Add bi_t::within() to test if big integer fits in an integral type

OTheDev · Feb 23, 2024 · 6ef6dac · 6ef6dac
1 parent 37e57dc
commit 6ef6dac
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Showing 4 changed files with 77 additions and 1 deletion.
diff --git a/include/bi.hpp b/include/bi.hpp
@@ -139,6 +139,8 @@ class BI_API bi_t {
   int sign() const noexcept;
   bool odd() const noexcept;
   bool even() const noexcept;
+  template <std::integral T>
+  bool within() const noexcept;
 
   // Friends
   BI_API friend std::ostream& operator<<(std::ostream& os, const bi_t& x);

diff --git a/src/bi.cpp b/src/bi.cpp
@@ -813,6 +813,28 @@ std::string bi_t::to_string() const {
  *  @complexity O(1)
  */
 
+/**
+ *  @brief Return `true` if this integer fits in an integral type T, `false`
+ *  otherwise.
+ *
+ *  For `bi_t` object `x` and integral type `T`, `x.within<T>()` evaluates to
+ *  @code
+ *  x >= std::numeric_limits<T>::min() && x <= std::numeric_limits<T>::max()
+ *  @endcode
+ *
+ *  Example:
+ *  @code{.cpp}
+ *  bi_t x = std::numeric_limits<int32_t>::max();
+ *  bool fits_in_int32 = x.within<int32_t>();  // true
+ *  bool fits_in_int16 = x.within<int16_t>();  // false
+ *  @endcode
+ */
+template <std::integral T>
+bool bi_t::within() const noexcept {
+  return (*this) >= std::numeric_limits<T>::min() &&
+         (*this) <= std::numeric_limits<T>::max();
+}
+
 ///@}
 
 /**
@@ -866,12 +888,16 @@ bi_t abs(const bi_t& value) {
   return value;
 }
 
+/// @cond
 BI_INST_TEMPLATE_FOR_INTEGRAL_TYPES(bi_t::bi_t, BI_EMPTY);
 BI_INST_TEMPLATE_FOR_INTEGRAL_TYPES(bi_t& bi_t::operator=, BI_EMPTY);
-
 BI_INST_TEMPLATE_FOR_INTEGRAL_TYPES(std::strong_ordering bi_t::operator<=>,
                                     const noexcept);
 BI_INST_TEMPLATE_FOR_INTEGRAL_TYPES(bool bi_t::operator==, const noexcept);
 
 BI_INST_TEMPLATE_FOR_INTEGRAL_TYPES_CONV(bi_t::operator, const noexcept);
+
+BI_INST_TEMPLATE_FOR_INTEGRAL_TYPES_NOARG(bool bi_t::within, const noexcept);
+/// @endcond
+
 };  // namespace bi
diff --git a/src/inst_integral.hpp b/src/inst_integral.hpp
@@ -43,10 +43,15 @@ Extension Signed/Unsigned Integer Types (GCC, Clang)
 #define BI_INST_TEMPLATE_FOR_EXTENSION_INTEGRAL_TYPES_CONV(FUNC, END)          \
   template FUNC __int128() END;                                                \
   template FUNC unsigned __int128() END;
+
+#define BI_INST_TEMPLATE_FOR_EXTENSION_INTEGRAL_TYPES_NOARG(FUNC, END)         \
+  template FUNC<__int128>() END;                                               \
+  template FUNC<unsigned __int128>() END;
 #else
 #define BI_INST_TEMPLATE_FOR_EXTENSION_INTEGRAL_TYPES(FUNC, END)
 #define BI_INST_TEMPLATE_FOR_EXTENSION_INTEGRAL_TYPES_ARG(FUNC, ARG)
 #define BI_INST_TEMPLATE_FOR_EXTENSION_INTEGRAL_TYPES_CONV(FUNC, END)
+#define BI_INST_TEMPLATE_FOR_EXTENSION_INTEGRAL_TYPES_NOARG(FUNC, END)
 #endif
 
 #define BI_INST_TEMPLATE_FOR_INTEGRAL_TYPES(FUNC, END)                         \
@@ -88,6 +93,19 @@ Extension Signed/Unsigned Integer Types (GCC, Clang)
   template FUNC unsigned long long() END;                                      \
   BI_INST_TEMPLATE_FOR_EXTENSION_INTEGRAL_TYPES_CONV(FUNC, END)
 
+#define BI_INST_TEMPLATE_FOR_INTEGRAL_TYPES_NOARG(FUNC, END)                   \
+  template FUNC<signed char>() END;                                            \
+  template FUNC<short>() END;                                                  \
+  template FUNC<int>() END;                                                    \
+  template FUNC<long>() END;                                                   \
+  template FUNC<long long>() END;                                              \
+  template FUNC<unsigned char>() END;                                          \
+  template FUNC<unsigned short>() END;                                         \
+  template FUNC<unsigned>() END;                                               \
+  template FUNC<unsigned long>() END;                                          \
+  template FUNC<unsigned long long>() END;                                     \
+  BI_INST_TEMPLATE_FOR_EXTENSION_INTEGRAL_TYPES_NOARG(FUNC, END)
+
 // NOLINTEND(cppcoreguidelines-macro-usage)
 
 #endif  // BI_SRC_INST_INTEGRAL_HPP_
diff --git a/test/test.cpp b/test/test.cpp
@@ -1700,6 +1700,36 @@ TEST_F(BitwiseOperatorsTest, UnaryComplement) {
   }
 }
 
+TEST_F(BITest, WithinIntegral) {
+  bi_t x;
+
+  EXPECT_TRUE(x.within<digit>());
+
+  x = digit_max;
+  EXPECT_TRUE(x.within<digit>());
+  EXPECT_FALSE(x.within<sdigit>());
+
+  x += 1;
+  EXPECT_FALSE(x.within<digit>());
+
+  x = -static_cast<sddigit>(digit_max);
+  EXPECT_FALSE(x.within<digit>());
+  EXPECT_TRUE(x.within<sddigit>());
+  x -= 1;
+  EXPECT_TRUE(x.within<sddigit>());
+
+  x = ddigit_max;
+  EXPECT_TRUE(x.within<ddigit>());
+  EXPECT_FALSE(x.within<digit>());
+
+  // From documentation
+  x = std::numeric_limits<int32_t>::max();
+  bool fits_in_int32 = x.within<int32_t>();  // true
+  bool fits_in_int16 = x.within<int16_t>();  // false
+  EXPECT_TRUE(fits_in_int32);
+  EXPECT_FALSE(fits_in_int16);
+}
+
 // NOLINTEND(cppcoreguidelines-avoid-magic-numbers)
 
 }  // namespace