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//===--- CanTypeVisitor.h - TypeVisitor specialization ----------*- C++ -*-===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
//
// This file defines CanTypeVisitor, a specialized version of
// TypeVisitor for visiting fully type-checked canonical types.
//
//===----------------------------------------------------------------------===//
#ifndef SWIFT_AST_CANTYPEVISITOR_H
#define SWIFT_AST_CANTYPEVISITOR_H
#include "swift/AST/Types.h"
namespace swift {
/// This is a specialization of swift::TypeVisitor which:
/// - works only on canonical and fully-checked types and
/// - preserves the canonicality of the visited types in the
/// static (C++) type.
template<typename ImplClass, typename RetTy = void, typename... Args>
class CanTypeVisitor {
public:
RetTy visit(CanType T, Args... args) {
switch (T->getKind()) {
#define SUGARED_TYPE(CLASS, PARENT) \
case TypeKind::CLASS:
#define TYPE(CLASS, PARENT)
#include "swift/AST/TypeNodes.def"
llvm_unreachable("non-canonical type");
#define SUGARED_TYPE(CLASS, PARENT)
#define TYPE(CLASS, PARENT) \
case TypeKind::CLASS: \
return static_cast<ImplClass*>(this) \
->visit##CLASS##Type(cast<CLASS##Type>(T), \
::std::forward<Args>(args)...);
#include "swift/AST/TypeNodes.def"
}
llvm_unreachable("Not reachable, all cases handled");
}
// Provide default implementations of abstract "visit" implementations that
// just chain to their base class. This allows visitors to just implement
// the base behavior and handle all subclasses if they desire. Since this is
// a template, it will only instantiate cases that are used and thus we still
// require full coverage of the AST nodes by the visitor.
#define ABSTRACT_TYPE(CLASS, PARENT) \
RetTy visit##CLASS##Type(Can##CLASS##Type T, Args... args) { \
return static_cast<ImplClass*>(this) \
->visit##PARENT(T, std::forward<Args>(args)...); \
}
#define TYPE(CLASS, PARENT) ABSTRACT_TYPE(CLASS, PARENT)
#define ABSTRACT_SUGARED_TYPE(CLASS, PARENT)
#define SUGARED_TYPE(CLASS, PARENT)
// Don't allow unchecked types by default, but allow visitors to opt-in to
// handling them.
#define UNCHECKED_TYPE(CLASS, PARENT) \
RetTy visit##CLASS##Type(Can##CLASS##Type T, Args... args) { \
llvm_unreachable("unchecked type"); \
}
#include "swift/AST/TypeNodes.def"
};
} // end namespace swift
#endif