source: src/AST/Pass.impl.hpp@ 246c245

//
// Cforall Version 1.0.0 Copyright (C) 2019 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// Pass.impl.hpp --
//
// Author           : Thierry Delisle
// Created On       : Thu May 09 15::37::05 2019
// Last Modified By :
// Last Modified On :
// Update Count     :
//

#pragma once
// IWYU pragma: private, include "AST/Pass.hpp"

#include <type_traits>
#include <unordered_map>

#include "AST/TypeSubstitution.hpp"

#define VISIT_START( node ) \
        using namespace ast; \
        /* back-up the visit children */ \
        __attribute__((unused)) ast::__pass::visit_children_guard guard1( ast::__pass::visit_children(pass, 0) ); \
        /* setup the scope for passes that want to run code at exit */ \
        __attribute__((unused)) ast::__pass::guard_value          guard2( ast::__pass::at_cleanup    (pass, 0) ); \
        /* call the implementation of the previsit of this pass */ \
        __pass::previsit( pass, node, 0 );

#define VISIT( code... ) \
        /* if this node should visit its children */ \
        if ( __visit_children() ) { \
                /* visit the children */ \
                code \
        }

#define VISIT_END( type, node ) \
        /* call the implementation of the postvisit of this pass */ \
        auto __return = __pass::postvisit( pass, node, 0 ); \
        assertf(__return, "post visit should never return null"); \
        return __return;

#ifdef PEDANTIC_PASS_ASSERT
#define __pedantic_pass_assert(...) assert (__VA_ARGS__)
#define __pedantic_pass_assertf(...) assertf(__VA_ARGS__)
#else
#define __pedantic_pass_assert(...)
#define __pedantic_pass_assertf(...)
#endif

namespace ast {
        namespace __pass {
                // Check if this is either a null pointer or a pointer to an empty container
                template<typename T>
                static inline bool empty( T * ptr ) {
                        return !ptr || ptr->empty();
                }

                //------------------------------
                template<typename it_t, template <class...> class container_t>
                static inline void take_all( it_t it, container_t<ast::ptr<ast::Decl>> * decls, bool * mutated = nullptr ) {
                        if(empty(decls)) return;

                        std::transform(decls->begin(), decls->end(), it, [](const ast::Decl * decl) -> auto {
                                        return new DeclStmt( decl->location, decl );
                                });
                        decls->clear();
                        if(mutated) *mutated = true;
                }

                template<typename it_t, template <class...> class container_t>
                static inline void take_all( it_t it, container_t<ast::ptr<ast::Stmt>> * decls, bool * mutated = nullptr ) {
                        if(empty(decls)) return;

                        std::move(decls->begin(), decls->end(), it);
                        decls->clear();
                        if(mutated) *mutated = true;
                }

                //------------------------------
                /// Check if should be skipped, different for pointers and containers
                template<typename node_t>
                bool skip( const ast::ptr<node_t> & val) {
                        return !val;
                }

                template< template <class...> class container_t, typename node_t >
                bool skip( const container_t<ast::ptr< node_t >> & val ) {
                        return val.empty();
                }

                //------------------------------
                /// Get the value to visit, different for pointers and containers
                template<typename node_t>
                auto get( const ast::ptr<node_t> & val, int ) -> decltype(val.get()) {
                        return val.get();
                }

                template<typename node_t>
                const node_t & get( const node_t & val, long) {
                        return val;
                }


                //------------------------------
                /// Check if value was mutated, different for pointers and containers
                template<typename lhs_t, typename rhs_t>
                bool differs( const lhs_t * old_val, const rhs_t * new_val ) {
                        return old_val != new_val;
                }

                template< template <class...> class container_t, typename node_t >
                bool differs( const container_t<ast::ptr< node_t >> &, const container_t<ast::ptr< node_t >> & new_val ) {
                        return !new_val.empty();
                }
        }

        template< typename pass_t >
        template< typename node_t >
        auto Pass< pass_t >::call_accept( const node_t * node )
                -> typename std::enable_if<
                                !std::is_base_of<ast::Expr, node_t>::value &&
                                !std::is_base_of<ast::Stmt, node_t>::value
                        , decltype( node->accept(*this) )
                >::type

