//===- TemplateBase.h - Core classes for C++ templates ----------*- 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 provides definitions which are common for all kinds of

//  template representation.

//

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

#ifndef LLVM_CLANG_AST_TEMPLATEBASE_H

#define LLVM_CLANG_AST_TEMPLATEBASE_H

#include "clang/AST/DependenceFlags.h"

#include "clang/AST/NestedNameSpecifier.h"

#include "clang/AST/TemplateName.h"

#include "clang/AST/Type.h"

#include "clang/Basic/LLVM.h"

#include "clang/Basic/SourceLocation.h"

#include "llvm/ADT/APInt.h"

#include "llvm/ADT/APSInt.h"

#include "llvm/ADT/ArrayRef.h"

#include "llvm/ADT/None.h"

#include "llvm/ADT/Optional.h"

#include "llvm/ADT/SmallVector.h"

#include "llvm/Support/Compiler.h"

#include "llvm/Support/TrailingObjects.h"

#include <cassert>

#include <cstddef>

#include <cstdint>

namespace llvm {

class FoldingSetNodeID;

// Provide PointerLikeTypeTraits for clang::Expr*, this default one requires a

// full definition of Expr, but this file only sees a forward del because of

// the dependency.

template <> struct PointerLikeTypeTraits<clang::Expr *> {

  static inline void *getAsVoidPointer(clang::Expr *P) { return P; }

  static inline clang::Expr *getFromVoidPointer(void *P) {

    return static_cast<clang::Expr *>(P);

  }

  static constexpr int NumLowBitsAvailable = 2;

};

} // namespace llvm

namespace clang {

class ASTContext;

class Expr;

struct PrintingPolicy;

class TypeSourceInfo;

class ValueDecl;

/// Represents a template argument.

class TemplateArgument {

public:

  /// The kind of template argument we're storing.

  enum ArgKind {

    /// Represents an empty template argument, e.g., one that has not

    /// been deduced.

    Null = 0,

    /// The template argument is a type.

    Type,

    /// The template argument is a declaration that was provided for a pointer,

    /// reference, or pointer to member non-type template parameter.

    Declaration,

    /// The template argument is a null pointer or null pointer to member that

    /// was provided for a non-type template parameter.

    NullPtr,

    /// The template argument is an integral value stored in an llvm::APSInt

    /// that was provided for an integral non-type template parameter.

    Integral,

    /// The template argument is a template name that was provided for a

    /// template template parameter.

    Template,

    /// The template argument is a pack expansion of a template name that was

    /// provided for a template template parameter.

    TemplateExpansion,

    /// The template argument is an expression, and we've not resolved it to one

    /// of the other forms yet, either because it's dependent or because we're

    /// representing a non-canonical template argument (for instance, in a

    /// TemplateSpecializationType).

    Expression,

    /// The template argument is actually a parameter pack. Arguments are stored

    /// in the Args struct.

    Pack

  };

private:

  /// The kind of template argument we're storing.

  struct DA {

    unsigned Kind;

    void *QT;

    ValueDecl *D;

  };

  struct I {

    unsigned Kind;

    // We store a decomposed APSInt with the data allocated by ASTContext if

    // BitWidth > 64. The memory may be shared between multiple

    // TemplateArgument instances.

    unsigned BitWidth : 31;

    unsigned IsUnsigned : 1;

    union {

      /// Used to store the <= 64 bits integer value.

      uint64_t VAL;

      /// Used to store the >64 bits integer value.

      const uint64_t *pVal;

    };

    void *Type;

  };

  struct A {

    unsigned Kind;

    unsigned NumArgs;

    const TemplateArgument *Args;

  };

  struct TA {

    unsigned Kind;

    unsigned NumExpansions;

    void *Name;

  };

  struct TV {

    unsigned Kind;

    uintptr_t V;

  };

  union {

    struct DA DeclArg;

    struct I Integer;

    struct A Args;

    struct TA TemplateArg;

    struct TV TypeOrValue;

  };

public:

  /// Construct an empty, invalid template argument.

  constexpr TemplateArgument() : TypeOrValue({Null, 0}) {}

  /// Construct a template type argument.

