Common/Utilities: Centralize string -> T conversion in StringConvert.h (PR #25335)

(cherry picked from commit cd30e0b86c)

src/common/Utilities/StringConvert.h

@@ -0,0 +1,180 @@
+/*
+ * This file is part of the TrinityCore Project. See AUTHORS file for Copyright information
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef TRINITY_STRINGCONVERT_H
+#define TRINITY_STRINGCONVERT_H
+
+#include "Define.h"
+#include "Errors.h"
+#include "Optional.h"
+#include "Types.h"
+#include "Util.h"
+#include <charconv>
+#include <string>
+#include <string_view>
+#include <type_traits>
+
+namespace Trinity::Impl::StringConvertImpl
+{
+    template <typename T, typename = void> struct For
+    {
+        static_assert(Trinity::dependant_false_v<T>, "Unsupported type used for ToString or StringTo");
+        /*
+        static Optional<T> FromString(std::string_view str, ...);
+        static std::string ToString(T&& val, ...);
+        */
+    };
+
+    // @todo relax this once proper std::from_chars support exists
+    template <typename T>
+    struct For<T, std::enable_if_t<std::is_integral_v<T> && !std::is_same_v<T, bool>>>
+    {
+        static Optional<T> FromString(std::string_view str, int base = 10)
+        {
+            if (base == 0)
+            {
+                if (StringEqualI(str.substr(0, 2), "0x"))
+                {
+                    base = 16;
+                    str.remove_prefix(2);
+                }
+                else if (StringEqualI(str.substr(0, 2), "0b"))
+                {
+                    base = 2;
+                    str.remove_prefix(2);
+                }
+                else
+                    base = 10;
+
+                if (str.empty())
+                    return std::nullopt;
+            }
+
+            char const* const start = str.data();
+            char const* const end = (start + str.length());
+
+            T val;
+            std::from_chars_result const res = std::from_chars(start, end, val, base);
+            if (res.ptr == end)
+                return val;
+            else
+                return std::nullopt;
+        }
+
+        static std::string ToString(T val)
+        {
+            std::string buf(20,'\0'); /* 2^64 is 20 decimal characters, -(2^63) is 20 including the sign */
+            char* const start = buf.data();
+            char* const end = (start + buf.length());
+            std::to_chars_result const res = std::to_chars(start, end, val);
+            ASSERT(res.ec == std::errc());
+            buf.resize(res.ptr - start);
+            return buf;
+        }
+    };
+
+#ifdef TRINITY_NEED_CHARCONV_WORKAROUND
+    /*
+        If this is defined, std::from_chars will cause linkage errors for 64-bit types.
+        (This is a bug in clang-7.)
+
+        If the clang requirement is bumped to >= clang-8, remove this ifdef block and its
+        associated check in cmake/compiler/clang/settings.cmake
+    */
+    template <>
+    struct For<uint64, void>
+    {
+        static Optional<uint64> FromString(std::string_view str, int base = 10)
+        {
+            if (str.empty())
+                return std::nullopt;
+            try
+            {
+                size_t n;
+                uint64 val = std::stoull(std::string(str), &n, base);
+                if (n != str.length())
+                    return std::nullopt;
+                return val;
+            }
+            catch (...) { return std::nullopt; }
+        }
+
+        static std::string ToString(uint64 val)
+        {
+            return std::to_string(val);
+        }
+    };
+
+    template <>
+    struct For<int64, void>
+    {
+        static Optional<int64> FromString(std::string_view str, int base = 10)
+        {
+            try {
+                if (str.empty())
+                    return std::nullopt;
+                size_t n;
+                int64 val = std::stoll(std::string(str), &n, base);
+                if (n != str.length())
+                    return std::nullopt;
+                return val;
+            }
+            catch (...) { return std::nullopt; }
+        }
+
+        static std::string ToString(int64 val)
+        {
+            return std::to_string(val);
+        }
+    };
+#endif
+
+    template <>
+    struct For<bool, void>
+    {
+        static Optional<bool> FromString(std::string_view str)
+        {
+            if ((str == "1") || StringEqualI(str, "y") || StringEqualI(str, "on") || StringEqualI(str, "yes") || StringEqualI(str, "true"))
+                return true;
+            if ((str == "0") || StringEqualI(str, "n") || StringEqualI(str, "off") || StringEqualI(str, "no") || StringEqualI(str, "false"))
+                return false;
+            return std::nullopt;
+        }
+
+        static std::string ToString(bool val)
+        {
+            return (val ? "1" : "0");
+        }
+    };
+}
+
+namespace Trinity
+{
+    template <typename Result, typename... Params>
+    Optional<Result> StringTo(std::string_view str, Params&&... params)
+    {
+        return Trinity::Impl::StringConvertImpl::For<Result>::FromString(str, std::forward<Params>(params)...);
+    }
+
+    template <typename Type, typename... Params>
+    std::string ToString(Type&& val, Params&&... params)
+    {
+        return Trinity::Impl::StringConvertImpl::For<std::decay_t<Type>>::ToString(std::forward<Type>(val), std::forward<Params>(params)...);
+    }
+}
+
+#endif