        {
                __pedantic_pass_assert( __visit_children() );
                __pedantic_pass_assert( expr );

                static_assert( !std::is_base_of<ast::Expr, node_t>::value, "ERROR");
                static_assert( !std::is_base_of<ast::Stmt, node_t>::value, "ERROR");

                return node->accept( *this );
        }

        template< typename pass_t >
        const ast::Expr * Pass< pass_t >::call_accept( const ast::Expr * expr ) {
                __pedantic_pass_assert( __visit_children() );
                __pedantic_pass_assert( expr );

                const ast::TypeSubstitution ** env_ptr = __pass::env( pass, 0);
                if ( env_ptr && expr->env ) {
                        *env_ptr = expr->env;
                }

                return expr->accept( *this );
        }

        template< typename pass_t >
        const ast::Stmt * Pass< pass_t >::call_accept( const ast::Stmt * stmt ) {
                __pedantic_pass_assert( __visit_children() );
                __pedantic_pass_assert( stmt );

                // add a few useful symbols to the scope
                using __pass::empty;

                // get the stmts/decls that will need to be spliced in
                auto stmts_before = __pass::stmtsToAddBefore( pass, 0);
                auto stmts_after  = __pass::stmtsToAddAfter ( pass, 0);
                auto decls_before = __pass::declsToAddBefore( pass, 0);
                auto decls_after  = __pass::declsToAddAfter ( pass, 0);

                // These may be modified by subnode but most be restored once we exit this statemnet.
                ValueGuardPtr< const ast::TypeSubstitution * > __old_env         ( __pass::env( pass, 0) );
                ValueGuardPtr< typename std::remove_pointer< decltype(stmts_before) >::type > __old_decls_before( stmts_before );
                ValueGuardPtr< typename std::remove_pointer< decltype(stmts_after ) >::type > __old_decls_after ( stmts_after  );
                ValueGuardPtr< typename std::remove_pointer< decltype(decls_before) >::type > __old_stmts_before( decls_before );
                ValueGuardPtr< typename std::remove_pointer< decltype(decls_after ) >::type > __old_stmts_after ( decls_after  );

                // Now is the time to actually visit the node
                const ast::Stmt * nstmt = stmt->accept( *this );

                // If the pass doesn't want to add anything then we are done
                if( empty(stmts_before) && empty(stmts_after) && empty(decls_before) && empty(decls_after) ) {
                        return nstmt;
                }

                // Make sure that it is either adding statements or declartions but not both
                // this is because otherwise the order would be awkward to predict
                assert(( empty( stmts_before ) && empty( stmts_after ))
                    || ( empty( decls_before ) && empty( decls_after )) );

                // Create a new Compound Statement to hold the new decls/stmts
                ast::CompoundStmt * compound = new ast::CompoundStmt( stmt->location );

                // Take all the declarations that go before
                __pass::take_all( std::back_inserter( compound->kids ), decls_before );
                __pass::take_all( std::back_inserter( compound->kids ), stmts_before );

                // Insert the original declaration
                compound->kids.emplace_back( nstmt );

                // Insert all the declarations that go before
                __pass::take_all( std::back_inserter( compound->kids ), decls_after );
                __pass::take_all( std::back_inserter( compound->kids ), stmts_after );

                return compound;
        }

        template< typename pass_t >
        template< template <class...> class container_t >
        container_t< ptr<Stmt> > Pass< pass_t >::call_accept( const container_t< ptr<Stmt> > & statements ) {
                __pedantic_pass_assert( __visit_children() );
                if( statements.empty() ) return {};

                // We are going to aggregate errors for all these statements
                SemanticErrorException errors;

                // add a few useful symbols to the scope
                using __pass::empty;

                // get the stmts/decls that will need to be spliced in
                auto stmts_before = __pass::stmtsToAddBefore( pass, 0);
                auto stmts_after  = __pass::stmtsToAddAfter ( pass, 0);
                auto decls_before = __pass::declsToAddBefore( pass, 0);
                auto decls_after  = __pass::declsToAddAfter ( pass, 0);

                // These may be modified by subnode but most be restored once we exit this statemnet.
                ValueGuardPtr< typename std::remove_pointer< decltype(stmts_before) >::type > __old_decls_before( stmts_before );
                ValueGuardPtr< typename std::remove_pointer< decltype(stmts_after ) >::type > __old_decls_after ( stmts_after  );
                ValueGuardPtr< typename std::remove_pointer< decltype(decls_before) >::type > __old_stmts_before( decls_before );
                ValueGuardPtr< typename std::remove_pointer< decltype(decls_after ) >::type > __old_stmts_after ( decls_after  );