  TemplateArgument(QualType T, bool isNullPtr = false) {

    TypeOrValue.Kind = isNullPtr ? 
NullPtr17.9k
 : 
Type46.0M
;

    TypeOrValue.V = reinterpret_cast<uintptr_t>(T.getAsOpaquePtr());

  }

  /// Construct a template argument that refers to a

  /// declaration, which is either an external declaration or a

  /// template declaration.

  TemplateArgument(ValueDecl *D, QualType QT) {

    assert(D && "Expected decl");

    DeclArg.Kind = Declaration;

    DeclArg.QT = QT.getAsOpaquePtr();

    DeclArg.D = D;

  }

  /// Construct an integral constant template argument. The memory to

  /// store the value is allocated with Ctx.

  TemplateArgument(ASTContext &Ctx, const llvm::APSInt &Value, QualType Type);

  /// Construct an integral constant template argument with the same

  /// value as Other but a different type.

  TemplateArgument(const TemplateArgument &Other, QualType Type) {

    Integer = Other.Integer;

    Integer.Type = Type.getAsOpaquePtr();

  }

  /// Construct a template argument that is a template.

  ///

  /// This form of template argument is generally used for template template

  /// parameters. However, the template name could be a dependent template

  /// name that ends up being instantiated to a function template whose address

  /// is taken.

  ///

  /// \param Name The template name.

  TemplateArgument(TemplateName Name) {

    TemplateArg.Kind = Template;

    TemplateArg.Name = Name.getAsVoidPointer();

    TemplateArg.NumExpansions = 0;

  }

  /// Construct a template argument that is a template pack expansion.

  ///

  /// This form of template argument is generally used for template template

  /// parameters. However, the template name could be a dependent template

  /// name that ends up being instantiated to a function template whose address

  /// is taken.

  ///

  /// \param Name The template name.

  ///

  /// \param NumExpansions The number of expansions that will be generated by

  /// instantiating

  TemplateArgument(TemplateName Name, Optional<unsigned> NumExpansions) {

    TemplateArg.Kind = TemplateExpansion;

    TemplateArg.Name = Name.getAsVoidPointer();

    if (NumExpansions)

      TemplateArg.NumExpansions = *NumExpansions + 1;

    else

      TemplateArg.NumExpansions = 0;

  }

  /// Construct a template argument that is an expression.

  ///

  /// This form of template argument only occurs in template argument

  /// lists used for dependent types and for expression; it will not

  /// occur in a non-dependent, canonical template argument list.

  TemplateArgument(Expr *E) {

    TypeOrValue.Kind = Expression;

    TypeOrValue.V = reinterpret_cast<uintptr_t>(E);

  }

  /// Construct a template argument that is a template argument pack.

  ///

  /// We assume that storage for the template arguments provided

  /// outlives the TemplateArgument itself.

  explicit TemplateArgument(ArrayRef<TemplateArgument> Args) {

    this->Args.Kind = Pack;

    this->Args.Args = Args.data();

    this->Args.NumArgs = Args.size();

  }

  TemplateArgument(TemplateName, bool) = delete;

  static TemplateArgument getEmptyPack() { return TemplateArgument(None); }

  /// Create a new template argument pack by copying the given set of

  /// template arguments.

  static TemplateArgument CreatePackCopy(ASTContext &Context,

                                         ArrayRef<TemplateArgument> Args);

  /// Return the kind of stored template argument.

  ArgKind getKind() const { return (ArgKind)TypeOrValue.Kind; }

  /// Determine whether this template argument has no value.

  bool isNull() const { return getKind() == Null; }

  TemplateArgumentDependence getDependence() const;

  /// Whether this template argument is dependent on a template

  /// parameter such that its result can change from one instantiation to

  /// another.

  bool isDependent() const;

  /// Whether this template argument is dependent on a template

  /// parameter.

  bool isInstantiationDependent() const;

  /// Whether this template argument contains an unexpanded

  /// parameter pack.

  bool containsUnexpandedParameterPack() const;

  /// Determine whether this template argument is a pack expansion.

  bool isPackExpansion() const;

  /// Retrieve the type for a type template argument.

