Index: base/numerics/safe_conversions_impl.h |
diff --git a/base/numerics/safe_conversions_impl.h b/base/numerics/safe_conversions_impl.h |
index 8bc30214f188abb48c72d6633506156af403863f..96a988c588e8281e9668830e6caf75a031250df5 100644 |
--- a/base/numerics/safe_conversions_impl.h |
+++ b/base/numerics/safe_conversions_impl.h |
@@ -8,96 +8,98 @@ |
#include <limits> |
#include "base/macros.h" |
+#include "base/template_util.h" |
namespace base { |
namespace internal { |
-enum DstSign { |
- DST_UNSIGNED, |
- DST_SIGNED |
+using std::numeric_limits; |
+ |
+enum DstSignId { |
+ DST_UNSIGNED = 0, |
+ DST_SIGNED = 1 |
}; |
-enum SrcSign { |
- SRC_UNSIGNED, |
- SRC_SIGNED |
+enum SrcSignId { |
+ SRC_UNSIGNED = 0, |
+ SRC_SIGNED = 1 |
Ryan Sleevi
2014/02/10 23:42:41
Why use these enums versus a bool?
jschuh
2014/02/11 00:43:28
It makes the template instantiations easier to fol
|
}; |
-enum DstRange { |
+enum DstRangeId { |
OVERLAPS_RANGE, |
CONTAINS_RANGE |
Ryan Sleevi
2014/02/10 23:42:41
Why no literals for these, compared with 19/20 and
jschuh
2014/02/11 00:43:28
Forgot.
|
}; |
+// Retrieve the max exponent for floating types and compute it for integrals. |
+template <typename NumericType> |
+struct MaxExponent { |
+ static const int value = numeric_limits<NumericType>::is_iec559 ? |
+ numeric_limits<NumericType>::max_exponent : |
+ (sizeof(NumericType) * 8 + 1 - |
+ numeric_limits<NumericType>::is_signed); |
+}; |
+ |
// Helper templates to statically determine if our destination type can contain |
-// all values represented by the source type. |
+// maximum and minimum values represented by the source type. |
template <typename Dst, typename Src, |
Ryan Sleevi
2014/02/10 23:42:41
We traditionally format template arguments as with
jschuh
2014/02/11 00:43:28
Done.
|
- DstSign IsDstSigned = std::numeric_limits<Dst>::is_signed ? |
- DST_SIGNED : DST_UNSIGNED, |
- SrcSign IsSrcSigned = std::numeric_limits<Src>::is_signed ? |
- SRC_SIGNED : SRC_UNSIGNED> |
+ DstSignId DstSign = numeric_limits<Dst>::is_signed ? |
+ DST_SIGNED : DST_UNSIGNED, |
+ SrcSignId SrcSign = numeric_limits<Src>::is_signed ? |
+ SRC_SIGNED : SRC_UNSIGNED> |
struct StaticRangeCheck {}; |
+// Both signed, narrowing. |
template <typename Dst, typename Src> |
struct StaticRangeCheck<Dst, Src, DST_SIGNED, SRC_SIGNED> { |
- typedef std::numeric_limits<Dst> DstLimits; |
- typedef std::numeric_limits<Src> SrcLimits; |
- // Compare based on max_exponent, which we must compute for integrals. |
- static const size_t kDstMaxExponent = DstLimits::is_iec559 ? |
- DstLimits::max_exponent : |
- (sizeof(Dst) * 8 - 1); |
- static const size_t kSrcMaxExponent = SrcLimits::is_iec559 ? |
- SrcLimits::max_exponent : |
- (sizeof(Src) * 8 - 1); |
- static const DstRange value = kDstMaxExponent >= kSrcMaxExponent ? |
- CONTAINS_RANGE : OVERLAPS_RANGE; |
+ static const DstRangeId value = MaxExponent<Dst>::value >= |
+ MaxExponent<Src>::value ? |
+ CONTAINS_RANGE : OVERLAPS_RANGE; |
}; |
+// Both unsigned, narrowing (handled same as both signed narrowing). |
template <typename Dst, typename Src> |
-struct StaticRangeCheck<Dst, Src, DST_UNSIGNED, SRC_UNSIGNED> { |
- static const DstRange value = sizeof(Dst) >= sizeof(Src) ? |
- CONTAINS_RANGE : OVERLAPS_RANGE; |
-}; |
+struct StaticRangeCheck<Dst, Src, DST_UNSIGNED, SRC_UNSIGNED> : |
+ StaticRangeCheck<Dst, Src, DST_SIGNED, SRC_SIGNED> {}; |
Ryan Sleevi
2014/02/10 23:42:41
Doesn't this actually leave ::value unspecified?