                // update pass statitistics
                pass_visitor_stats.depth++;
                pass_visitor_stats.max->push(pass_visitor_stats.depth);
                pass_visitor_stats.avg->push(pass_visitor_stats.depth);

                bool mutated = false;
                container_t< ptr<Stmt> > new_kids;
                for( const Stmt * stmt : statements ) {
                        try {
                                __pedantic_pass_assert( stmt );
                                const ast::Stmt * new_stmt = stmt->accept( *this );
                                assert( new_stmt );
                                if(new_stmt != stmt ) mutated = true;

                                // Make sure that it is either adding statements or declartions but not both
                                // this is because otherwise the order would be awkward to predict
                                assert(( empty( stmts_before ) && empty( stmts_after ))
                                    || ( empty( decls_before ) && empty( decls_after )) );



                                // Take all the statements which should have gone after, N/A for first iteration
                                __pass::take_all( std::back_inserter( new_kids ), decls_before, &mutated );
                                __pass::take_all( std::back_inserter( new_kids ), stmts_before, &mutated );

                                // Now add the statement if there is one
                                new_kids.emplace_back( new_stmt );

                                // Take all the declarations that go before
                                __pass::take_all( std::back_inserter( new_kids ), decls_after, &mutated );
                                __pass::take_all( std::back_inserter( new_kids ), stmts_after, &mutated );
                        }
                        catch ( SemanticErrorException &e ) {
                                errors.append( e );
                        }
                }
                pass_visitor_stats.depth--;
                if ( !errors.isEmpty() ) { throw errors; }

                return mutated ? new_kids : container_t< ptr<Stmt> >();
        }

        template< typename pass_t >
        template< template <class...> class container_t, typename node_t >
        container_t< ast::ptr<node_t> > Pass< pass_t >::call_accept( const container_t< ast::ptr<node_t> > & container ) {
                __pedantic_pass_assert( __visit_children() );
                if( container.empty() ) return {};
                SemanticErrorException errors;

                pass_visitor_stats.depth++;
                pass_visitor_stats.max->push(pass_visitor_stats.depth);
                pass_visitor_stats.avg->push(pass_visitor_stats.depth);

                bool mutated = false;
                container_t< ast::ptr<node_t> > new_kids;
                for ( const node_t * node : container ) {
                        try {
                                __pedantic_pass_assert( node );
                                const node_t * new_stmt = strict_dynamic_cast< const node_t * >( node->accept( *this ) );
                                if(new_stmt != node ) mutated = true;

                                new_kids.emplace_back( new_stmt );
                        }
                        catch( SemanticErrorException &e ) {
                                errors.append( e );
                        }
                }
                pass_visitor_stats.depth--;
                if ( ! errors.isEmpty() ) { throw errors; }

                return mutated ? new_kids : container_t< ast::ptr<node_t> >();
        }

        template< typename pass_t >
        template<typename node_t, typename parent_t, typename child_t>
        void Pass< pass_t >::maybe_accept(
                const node_t * & parent,
                child_t parent_t::*child
        ) {
                static_assert( std::is_base_of<parent_t, node_t>::value, "Error deducing member object" );

                if(__pass::skip(parent->*child)) return;
                const auto & old_val = __pass::get(parent->*child, 0);

                static_assert( !std::is_same<const ast::Node * &, decltype(old_val)>::value, "ERROR");

                auto new_val = call_accept( old_val );

                static_assert( !std::is_same<const ast::Node *, decltype(new_val)>::value || std::is_same<int, decltype(old_val)>::value, "ERROR");

                if( __pass::differs(old_val, new_val) ) {
                        auto new_parent = mutate(parent);
                        new_parent->*child = new_val;
                        parent = new_parent;
                }
        }

}

//------------------------------------------------------------------------------------------------------------------------------------------------------------------------
//========================================================================================================================================================================
//========================================================================================================================================================================
//========================================================================================================================================================================
//========================================================================================================================================================================
//========================================================================================================================================================================
//------------------------------------------------------------------------------------------------------------------------------------------------------------------------

template< typename pass_t >
inline void ast::accept_all( std::list< ast::ptr<ast::Decl> > & decls, ast::Pass< pass_t > & visitor ) {
        // We are going to aggregate errors for all these statements
        SemanticErrorException errors;

