From ddd49af722a6d3dc7661c1ced6e0ee124c8b28f0 Mon Sep 17 00:00:00 2001
From: Xiaobaibai <824395314@qq.com>
Date: Fri, 14 Jun 2019 02:43:02 +0800
Subject: [PATCH] updated magical ExpressionBuilder (compile-time codegen)

---
 dlls/weapons/ExpressionBuilder.hpp  | 77 +++++++++++++++++++----------
 dlls/weapons/WeaponDataVaribles.hpp | 12 +++--
 2 files changed, 59 insertions(+), 30 deletions(-)

diff --git a/dlls/weapons/ExpressionBuilder.hpp b/dlls/weapons/ExpressionBuilder.hpp
index ec9c3d15d..6a093760d 100644
--- a/dlls/weapons/ExpressionBuilder.hpp
+++ b/dlls/weapons/ExpressionBuilder.hpp
@@ -29,15 +29,26 @@ namespace ExpressionBuilder
 			const UnderlyingType c;
 			constexpr explicit ConstantType(UnderlyingType a) : c(a) {}
 			template<class T>
-			constexpr UnderlyingType operator()(T x) const
+			constexpr ConstantType<UnderlyingType> operator()(T x) const
 			{
-				return c;
+				return ConstantType<UnderlyingType>(c); // *this
 			}
 			constexpr operator UnderlyingType() const { return c; }
 		};
 
+		template<class T>
+		constexpr auto varcon(T x) -> typename std::enable_if<!IsExpression<T>::value, ConstantType<T>>::type
+		{
+			return ConstantType<T>(x);
+		}
+		template<class T>
+		constexpr auto varcon(T x) -> typename std::enable_if<IsExpression<T>::value, T>::type
+		{
+			return x;
+		}
+
 		template<class Varible, class Constant>
-		struct BindedType
+		struct BindedType : Expression
 		{
 			const Varible var;
 			const Constant con;
@@ -46,29 +57,29 @@ namespace ExpressionBuilder
 			template<class T>
 			constexpr auto operator()(T x) const -> BindedType<Varible, Constant>
 			{
-				return BindedType<Varible, Constant>(var, con);
+				return BindedType<Varible, Constant>(var.template operator()(x), con.template operator()(x));
 			}
 		};
 
-		template<char Name>
+		template<class IdentifierName>
 		struct VaribleType : Expression
 		{
-			template<class UnderlyingType>
-			constexpr auto operator=(UnderlyingType c) const -> BindedType<VaribleType<Name>, ConstantType<UnderlyingType>>
+			template<class T>
+			constexpr auto operator=(T c) const -> BindedType<VaribleType<IdentifierName>, decltype(varcon(c))>
 			{
-				return BindedType<VaribleType<Name>, ConstantType<UnderlyingType>>(VaribleType<Name>(), ConstantType<UnderlyingType>(c));
+				return BindedType<VaribleType<IdentifierName>, decltype(varcon(c))>(VaribleType<IdentifierName>(), varcon(c));
 			}
 
-			template<class UnderlyingType>
-			constexpr auto operator()(BindedType<VaribleType<Name>, ConstantType<UnderlyingType>> x) const -> UnderlyingType
+			template<class T>
+			constexpr auto operator()(BindedType<VaribleType<IdentifierName>, T> x) const -> decltype(x.con(x))
 			{
-				return x.con.c;
+				return x.con(x);
 			}
 
 			template<class T>
-			constexpr auto operator()(T x) const -> VaribleType<Name>
+			constexpr auto operator()(T x) const -> VaribleType<IdentifierName>
 			{
-				return VaribleType<Name>();
+				return VaribleType<IdentifierName>(); // *this
 			}
 		};
 
@@ -80,17 +91,6 @@ namespace ExpressionBuilder
 			constexpr BinaryOperator(Exp1 a, Exp2 b) : _1(a), _2(b) {}
 		};
 
