From f625cb15031c6f7605514043a39e1cd72c588bf6 Mon Sep 17 00:00:00 2001
From: "matthias@arch" <matthiasqui@protonmail.com>
Date: Wed, 28 Sep 2022 15:31:56 +0200
Subject: [PATCH] Added more concepts

---
 src/util/string_concepts.hpp   |  59 ++++++++++-
 src/util/string_conversion.cpp |   4 +-
 src/util/string_conversion.hpp | 182 ++++++++++++++++++---------------
 3 files changed, 157 insertions(+), 88 deletions(-)

diff --git a/src/util/string_concepts.hpp b/src/util/string_concepts.hpp
index b398844..2cd287f 100644
--- a/src/util/string_concepts.hpp
+++ b/src/util/string_concepts.hpp
@@ -10,13 +10,19 @@ namespace gz::util {
 // CONVERT TO STRING CONCEPTS
 //
     // ELEMENTARY TYPES
-    /// is (similar or convertible to) std::string
+    /// same as std::string
     template<typename T> 
     concept Stringy = std::same_as<T, std::string> || std::convertible_to<T, std::string_view>;
 
+    /// can construct std::string from T
+    template<typename T> 
+    concept CanConstructString = !Stringy<T> && requires(const T& t) {
+        { std::string(t) } -> std::same_as<std::string>;
+    };
+
     /// has .to_string() const member
     template<typename T>
-    concept HasToStringMember = !Stringy<T> && requires(const T& t) { { t.to_string() }-> Stringy; };
+    concept HasToStringMember = !Stringy<T> && requires(const T& t) { { t.toString() }-> Stringy; };
 
     /// works with std::to_string(), except bool
     template<typename T>
@@ -84,11 +90,56 @@ namespace gz::util {
     // POINTER
     /// Everything from string-convertibleNoPtr but "behind" a pointer
     template<typename T>
-    concept PointerConvertibleToString = requires(const T t) { { *t } -> _ElementaryTypeOrContainerConvertibleToString; };
+    concept PointerConvertibleToString = !_ElementaryTypeOrContainerConvertibleToString<T> and 
+        requires(const T t) { { *t } -> _ElementaryTypeOrContainerConvertibleToString; };
 
 } // namespace gz::util
 
-namespace gz {
+
+//
+// CONVERT TO STRING
+//
+template<typename T>
+concept False = false;
+/**
+ * @brief Declaration of fromString in global namespace, so that concepts can use it
+ * @details
+ *  This declaration only exists so that ::fromString can be used in concepts.
+ */
+template<False T>
+T fromString(const std::string& s);
+/**
+ * @brief Declaration of toString in global namespace, so that concepts can use it
+ *  This declaration only exists so that ::toString can be used in concepts.
+ */
+template<False T>
+std::string toString(const T& s);
+
+namespace gz::util {
+    template<typename T>
+    concept ConstructibleFromStringGlobal = requires(const std::string& s) {
+        { ::fromString<T>(s) } -> std::same_as<T>;
+    };
+    template<typename T>
+    concept ConvertibleToStringGlobal = requires(const T& t) { 
+        { ::toString(t) } -> Stringy; 
+    };
+
+    /**
+     * @brief toString is implemented for these types
+     */
+    template<typename T>
+    concept GetTypeFromStringImplemented = 
+        std::same_as<T, int> or
+        std::same_as<T, long> or
+        std::same_as<T, long long> or
+        std::same_as<T, unsigned int> or
+        std::same_as<T, unsigned long> or
+        std::same_as<T, unsigned long long> or
+        std::same_as<T, float> or
+        std::same_as<T, double> or
+        std::same_as<T, long double> or
+        std::same_as<T, bool>;
 }
 
 /**
diff --git a/src/util/string_conversion.cpp b/src/util/string_conversion.cpp
index 43daa37..203fc31 100644
--- a/src/util/string_conversion.cpp
+++ b/src/util/string_conversion.cpp
@@ -105,14 +105,14 @@ std::string getStringOr(const std::string& s, const std::string& fallback) noexc
 // CONVERT FROM STRING
 //
 template<>
-bool from_string<bool>(const std::string& s) { 
+bool fromString<bool>(const std::string& s) { 
     if (s == "true" or s == "True" or s == "1") {
         return true;
     }
     else if (s == "false" or s == "False" or s == "0") {
         return false;
     }
-    throw InvalidArgument("s is not a bool: '" + s + "'", "from_string<bool>");
+    throw InvalidArgument("s is not a bool: '" + s + "'", "fromString<bool>");
 }
 
 
diff --git a/src/util/string_conversion.hpp b/src/util/string_conversion.hpp
index a0110d3..9adb982 100644
--- a/src/util/string_conversion.hpp
+++ b/src/util/string_conversion.hpp
@@ -78,20 +78,28 @@ namespace gz {
  * @{
  */
     /**
-     * @brief Construct a string from a string like-type
+     * @brief Return the string
      */
     template<util::Stringy T>
-    inline std::string to_string(const T& t) {
-        return t;
+    inline std::string toString(const T& t) {
+        return static_cast<std::string>(t);
+    }
+
+    /**
+     * @brief Construct a string from a string like-type
+     */
+    template<util::CanConstructString T>
+    inline std::string toString(const T& t) {
+        return std::string(t);
     }
 
