |
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| 207 | // tab-width: 4 // |
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| 208 | // mode: c++ // |
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| 209 | // compile-command: "make install" // |
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| 210 | // End: // |
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