Line data    Source code

       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             : 
      15             : namespace v8 {
      16             : namespace base {
      17             : 
      18             : // Convenience function that returns true if the supplied value is in range
      19             : // for the destination type.
      20             : template <typename Dst, typename Src>
      21             : inline 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.
      29             : template <typename Dst, typename Src>
      30             : inline 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.
      38             : template <typename Dst, typename Src>
      39        3509 : inline 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        3509 :   switch (internal::DstRangeRelationToSrcRange<Dst>(value)) {
      45             :     case internal::RANGE_VALID:
      46           5 :       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        3504 :       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           0 :       UNREACHABLE();
      57             :   }
      58             : 
      59           0 :   UNREACHABLE();
      60             : }
      61             : 
      62             : }  // namespace base
      63             : }  // namespace v8
      64             : 
      65             : #endif  // V8_BASE_SAFE_CONVERSIONS_H_