  QualType getAsType() const {

    assert(getKind() == Type && "Unexpected kind");

    return QualType::getFromOpaquePtr(reinterpret_cast<void*>(TypeOrValue.V));

  }

  /// Retrieve the declaration for a declaration non-type

  /// template argument.

  ValueDecl *getAsDecl() const {

    assert(getKind() == Declaration && "Unexpected kind");

    return DeclArg.D;

  }

  QualType getParamTypeForDecl() const {

    assert(getKind() == Declaration && "Unexpected kind");

    return QualType::getFromOpaquePtr(DeclArg.QT);

  }

  /// Retrieve the type for null non-type template argument.

  QualType getNullPtrType() const {

    assert(getKind() == NullPtr && "Unexpected kind");

    return QualType::getFromOpaquePtr(reinterpret_cast<void*>(TypeOrValue.V));

  }

  /// Retrieve the template name for a template name argument.

  TemplateName getAsTemplate() const {

    assert(getKind() == Template && "Unexpected kind");

    return TemplateName::getFromVoidPointer(TemplateArg.Name);

  }

  /// Retrieve the template argument as a template name; if the argument

  /// is a pack expansion, return the pattern as a template name.

  TemplateName getAsTemplateOrTemplatePattern() const {

    assert((getKind() == Template || getKind() == TemplateExpansion) &&

           "Unexpected kind");

    return TemplateName::getFromVoidPointer(TemplateArg.Name);

  }

  /// Retrieve the number of expansions that a template template argument

  /// expansion will produce, if known.

  Optional<unsigned> getNumTemplateExpansions() const;

  /// Retrieve the template argument as an integral value.

  // FIXME: Provide a way to read the integral data without copying the value.

  llvm::APSInt getAsIntegral() const {

    assert(getKind() == Integral && "Unexpected kind");

    using namespace llvm;

    if (Integer.BitWidth <= 64)

      return APSInt(APInt(Integer.BitWidth, Integer.VAL), Integer.IsUnsigned);

    unsigned NumWords = APInt::getNumWords(Integer.BitWidth);

    return APSInt(APInt(Integer.BitWidth, makeArrayRef(Integer.pVal, NumWords)),

                  Integer.IsUnsigned);

  }

  /// Retrieve the type of the integral value.

  QualType getIntegralType() const {

    assert(getKind() == Integral && "Unexpected kind");

    return QualType::getFromOpaquePtr(Integer.Type);

  }

  void setIntegralType(QualType T) {

    assert(getKind() == Integral && "Unexpected kind");

    Integer.Type = T.getAsOpaquePtr();

  }

  /// If this is a non-type template argument, get its type. Otherwise,

  /// returns a null QualType.

  QualType getNonTypeTemplateArgumentType() const;

  /// Retrieve the template argument as an expression.

  Expr *getAsExpr() const {

    assert(getKind() == Expression && "Unexpected kind");

    return reinterpret_cast<Expr *>(TypeOrValue.V);

  }

  /// Iterator that traverses the elements of a template argument pack.

  using pack_iterator = const TemplateArgument *;

  /// Iterator referencing the first argument of a template argument

  /// pack.

  pack_iterator pack_begin() const {

    assert(getKind() == Pack);

    return Args.Args;

  }

  /// Iterator referencing one past the last argument of a template

  /// argument pack.

  pack_iterator pack_end() const {

    assert(getKind() == Pack);

    return Args.Args + Args.NumArgs;

  }

  /// Iterator range referencing all of the elements of a template

  /// argument pack.

  ArrayRef<TemplateArgument> pack_elements() const {

    return llvm::makeArrayRef(pack_begin(), pack_end());

  }

  /// The number of template arguments in the given template argument

  /// pack.

  unsigned pack_size() const {

    assert(getKind() == Pack);

    return Args.NumArgs;

  }

  /// Return the array of arguments in this template argument pack.

  ArrayRef<TemplateArgument> getPackAsArray() const {

    assert(getKind() == Pack);

    return llvm::makeArrayRef(Args.Args, Args.NumArgs);

  }

  /// Determines whether two template arguments are superficially the

  /// same.

  bool structurallyEquals(const TemplateArgument &Other) const;

  /// When the template argument is a pack expansion, returns

  /// the pattern of the pack expansion.

