From f45aa5cac1579e87cbc599ffb58e10e662066792 Mon Sep 17 00:00:00 2001
From: Treeston <treeston.mmoc@gmail.com>
Date: Wed, 2 Sep 2020 22:04:45 +0200
Subject: Common/Util: Trinity::StringTo<double> support (PR #25364)

---
 src/common/Utilities/StringConvert.h               | 86 +++++++++++++++++++++-
 .../game/Chat/ChatCommands/ChatCommandArgs.h       | 30 ++------
 2 files changed, 90 insertions(+), 26 deletions(-)

(limited to 'src')

diff --git a/src/common/Utilities/StringConvert.h b/src/common/Utilities/StringConvert.h
index f264c0222fa..4ec3324fb33 100644
--- a/src/common/Utilities/StringConvert.h
+++ b/src/common/Utilities/StringConvert.h
@@ -39,7 +39,6 @@ namespace Trinity::Impl::StringConvertImpl
         */
     };
 
-    // @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>>>
     {
@@ -171,6 +170,91 @@ namespace Trinity::Impl::StringConvertImpl
             return (val ? "1" : "0");
         }
     };
+
+#if TRINITY_COMPILER == TRINITY_COMPILER_MICROSOFT
+    template <typename T>
+    struct For<T, std::enable_if_t<std::is_floating_point_v<T>>>
+    {
+        static Optional<T> FromString(std::string_view str, std::chars_format fmt = std::chars_format())
+        {
+            if (str.empty())
+                return std::nullopt;
+
+            if (fmt == std::chars_format())
+            {
+                if (StringEqualI(str.substr(0, 2), "0x"))
+                {
+                    fmt = std::chars_format::hex;
+                    str.remove_prefix(2);
+                }
+                else
+                    fmt = std::chars_format::general;
+
+                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, fmt);
+            if ((res.ptr == end) && (res.ec == std::errc()))
+                return val;
+            else
+                return std::nullopt;
+        }
+
+        // this allows generic converters for all numeric types (easier templating!)
+        static Optional<T> FromString(std::string_view str, int base)
+        {
+            if (base == 16)
+                return FromString(str, std::chars_format::hex);
+            else if (base == 10)
+                return FromString(str, std::chars_format::general);
+            else
+                return FromString(str, std::chars_format());
+        }
+
+        static std::string ToString(T val)
+        {
+            return std::to_string(val);
+        }
+    };
+#else
+    // @todo replace this once libc++ supports double args to from_chars
+    template <typename T>
+    struct For<T, std::enable_if_t<std::is_floating_point_v<T>>>
+    {
+        static Optional<T> FromString(std::string_view str, int base = 0)
+        {
+            try {
+                if (str.empty())
+                    return std::nullopt;
+
+                if ((base == 10) && StringEqualI(str.substr(0, 2), "0x"))
+                    return std::nullopt;
+
+                std::string tmp;
+                if (base == 16)
+                    tmp.append("0x");
+                tmp.append(str);
+
+                size_t n;
+                T val = static_cast<T>(std::stold(tmp, &n));
+                if (n != tmp.length())
+                    return std::nullopt;
+                return val;
+            }
+            catch (...) { return std::nullopt; }
+        }
+
+        static std::string ToString(T val)
+        {
+            return std::to_string(val);
+        }
+    };
+#endif
 }
 
 namespace Trinity
diff --git a/src/server/game/Chat/ChatCommands/ChatCommandArgs.h b/src/server/game/Chat/ChatCommands/ChatCommandArgs.h
index 583edcd40e2..9f10013989c 100644
--- a/src/server/game/Chat/ChatCommands/ChatCommandArgs.h
+++ b/src/server/game/Chat/ChatCommands/ChatCommandArgs.h
@@ -45,9 +45,9 @@ namespace Trinity::Impl::ChatCommands
 template <typename T, typename = void>
 struct ArgInfo { static_assert(!std::is_same_v<T,T>, "Invalid command parameter type - see ChatCommandArgs.h for possible types"); };
 
-// catch-all for integral types
+// catch-all for number types
 template <typename T>
-struct ArgInfo<T, std::enable_if_t<std::is_integral_v<T>>>
+struct ArgInfo<T, std::enable_if_t<std::is_integral_v<T> || std::is_floating_point_v<T>>>
 {
     static Optional<std::string_view> TryConsume(T& val, std::string_view args)
     {
@@ -59,34 +59,14 @@ struct ArgInfo<T, std::enable_if_t<std::is_integral_v<T>>>
             val = *v;
         else
             return std::nullopt;
-        return tail;
-    }
-};
-
-// catch-all for floating point types
-template <typename T>
-struct ArgInfo<T, std::enable_if_t<std::is_floating_point_v<T>>>
-{
-    static Optional<std::string_view> TryConsume(T& val, std::string_view args)
-    {
-        auto [token, tail] = tokenize(args);
-        if (token.empty())
-            return std::nullopt;
 
-        try
+        if constexpr (std::is_floating_point_v<T>)
         {
-            // @todo replace this once libc++ supports double args to from_chars for required minimum
-            size_t processedChars = 0;
-            val = std::stold(std::string(token), &processedChars);
-            if (processedChars != token.length())
+            if (!std::isfinite(val))
                 return std::nullopt;
         }
-        catch (...) { return std::nullopt; }
 
-        if (std::isfinite(val))
-            return tail;
-        else
-            return std::nullopt;
+        return tail;
     }
 };
 
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