libweave: Added base/ files required by libweave
These files cloned from
https://android.googlesource.com/platform/external/libchrome/+/3ca9d0096f5618f5bbad8b1363a069d13fc3026e
They are unchanged and not included into build yet.
BUG=brillo:1256
TEST=`FEATURES=test emerge-gizmo libweave buffet`
Change-Id: I91ccf741ffa3f8fc09f83ae7f6adfa279845434c
111
Change-Id: I27ef0b115216f9fd9865abecaf9e63749ec7a35c
Reviewed-on: https://chromium-review.googlesource.com/294331
Reviewed-by: Vitaly Buka <vitalybuka@chromium.org>
Commit-Queue: Vitaly Buka <vitalybuka@chromium.org>
Tested-by: Vitaly Buka <vitalybuka@chromium.org>
diff --git a/libweave/external/base/numerics/safe_conversions.h b/libweave/external/base/numerics/safe_conversions.h
new file mode 100644
index 0000000..5dd5191
--- /dev/null
+++ b/libweave/external/base/numerics/safe_conversions.h
@@ -0,0 +1,125 @@
+// 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_CONVERSIONS_H_
+#define BASE_NUMERICS_SAFE_CONVERSIONS_H_
+
+#include <limits>
+
+#include "base/logging.h"
+#include "base/numerics/safe_conversions_impl.h"
+
+namespace base {
+
+// Convenience function that returns true if the supplied value is in range
+// for the destination type.
+template <typename Dst, typename Src>
+inline bool IsValueInRangeForNumericType(Src value) {
+ return internal::DstRangeRelationToSrcRange<Dst>(value) ==
+ internal::RANGE_VALID;
+}
+
+// checked_cast<> is analogous to static_cast<> for numeric types,
+// except that it CHECKs that the specified numeric conversion will not
+// overflow or underflow. NaN source will always trigger a CHECK.
+template <typename Dst, typename Src>
+inline Dst checked_cast(Src value) {
+ CHECK(IsValueInRangeForNumericType<Dst>(value));
+ return static_cast<Dst>(value);
+}
+
+// saturated_cast<> is analogous to static_cast<> for numeric types, except
+// that the specified numeric conversion will saturate rather than overflow or
+// underflow. NaN assignment to an integral will trigger a CHECK condition.
+template <typename Dst, typename Src>
+inline Dst saturated_cast(Src value) {
+ // Optimization for floating point values, which already saturate.
+ if (std::numeric_limits<Dst>::is_iec559)
+ return static_cast<Dst>(value);
+
+ switch (internal::DstRangeRelationToSrcRange<Dst>(value)) {
+ case internal::RANGE_VALID:
+ return static_cast<Dst>(value);
+
+ case internal::RANGE_UNDERFLOW:
+ return std::numeric_limits<Dst>::min();
+
+ case internal::RANGE_OVERFLOW:
+ return std::numeric_limits<Dst>::max();
+
+ // Should fail only on attempting to assign NaN to a saturated integer.
+ case internal::RANGE_INVALID:
+ CHECK(false);
+ return std::numeric_limits<Dst>::max();
+ }
+
+ NOTREACHED();
+ return static_cast<Dst>(value);
+}
+
+// strict_cast<> is analogous to static_cast<> for numeric types, except that
+// it will cause a compile failure if the destination type is not large enough
+// to contain any value in the source type. It performs no runtime checking.
+template <typename Dst, typename Src>
+inline Dst strict_cast(Src value) {
+ static_assert(std::numeric_limits<Src>::is_specialized,
+ "Argument must be numeric.");
+ static_assert(std::numeric_limits<Dst>::is_specialized,
+ "Result must be numeric.");
+ static_assert((internal::StaticDstRangeRelationToSrcRange<Dst, Src>::value ==
+ internal::NUMERIC_RANGE_CONTAINED),
+ "The numeric conversion is out of range for this type. You "
+ "should probably use one of the following conversion "
+ "mechanisms on the value you want to pass:\n"
+ "- base::checked_cast\n"
+ "- base::saturated_cast\n"
+ "- base::CheckedNumeric");
+
+ return static_cast<Dst>(value);
+}
+
+// StrictNumeric implements compile time range checking between numeric types by
+// wrapping assignment operations in a strict_cast. This class is intended to be
+// used for function arguments and return types, to ensure the destination type
+// can always contain the source type. This is essentially the same as enforcing
+// -Wconversion in gcc and C4302 warnings on MSVC, but it can be applied
+// incrementally at API boundaries, making it easier to convert code so that it
+// compiles cleanly with truncation warnings enabled.
+// This template should introduce no runtime overhead, but it also provides no
+// runtime checking of any of the associated mathematical operations. Use
+// CheckedNumeric for runtime range checks of tha actual value being assigned.
+template <typename T>
+class StrictNumeric {
+ public:
+ typedef T type;
+
+ StrictNumeric() : value_(0) {}
+
+ // Copy constructor.
+ template <typename Src>
+ StrictNumeric(const StrictNumeric<Src>& rhs)
+ : value_(strict_cast<T>(rhs.value_)) {}
+
+ // This is not an explicit constructor because we implicitly upgrade regular
+ // numerics to StrictNumerics to make them easier to use.
+ template <typename Src>
+ StrictNumeric(Src value)
+ : value_(strict_cast<T>(value)) {}
+
+ // The numeric cast operator basically handles all the magic.
+ template <typename Dst>
+ operator Dst() const {
+ return strict_cast<Dst>(value_);
+ }
+
+ private:
+ T value_;
+};
+
+// Explicitly make a shorter size_t typedef for convenience.
+typedef StrictNumeric<size_t> SizeT;
+
+} // namespace base
+
+#endif // BASE_NUMERICS_SAFE_CONVERSIONS_H_