  TemplateArgument getPackExpansionPattern() const;

  /// Print this template argument to the given output stream.

  void print(const PrintingPolicy &Policy, raw_ostream &Out,

             bool IncludeType) const;

  /// Debugging aid that dumps the template argument.

  void dump(raw_ostream &Out) const;

  /// Debugging aid that dumps the template argument to standard error.

  void dump() const;

  /// Used to insert TemplateArguments into FoldingSets.

  void Profile(llvm::FoldingSetNodeID &ID, const ASTContext &Context) const;

};

/// Location information for a TemplateArgument.

struct TemplateArgumentLocInfo {

private:

  struct TemplateTemplateArgLocInfo {

    // FIXME: We'd like to just use the qualifier in the TemplateName,

    // but template arguments get canonicalized too quickly.

    NestedNameSpecifier *Qualifier;

    void *QualifierLocData;

    SourceLocation TemplateNameLoc;

    SourceLocation EllipsisLoc;

  };

  llvm::PointerUnion<TemplateTemplateArgLocInfo *, Expr *, TypeSourceInfo *>

      Pointer;

  TemplateTemplateArgLocInfo *getTemplate() const {

    return Pointer.get<TemplateTemplateArgLocInfo *>();

  }

public:

  TemplateArgumentLocInfo() {}

  TemplateArgumentLocInfo(TypeSourceInfo *Declarator) { Pointer = Declarator; }

  TemplateArgumentLocInfo(Expr *E) { Pointer = E; }

  // Ctx is used for allocation -- this case is unusually large and also rare,

  // so we store the payload out-of-line.

  TemplateArgumentLocInfo(ASTContext &Ctx, NestedNameSpecifierLoc QualifierLoc,

                          SourceLocation TemplateNameLoc,

                          SourceLocation EllipsisLoc);

  TypeSourceInfo *getAsTypeSourceInfo() const {

    return Pointer.get<TypeSourceInfo *>();

  }

  Expr *getAsExpr() const { return Pointer.get<Expr *>(); }

  NestedNameSpecifierLoc getTemplateQualifierLoc() const {

    const auto *Template = getTemplate();

    return NestedNameSpecifierLoc(Template->Qualifier,

                                  Template->QualifierLocData);

  }

  SourceLocation getTemplateNameLoc() const {

    return getTemplate()->TemplateNameLoc;

  }

  SourceLocation getTemplateEllipsisLoc() const {

    return getTemplate()->EllipsisLoc;

  }

};

/// Location wrapper for a TemplateArgument.  TemplateArgument is to

/// TemplateArgumentLoc as Type is to TypeLoc.

class TemplateArgumentLoc {

  TemplateArgument Argument;

  TemplateArgumentLocInfo LocInfo;

public:

  TemplateArgumentLoc() {}

  TemplateArgumentLoc(const TemplateArgument &Argument,

                      TemplateArgumentLocInfo Opaque)

      : Argument(Argument), LocInfo(Opaque) {}

  TemplateArgumentLoc(const TemplateArgument &Argument, TypeSourceInfo *TInfo)

      : Argument(Argument), LocInfo(TInfo) {

    assert(Argument.getKind() == TemplateArgument::Type);

  }

  TemplateArgumentLoc(const TemplateArgument &Argument, Expr *E)

      : Argument(Argument), LocInfo(E) {

    // Permit any kind of template argument that can be represented with an

    // expression.

    assert(Argument.getKind() == TemplateArgument::NullPtr ||

           Argument.getKind() == TemplateArgument::Integral ||

           Argument.getKind() == TemplateArgument::Declaration ||

           Argument.getKind() == TemplateArgument::Expression);

  }

  TemplateArgumentLoc(ASTContext &Ctx, const TemplateArgument &Argument,

                      NestedNameSpecifierLoc QualifierLoc,

                      SourceLocation TemplateNameLoc,

                      SourceLocation EllipsisLoc = SourceLocation())

      : Argument(Argument),

        LocInfo(Ctx, QualifierLoc, TemplateNameLoc, EllipsisLoc) {

    assert(Argument.getKind() == TemplateArgument::Template ||

           Argument.getKind() == TemplateArgument::TemplateExpansion);

  }

  /// - Fetches the primary location of the argument.

