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More constexpr friendly replace and insert with is_constant_evaluated

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This commit is contained in:
Krystian Stasiowski
2020-01-03 19:01:34 -05:00
parent e1e992380a
commit 26b9f7df27
3 changed files with 33 additions and 2 deletions
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10
include/boost/static_string/config.hpp
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@ -25,6 +25,16 @@
#define BOOST_STATIC_STRING_USE_DEDUCT
#endif
// Include <version> if we can
#if __has_include(<version>)
#include <version>
#endif
// Can we use is_constant_evaluated?
#if __cpp_lib_is_constant_evaluated >= 201811L
#define BOOST_STATIC_STRING_USE_IS_CONST_EVAL
#endif
// Can we use [[nodiscard]]?
#ifdef __has_attribute
#if __has_attribute(nodiscard)

20
include/boost/static_string/impl/static_string.hpp
View File

@ -363,7 +363,15 @@ insert(
const auto s = &*first;
BOOST_STATIC_STRING_THROW_IF(
count > max_size() - curr_size, std::length_error{"count > max_size() - size()"});
const bool inside = s <= &curr_data[curr_size] && s >= curr_data;
// Makes this more constexpr friendly if we can use is_constant_evaluated
const bool inside =
#ifdef BOOST_STATIC_STRING_USE_IS_CONST_EVAL
std::is_constant_evaluated() ?
detail::is_inside(curr_data, curr_data + curr_size, s) :
s <= &curr_data[curr_size] && s >= curr_data;
#else
s <= &curr_data[curr_size] && s >= curr_data;
#endif
if (!inside || (inside && ((s - curr_data) + count <= index)))
{
Traits::move(&curr_data[index + count], &curr_data[index], curr_size - index + 1);
@ -683,7 +691,15 @@ replace(
curr_size - (std::min)(n1, curr_size - pos) >= max_size() - n2,
std::length_error{"replaced string exceeds max_size()"});
n1 = (std::min)(n1, curr_size - pos);
const bool inside = s <= &curr_data[curr_size] && s >= curr_data;
// Makes this more constexpr friendly if we can use is_constant_evaluated
const bool inside =
#ifdef BOOST_STATIC_STRING_USE_IS_CONST_EVAL
std::is_constant_evaluated() ?
detail::is_inside(curr_data, curr_data + curr_size, s) :
s <= &curr_data[curr_size] && s >= curr_data;
#else
s <= &curr_data[curr_size] && s >= curr_data;
#endif
if (inside && size_type(s - curr_data) == pos && n1 == n2)
return *this;
if (!inside || (inside && ((s - curr_data) + n2 <= pos)))