//===- 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 {
protected:
enum Kind {
Overloaded,
Assumed, // defined in DeclarationName.h
SubstTemplateTemplateParm,
SubstTemplateTemplateParmPack
};
struct BitsTag {
/// A Kind.
unsigned Kind : 2;
// The template parameter index.
unsigned Index : 15;
/// The pack index, or the number of stored templates
/// or template arguments, depending on which subclass we have.
unsigned Data : 15;
};
union {
struct BitsTag Bits;
void *PointerAlignment;
};
UncommonTemplateNameStorage(Kind Kind, unsigned Index, unsigned Data) {
Bits.Kind = Kind;
Bits.Index = Index;
Bits.Data = Data;
}
public:
OverloadedTemplateStorage *getAsOverloadedStorage() {
return Bits.Kind == Overloaded
? reinterpret_cast<OverloadedTemplateStorage *>(this)
: nullptr;
}
AssumedTemplateStorage *getAsAssumedTemplateName() {
return Bits.Kind == Assumed
? reinterpret_cast<AssumedTemplateStorage *>(this)
: nullptr;
}
SubstTemplateTemplateParmStorage *getAsSubstTemplateTemplateParm() {
return Bits.Kind == SubstTemplateTemplateParm
? reinterpret_cast<SubstTemplateTemplateParmStorage *>(this)
: nullptr;
}
SubstTemplateTemplateParmPackStorage *getAsSubstTemplateTemplateParmPack() {
return Bits.Kind == SubstTemplateTemplateParmPack
? reinterpret_cast<SubstTemplateTemplateParmPackStorage *>(this)
: nullptr;
}
};
/// A structure for storing the information associated with an
/// overloaded template name.
class OverloadedTemplateStorage : public UncommonTemplateNameStorage {
friend class ASTContext;
OverloadedTemplateStorage(unsigned size)
: UncommonTemplateNameStorage(Overloaded, 0, size) {}
NamedDecl **getStorage() {
return reinterpret_cast<NamedDecl **>(this + 1);
}
NamedDecl * const *getStorage() const {
return reinterpret_cast<NamedDecl *const *>(this + 1);
}
public:
unsigned size() const { return Bits.Data; }
using iterator = NamedDecl *const *;
iterator begin() const { return getStorage(); }
iterator end() const { return getStorage() + Bits.Data; }
llvm::ArrayRef<NamedDecl*> decls() const {
return llvm::ArrayRef(begin(), end());
}
};
/// 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 {
const TemplateArgument *Arguments;
llvm::PointerIntPair<Decl *, 1, bool> AssociatedDeclAndFinal;
public:
SubstTemplateTemplateParmPackStorage(ArrayRef<TemplateArgument> ArgPack,
Decl *AssociatedDecl, unsigned Index,
bool Final);
/// A template-like entity which owns the whole pattern being substituted.
/// This will own a set of template parameters.
Decl *getAssociatedDecl() const;
/// Returns the index of the replaced parameter in the associated declaration.
/// This should match the result of `getParameterPack()->getIndex()`.
unsigned getIndex() const { return Bits.Index; }
// When true the substitution will be 'Final' (subst node won't be placed).
bool getFinal() const;
/// Retrieve the template template parameter pack being substituted.
TemplateTemplateParmDecl *getParameterPack() const;
/// Retrieve the template template argument pack with which this
/// parameter was substituted.
TemplateArgument getArgumentPack() const;
void Profile(llvm::FoldingSetNodeID &ID, ASTContext &Context);
static void Profile(llvm::FoldingSetNodeID &ID, ASTContext &Context,
const TemplateArgument &ArgPack, Decl *AssociatedDecl,
unsigned Index, bool Final);
};
/// 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
class TemplateName {
// NameDecl is either a TemplateDecl or a UsingShadowDecl depending on the
// NameKind.
// !! There is no free low bits in 32-bit builds to discriminate more than 4
// pointer types in PointerUnion.
using StorageType =
llvm::PointerUnion<Decl *, UncommonTemplateNameStorage *,
QualifiedTemplateName *, DependentTemplateName *>;
StorageType Storage;
explicit TemplateName(void *Ptr);
public:
// Kind of name that is actually stored.
enum NameKind {
/// A single template declaration.