jschuh
2014/02/11 00:43:28
No, it's inheriting value from the DST_SIGNED, SRC
|
+// Unsigned to signed, overlapping. |
template <typename Dst, typename Src> |
struct StaticRangeCheck<Dst, Src, DST_SIGNED, SRC_UNSIGNED> { |
- typedef std::numeric_limits<Dst> DstLimits; |
- typedef std::numeric_limits<Src> SrcLimits; |
- // Compare based on max_exponent, which we must compute for integrals. |
- static const size_t kDstMaxExponent = DstLimits::is_iec559 ? |
- DstLimits::max_exponent : |
- (sizeof(Dst) * 8 - 1); |
- static const size_t kSrcMaxExponent = sizeof(Src) * 8; |
- static const DstRange value = kDstMaxExponent >= kSrcMaxExponent ? |
- CONTAINS_RANGE : OVERLAPS_RANGE; |
+ typedef numeric_limits<Dst> DstLimits; |
+ typedef numeric_limits<Src> SrcLimits; |
Ryan Sleevi
2014/02/10 23:42:41
Unused?
jschuh
2014/02/11 00:43:28
Done.
|
+ static const DstRangeId value = MaxExponent<Dst>::value > |
+ MaxExponent<Src>::value ? |
+ CONTAINS_RANGE : OVERLAPS_RANGE; |
}; |
+// Signed to unsigned, overlapping. |
template <typename Dst, typename Src> |
struct StaticRangeCheck<Dst, Src, DST_UNSIGNED, SRC_SIGNED> { |
- static const DstRange value = OVERLAPS_RANGE; |
+ static const DstRangeId value = OVERLAPS_RANGE; |
}; |
-enum RangeCheckResult { |
+enum RangeCheckId { |
TYPE_VALID = 0, // Value can be represented by the destination type. |
TYPE_UNDERFLOW = 1, // Value would overflow. |
TYPE_OVERFLOW = 2, // Value would underflow. |
TYPE_INVALID = 3 // Source value is invalid (i.e. NaN). |
}; |
-// This macro creates a RangeCheckResult from an upper and lower bound |
+// This macro creates a RangeCheckId from an upper and lower bound |
// check by taking advantage of the fact that only NaN can be out of range in |
// both directions at once. |
#define BASE_NUMERIC_RANGE_CHECK_RESULT(is_in_upper_bound, is_in_lower_bound) \ |
- RangeCheckResult(((is_in_upper_bound) ? 0 : TYPE_OVERFLOW) | \ |
+ RangeCheckId(((is_in_upper_bound) ? 0 : TYPE_OVERFLOW) | \ |
((is_in_lower_bound) ? 0 : TYPE_UNDERFLOW)) |
template <typename Dst, |
typename Src, |
- DstSign IsDstSigned = std::numeric_limits<Dst>::is_signed ? |
- DST_SIGNED : DST_UNSIGNED, |
- SrcSign IsSrcSigned = std::numeric_limits<Src>::is_signed ? |
- SRC_SIGNED : SRC_UNSIGNED, |
- DstRange IsSrcRangeContained = StaticRangeCheck<Dst, Src>::value> |
+ DstSignId DstSign = numeric_limits<Dst>::is_signed ? |
+ DST_SIGNED : DST_UNSIGNED, |
+ SrcSignId SrcSign = numeric_limits<Src>::is_signed ? |
+ SRC_SIGNED : SRC_UNSIGNED, |
+ DstRangeId DstRange = StaticRangeCheck<Dst, Src>::value> |
struct RangeCheckImpl {}; |
// The following templates are for ranges that must be verified at runtime. We |
@@ -105,9 +107,9 @@ struct RangeCheckImpl {}; |
// compiler warnings on signed an unsigned comparisons. |
// Dst range always contains the result: nothing to check. |
-template <typename Dst, typename Src, DstSign IsDstSigned, SrcSign IsSrcSigned> |
-struct RangeCheckImpl<Dst, Src, IsDstSigned, IsSrcSigned, CONTAINS_RANGE> { |
- static RangeCheckResult Check(Src value) { |
+template <typename Dst, typename Src, DstSignId DstSign, SrcSignId SrcSign> |
+struct RangeCheckImpl<Dst, Src, DstSign, SrcSign, CONTAINS_RANGE> { |
+ static RangeCheckId Check(Src value) { |
return TYPE_VALID; |
} |
}; |
