source: src/AST/TypeSubstitution.hpp @ baee756

//
// Cforall Version 1.0.0 Copyright (C) 2015 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// TypeSubstitution.h --
//
// Author           : Richard C. Bilson
// Created On       : Mon May 18 07:44:20 2015
// Last Modified By : Peter A. Buhr
// Last Modified On : Tue Apr 30 22:52:47 2019
// Update Count     : 9
//

#pragma once

#include <cassert>                 // for assert
#include <list>                    // for list<>::iterator, _List_iterator
#include <unordered_map>
#include <unordered_set>
#include <string>                  // for string, operator!=
#include <utility>                 // for pair

#include "Fwd.hpp"        // for UniqueId
#include "ParseNode.hpp"
#include "Type.hpp"
#include "Common/SemanticError.h"  // for SemanticError
#include "Visitor.hpp"
#include "Decl.hpp"
#include "Expr.hpp"
#include "Node.hpp"

namespace ast {

class TypeSubstitution : public Node {
  public:
        TypeSubstitution();
        template< typename FormalIterator, typename ActualIterator >
        TypeSubstitution( FormalIterator formalBegin, FormalIterator formalEnd, ActualIterator actualBegin );
        TypeSubstitution( const TypeSubstitution &other );
        virtual ~TypeSubstitution();

        TypeSubstitution &operator=( const TypeSubstitution &other );

        template< typename SynTreeClass >
        struct ApplyResult {
                ast::ptr<SynTreeClass> node;
                int count;
        };

        template< typename SynTreeClass > ApplyResult<SynTreeClass> apply( const SynTreeClass * input ) const;
        template< typename SynTreeClass > ApplyResult<SynTreeClass> applyFree( const SynTreeClass * input ) const;

        template< typename node_t, enum Node::ref_type ref_t >
        int apply( ptr_base< node_t, ref_t > & input ) const {
                const node_t * p = input.get();
                auto ret = apply(p);
                input = ret.node;
                return ret.count;
        }

        template< typename node_t, enum Node::ref_type ref_t >
        int applyFree( ptr_base< node_t, ref_t > & input ) const {
                const node_t * p = input.get();
                auto ret = applyFree(p);
                input = ret.node;
                return ret.count;
        }

        void add( std::string formalType, const Type *actualType );
        void add( const TypeSubstitution &other );
        void remove( std::string formalType );
        const Type *lookup( std::string formalType ) const;
        bool empty() const;

        void addVar( std::string formalExpr, const Expr *actualExpr );

        template< typename FormalIterator, typename ActualIterator >
        void add( FormalIterator formalBegin, FormalIterator formalEnd, ActualIterator actualBegin );

        /// create a new TypeSubstitution using bindings from env containing all of the type variables in expr
        static TypeSubstitution * newFromExpr( const Expr * expr, const TypeSubstitution * env );

        void normalize();

        const TypeSubstitution * accept( Visitor & v ) const override { return v.visit( this ); }

        TypeSubstitution * clone() const override { return new TypeSubstitution( *this ); }

  private:

        // Mutator that performs the substitution
        struct Substituter;

        // TODO: worry about traversing into a forall-qualified function type or type decl with assertions

        void initialize( const TypeSubstitution &src, TypeSubstitution &dest );

        template<typename core_t>
        friend class Pass;

        typedef std::unordered_map< std::string, ptr<Type> > TypeEnvType;
        typedef std::unordered_map< std::string, ptr<Expr> > VarEnvType;
        TypeEnvType typeEnv;
        VarEnvType varEnv;

  public:
        // has to come after declaration of typeEnv
        auto begin()       -> decltype( typeEnv.begin() ) { return typeEnv.begin(); }
        auto   end()       -> decltype( typeEnv.  end() ) { return typeEnv.  end(); }
        auto begin() const -> decltype( typeEnv.begin() ) { return typeEnv.begin(); }
        auto   end() const -> decltype( typeEnv.  end() ) { return typeEnv.  end(); }