     /**
      * @overload
-     * @brief Construct a string from a type having a to_string() const member function
+     * @brief Construct a string from a type having a toString() const member function
      */
     template<util::HasToStringMember T>
-    inline std::string to_string(const T& t) {
-        return t.to_string();
+    inline std::string toString(const T& t) {
+        return t.toString();
     }
 
     /**
@@ -100,7 +108,7 @@ namespace gz {
      * @returns std::to_string(t)
      */
     template<util::WorksWithStdToString T>
-    inline std::string to_string(const T& t) {
+    inline std::string toString(const T& t) {
         return std::to_string(t);
     }
 
@@ -110,7 +118,7 @@ namespace gz {
      *  Unlike std::to_string(bool), which returns 0 or 1, this function returns "true" or "false"
      * @returns "true" or "false"
      */
-    inline std::string to_string(const bool& b) {
+    inline std::string toString(const bool& b) {
         return b ? "true" : "false";
     }
 
@@ -119,10 +127,10 @@ namespace gz {
      * @brief Construct a string from a forward range
      */
     template<util::ContainerConvertibleToString T>
-    std::string to_string(const T& t) {
+    std::string toString(const T& t) {
         std::string s = "[ ";
         for (auto it = t.begin(); it != t.end(); it++) {
-            s += to_string(*it) + ", ";
+            s += toString(*it) + ", ";
         }
         if (s.size() > 2) {
             s.erase(s.size() - 2);
@@ -136,8 +144,8 @@ namespace gz {
      * @brief Construct a string from a pair
      */
     template<util::PairConvertibleToString T>
-    inline std::string to_string(const T& t) {
-        return "{ " + to_string(t.first) + ", " + to_string(t.second) + " }";
+    inline std::string toString(const T& t) {
+        return "{ " + toString(t.first) + ", " + toString(t.second) + " }";
     }
 
     /**
@@ -145,11 +153,11 @@ namespace gz {
      * @brief Construct a string from a forward range holding a pair, eg a map
      */
     template<util::MapConvertibleToString T>
-    std::string to_string(const T& t) {
+    std::string toString(const T& t) {
         std::string s = "{ ";
         for (const auto& [k, v] : t) {
-            s += to_string(k) + ": ";
-            s += to_string(v) + ", ";
+            s += toString(k) + ": ";
+            s += toString(v) + ", ";
         }
         if (s.size() > 2) {
             s.erase(s.size() - 2);
@@ -163,8 +171,8 @@ namespace gz {
      * @brief Construct a string from the element the pointer points at
      */
     template<util::PointerConvertibleToString T>
-    inline std::string to_string(const T& t) {
-        return to_string(*t);        
+    inline std::string toString(const T& t) {
+        return toString(*t);        
     }
 
     /**
@@ -172,10 +180,10 @@ namespace gz {
      * @brief Construct a string from a vector with x, y members
      */
     template<util::Vector2ConvertibleToString T>
-    inline std::string to_string(const T& t) {
+    inline std::string toString(const T& t) {
         std::string s = "( ";
-        s += to_string(t.x) + ", ";
-        s += to_string(t.z) + " )";
+        s += toString(t.x) + ", ";
+        s += toString(t.z) + " )";
         return s;
     }
 
@@ -184,11 +192,11 @@ namespace gz {
      * @brief Construct a string from a vector with x, y members
      */
     template<util::Vector3ConvertibleToString T>
-    inline std::string to_string(const T& t) {
+    inline std::string toString(const T& t) {
         std::string s = "( ";
-        s += to_string(t.x) + ", ";
-        s += to_string(t.y) + ", ";
-        s += to_string(t.z) + " )";
+        s += toString(t.x) + ", ";
+        s += toString(t.y) + ", ";
+        s += toString(t.z) + " )";
         return s;
     }
 