Template,
/// A set of overloaded template declarations.
OverloadedTemplate,
/// An unqualified-id that has been assumed to name a function template
/// that will be found by ADL.
AssumedTemplate,
/// A qualified template name, where the qualification is kept
/// to describe the source code as written.
QualifiedTemplate,
/// A dependent template name that has not been resolved to a
/// template (or set of templates).
DependentTemplate,
/// A template template parameter that has been substituted
/// for some other template name.
SubstTemplateTemplateParm,
/// A template template parameter pack that has been substituted for
/// a template template argument pack, but has not yet been expanded into
/// individual arguments.
SubstTemplateTemplateParmPack,
/// A template name that refers to a template declaration found through a
/// specific using shadow declaration.
UsingTemplate,
};
TemplateName() = default;
explicit TemplateName(TemplateDecl *Template);
explicit TemplateName(OverloadedTemplateStorage *Storage);
explicit TemplateName(AssumedTemplateStorage *Storage);
explicit TemplateName(SubstTemplateTemplateParmStorage *Storage);
explicit TemplateName(SubstTemplateTemplateParmPackStorage *Storage);
explicit TemplateName(QualifiedTemplateName *Qual);
explicit TemplateName(DependentTemplateName *Dep);
explicit TemplateName(UsingShadowDecl *Using);
/// Determine whether this template name is NULL.
bool isNull() const;
// Get the kind of name that is actually stored.
NameKind getKind() const;
/// Retrieve the underlying template declaration that
/// this template name refers to, if known.
///
/// \returns The template declaration that this template name refers
/// to, if any. If the template name does not refer to a specific
/// declaration because it is a dependent name, or if it refers to a
/// set of function templates, returns NULL.
TemplateDecl *getAsTemplateDecl() const;
/// Retrieve the underlying, overloaded function template
/// declarations that this template name refers to, if known.
///
/// \returns The set of overloaded function templates that this template
/// name refers to, if known. If the template name does not refer to a
/// specific set of function templates because it is a dependent name or
/// refers to a single template, returns NULL.
OverloadedTemplateStorage *getAsOverloadedTemplate() const;
/// Retrieve information on a name that has been assumed to be a
/// template-name in order to permit a call via ADL.
AssumedTemplateStorage *getAsAssumedTemplateName() const;
/// Retrieve the substituted template template parameter, if
/// known.
///
/// \returns The storage for the substituted template template parameter,
/// if known. Otherwise, returns NULL.
SubstTemplateTemplateParmStorage *getAsSubstTemplateTemplateParm() const;
/// Retrieve the substituted template template parameter pack, if
/// known.
///
/// \returns The storage for the substituted template template parameter pack,
/// if known. Otherwise, returns NULL.
SubstTemplateTemplateParmPackStorage *
getAsSubstTemplateTemplateParmPack() const;
/// Retrieve the underlying qualified template name
/// structure, if any.
QualifiedTemplateName *getAsQualifiedTemplateName() const;
/// Retrieve the underlying dependent template name
/// structure, if any.
DependentTemplateName *getAsDependentTemplateName() const;
/// Retrieve the using shadow declaration through which the underlying
/// template declaration is introduced, if any.
UsingShadowDecl *getAsUsingShadowDecl() const;
TemplateName getUnderlying() const;
/// Get the template name to substitute when this template name is used as a
/// template template argument. This refers to the most recent declaration of
/// the template, including any default template arguments.
TemplateName getNameToSubstitute() const;
TemplateNameDependence getDependence() const;
/// Determines whether this is a dependent template name.
bool isDependent() const;
/// Determines whether this is a template name that somehow
/// depends on a template parameter.
bool isInstantiationDependent() const;
/// Determines whether this template name contains an
/// unexpanded parameter pack (for C++0x variadic templates).
bool containsUnexpandedParameterPack() const;
enum class Qualified { None, AsWritten, Fully };
/// Print the template name.
///
/// \param OS the output stream to which the template name will be
/// printed.