        auto beginVar()       -> decltype( varEnv.begin() ) { return varEnv.begin(); }
        auto   endVar()       -> decltype( varEnv.  end() ) { return varEnv.  end(); }
        auto beginVar() const -> decltype( varEnv.begin() ) { return varEnv.begin(); }
        auto   endVar() const -> decltype( varEnv.  end() ) { return varEnv.  end(); }
};

template< typename FormalIterator, typename ActualIterator >
void TypeSubstitution::add( FormalIterator formalBegin, FormalIterator formalEnd, ActualIterator actualBegin ) {
        // FormalIterator points to a TypeDecl
        // ActualIterator points to a Type
        FormalIterator formalIt = formalBegin;
        ActualIterator actualIt = actualBegin;
        for ( ; formalIt != formalEnd; ++formalIt, ++actualIt ) {
                if ( const TypeDecl *formal = formalIt->template as<TypeDecl>() ) {
                        if ( const TypeExpr *actual = actualIt->template as<TypeExpr>() ) {
                                if ( formal->name != "" ) {
                                        typeEnv[ formal->name ] = actual->type;
                                } // if
                        } else {
                                SemanticError( formal, toString( "Attempt to provide non-type parameter: ", toString( *actualIt ).c_str(), " for type parameter " ) );
                        } // if
                } else {
                        // TODO: type check the formal and actual parameters
                        if ( (*formalIt)->name != "" ) {
                                varEnv[ (*formalIt)->name ] = *actualIt;
                        } // if
                } // if
        } // for
}

template< typename FormalIterator, typename ActualIterator >
TypeSubstitution::TypeSubstitution( FormalIterator formalBegin, FormalIterator formalEnd, ActualIterator actualBegin ) {
        add( formalBegin, formalEnd, actualBegin );
}

} // namespace ast

// include needs to happen after TypeSubstitution is defined so that both TypeSubstitution and
// PassVisitor are defined before PassVisitor implementation accesses TypeSubstitution internals.
#include "Pass.hpp"
#include "Copy.hpp"

namespace ast {

// definitition must happen after PassVisitor is included so that WithGuards can be used
struct TypeSubstitution::Substituter : public WithGuards, public WithVisitorRef<Substituter>, public PureVisitor {
                static size_t traceId;

                Substituter( const TypeSubstitution & sub, bool freeOnly ) : sub( sub ), freeOnly( freeOnly ) {}

                const Type * postvisit( const TypeInstType * aggregateUseType );
                const Expr * postvisit( const NameExpr * nameExpr );

                /// Records type variable bindings from forall-statements
                void previsit( const ParameterizedType * type );
                /// Records type variable bindings from forall-statements and instantiations of generic types
                void handleAggregateType( const BaseInstType * type );

                void previsit( const StructInstType * aggregateUseType );
                void previsit( const UnionInstType * aggregateUseType );

                const TypeSubstitution & sub;
                int subCount = 0;
                bool freeOnly;
                typedef std::unordered_set< std::string > BoundVarsType;
                BoundVarsType boundVars;

};

template< typename SynTreeClass >
TypeSubstitution::ApplyResult<SynTreeClass> TypeSubstitution::apply( const SynTreeClass * input ) const {
        assert( input );
        Pass<Substituter> sub( *this, false );
        input = strict_dynamic_cast< const SynTreeClass * >( input->accept( sub ) );
        return { input, sub.core.subCount };
}

template< typename SynTreeClass >
TypeSubstitution::ApplyResult<SynTreeClass> TypeSubstitution::applyFree( const SynTreeClass * input ) const {
        assert( input );
        Pass<Substituter> sub( *this, true );
        input = strict_dynamic_cast< const SynTreeClass * >( input->accept( sub ) );
        return { input, sub.core.subCount };
}

} // namespace ast

// Local Variables: //
// tab-width: 4 //
// mode: c++ //
// compile-command: "make install" //
// End: //