  SourceLocation getLocation() const {

    if (Argument.getKind() == TemplateArgument::Template ||

        
Argument.getKind() == TemplateArgument::TemplateExpansion19.1k
)

      return getTemplateNameLoc();

    return getSourceRange().getBegin();

  }

  /// - Fetches the full source range of the argument.

  SourceRange getSourceRange() const LLVM_READONLY;

  const TemplateArgument &getArgument() const {

    return Argument;

  }

  TemplateArgumentLocInfo getLocInfo() const {

    return LocInfo;

  }

  TypeSourceInfo *getTypeSourceInfo() const {

    if (Argument.getKind() != TemplateArgument::Type)

      return nullptr;

    return LocInfo.getAsTypeSourceInfo();

  }

  Expr *getSourceExpression() const {

    assert(Argument.getKind() == TemplateArgument::Expression);

    return LocInfo.getAsExpr();

  }

  Expr *getSourceDeclExpression() const {

    assert(Argument.getKind() == TemplateArgument::Declaration);

    return LocInfo.getAsExpr();

  }

  Expr *getSourceNullPtrExpression() const {

    assert(Argument.getKind() == TemplateArgument::NullPtr);

    return LocInfo.getAsExpr();

  }

  Expr *getSourceIntegralExpression() const {

    assert(Argument.getKind() == TemplateArgument::Integral);

    return LocInfo.getAsExpr();

  }

  NestedNameSpecifierLoc getTemplateQualifierLoc() const {

    if (Argument.getKind() != TemplateArgument::Template &&

        
Argument.getKind() != TemplateArgument::TemplateExpansion38
)

      return NestedNameSpecifierLoc();

    return LocInfo.getTemplateQualifierLoc();

  }

  SourceLocation getTemplateNameLoc() const {

    if (Argument.getKind() != TemplateArgument::Template &&

        
Argument.getKind() != TemplateArgument::TemplateExpansion56
)

      return SourceLocation();

    return LocInfo.getTemplateNameLoc();

  }

  SourceLocation getTemplateEllipsisLoc() const {

    if (Argument.getKind() != TemplateArgument::TemplateExpansion)

      return SourceLocation();

    return LocInfo.getTemplateEllipsisLoc();

  }

};

/// A convenient class for passing around template argument

/// information.  Designed to be passed by reference.

class TemplateArgumentListInfo {

  SmallVector<TemplateArgumentLoc, 8> Arguments;

  SourceLocation LAngleLoc;

  SourceLocation RAngleLoc;

public:

  TemplateArgumentListInfo() = default;

  TemplateArgumentListInfo(SourceLocation LAngleLoc,

                           SourceLocation RAngleLoc)

      : LAngleLoc(LAngleLoc), RAngleLoc(RAngleLoc) {}

  // This can leak if used in an AST node, use ASTTemplateArgumentListInfo

  // instead.

  void *operator new(size_t bytes, ASTContext &C) = delete;

  SourceLocation getLAngleLoc() const { return LAngleLoc; }

  SourceLocation getRAngleLoc() const { return RAngleLoc; }

  void setLAngleLoc(SourceLocation Loc) { LAngleLoc = Loc; }

  void setRAngleLoc(SourceLocation Loc) { RAngleLoc = Loc; }

  unsigned size() const { return Arguments.size(); }

  const TemplateArgumentLoc *getArgumentArray() const {

    return Arguments.data();

  }

  llvm::ArrayRef<TemplateArgumentLoc> arguments() const {

    return Arguments;

  }

  const TemplateArgumentLoc &operator[](unsigned I) const {

    return Arguments[I];

  }

  TemplateArgumentLoc &operator[](unsigned I) {

    return Arguments[I];

  }

  void addArgument(const TemplateArgumentLoc &Loc) {

    Arguments.push_back(Loc);

  }

};

/// Represents an explicit template argument list in C++, e.g.,

/// the "<int>" in "sort<int>".