        // add a few useful symbols to the scope
        using __pass::empty;

        // get the stmts/decls that will need to be spliced in
        auto decls_before = __pass::declsToAddBefore( visitor.pass, 0);
        auto decls_after  = __pass::declsToAddAfter ( visitor.pass, 0);

        // update pass statitistics
        pass_visitor_stats.depth++;
        pass_visitor_stats.max->push(pass_visitor_stats.depth);
        pass_visitor_stats.avg->push(pass_visitor_stats.depth);

        for ( std::list< ast::ptr<ast::Decl> >::iterator i = decls.begin(); ; ++i ) {
                // splice in new declarations after previous decl
                if ( !empty( decls_after ) ) { decls.splice( i, *decls_after ); }

                if ( i == decls.end() ) break;

                try {
                        // run visitor on declaration
                        ast::ptr<ast::Decl> & node = *i;
                        assert( node );
                        node = node->accept( visitor );
                }
                catch( SemanticErrorException &e ) {
                        errors.append( e );
                }

                // splice in new declarations before current decl
                if ( !empty( decls_before ) ) { decls.splice( i, *decls_before ); }
        }
        pass_visitor_stats.depth--;
        if ( !errors.isEmpty() ) { throw errors; }
}

// A NOTE ON THE ORDER OF TRAVERSAL
//
// Types and typedefs have their base types visited before they are added to the type table.  This is ok, since there is
// no such thing as a recursive type or typedef.
//
//             typedef struct { T *x; } T; // never allowed
//
// for structs/unions, it is possible to have recursion, so the decl should be added as if it's incomplete to begin, the
// members are traversed, and then the complete type should be added (assuming the type is completed by this particular
// declaration).
//
//             struct T { struct T *x; }; // allowed
//
// It is important to add the complete type to the symbol table *after* the members/base has been traversed, since that
// traversal may modify the definition of the type and these modifications should be visible when the symbol table is
// queried later in this pass.

//--------------------------------------------------------------------------
// ObjectDecl
template< typename pass_t >
const ast::DeclWithType * ast::Pass< pass_t >::visit( const ast::ObjectDecl * node ) {
        VISIT_START( node );

        VISIT(
                {
                        guard_indexer guard { *this };
                        maybe_accept( node, &ObjectDecl::type );
                }
                maybe_accept( node, &ObjectDecl::init          );
                maybe_accept( node, &ObjectDecl::bitfieldWidth );
                maybe_accept( node, &ObjectDecl::attributes    );
        )

        __pass::indexer::addId( pass, 0, node );

        VISIT_END( DeclWithType, node );
}

//--------------------------------------------------------------------------
// FunctionDecl
template< typename pass_t >
const ast::DeclWithType * ast::Pass< pass_t >::visit( const ast::FunctionDecl * node ) {
        VISIT_START( node );

        __pass::indexer::addId( pass, 0, node );

        VISIT(maybe_accept( node, &FunctionDecl::withExprs );)
        {
                // with clause introduces a level of scope (for the with expression members).
                // with clause exprs are added to the indexer before parameters so that parameters
                // shadow with exprs and not the other way around.
                guard_indexer guard { *this };
                __pass::indexer::addWith( pass, 0, node->withExprs, node );
                {
                        guard_indexer guard { *this };
                        // implicit add __func__ identifier as specified in the C manual 6.4.2.2
                        static ast::ObjectDecl func(
                                node->location, "__func__",
                                new ast::ArrayType(
                                        new ast::BasicType( ast::BasicType::Char, ast::CV::Qualifiers( ast::CV::Const ) ),
                                        nullptr, VariableLen, DynamicDim
                                )
                        );
                        __pass::indexer::addId( pass, 0, &func );
                        VISIT(
                                maybe_accept( node, &FunctionDecl::type );
                                // function body needs to have the same scope as parameters - CompoundStmt will not enter
                                // a new scope if inFunction is true
                                ValueGuard< bool > oldInFunction( inFunction );
                                inFunction = true;
                                maybe_accept( node, &FunctionDecl::stmts );
                                maybe_accept( node, &FunctionDecl::attributes );
                        )
                }
        }

        VISIT_END( DeclWithType, node );
}

//--------------------------------------------------------------------------
// StructDecl
template< typename pass_t >
const ast::Decl * ast::Pass< pass_t >::visit( const ast::StructDecl * node ) {
        VISIT_START( node );

