Merge pull request #1810 from evoskuil/master

Add is_max/is_min, tests.

Author: evoskuil

include/bitcoin/system/impl/math/limits.ipp

@@ -78,6 +78,18 @@ constexpr Result limit(Integer value, Result minimum, Result maximum) NOEXCEPT
 // Integral bounds (dispatch for absolute_min/unsigned_max).
 // ----------------------------------------------------------------------------
 
+template <typename Integer, if_integer<Integer>>
+constexpr bool is_max(Integer value) NOEXCEPT
+{
+    return value == system::maximum<Integer>;
+}
+
+template <typename Integer, if_integer<Integer>>
+constexpr bool is_min(Integer value) NOEXCEPT
+{
+    return value == system::minimum<Integer>;
+}
+
 template <typename Signed, if_signed_integral_integer<Signed>>
 constexpr to_unsigned_type<Signed> absolute_minimum() NOEXCEPT
 {

include/bitcoin/system/math/limits.hpp

@@ -72,6 +72,12 @@ constexpr Integer maximum = std::numeric_limits<Integer>::max();
 template <typename Integer, if_integer<Integer> = true>
 constexpr Integer minimum = std::numeric_limits<Integer>::min();
 
+/// Is the maximum/minimum value of a integral integer?
+template <typename Integer, if_integer<Integer> = true>
+constexpr bool is_max(Integer value) NOEXCEPT;
+template <typename Integer, if_integer<Integer> = true>
+constexpr bool is_min(Integer value) NOEXCEPT;
+
 // dispatch for absolute_min/unsigned_max
 template <typename Signed, if_signed_integral_integer<Signed> = true>
 constexpr to_unsigned_type<Signed> absolute_minimum() NOEXCEPT;

test/math/limits.cpp

@@ -177,6 +177,37 @@ static_assert(minimum<uint64_t> == min_uint64);
 static_assert(minimum<uintx_t<42>> == zero);
 static_assert(is_same_type<decltype(minimum<int64_t>), const int64_t>);
 
+// is_min
+
+static_assert(is_min<int8_t >(min_int8));
+static_assert(is_min<int8_t >(min_int8));
+static_assert(is_min<int16_t>(min_int16));
+static_assert(is_min<int32_t>(min_int32));
+static_assert(is_min<int64_t>(min_int64));
+static_assert(is_min<uint8_t >(min_uint8));
+static_assert(is_min<uint16_t>(min_uint16));
+static_assert(is_min<uint32_t>(min_uint32));
+static_assert(is_min<uint64_t>(min_uint64));
+static_assert(!is_min<int8_t >(max_int8));
+static_assert(!is_min<int16_t>(max_int16));
+static_assert(!is_min<int32_t>(max_int32));
+static_assert(!is_min<int64_t>(max_int64));
+static_assert(!is_min<uint8_t >(max_uint8));
+static_assert(!is_min<uint16_t>(max_uint16));
+static_assert(!is_min<uint32_t>(max_uint32));
+static_assert(!is_min<uint64_t>(max_uint64));
+static_assert(!is_min<int8_t >(add1(min_int8)));
+static_assert(!is_min<int8_t >(add1(min_int8)));
+static_assert(!is_min<int16_t>(add1(min_int16)));
+static_assert(!is_min<int32_t>(add1(min_int32)));
+static_assert(!is_min<int64_t>(add1(min_int64)));
+static_assert(!is_min<uint8_t >(add1(min_uint8)));
+static_assert(!is_min<uint16_t>(add1(min_uint16)));
+static_assert(!is_min<uint32_t>(add1(min_uint32)));
+static_assert(!is_min<uint64_t>(add1(min_uint64)));
+static_assert(is_min<uintx_t<42>>(zero));
+static_assert(is_same_type<decltype(is_min<int64_t>(0)), bool>);
+
 // maximum<T>
 
 static_assert(maximum<int8_t > == max_int8);
@@ -190,6 +221,36 @@ static_assert(maximum<uint64_t> == max_uint64);
 static_assert(maximum<uintx_t<42>> == sub1(power2<uintx_t<42>>(42u)));
 static_assert(is_same_type<decltype(maximum<int16_t>), const int16_t>);
 
+// is_max
+
+static_assert(is_max<int8_t >(max_int8));
+static_assert(is_max<int16_t>(max_int16));
+static_assert(is_max<int32_t>(max_int32));
+static_assert(is_max<int64_t>(max_int64));
+static_assert(is_max<uint8_t >(max_uint8));
+static_assert(is_max<uint16_t>(max_uint16));
+static_assert(is_max<uint32_t>(max_uint32));
+static_assert(is_max<uint64_t>(max_uint64));
+static_assert(!is_max<int8_t >(min_int8));
+static_assert(!is_max<int8_t >(min_int8));
+static_assert(!is_max<int16_t>(min_int16));
+static_assert(!is_max<int32_t>(min_int32));
+static_assert(!is_max<int64_t>(min_int64));
+static_assert(!is_max<uint8_t >(min_uint8));
+static_assert(!is_max<uint16_t>(min_uint16));
+static_assert(!is_max<uint32_t>(min_uint32));
+static_assert(!is_max<uint64_t>(min_uint64));
+static_assert(!is_max<int8_t >(sub1(max_int8)));
+static_assert(!is_max<int16_t>(sub1(max_int16)));
+static_assert(!is_max<int32_t>(sub1(max_int32)));
+static_assert(!is_max<int64_t>(sub1(max_int64)));
+static_assert(!is_max<uint8_t >(sub1(max_uint8)));
+static_assert(!is_max<uint16_t>(sub1(max_uint16)));
+static_assert(!is_max<uint32_t>(sub1(max_uint32)));
+static_assert(!is_max<uint64_t>(sub1(max_uint64)));
+static_assert(is_max<uintx_t<42>>(sub1(power2<uintx_t<42>>(42u))));
+static_assert(is_same_type<decltype(is_max<int16_t>(0)), bool>);
+
 // absolute_min<T>
 
 static_assert(absolute_min<int8_t > == power2(sub1(bits<int8_t>)));