///
/// \param Qual print the (Qualified::None) simple name,
/// (Qualified::AsWritten) any written (possibly partial) qualifier, or
/// (Qualified::Fully) the fully qualified name.
void print(raw_ostream &OS, const PrintingPolicy &Policy,
Qualified Qual = Qualified::AsWritten) const;
/// Debugging aid that dumps the template name.
void dump(raw_ostream &OS) const;
/// Debugging aid that dumps the template name to standard
/// error.
void dump() const;
void Profile(llvm::FoldingSetNodeID &ID) {
ID.AddPointer(Storage.getOpaqueValue());
}
/// Retrieve the template name as a void pointer.
void *getAsVoidPointer() const { return Storage.getOpaqueValue(); }
/// Build a template name from a void pointer.
static TemplateName getFromVoidPointer(void *Ptr) {
return TemplateName(Ptr);
}
};
/// 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 {
friend class ASTContext;
TemplateName Replacement;
Decl *AssociatedDecl;
SubstTemplateTemplateParmStorage(TemplateName Replacement,
Decl *AssociatedDecl, unsigned Index,
std::optional<unsigned> PackIndex)
: UncommonTemplateNameStorage(SubstTemplateTemplateParm, Index,
PackIndex ? *PackIndex + 1 : 0),
Replacement(Replacement), AssociatedDecl(AssociatedDecl) {
assert(AssociatedDecl != nullptr);
}
public:
/// A template-like entity which owns the whole pattern being substituted.
/// This will own a set of template parameters.
Decl *getAssociatedDecl() const { return AssociatedDecl; }
/// Returns the index of the replaced parameter in the associated declaration.
/// This should match the result of `getParameter()->getIndex()`.
unsigned getIndex() const { return Bits.Index; }
std::optional<unsigned> getPackIndex() const {
if (Bits.Data == 0)
return std::nullopt;
return Bits.Data - 1;
}
TemplateTemplateParmDecl *getParameter() const;
TemplateName getReplacement() const { return Replacement; }
void Profile(llvm::FoldingSetNodeID &ID);
static void Profile(llvm::FoldingSetNodeID &ID, TemplateName Replacement,
Decl *AssociatedDecl, unsigned Index,
std::optional<unsigned> PackIndex);
};
inline TemplateName TemplateName::getUnderlying() const {
if (SubstTemplateTemplateParmStorage *subst
= getAsSubstTemplateTemplateParm())
return subst->getReplacement().getUnderlying();
return *this;
}
/// Represents a template name that was expressed as a
/// qualified name.
///
/// This kind of template name refers 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". The QualifiedTemplateName class is only
/// used to provide "sugar" for template names that were expressed
/// with a qualified name, 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 {
friend class ASTContext;
/// The nested name specifier that qualifies the template name.
///
/// The bit is used to indicate whether the "template" keyword was
/// present before the template name itself. Note that the
/// "template" keyword is always redundant in this case (otherwise,
/// the template name would be a dependent name and we would express
/// this name with DependentTemplateName).
llvm::PointerIntPair<NestedNameSpecifier *, 1> Qualifier;
/// The underlying template name, it is either
/// 1) a Template -- a template declaration that this qualified name refers
/// to.
/// 2) or a UsingTemplate -- a template declaration introduced by a
/// using-shadow declaration.
TemplateName UnderlyingTemplate;
QualifiedTemplateName(NestedNameSpecifier *NNS, bool TemplateKeyword,
TemplateName Template)
: Qualifier(NNS, TemplateKeyword ? 1 : 0), UnderlyingTemplate(Template) {
assert(UnderlyingTemplate.getKind() == TemplateName::Template ||
UnderlyingTemplate.getKind() == TemplateName::UsingTemplate);
}
public:
/// Return the nested name specifier that qualifies this name.
NestedNameSpecifier *getQualifier() const { return Qualifier.getPointer(); }
/// Whether the template name was prefixed by the "template"
/// keyword.
bool hasTemplateKeyword() const { return Qualifier.getInt(); }
/// Return the underlying template name.