@@ -197,14 +205,23 @@ namespace gz {
      * @brief Construct a string from a vector with x, y, z, w members
      */
     template<util::Vector4ConvertibleToString T>
-    inline std::string to_string(const T& t) {
+    inline std::string toString(const T& t) {
         std::string s = "( ";
-        s += to_string(t.x) + ", ";
-        s += to_string(t.y) + ", ";
-        s += to_string(t.z) + ", ";
-        s += to_string(t.w) + " )";
+        s += toString(t.x) + ", ";
+        s += toString(t.y) + ", ";
+        s += toString(t.z) + ", ";
+        s += toString(t.w) + " )";
         return s;
     }
+
+    /**
+     * @overload
+     * @brief Construct a string from a type that has toString declared in global namespace
+     */
+    template<util::ConvertibleToStringGlobal T>
+    inline std::string toString(const T& t) {
+        return ::toString(t);
+    }
 /**
 * @}
 */
@@ -215,59 +232,50 @@ namespace gz {
 /**
  * @name Construct a type from a string
  * @note 
- *  The from_string()functions (except for the bool one) simply return std::stoXX. These can throw std::invalid_argument and std::out_of_range.
+ *  The fromString()functions (except for the bool one) simply return std::stoXX. These can throw std::invalid_argument and std::out_of_range.
  *  See https://en.cppreference.com/w/cpp/string/basic_string/stol
  */
-    template<typename T>
-    concept GetTypeFromStringImplemented = 
-        std::same_as<T, int> or
-        std::same_as<T, long> or
-        std::same_as<T, long long> or
-        std::same_as<T, unsigned int> or
-        std::same_as<T, unsigned long> or
-        std::same_as<T, unsigned long long> or
-        std::same_as<T, float> or
-        std::same_as<T, double> or
-        std::same_as<T, long double> or
-        std::same_as<T, bool>;
 
-    template<GetTypeFromStringImplemented T>
-    T from_string(const std::string& s);
+    /**
+     * @brief Declaration of fromString, but only for the types for which it is implemented
+     */
+    template<util::GetTypeFromStringImplemented T>
+    T fromString(const std::string& s);
 
     /// @returns std::stoi(s)
-    template<> inline int from_string<int>(const std::string& s) {
+    template<> inline int fromString<int>(const std::string& s) {
         return std::stoi(s);
     }
     /// @returns std::stol(s)
-    template<> inline long from_string<long>(const std::string& s) {
+    template<> inline long fromString<long>(const std::string& s) {
         return std::stol(s);
     }
     /// @returns std::stoll(s)
-    template<> inline long long from_string<long long>(const std::string& s) {
+    template<> inline long long fromString<long long>(const std::string& s) {
         return std::stoll(s);
     }
     /// @returns std::stoul(s)
-    template<> inline unsigned int from_string<unsigned int>(const std::string& s) {
+    template<> inline unsigned int fromString<unsigned int>(const std::string& s) {
         return std::stoul(s);
     }
     /// @returns std::stoul(s)
-    template<> inline unsigned long from_string<unsigned long>(const std::string& s) {
+    template<> inline unsigned long fromString<unsigned long>(const std::string& s) {
         return std::stoul(s);
     }
     /// @returns std::stoull(s)
-    template<> inline unsigned long long from_string<unsigned long long>(const std::string& s) {
+    template<> inline unsigned long long fromString<unsigned long long>(const std::string& s) {
         return std::stoull(s);
     }
     /// @returns std::stof(s)
-    template<> inline float from_string<float>(const std::string& s) {
+    template<> inline float fromString<float>(const std::string& s) {
         return std::stof(s);
     }
     /// @returns std::stod(s)
-    template<> inline double from_string<double>(const std::string& s) {
+    template<> inline double fromString<double>(const std::string& s) {
         return std::stod(s);
     }
     /// @returns std::stold(s)
-    template<> inline long double from_string<long double>(const std::string& s) {
+    template<> inline long double fromString<long double>(const std::string& s) {
         return std::stold(s);
     }
     /**
@@ -277,34 +285,44 @@ namespace gz {
      *  - returns false if s = "false" or "False" or "0"
      *  - throws InvalidArgument otherwise
      */
-    template<> bool from_string<bool>(const std::string& s);
+    template<> bool fromString<bool>(const std::string& s);
+
+    /**
+     * @overload
+     * @brief Construct T from a string using a fromString that is declared in global namespace
+     */
+    template<util::ConstructibleFromStringGlobal T>
+    inline T fromString(const std::string& s) {
+        return ::fromString<T>(s);
+    }
 /**
 * @}
 */
 
-
 //
 // CONCEPTS
 //
     /**
-     * @brief Any type where to_string(t) const exists returns a string-like type
+     * @brief Any type where toString(t) const exists returns a string-like type
      * @note The function only has to exist, it does not have to be noexcept!
      */  
     template<typename T>
-    concept ConvertibleToString = requires(const T& t) { { to_string(t) } -> util::Stringy; };
-    /* concept CovertibleToString = requires(const T& t) { { to_string(t) }; }; */
+    concept ConvertibleToString = requires(const T& t) { 
+        { toString(t) } -> util::Stringy; 
+    };
+    /* concept CovertibleToString = requires(const T& t) { { toString(t) }; }; */
 
