llvm/clang/include/clang/AST/TemplateName.h

//===- TemplateName.h - C++ Template Name Representation --------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
//  This file defines the TemplateName interface and subclasses.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_AST_TEMPLATENAME_H
#define LLVM_CLANG_AST_TEMPLATENAME_H

#include "clang/AST/DependenceFlags.h"
#include "clang/AST/NestedNameSpecifier.h"
#include "clang/Basic/LLVM.h"
#include "llvm/ADT/FoldingSet.h"
#include "llvm/ADT/PointerIntPair.h"
#include "llvm/ADT/PointerUnion.h"
#include "llvm/Support/PointerLikeTypeTraits.h"
#include <cassert>
#include <optional>

namespace clang {

class ASTContext;
class Decl;
class DependentTemplateName;
class IdentifierInfo;
class NamedDecl;
class NestedNameSpecifier;
enum OverloadedOperatorKind : int;
class OverloadedTemplateStorage;
class AssumedTemplateStorage;
struct PrintingPolicy;
class QualifiedTemplateName;
class SubstTemplateTemplateParmPackStorage;
class SubstTemplateTemplateParmStorage;
class TemplateArgument;
class TemplateDecl;
class TemplateTemplateParmDecl;
class UsingShadowDecl;

/// Implementation class used to describe either a set of overloaded
/// template names or an already-substituted template template parameter pack.
class UncommonTemplateNameStorage { … };

/// A structure for storing the information associated with an
/// overloaded template name.
class OverloadedTemplateStorage : public UncommonTemplateNameStorage { … };

/// A structure for storing an already-substituted template template
/// parameter pack.
///
/// This kind of template names occurs when the parameter pack has been
/// provided with a template template argument pack in a context where its
/// enclosing pack expansion could not be fully expanded.
class SubstTemplateTemplateParmPackStorage : public UncommonTemplateNameStorage,
                                             public llvm::FoldingSetNode { … };

/// Represents a C++ template name within the type system.
///
/// A C++ template name refers to a template within the C++ type
/// system. In most cases, a template name is simply a reference to a
/// class template, e.g.
///
/// \code
/// template<typename T> class X { };
///
/// X<int> xi;
/// \endcode
///
/// Here, the 'X' in \c X<int> is a template name that refers to the
/// declaration of the class template X, above. Template names can
/// also refer to function templates, C++0x template aliases, etc.
///
/// Some template names are dependent. For example, consider:
///
/// \code
/// template<typename MetaFun, typename T1, typename T2> struct apply2 {
///   typedef typename MetaFun::template apply<T1, T2>::type type;
/// };
/// \endcode
///
/// Here, "apply" is treated as a template name within the typename
/// specifier in the typedef. "apply" is a nested template, and can
/// only be understood in the context of a template instantiation,
/// hence is represented as a dependent template name.
class TemplateName { … };

/// Insertion operator for diagnostics.  This allows sending TemplateName's
/// into a diagnostic with <<.
const StreamingDiagnostic &operator<<(const StreamingDiagnostic &DB,
                                      TemplateName N);

/// A structure for storing the information associated with a
/// substituted template template parameter.
class SubstTemplateTemplateParmStorage
  : public UncommonTemplateNameStorage, public llvm::FoldingSetNode { … };

inline TemplateName TemplateName::getUnderlying() const { … }

/// Represents a template name as written in source code.
///
/// This kind of template name may refer to a template name that was
/// preceded by a nested name specifier, e.g., \c std::vector. Here,
/// the nested name specifier is "std::" and the template name is the
/// declaration for "vector". It may also have been written with the
/// 'template' keyword. The QualifiedTemplateName class is only
/// used to provide "sugar" for template names, so that they can
/// be differentiated from canonical template names. and has no
/// semantic meaning. In this manner, it is to TemplateName what
/// ElaboratedType is to Type, providing extra syntactic sugar
/// for downstream clients.
class QualifiedTemplateName : public llvm::FoldingSetNode { … };

/// Represents a dependent template name that cannot be
/// resolved prior to template instantiation.
///
/// This kind of template name refers to a dependent template name,
/// including its nested name specifier (if any). For example,
/// DependentTemplateName can refer to "MetaFun::template apply",
/// where "MetaFun::" is the nested name specifier and "apply" is the
/// template name referenced. The "template" keyword is implied.
class DependentTemplateName : public llvm::FoldingSetNode { … };

} // namespace clang.

namespace llvm {

/// The clang::TemplateName class is effectively a pointer.
template<>
struct PointerLikeTypeTraits<clang::TemplateName> { … };

} // namespace llvm.

#endif // LLVM_CLANG_AST_TEMPLATENAME_H