TemplateName getUnderlyingTemplate() const { return UnderlyingTemplate; }
void Profile(llvm::FoldingSetNodeID &ID) {
Profile(ID, getQualifier(), hasTemplateKeyword(), UnderlyingTemplate);
}
static void Profile(llvm::FoldingSetNodeID &ID, NestedNameSpecifier *NNS,
bool TemplateKeyword, TemplateName TN) {
ID.AddPointer(NNS);
ID.AddBoolean(TemplateKeyword);
ID.AddPointer(TN.getAsVoidPointer());
}
};
/// 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 {
friend class ASTContext;
/// The nested name specifier that qualifies the template
/// name.
///
/// The bit stored in this qualifier describes whether the \c Name field
/// is interpreted as an IdentifierInfo pointer (when clear) or as an
/// overloaded operator kind (when set).
llvm::PointerIntPair<NestedNameSpecifier *, 1, bool> Qualifier;
/// The dependent template name.
union {
/// The identifier template name.
///
/// Only valid when the bit on \c Qualifier is clear.
const IdentifierInfo *Identifier;
/// The overloaded operator name.
///
/// Only valid when the bit on \c Qualifier is set.
OverloadedOperatorKind Operator;
};
/// The canonical template name to which this dependent
/// template name refers.
///
/// The canonical template name for a dependent template name is
/// another dependent template name whose nested name specifier is
/// canonical.
TemplateName CanonicalTemplateName;
DependentTemplateName(NestedNameSpecifier *Qualifier,
const IdentifierInfo *Identifier)
: Qualifier(Qualifier, false), Identifier(Identifier),
CanonicalTemplateName(this) {}
DependentTemplateName(NestedNameSpecifier *Qualifier,
const IdentifierInfo *Identifier,
TemplateName Canon)
: Qualifier(Qualifier, false), Identifier(Identifier),
CanonicalTemplateName(Canon) {}
DependentTemplateName(NestedNameSpecifier *Qualifier,
OverloadedOperatorKind Operator)
: Qualifier(Qualifier, true), Operator(Operator),
CanonicalTemplateName(this) {}
DependentTemplateName(NestedNameSpecifier *Qualifier,
OverloadedOperatorKind Operator,
TemplateName Canon)
: Qualifier(Qualifier, true), Operator(Operator),
CanonicalTemplateName(Canon) {}
public:
/// Return the nested name specifier that qualifies this name.
NestedNameSpecifier *getQualifier() const { return Qualifier.getPointer(); }
/// Determine whether this template name refers to an identifier.
bool isIdentifier() const { return !Qualifier.getInt(); }
/// Returns the identifier to which this template name refers.
const IdentifierInfo *getIdentifier() const {
assert(isIdentifier() && "Template name isn't an identifier?");
return Identifier;
}
/// Determine whether this template name refers to an overloaded
/// operator.
bool isOverloadedOperator() const { return Qualifier.getInt(); }
/// Return the overloaded operator to which this template name refers.
OverloadedOperatorKind getOperator() const {
assert(isOverloadedOperator() &&
"Template name isn't an overloaded operator?");
return Operator;
}
void Profile(llvm::FoldingSetNodeID &ID) {
if (isIdentifier())
Profile(ID, getQualifier(), getIdentifier());
else
Profile(ID, getQualifier(), getOperator());
}
static void Profile(llvm::FoldingSetNodeID &ID, NestedNameSpecifier *NNS,
const IdentifierInfo *Identifier) {
ID.AddPointer(NNS);
ID.AddBoolean(false);
ID.AddPointer(Identifier);
}
static void Profile(llvm::FoldingSetNodeID &ID, NestedNameSpecifier *NNS,
OverloadedOperatorKind Operator) {
ID.AddPointer(NNS);
ID.AddBoolean(true);
ID.AddInteger(Operator);
}
};
} // namespace clang.
namespace llvm {
/// The clang::TemplateName class is effectively a pointer.
template<>
struct PointerLikeTypeTraits<clang::TemplateName> {
static inline void *getAsVoidPointer(clang::TemplateName TN) {
return TN.getAsVoidPointer();
}
static inline clang::TemplateName getFromVoidPointer(void *Ptr) {
return clang::TemplateName::getFromVoidPointer(Ptr);
}
// No bits are available!
static constexpr int NumLowBitsAvailable = 0;
};
} // namespace llvm.
#endif // LLVM_CLANG_AST_TEMPLATENAME_H