     /**
-     * @brief Any type where from_string(string) exists and returns T
+     * @brief Any type where fromString(string) exists and returns T
      * @note The function only has to exist, it does not have to be noexcept!
      */  
     template<typename T>
     concept ConstructibleFromString = requires(const std::string& s) {
-        { from_string<T>(s) } -> std::same_as<T>;
+        { fromString<T>(s) } -> std::same_as<T>;
     };
 
     /**
-     * @brief Any type where to_string(t) and from_string(string) exist
+     * @brief Any type where toString(t) and fromString(string) exist
      */  
     template<typename T>
     concept StringConvertible = ConvertibleToString<T> and ConstructibleFromString<T>;
@@ -328,29 +346,29 @@ namespace gz {
  *  If you want to use your own data type with one of these, 
  *  you can easily @ref sc_overloads "write your own string conversion" function for your custom datatype.
  *  
- * @section sc_to_string Convert to string
- *  You can use the to_string() function to turn certain types into strings.
+ * @section sc_toString Convert to string
+ *  You can use the toString() function to turn certain types into strings.
  *  Concepts are used to determine the correct overload of the function.
  *
  *  The concept ConvertibleToString is satisfied for types that can be converted to string 
- *  using to_string().
+ *  using toString().
  *  
- * @section sc_from_string Construct from string
- *  You can use the from_string() function to create certain types from a string.
+ * @section sc_fromString Construct from string
+ *  You can use the fromString() function to create certain types from a string.
  *
- *  The concept ConstructibleFromString is satisfied for types that can be constructed from a string with from_string().
+ *  The concept ConstructibleFromString is satisfied for types that can be constructed from a string with fromString().
  *
  *  When constructing something from a string, there is of course the problem that errors occur at runtime when
- *  the string is unsuitable for construction. In this case, the from_string functions from this library throw a InvalidArgument exception.
+ *  the string is unsuitable for construction. In this case, the fromString functions from this library throw a InvalidArgument exception.
  *
  * @section sc_overloads Overloading the string conversion functions
- *  @subsection sc_to_string_ov Overload for to_string
+ *  @subsection sc_toString_ov Overload for toString
  *   If you want your custom type to be convertible to string, you have different options.
- *   You can either add an <code>to_string() const</code> member to your class or overload 
- *   <code>std::string to_string(const T&)</code>.
+ *   You can either add an <code>toString() const</code> member to your class or overload 
+ *   <code>std::string toString(const T&)</code>.
  *   Example for a class called <code>Custom</code>
  *   @code
- *    std::string to_string(const Custom& c) {
+ *    std::string toString(const Custom& c) {
  *        std::string s;
  *        ...
  *        return s;
@@ -360,20 +378,20 @@ namespace gz {
  *   so you have to at least declare it in a header file.
  *    
 
- *  @subsection sc_from_string_ov Overload for from_string
- *   Writing an overload for from_string needs a little bit more boiler plate.
- *   Since from_string is a templated function, you need to declare it as such.
+ *  @subsection sc_fromString_ov Overload for fromString
+ *   Writing an overload for fromString needs a little bit more boiler plate.
+ *   Since fromString is a templated function, you need to declare it as such.
  *   The function declaration in this library uses a concept so that it is only
  *   declared for the types that are actully implemented.
  *   Example for a class called <code>Custom</code>
  *   @code
  *    // declare as template, but only for Custom
  *    template<std::same_as<Custom> T>
- *    Custom from_string(const std::string& s);
+ *    Custom fromString(const std::string& s);
  *
  *    // instantiation/definition, but only for Custom
  *    template<>
- *    Custom from_string<Custom>(const std::string& s) {
+ *    Custom fromString<Custom>(const std::string& s) {
  *        ... 
  *        return Custom(...);
  *     };
@@ -384,15 +402,15 @@ namespace gz {
  *   In other words:
  *   @code
  *    Custom c1;
- *    Custom c2 = from_string(to_string(c1));
+ *    Custom c2 = fromString(toString(c1));
  *    assert(c1 == c2);
  *   @endcode
  *
- *   SettingsManager expects the strings from to_string() to be a single line.
+ *   SettingsManager expects the strings from toString() to be a single line.
  *   If it has multiple lines, it will not load it correctly when loading from a file.
  *
- *  @todo Implement from_string for vectors that hold ConstructibleFromString types
- *  @todo Make from_string throw InvalidArgument, write docs
- *  @todo Make macro for all types/concepts where someone would want to implement from_string and to_string explicitly, eg vectors
+ *  @todo Implement fromString for vectors that hold ConstructibleFromString types
+ *  @todo Make fromString throw InvalidArgument, write docs
+ *  @todo Make macro for all types/concepts where someone would want to implement fromString and toString explicitly, eg vectors
  */
 } // namespace gz