        // make up a forward declaration and add it before processing the members
        // needs to be on the heap because addStruct saves the pointer
        __pass::indexer::addStructFwd( pass, 0, node );

        VISIT({
                guard_indexer guard { * this };
                maybe_accept( node, &StructDecl::params  );
                maybe_accept( node, &StructDecl::members );
        })

        // this addition replaces the forward declaration
        __pass::indexer::addStruct( pass, 0, node );

        VISIT_END( Decl, node );
}

//--------------------------------------------------------------------------
// UnionDecl
template< typename pass_t >
const ast::Decl * ast::Pass< pass_t >::visit( const ast::UnionDecl * node ) {
        VISIT_START( node );

        // make up a forward declaration and add it before processing the members
        __pass::indexer::addUnionFwd( pass, 0, node );

        VISIT({
                guard_indexer guard { * this };
                maybe_accept( node, &UnionDecl::params  );
                maybe_accept( node, &UnionDecl::members );
        })

        __pass::indexer::addUnion( pass, 0, node );

        VISIT_END( Decl, node );
}

//--------------------------------------------------------------------------
// EnumDecl
template< typename pass_t >
const ast::Decl * ast::Pass< pass_t >::visit( const ast::EnumDecl * node ) {
        VISIT_START( node );

        __pass::indexer::addEnum( pass, 0, node );

        VISIT(
                // unlike structs, traits, and unions, enums inject their members into the global scope
                maybe_accept( node, &EnumDecl::params  );
                maybe_accept( node, &EnumDecl::members );
        )

        VISIT_END( Decl, node );
}

//--------------------------------------------------------------------------
// TraitDecl
template< typename pass_t >
const ast::Decl * ast::Pass< pass_t >::visit( const ast::TraitDecl * node ) {
        VISIT_START( node );

        VISIT({
                guard_indexer guard { *this };
                maybe_accept( node, &TraitDecl::params  );
                maybe_accept( node, &TraitDecl::members );
        })

        __pass::indexer::addTrait( pass, 0, node );

        VISIT_END( Decl, node );
}

//--------------------------------------------------------------------------
// TypeDecl
template< typename pass_t >
const ast::Decl * ast::Pass< pass_t >::visit( const ast::TypeDecl * node ) {
        VISIT_START( node );

        VISIT({
                guard_indexer guard { *this };
                maybe_accept( node, &TypeDecl::params );
                maybe_accept( node, &TypeDecl::base   );
        })

        // see A NOTE ON THE ORDER OF TRAVERSAL, above
        // note that assertions come after the type is added to the symtab, since they are not part of the type proper
        // and may depend on the type itself
        __pass::indexer::addType( pass, 0, node );

        VISIT(
                maybe_accept( node, &TypeDecl::assertions );

                {
                        guard_indexer guard { *this };
                        maybe_accept( node, &TypeDecl::init );
                }
        )

        VISIT_END( Decl, node );
}

//--------------------------------------------------------------------------
// TypedefDecl
template< typename pass_t >
const ast::Decl * ast::Pass< pass_t >::visit( const ast::TypedefDecl * node ) {
        VISIT_START( node );

        VISIT({
                guard_indexer guard { *this };
                maybe_accept( node, &TypedefDecl::params );
                maybe_accept( node, &TypedefDecl::base   );
        })

        __pass::indexer::addType( pass, 0, node );

        maybe_accept( node, &TypedefDecl::assertions );

        VISIT_END( Decl, node );
}

//--------------------------------------------------------------------------
// AsmDecl
template< typename pass_t >
const ast::AsmDecl * ast::Pass< pass_t >::visit( const ast::AsmDecl * node ) {
        VISIT_START( node );

        VISIT(
                maybe_accept( node, &AsmDecl::stmt );
        )

        VISIT_END( AsmDecl, node );
}

//--------------------------------------------------------------------------
// StaticAssertDecl
template< typename pass_t >
const ast::StaticAssertDecl * ast::Pass< pass_t >::visit( const ast::StaticAssertDecl * node ) {
        VISIT_START( node );

        VISIT(
                maybe_accept( node, &StaticAssertDecl::condition );
                maybe_accept( node, &StaticAssertDecl::msg       );
        )