-		template<class T>
-		constexpr auto varcon(T x) -> typename std::enable_if<!IsExpression<T>::value, ConstantType<T>>::type
-		{
-			return ConstantType<T>(x);
-		}
-		template<class T>
-		constexpr auto varcon(T x) -> typename std::enable_if<IsExpression<T>::value, T>::type
-		{
-			return x;
-		}
-
 		template<class Exp1, class Exp2>
 		struct OperatorPlus_t : BinaryOperator<Exp1, Exp2>
 		{
@@ -134,25 +134,48 @@ namespace ExpressionBuilder
 		{
 			return OperatorPlus_t<decltype(varcon(_1)), decltype(varcon(_2))>(varcon(_1), varcon(_2));
 		}
+		template<class T1, class T2>
+		constexpr auto operator+(ConstantType<T1> _1, ConstantType<T2> _2) -> ConstantType<decltype(_1.c + _2.c)>
+		{
+			return ConstantType<decltype(_1.c + _2.c)>(_1.c + _2.c);
+		}
 		template<class Exp1, class Exp2, class = typename std::enable_if<IsExpression<Exp1>::value || IsExpression<Exp2>::value>::type>
 		constexpr auto operator-(Exp1 _1, Exp2 _2) -> OperatorMinus_t<decltype(varcon(_1)), decltype(varcon(_2))>
 		{
 			return OperatorMinus_t<decltype(varcon(_1)), decltype(varcon(_2))>(varcon(_1), varcon(_2));
 		}
+		template<class T1, class T2>
+		constexpr auto operator-(ConstantType<T1> _1, ConstantType<T2> _2) -> ConstantType<decltype(_1.c - _2.c)>
+		{
+			return ConstantType<decltype(_1.c - _2.c)>(_1.c - _2.c);
+		}
 		template<class Exp1, class Exp2, class = typename std::enable_if<IsExpression<Exp1>::value || IsExpression<Exp2>::value>::type>
 		constexpr auto operator*(Exp1 _1, Exp2 _2) -> OperatorMul_t<decltype(varcon(_1)), decltype(varcon(_2))>
 		{
 			return OperatorMul_t<decltype(varcon(_1)), decltype(varcon(_2))>(varcon(_1), varcon(_2));
 		}
+		template<class T1, class T2>
+		constexpr auto operator*(ConstantType<T1> _1, ConstantType<T2> _2) -> ConstantType<decltype(_1.c * _2.c)>
+		{
+			return ConstantType<decltype(_1.c * _2.c)>(_1.c * _2.c);
+		}
 		template<class Exp1, class Exp2, class = typename std::enable_if<IsExpression<Exp1>::value || IsExpression<Exp2>::value>::type>
 		constexpr auto operator/(Exp1 _1, Exp2 _2) -> OperatorDiv_t<decltype(varcon(_1)), decltype(varcon(_2))>
 		{
 			return OperatorDiv_t<decltype(varcon(_1)), decltype(varcon(_2))>(varcon(_1), varcon(_2));
 		}
+		template<class T1, class T2>
+		constexpr auto operator/(ConstantType<T1> _1, ConstantType<T2> _2) -> ConstantType<decltype(_1.c / _2.c)>
+		{
+			return ConstantType<decltype(_1.c / _2.c)>(_1.c / _2.c);
+		}
+		class x_id;
+		class y_id;
+		class z_id;
 	}
 
 	using detail::VaribleType;
-	constexpr const detail::VaribleType<'x'> x{};
-	constexpr const detail::VaribleType<'y'> y{};
-	constexpr const detail::VaribleType<'z'> z{};
+	constexpr const detail::VaribleType<detail::x_id> x{};
+	constexpr const detail::VaribleType<detail::y_id> y{};
+	constexpr const detail::VaribleType<detail::z_id> z{};
 }
diff --git a/dlls/weapons/WeaponDataVaribles.hpp b/dlls/weapons/WeaponDataVaribles.hpp
index a3d32e20e..c14d0aa8b 100644
--- a/dlls/weapons/WeaponDataVaribles.hpp
+++ b/dlls/weapons/WeaponDataVaribles.hpp
@@ -18,8 +18,14 @@ GNU General Public License for more details.
 namespace WeaponTemplate {
 	namespace Varibles
 	{
-		constexpr auto A = ExpressionBuilder::VaribleType<'A'>{};
-		constexpr auto T = ExpressionBuilder::VaribleType<'T'>{};
-		constexpr auto N = ExpressionBuilder::VaribleType<'N'>{};
+		namespace detail
+		{
+			class id_A;
+			class id_T;
+			class id_N;
+		}
+		constexpr auto A = ExpressionBuilder::VaribleType<detail::id_A>{};
+		constexpr auto T = ExpressionBuilder::VaribleType<detail::id_T>{};
+		constexpr auto N = ExpressionBuilder::VaribleType<detail::id_N>{};
 	}
 }