src/base/macros.h

// Copyright 2014 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef V8_BASE_MACROS_H_
#define V8_BASE_MACROS_H_

#include "include/v8stdint.h"


// The expression OFFSET_OF(type, field) computes the byte-offset
// of the specified field relative to the containing type. This
// corresponds to 'offsetof' (in stddef.h), except that it doesn't
// use 0 or NULL, which causes a problem with the compiler warnings
// we have enabled (which is also why 'offsetof' doesn't seem to work).
// Here we simply use the non-zero value 4, which seems to work.
#define OFFSET_OF(type, field)                                          \
  (reinterpret_cast<intptr_t>(&(reinterpret_cast<type*>(4)->field)) - 4)


// The expression ARRAY_SIZE(a) is a compile-time constant of type
// size_t which represents the number of elements of the given
// array. You should only use ARRAY_SIZE on statically allocated
// arrays.
#define ARRAY_SIZE(a)                                   \
  ((sizeof(a) / sizeof(*(a))) /                         \
  static_cast<size_t>(!(sizeof(a) % sizeof(*(a)))))


// A macro to disallow the evil copy constructor and operator= functions
// This should be used in the private: declarations for a class
#define DISALLOW_COPY_AND_ASSIGN(TypeName)  \
  TypeName(const TypeName&) V8_DELETE;      \
  void operator=(const TypeName&) V8_DELETE


// A macro to disallow all the implicit constructors, namely the
// default constructor, copy constructor and operator= functions.
//
// This should be used in the private: declarations for a class
// that wants to prevent anyone from instantiating it. This is
// especially useful for classes containing only static methods.
#define DISALLOW_IMPLICIT_CONSTRUCTORS(TypeName)  \
  TypeName() V8_DELETE;                           \
  DISALLOW_COPY_AND_ASSIGN(TypeName)


// Newly written code should use V8_INLINE and V8_NOINLINE directly.
#define INLINE(declarator)    V8_INLINE declarator
#define NO_INLINE(declarator) V8_NOINLINE declarator


// Newly written code should use V8_WARN_UNUSED_RESULT.
#define MUST_USE_RESULT V8_WARN_UNUSED_RESULT


// Define V8_USE_ADDRESS_SANITIZER macros.
#if defined(__has_feature)
#if __has_feature(address_sanitizer)
#define V8_USE_ADDRESS_SANITIZER 1
#endif
#endif

// Define DISABLE_ASAN macros.
#ifdef V8_USE_ADDRESS_SANITIZER
#define DISABLE_ASAN __attribute__((no_sanitize_address))
#else
#define DISABLE_ASAN
#endif


#if V8_CC_GNU
#define V8_IMMEDIATE_CRASH() __builtin_trap()
#else
#define V8_IMMEDIATE_CRASH() ((void(*)())0)()
#endif


// Use C++11 static_assert if possible, which gives error
// messages that are easier to understand on first sight.
#if V8_HAS_CXX11_STATIC_ASSERT
#define STATIC_ASSERT(test) static_assert(test, #test)
#else
// This is inspired by the static assertion facility in boost.  This
// is pretty magical.  If it causes you trouble on a platform you may
// find a fix in the boost code.
template <bool> class StaticAssertion;
template <> class StaticAssertion<true> { };
// This macro joins two tokens.  If one of the tokens is a macro the
// helper call causes it to be resolved before joining.
#define SEMI_STATIC_JOIN(a, b) SEMI_STATIC_JOIN_HELPER(a, b)
#define SEMI_STATIC_JOIN_HELPER(a, b) a##b
// Causes an error during compilation of the condition is not
// statically known to be true.  It is formulated as a typedef so that
// it can be used wherever a typedef can be used.  Beware that this
// actually causes each use to introduce a new defined type with a
// name depending on the source line.
template <int> class StaticAssertionHelper { };
#define STATIC_ASSERT(test)                                                    \
  typedef                                                                     \
    StaticAssertionHelper<sizeof(StaticAssertion<static_cast<bool>((test))>)> \
    SEMI_STATIC_JOIN(__StaticAssertTypedef__, __LINE__) V8_UNUSED

#endif


// The USE(x) template is used to silence C++ compiler warnings
// issued for (yet) unused variables (typically parameters).
template <typename T>
inline void USE(T) { }


#define IS_POWER_OF_TWO(x) ((x) != 0 && (((x) & ((x) - 1)) == 0))

// The following macro works on both 32 and 64-bit platforms.
// Usage: instead of writing 0x1234567890123456
//      write V8_2PART_UINT64_C(0x12345678,90123456);
#define V8_2PART_UINT64_C(a, b) (((static_cast<uint64_t>(a) << 32) + 0x##b##u))

#endif   // V8_BASE_MACROS_H_