1// Copyright 2014 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5// Slightly adapted for inclusion in V8.
6// Copyright 2014 the V8 project authors. All rights reserved.
7
8#ifndef V8_BASE_SAFE_CONVERSIONS_H_
9#define V8_BASE_SAFE_CONVERSIONS_H_
10
11#include <limits>
12
13#include "src/base/safe_conversions_impl.h"
14
15namespace v8 {
16namespace base {
17
18// Convenience function that returns true if the supplied value is in range
19// for the destination type.
20template <typename Dst, typename Src>
21inline bool IsValueInRangeForNumericType(Src value) {
22  return internal::DstRangeRelationToSrcRange<Dst>(value) ==
23         internal::RANGE_VALID;
24}
25
26// checked_cast<> is analogous to static_cast<> for numeric types,
27// except that it CHECKs that the specified numeric conversion will not
28// overflow or underflow. NaN source will always trigger a CHECK.
29template <typename Dst, typename Src>
30inline Dst checked_cast(Src value) {
31  CHECK(IsValueInRangeForNumericType<Dst>(value));
32  return static_cast<Dst>(value);
33}
34
35// saturated_cast<> is analogous to static_cast<> for numeric types, except
36// that the specified numeric conversion will saturate rather than overflow or
37// underflow. NaN assignment to an integral will trigger a CHECK condition.
38template <typename Dst, typename Src>
39inline Dst saturated_cast(Src value) {
40  // Optimization for floating point values, which already saturate.
41  if (std::numeric_limits<Dst>::is_iec559)
42    return static_cast<Dst>(value);
43
44  switch (internal::DstRangeRelationToSrcRange<Dst>(value)) {
45    case internal::RANGE_VALID:
46      return static_cast<Dst>(value);
47
48    case internal::RANGE_UNDERFLOW:
49      return std::numeric_limits<Dst>::min();
50
51    case internal::RANGE_OVERFLOW:
52      return std::numeric_limits<Dst>::max();
53
54    // Should fail only on attempting to assign NaN to a saturated integer.
55    case internal::RANGE_INVALID:
56      CHECK(false);
57      return std::numeric_limits<Dst>::max();
58  }
59
60  UNREACHABLE();
61  return static_cast<Dst>(value);
62}
63
64}  // namespace base
65}  // namespace v8
66
67#endif  // V8_BASE_SAFE_CONVERSIONS_H_
68