        VISIT_END( StaticAssertDecl, node );
}

//--------------------------------------------------------------------------
// CompoundStmt
template< typename pass_t >
const ast::CompoundStmt * ast::Pass< pass_t >::visit( const ast::CompoundStmt * node ) {
        VISIT_START( node );
        VISIT({
                // do not enter a new scope if inFunction is true - needs to check old state before the assignment
                auto guard1 = makeFuncGuard( [this, inFunction = this->inFunction]() {
                        if ( ! inFunction ) __pass::indexer::enter(pass, 0);
                }, [this, inFunction = this->inFunction]() {
                        if ( ! inFunction ) __pass::indexer::leave(pass, 0);
                });
                ValueGuard< bool > guard2( inFunction );
                guard_scope guard3 { *this };
                inFunction = false;
                maybe_accept( node, &CompoundStmt::kids );
        })
        VISIT_END( CompoundStmt, node );
}

//--------------------------------------------------------------------------
// ExprStmt
template< typename pass_t >
const ast::Stmt * ast::Pass< pass_t >::visit( const ExprStmt * node ) {
        VISIT_START( node );

        VISIT(
                maybe_accept( node, &ExprStmt::expr );
        )

        VISIT_END( Stmt, node );
}

//--------------------------------------------------------------------------
// AsmStmt
template< typename pass_t >
const ast::Stmt * ast::Pass< pass_t >::visit( const ast::AsmStmt * node ) {
        VISIT_START( node )

        VISIT(
                maybe_accept( node, &AsmStmt::instruction );
                maybe_accept( node, &AsmStmt::output      );
                maybe_accept( node, &AsmStmt::input       );
                maybe_accept( node, &AsmStmt::clobber     );
        )

        VISIT_END( Stmt, node );
}

//--------------------------------------------------------------------------
// DirectiveStmt
template< typename pass_t >
const ast::Stmt * ast::Pass< pass_t >::visit( const ast::DirectiveStmt * node ) {
        VISIT_START( node )

        VISIT_END( Stmt, node );
}

//--------------------------------------------------------------------------
// IfStmt
template< typename pass_t >
const ast::Stmt * ast::Pass< pass_t >::visit( const ast::IfStmt * node ) {
        VISIT_START( node );
        VISIT({
                // if statements introduce a level of scope (for the initialization)
                guard_indexer guard { *this };
                maybe_accept( node, &IfStmt::inits    );
                maybe_accept( node, &IfStmt::cond     );
                maybe_accept( node, &IfStmt::thenPart );
                maybe_accept( node, &IfStmt::elsePart );
        })
        VISIT_END( Stmt, node );
}

//--------------------------------------------------------------------------
// WhileStmt
template< typename pass_t >
const ast::Stmt * ast::Pass< pass_t >::visit( const WhileStmt * node ) {
        VISIT_START( node );

        VISIT({
                // while statements introduce a level of scope (for the initialization)
                guard_indexer guard { *this };
                maybe_accept( node, &WhileStmt::inits );
                maybe_accept( node, &WhileStmt::cond  );
                maybe_accept( node, &WhileStmt::body  );
        })

        VISIT_END( Stmt, node );
}

//--------------------------------------------------------------------------
// ForStmt
template< typename pass_t >
const ast::Stmt * ast::Pass< pass_t >::visit( const ast::ForStmt * node ) {
        VISIT_START( node );

        VISIT({
                // for statements introduce a level of scope (for the initialization)
                guard_indexer guard { *this };
                maybe_accept( node, &ForStmt::inits );
                maybe_accept( node, &ForStmt::cond  );
                maybe_accept( node, &ForStmt::inc   );
                maybe_accept( node, &ForStmt::body  );
        })

        VISIT_END( Stmt, node );
}

//--------------------------------------------------------------------------
// SwitchStmt
template< typename pass_t >
const ast::Stmt * ast::Pass< pass_t >::visit( const ast::SwitchStmt * node ) {
        VISIT_START( node );

        VISIT(
                maybe_accept( node, &SwitchStmt::cond  );
                maybe_accept( node, &SwitchStmt::stmts );
        )

        VISIT_END( Stmt, node );
}

//--------------------------------------------------------------------------
// CaseStmt
template< typename pass_t >
const ast::Stmt * ast::Pass< pass_t >::visit( const ast::CaseStmt * node ) {
        VISIT_START( node );

        VISIT(
                maybe_accept( node, &CaseStmt::cond  );
                maybe_accept( node, &CaseStmt::stmts );
        )

