Merge pull request #1783 from evoskuil/master

Expand float to integer casting.

Author: evoskuil

Makefile.am

@@ -349,6 +349,7 @@ test_libbitcoin_system_test_SOURCES = \
     test/math/byteswap.cpp \
     test/math/cast.cpp \
     test/math/division.cpp \
+    test/math/expectations.cpp \
     test/math/limits.cpp \
     test/math/logarithm.cpp \
     test/math/multiplication.cpp \

builds/cmake/CMakeLists.txt

@@ -828,6 +828,7 @@ if (with-tests)
         "../../test/math/byteswap.cpp"
         "../../test/math/cast.cpp"
         "../../test/math/division.cpp"
+        "../../test/math/expectations.cpp"
         "../../test/math/limits.cpp"
         "../../test/math/logarithm.cpp"
         "../../test/math/multiplication.cpp"

builds/msvc/vs2022/libbitcoin-system-test/libbitcoin-system-test.vcxproj

@@ -275,6 +275,7 @@
     </ClCompile>
     <ClCompile Include="..\..\..\..\test\math\cast.cpp" />
     <ClCompile Include="..\..\..\..\test\math\division.cpp" />
+    <ClCompile Include="..\..\..\..\test\math\expectations.cpp" />
     <ClCompile Include="..\..\..\..\test\math\limits.cpp" />
     <ClCompile Include="..\..\..\..\test\math\logarithm.cpp" />
     <ClCompile Include="..\..\..\..\test\math\multiplication.cpp" />

builds/msvc/vs2022/libbitcoin-system-test/libbitcoin-system-test.vcxproj.filters

@@ -477,6 +477,9 @@
     <ClCompile Include="..\..\..\..\test\math\division.cpp">
       <Filter>src\math</Filter>
     </ClCompile>
+    <ClCompile Include="..\..\..\..\test\math\expectations.cpp">
+      <Filter>src\math</Filter>
+    </ClCompile>
     <ClCompile Include="..\..\..\..\test\math\limits.cpp">
       <Filter>src\math</Filter>
     </ClCompile>

include/bitcoin/system/constraints.hpp

@@ -255,6 +255,8 @@ using if_little_endian_integral_integer = bool_if<
     is_integral_integer<Integer> &&
     is_little_endian>;
 
+/// Floating pont types (native, floating point, non-bool).
+
 template <typename Integer>
 using if_floating_point = bool_if<
     is_floating_point<Integer>>;

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

@@ -209,31 +209,71 @@ constexpr Unsigned to_unsigned(Unsigned value) NOEXCEPT
 
 // Floating point casts.
 // ----------------------------------------------------------------------------
+// inlines below be not constant until c++23.
 
 template <typename Integer, typename Float,
     if_integral_integer<Integer>,
     if_floating_point<Float>>
-constexpr bool to_integer(Integer& out, Float value) NOEXCEPT
+inline bool to_integer(Integer& out, Float value, bool whole) NOEXCEPT
 {
     if (!std::isfinite(value))
         return false;
 
+    // TODO: Could use tolerance for fp epsilon to handle representation error.
     Float integer{};
-    const Float fractional = std::modf(value, &integer);
-    if (fractional != 0.0)
+    if ((std::modf(value, &integer) != 0.0) && whole)
         return false;
 
     if (integer > static_cast<Float>(std::numeric_limits<Integer>::max()) ||
         integer < static_cast<Float>(std::numeric_limits<Integer>::min()))
         return false;
 
-    // Floating point conversion in c++ requires explicit or implicit cast.
-    BC_PUSH_WARNING(NO_CASTS_FOR_ARITHMETIC_CONVERSION)
-    out = static_cast<Integer>(integer);
-    BC_POP_WARNING()
+    out = to_integer<Integer>(integer);
     return true;
 }
 
