Add constexpr version of ozo::detail::ltob36

Author: massaraksh111

include/ozo/detail/base36.h

@@ -1,13 +1,37 @@
 #pragma once
 
-#include <boost/range/algorithm/reverse.hpp>
-#include <string_view>
+#include <boost/hana/string.hpp>
+#include <boost/hana/if.hpp>
 #include <string>
+#include <cmath>
 
 namespace ozo::detail {
 
-inline long b36tol(std::string_view in) {
-    return strtol(in.data(), nullptr, 36);
+template<unsigned long u>
+constexpr auto ultob36() {
+    constexpr int base = 36;
+    constexpr int d = u % base;
+    constexpr char sym = boost::hana::if_(d < 10, '0' + d, 'A' + d - 10);
+    constexpr auto str = boost::hana::string_c<sym>;
+
+    if constexpr (u / base > 0) {
+        return ultob36<u / base>() + str;
+    } else {
+        return str;
+    }
+}
+
+template<long i>
+constexpr auto ltob36() {
+    return ultob36<static_cast<unsigned long>(i)>();
+}
+
+inline void reverse(std::string& str) {
+    const std::size_t size = str.size();
+    const std::size_t times = std::ceil(size / 2);
+    for (std::size_t count = 0; count < times; count++) {
+        std::swap(str[count], str[size - count - 1]);
+    }
 }
 
 inline std::string ltob36(long i) {
@@ -20,7 +44,8 @@ inline std::string ltob36(long i) {
         u /= base;
     } while (u > 0);
 
-    boost::range::reverse(out);
+    reverse(out);
+
     return out;
 }
 

include/ozo/error.h

@@ -524,7 +524,9 @@ class category final : public error_category {
     const char* name() const noexcept override final { return "ozo::sqlstate::category"; }
 
     std::string message(int value) const override final {
-        #define OZO_SQLSTATE_NAME(value) case value: return std::string(#value) + "(" + detail::ltob36(value) + ")";
+        #define OZO_SQLSTATE_NAME(value) case value: return boost::hana::to<char const*>(\
+                BOOST_HANA_STRING(#value) + BOOST_HANA_STRING("(") +\
+                detail::ltob36<value>() + BOOST_HANA_STRING(")"));
         switch (value) {
             OZO_SQLSTATE_NAME(successful_completion)
             OZO_SQLSTATE_NAME(warning)

tests/binary_serialization.cpp

@@ -2,6 +2,7 @@
 #include <ozo/io/array.h>
 #include <ozo/ext/std.h>
 #include <ozo/pg/types.h>
+#include <boost/range/iterator_range.hpp>
 
 #include <gtest/gtest.h>
 #include <gmock/gmock.h>

tests/detail/base36.cpp

@@ -1,19 +1,18 @@
 #include <ozo/detail/base36.h>
+#include <boost/hana/comparing.hpp>
 
 #include <gtest/gtest.h>
 
 namespace {
 
-TEST(b36tol, should_with_HV001_return_29999809) {
-    EXPECT_EQ(ozo::detail::b36tol("HV001"), 29999809);
+TEST(ltob36, should_verify_runtime_version_of_ltob36) {
+    EXPECT_EQ(ozo::detail::ltob36(29999809), "HV001");
+    EXPECT_EQ(ozo::detail::ltob36(833328), "HV00");
+    EXPECT_EQ(ozo::detail::ltob36(0), "0");
 }
 
-TEST(b36tol, should_with_hv001_return_29999809) {
-    EXPECT_EQ(ozo::detail::b36tol("hv001"), 29999809);
-}
-
-TEST(ltob36, should_with_29999809_return_HV001) {
-    EXPECT_EQ("HV001", ozo::detail::ltob36(29999809));
-}
+static_assert(ozo::detail::ltob36<29999809>() == BOOST_HANA_STRING("HV001"));
+static_assert(ozo::detail::ltob36<833328>() == BOOST_HANA_STRING("HV00"));
+static_assert(ozo::detail::ltob36<0>() == BOOST_HANA_STRING("0"));
 
 } // namespace