        VISIT_END( Stmt, node );
}

//--------------------------------------------------------------------------
// BranchStmt
template< typename pass_t >
const ast::Stmt * ast::Pass< pass_t >::visit( const ast::BranchStmt * node ) {
        VISIT_START( node );
        VISIT_END( Stmt, node );
}

//--------------------------------------------------------------------------
// ReturnStmt
template< typename pass_t >
const ast::Stmt * ast::Pass< pass_t >::visit( const ast::ReturnStmt * node ) {
        VISIT_START( node );

        VISIT(
                maybe_accept( node, &ReturnStmt::expr );
        )

        VISIT_END( Stmt, node );
}

//--------------------------------------------------------------------------
// ThrowStmt
template< typename pass_t >
const ast::Stmt * ast::Pass< pass_t >::visit( const ast::ThrowStmt * node ) {
        VISIT_START( node );

        VISIT(
                maybe_accept( node, &ThrowStmt::expr   );
                maybe_accept( node, &ThrowStmt::target );
        )

        VISIT_END( Stmt, node );
}

//--------------------------------------------------------------------------
// TryStmt
template< typename pass_t >
const ast::Stmt * ast::Pass< pass_t >::visit( const ast::TryStmt * node ) {
        VISIT_START( node );

        VISIT(
                maybe_accept( node, &TryStmt::body     );
                maybe_accept( node, &TryStmt::handlers );
                maybe_accept( node, &TryStmt::finally  );
        )

        VISIT_END( Stmt, node );
}

//--------------------------------------------------------------------------
// SingleInit
template< typename pass_t >
const ast::Init * ast::Pass< pass_t >::visit( const ast::SingleInit * node ) {
        VISIT_START( node );

        VISIT(
                maybe_accept( node, &SingleInit::value );
        )

        VISIT_END( Init, node );
}

//--------------------------------------------------------------------------
// ListInit
template< typename pass_t >
const ast::Init * ast::Pass< pass_t >::visit( const ast::ListInit * node ) {
        VISIT_START( node );

        VISIT(
                maybe_accept( node, &ListInit::designations );
                maybe_accept( node, &ListInit::initializers );
        )

        VISIT_END( Init, node );
}

//--------------------------------------------------------------------------
// ConstructorInit
template< typename pass_t >
const ast::Init * ast::Pass< pass_t >::visit( const ast::ConstructorInit * node ) {
        VISIT_START( node );

        VISIT(
                maybe_accept( node, &ConstructorInit::ctor );
                maybe_accept( node, &ConstructorInit::dtor );
                maybe_accept( node, &ConstructorInit::init );
        )

        VISIT_END( Init, node );
}

//--------------------------------------------------------------------------
// Attribute
template< typename pass_t >
const ast::Attribute * ast::Pass< pass_t >::visit( const ast::Attribute * node  )  {
        VISIT_START( node );

        VISIT(
                maybe_accept( node, &Attribute::parameters );
        )

        VISIT_END( Attribute, node );
}

//--------------------------------------------------------------------------
// TypeSubstitution
template< typename pass_t >
const ast::TypeSubstitution * ast::Pass< pass_t >::visit( const ast::TypeSubstitution * node ) {
        VISIT_START( node );

        VISIT(
                {
                        bool mutated = false;
                        std::unordered_map< std::string, ast::ptr< ast::Type > > new_map;
                        for ( const auto & p : node->typeEnv ) {
                                guard_indexer guard { *this };
                                auto new_node = p.second->accept( *this );
                                if (new_node != p.second) mutated = false;
                                new_map.insert({ p.first, new_node });
                        }
                        if (mutated) {
                                auto new_node = mutate( node );
                                new_node->typeEnv.swap( new_map );
                                node = new_node;
                        }
                }

                {
                        bool mutated = false;
                        std::unordered_map< std::string, ast::ptr< ast::Expr > > new_map;
                        for ( const auto & p : node->varEnv ) {
                                guard_indexer guard { *this };
                                auto new_node = p.second->accept( *this );
                                if (new_node != p.second) mutated = false;
                                new_map.insert({ p.first, new_node });
                        }
                        if (mutated) {
                                auto new_node = mutate( node );
                                new_node->varEnv.swap( new_map );
                                node = new_node;
                        }
                }
        )

        VISIT_END( TypeSubstitution, node );
}

#undef VISIT_START
#undef VISIT
#undef VISIT_END