/// This is safe to be used inside an AST node, in contrast with

/// TemplateArgumentListInfo.

struct ASTTemplateArgumentListInfo final

    : private llvm::TrailingObjects<ASTTemplateArgumentListInfo,

                                    TemplateArgumentLoc> {

private:

  friend class ASTNodeImporter;

  friend TrailingObjects;

  ASTTemplateArgumentListInfo(const TemplateArgumentListInfo &List);

public:

  /// The source location of the left angle bracket ('<').

  SourceLocation LAngleLoc;

  /// The source location of the right angle bracket ('>').

  SourceLocation RAngleLoc;

  /// The number of template arguments in TemplateArgs.

  unsigned NumTemplateArgs;

  SourceLocation getLAngleLoc() const { return LAngleLoc; }

  SourceLocation getRAngleLoc() const { return RAngleLoc; }

  /// Retrieve the template arguments

  const TemplateArgumentLoc *getTemplateArgs() const {

    return getTrailingObjects<TemplateArgumentLoc>();

  }

  unsigned getNumTemplateArgs() const { return NumTemplateArgs; }

  llvm::ArrayRef<TemplateArgumentLoc> arguments() const {

    return llvm::makeArrayRef(getTemplateArgs(), getNumTemplateArgs());

  }

  const TemplateArgumentLoc &operator[](unsigned I) const {

    return getTemplateArgs()[I];

  }

  static const ASTTemplateArgumentListInfo *

  Create(const ASTContext &C, const TemplateArgumentListInfo &List);

};

/// Represents an explicit template argument list in C++, e.g.,

/// the "<int>" in "sort<int>".

///

/// It is intended to be used as a trailing object on AST nodes, and

/// as such, doesn't contain the array of TemplateArgumentLoc itself,

/// but expects the containing object to also provide storage for

/// that.

struct alignas(void *) ASTTemplateKWAndArgsInfo {

  /// The source location of the left angle bracket ('<').

  SourceLocation LAngleLoc;

  /// The source location of the right angle bracket ('>').

  SourceLocation RAngleLoc;

  /// The source location of the template keyword; this is used

  /// as part of the representation of qualified identifiers, such as

  /// S<T>::template apply<T>.  Will be empty if this expression does

  /// not have a template keyword.

  SourceLocation TemplateKWLoc;

  /// The number of template arguments in TemplateArgs.

  unsigned NumTemplateArgs;

  void initializeFrom(SourceLocation TemplateKWLoc,

                      const TemplateArgumentListInfo &List,

                      TemplateArgumentLoc *OutArgArray);

  // FIXME: The parameter Deps is the result populated by this method, the

  // caller doesn't need it since it is populated by computeDependence. remove

  // it.

  void initializeFrom(SourceLocation TemplateKWLoc,

                      const TemplateArgumentListInfo &List,

                      TemplateArgumentLoc *OutArgArray,

                      TemplateArgumentDependence &Deps);

  void initializeFrom(SourceLocation TemplateKWLoc);

  void copyInto(const TemplateArgumentLoc *ArgArray,

                TemplateArgumentListInfo &List) const;

};

const StreamingDiagnostic &operator<<(const StreamingDiagnostic &DB,

                                      const TemplateArgument &Arg);

inline TemplateSpecializationType::iterator

    TemplateSpecializationType::end() const {

  return getArgs() + getNumArgs();

}

inline DependentTemplateSpecializationType::iterator

    DependentTemplateSpecializationType::end() const {

  return getArgs() + getNumArgs();

}

inline const TemplateArgument &

    TemplateSpecializationType::getArg(unsigned Idx) const {

  assert(Idx < getNumArgs() && "Template argument out of range");

  return getArgs()[Idx];

}

inline const TemplateArgument &

    DependentTemplateSpecializationType::getArg(unsigned Idx) const {

  assert(Idx < getNumArgs() && "Template argument out of range");

  return getArgs()[Idx];

}

inline const TemplateArgument &AutoType::getArg(unsigned Idx) const {

  assert(Idx < getNumArgs() && "Template argument out of range");

  return getArgs()[Idx];

}

} // namespace clang

#endif // LLVM_CLANG_AST_TEMPLATEBASE_H