@@ -115,64 +117,53 @@ struct RangeCheckImpl<Dst, Src, IsDstSigned, IsSrcSigned, CONTAINS_RANGE> { |
// Signed to signed narrowing. |
template <typename Dst, typename Src> |
struct RangeCheckImpl<Dst, Src, DST_SIGNED, SRC_SIGNED, OVERLAPS_RANGE> { |
- static RangeCheckResult Check(Src value) { |
- typedef std::numeric_limits<Dst> DstLimits; |
- return DstLimits::is_iec559 ? |
+ static RangeCheckId Check(Src value) { |
+ return numeric_limits<Dst>::is_iec559 ? |
BASE_NUMERIC_RANGE_CHECK_RESULT( |
- value <= static_cast<Src>(DstLimits::max()), |
- value >= static_cast<Src>(DstLimits::max() * -1)) : |
+ value <= numeric_limits<Dst>::max(), |
+ value >= -numeric_limits<Dst>::max()) : |
BASE_NUMERIC_RANGE_CHECK_RESULT( |
- value <= static_cast<Src>(DstLimits::max()), |
- value >= static_cast<Src>(DstLimits::min())); |
+ value <= numeric_limits<Dst>::max(), |
+ value >= numeric_limits<Dst>::min()); |
} |
}; |
// Unsigned to unsigned narrowing. |
template <typename Dst, typename Src> |
struct RangeCheckImpl<Dst, Src, DST_UNSIGNED, SRC_UNSIGNED, OVERLAPS_RANGE> { |
- static RangeCheckResult Check(Src value) { |
- typedef std::numeric_limits<Dst> DstLimits; |
+ static RangeCheckId Check(Src value) { |
return BASE_NUMERIC_RANGE_CHECK_RESULT( |
- value <= static_cast<Src>(DstLimits::max()), true); |
+ value <= numeric_limits<Dst>::max(), true); |
} |
}; |
// Unsigned to signed. |
template <typename Dst, typename Src> |
struct RangeCheckImpl<Dst, Src, DST_SIGNED, SRC_UNSIGNED, OVERLAPS_RANGE> { |
- static RangeCheckResult Check(Src value) { |
- typedef std::numeric_limits<Dst> DstLimits; |
+ static RangeCheckId Check(Src value) { |
return sizeof(Dst) > sizeof(Src) ? TYPE_VALID : |
BASE_NUMERIC_RANGE_CHECK_RESULT( |
- value <= static_cast<Src>(DstLimits::max()), true); |
+ value <= static_cast<Src>(numeric_limits<Dst>::max()), |
+ true); |
} |
}; |
// Signed to unsigned. |
template <typename Dst, typename Src> |
struct RangeCheckImpl<Dst, Src, DST_UNSIGNED, SRC_SIGNED, OVERLAPS_RANGE> { |
- static RangeCheckResult Check(Src value) { |
- typedef std::numeric_limits<Dst> DstLimits; |
- typedef std::numeric_limits<Src> SrcLimits; |
- // Compare based on max_exponent, which we must compute for integrals. |
- static const size_t kDstMaxExponent = sizeof(Dst) * 8; |
- static const size_t kSrcMaxExponent = SrcLimits::is_iec559 ? |
- SrcLimits::max_exponent : |
- (sizeof(Src) * 8 - 1); |
- return (kDstMaxExponent >= kSrcMaxExponent) ? |
+ static RangeCheckId Check(Src value) { |
+ return (MaxExponent<Dst>::value >= MaxExponent<Src>::value) ? |
BASE_NUMERIC_RANGE_CHECK_RESULT(true, value >= static_cast<Src>(0)) : |
BASE_NUMERIC_RANGE_CHECK_RESULT( |
- value <= static_cast<Src>(DstLimits::max()), |
+ value <= static_cast<Src>(numeric_limits<Dst>::max()), |
value >= static_cast<Src>(0)); |
} |
}; |
template <typename Dst, typename Src> |
-inline RangeCheckResult RangeCheck(Src value) { |
- COMPILE_ASSERT(std::numeric_limits<Src>::is_specialized, |
- argument_must_be_numeric); |
- COMPILE_ASSERT(std::numeric_limits<Dst>::is_specialized, |
- result_must_be_numeric); |
+inline RangeCheckId RangeCheck(Src value) { |
+ COMPILE_ASSERT(numeric_limits<Src>::is_specialized, argument_must_be_numeric); |
+ COMPILE_ASSERT(numeric_limits<Dst>::is_specialized, result_must_be_numeric); |
return RangeCheckImpl<Dst, Src>::Check(value); |
} |