third_party/blink/renderer/platform/wtf/size_limits.cc

/*
 * Copyright (C) 2010 Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
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 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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 */

#include <memory>
#include "base/memory/scoped_refptr.h"
#include "third_party/blink/renderer/platform/wtf/assertions.h"
#include "third_party/blink/renderer/platform/wtf/container_annotations.h"
#include "third_party/blink/renderer/platform/wtf/ref_counted.h"
#include "third_party/blink/renderer/platform/wtf/text/atomic_string.h"
#include "third_party/blink/renderer/platform/wtf/text/wtf_string.h"
#include "third_party/blink/renderer/platform/wtf/thread_restriction_verifier.h"
#include "third_party/blink/renderer/platform/wtf/vector.h"

namespace WTF {

struct SameSizeAsRefCounted {
  uint32_t a;
  // Don't add anything here because this should stay small.
};

template <typename T, unsigned inlineCapacity = 0>
struct SameSizeAsVectorWithInlineCapacity;

template <typename T>
struct SameSizeAsVectorWithInlineCapacity<T, 0> {
  void* buffer_pointer;
  unsigned capacity;
  unsigned size;
};

template <typename T, unsigned inlineCapacity>
struct SameSizeAsVectorWithInlineCapacity {
  SameSizeAsVectorWithInlineCapacity<T, 0> base_capacity;
#if !defined(ANNOTATE_CONTIGUOUS_CONTAINER)
  T inline_buffer[inlineCapacity];
#endif
};

#if !DCHECK_IS_ON()
static_assert(sizeof(RefCounted<int>) == sizeof(SameSizeAsRefCounted),
              "RefCounted should stay small");
#endif

static_assert(sizeof(std::unique_ptr<int>) == sizeof(int*),
              "std::unique_ptr should stay small");
static_assert(sizeof(scoped_refptr<RefCounted<int>>) == sizeof(int*),
              "RefPtr should stay small");
static_assert(sizeof(String) == sizeof(int*), "String should stay small");
static_assert(sizeof(AtomicString) == sizeof(String),
              "AtomicString should stay small");
static_assert(sizeof(Vector<int>) ==
                  sizeof(SameSizeAsVectorWithInlineCapacity<int>),
              "Vector should stay small");
static_assert(sizeof(Vector<int, 1>) ==
                  sizeof(SameSizeAsVectorWithInlineCapacity<int, 1>),
              "Vector should stay small");
static_assert(sizeof(Vector<int, 2>) ==
                  sizeof(SameSizeAsVectorWithInlineCapacity<int, 2>),
              "Vector should stay small");
static_assert(sizeof(Vector<int, 3>) ==
                  sizeof(SameSizeAsVectorWithInlineCapacity<int, 3>),
              "Vector should stay small");

}  // namespace WTF