Implement CheckedNumeric::UnsignedAbs()

base/numerics/safe_math.h

 // Copyright 2014 The Chromium 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 BASE_NUMERICS_SAFE_MATH_H_
 #define BASE_NUMERICS_SAFE_MATH_H_
 
 #include "base/numerics/safe_math_impl.h"
 
 namespace base {
@@ skipping 127 matching lines @@
     RangeConstraint validity;
     T value = CheckedAbs(state_.value(), &validity);
     // Absolute value is always valid for floating point.
     if (std::numeric_limits<T>::is_iec559)
       return CheckedNumeric<T>(value);
 
     validity = GetRangeConstraint(state_.validity() | validity);
     return CheckedNumeric<T>(value, validity);
   }
 
+  // This function is available only for integral types. It returns an unsigned
+  // integer of the same width as the source type, containing the absolute value
+  // of the source, and properly handling signed min.
+  CheckedNumeric<typename UnsignedOrFloatForSize<T>::type> UnsignedAbs() const {
+    return CheckedNumeric<typename UnsignedOrFloatForSize<T>::type>(
+        CheckedUnsignedAbs(state_.value()), state_.validity());
+  }
+
   CheckedNumeric& operator++() {
     *this += 1;
     return *this;
   }
 
   CheckedNumeric operator++(int) {
     CheckedNumeric value = *this;
     *this += 1;
     return value;
   }
@@ skipping 112 matching lines @@
 
 #undef BASE_NUMERIC_ARITHMETIC_OPERATORS
 
 }  // namespace internal
 
 using internal::CheckedNumeric;
 
 }  // namespace base
 
 #endif  // BASE_NUMERICS_SAFE_MATH_H_