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//===--- DeclAccessPair.h - A decl bundled with its path access -*- 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 DeclAccessPair class, which provides an
// efficient representation of a pair of a NamedDecl* and an
// AccessSpecifier. Generally the access specifier gives the
// natural access of a declaration when named in a class, as
// defined in C++ [class.access.base]p1.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CLANG_AST_DECLACCESSPAIR_H
#define LLVM_CLANG_AST_DECLACCESSPAIR_H
#include "clang/Basic/Specifiers.h"
#include "llvm/Support/DataTypes.h"
#include "llvm/Support/Endian.h"
namespace clang {
class NamedDecl;
/// A POD class for pairing a NamedDecl* with an access specifier.
/// Can be put into unions.
class DeclAccessPair {
/// Use the lower 2 bit to store AccessSpecifier. Use the higher
/// 61 bit to store the pointer to a NamedDecl or the DeclID to
/// a NamedDecl. If the 3rd bit is set, storing the DeclID, otherwise
/// storing the pointer.
llvm::support::detail::packed_endian_specific_integral<
uint64_t, llvm::endianness::native, alignof(void *)>
Ptr;
enum { ASMask = 0x3, Mask = 0x7 };
bool isDeclID() const { return (Ptr >> 2) & 0x1; }
public:
static DeclAccessPair make(NamedDecl *D, AccessSpecifier AS) {
DeclAccessPair p;
p.set(D, AS);
return p;
}
static DeclAccessPair makeLazy(uint64_t ID, AccessSpecifier AS) {
DeclAccessPair p;
p.Ptr = (ID << 3) | (0x1 << 2) | uint64_t(AS);
return p;
}
uint64_t getDeclID() const {
assert(isDeclID());
return (~Mask & Ptr) >> 3;
}
NamedDecl *getDecl() const {
assert(!isDeclID());
return reinterpret_cast<NamedDecl*>(~Mask & Ptr);
}
AccessSpecifier getAccess() const { return AccessSpecifier(ASMask & Ptr); }
void setDecl(NamedDecl *D) {
set(D, getAccess());
}
void setAccess(AccessSpecifier AS) {
set(getDecl(), AS);
}
void set(NamedDecl *D, AccessSpecifier AS) {
Ptr = uint64_t(AS) | reinterpret_cast<uint64_t>(D);
}
operator NamedDecl*() const { return getDecl(); }
NamedDecl *operator->() const { return getDecl(); }
};
// Make sure DeclAccessPair is pointer-aligned types.
static_assert(alignof(DeclAccessPair) == alignof(void *));
// Make sure DeclAccessPair is still POD.
static_assert(std::is_standard_layout_v<DeclAccessPair> &&
std::is_trivial_v<DeclAccessPair>);
}
#endif
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