+template <typename Integer, typename Float,
+    if_integral_integer<Integer>,
+    if_floating_point<Float>>
+inline Integer to_ceilinged_integer(Float value) NOEXCEPT
+{
+    return to_truncated_integer<Integer>(std::ceil(value));
+}
+
+template <typename Integer, typename Float,
+    if_integral_integer<Integer>,
+    if_floating_point<Float>>
+inline Integer to_floored_integer(Float value) NOEXCEPT
+{
+    return to_truncated_integer<Integer>(std::floor(value));
+}
+
+template <typename Integer, typename Float,
+    if_integral_integer<Integer>,
+    if_floating_point<Float>>
+inline Integer to_rounded_integer(Float value) NOEXCEPT
+{
+    return to_truncated_integer<Integer>(std::round(value));
+}
+
+template <typename Integer, typename Float,
+    if_integral_integer<Integer>,
+    if_floating_point<Float>>
+inline Integer to_truncated_integer(Float value) NOEXCEPT
+{
+    if (!std::isfinite(value))
+        return std::numeric_limits<Integer>::max();
+
+    const auto integer = std::trunc(value);
+    if (integer > static_cast<Float>(std::numeric_limits<Integer>::max()))
+        return std::numeric_limits<Integer>::max();
+
+    if (integer < static_cast<Float>(std::numeric_limits<Integer>::min()))
+        return std::numeric_limits<Integer>::min();
+
+    return to_integer<Integer>(integer);
+}
+
 template <typename Integer, typename Float,
     if_integral_integer<Integer>,
     if_floating_point<Float>>

include/bitcoin/system/math/cast.hpp

@@ -142,19 +142,53 @@ constexpr Unsigned to_unsigned(Unsigned value) NOEXCEPT;
 /// Floating point casts.
 /// ---------------------------------------------------------------------------
 
-/// Cast floating point to integral integer, overflow guarded.
+/// Cast floating point to integral integer (truncated).
+/// True for any finite value that falls within Integer domain.
+/// False if fractional part is non-zero when whole is set true.
 template <typename Integer = size_t, typename Float,
     if_integral_integer<Integer> = true,
     if_floating_point<Float> = true>
-constexpr bool to_integer(Integer& out, Float value) NOEXCEPT;
+inline bool to_integer(Integer& out, Float value, bool whole=true) NOEXCEPT;
 
-/// Cast floating point to integral integer, overflow unguarded.
+/// Cast floating point to integral integer (ceilinged).
+/// Any non-finite value returns the integer domain maximum.
+/// Overflow/underflow is clamped to respective integer upper/lower limit.
+template <typename Integer = size_t, typename Float,
+    if_integral_integer<Integer> = true,
+    if_floating_point<Float> = true>
+inline Integer to_ceilinged_integer(Float value) NOEXCEPT;
+
+/// Cast floating point to integral integer (floored).
+/// Any non-finite value returns the integer domain maximum.
+/// Overflow/underflow is clamped to respective integer upper/lower limit.
+template <typename Integer = size_t, typename Float,
+    if_integral_integer<Integer> = true,
+    if_floating_point<Float> = true>
+inline Integer to_floored_integer(Float value) NOEXCEPT;
+
+/// Cast floating point to integral integer (rounded).
+/// Any non-finite value returns the integer domain maximum.
+/// Overflow/underflow is clamped to respective integer upper/lower limit.
+template <typename Integer = size_t, typename Float,
+    if_integral_integer<Integer> = true,
+    if_floating_point<Float> = true>
+inline Integer to_rounded_integer(Float value) NOEXCEPT;
+
+/// Cast floating point to integral integer (truncated).
+/// Any non-finite value returns the integer domain maximum.
+/// Overflow/underflow is clamped to respective integer upper/lower limit.
+template <typename Integer = size_t, typename Float,
+    if_integral_integer<Integer> = true,
+    if_floating_point<Float> = true>
+inline Integer to_truncated_integer(Float value) NOEXCEPT;
+
+/// Cast floating point to integral integer, overflow/underflow UNGUARDED.
 template <typename Integer = size_t, typename Float,
     if_integral_integer<Integer> = true,
     if_floating_point<Float> = true>
 constexpr Integer to_integer(Float value) NOEXCEPT;
 
-/// Cast integral integer to floating point, overflow unguarded.
+/// Cast integral integer to floating point, overflow/underflow not possible.
 template <typename Float = double, typename Integer,
     if_floating_point<Float> = true,
     if_integral_integer<Integer> = true>

test/math/addition.cpp

@@ -18,7 +18,7 @@
  */
 #include "../test.hpp"
 
- // creates addition_tests namespace
+// creates addition_tests namespace
 BOOST_AUTO_TEST_SUITE(addition_tests)
 
 constexpr uint32_t pos_uint32 = 42;