Add functions for powers and factors

include/boost/charconv/detail/power_factor.hpp

@@ -0,0 +1,43 @@
+// Copyright 2020-2023 Junekey Jeon
+// Copyright 2023 Matt Borland
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#ifndef BOOST_CHARCONV_DETAIL_POWER_FACTOR_HPP
+#define BOOST_CHARCONV_DETAIL_POWER_FACTOR_HPP
+
+#include <boost/charconv/detail/config.hpp>
+#include <cstdint>
+
+namespace boost { namespace charconv { namespace detail {
+
+template <int k, typename Integer>
+BOOST_CHARCONV_CXX14_CONSTEXPR Integer compute_power(Integer a) noexcept 
+{
+    Integer p = 1;
+    for (Integer i = 0; i < k; ++i) 
+    {
+        p *= a;
+    }
+
+    return p;
+}
+
+template <unsigned a, typename Unsigned_Integer>
+BOOST_CHARCONV_CXX14_CONSTEXPR int count_factors(Unsigned_Integer n) noexcept 
+{
+    static_assert(a > 1);
+    
+    int c = 0;
+    while (n % a == 0)
+    {
+        n /= a;
+        ++c;
+    }
+
+    return c;
+}
+
+}}} // Namespaces
+
+#endif // BOOST_CHARCONV_DETAIL_POWER_FACTOR_HPP