From f63675d062156627dc23aa74d51356a7ab77c914 Mon Sep 17 00:00:00 2001
From: Adrian Kummerlaender
Date: Thu, 15 Jan 2015 20:06:41 +0100
Subject: Completed basic math operators and fixed their result type * the
 result type now depends on the `decltype` of the performed operation

---
 src/operation.h | 42 ++++++++++++++++++++++++++++++++++++++++--
 src/type.h      |  9 +++++++++
 test.cc         |  6 ++++--
 3 files changed, 53 insertions(+), 4 deletions(-)

diff --git a/src/operation.h b/src/operation.h
index c906b55..66dbc41 100644
--- a/src/operation.h
+++ b/src/operation.h
@@ -15,7 +15,10 @@ struct add {
 		"only values of the same type may be added"
 	);
 
-	typedef Int<X::value + Y::value> type;
+	typedef std::integral_constant<
+		decltype(X::value + Y::value),
+		X::value + Y::value
+	> type;
 };
 
 template <
@@ -28,7 +31,42 @@ struct substract {
 		"only values of the same type may be substracted"
 	);
 
-	typedef Int<X::value - Y::value> type;
+	typedef std::integral_constant<
+		decltype(X::value - Y::value),
+		X::value - Y::value
+	> type;
+};
+
+template <
+	typename X,
+	typename Y
+>
+struct multiply {
+	static_assert(
+		equal_type<X, Y>::value,
+		"only values of the same type may be multiplied"
+	);
+
+	typedef std::integral_constant<
+		decltype(X::value * Y::value),
+		X::value * Y::value
+	> type;
+};
+
+template <
+	typename X,
+	typename Y
+>
+struct divide {
+	static_assert(
+		equal_type<X, Y>::value,
+		"only values of the same type may be divided"
+	);
+
+	typedef std::integral_constant<
+		decltype(X::value / Y::value),
+		X::value / Y::value
+	> type;
 };
 
 }
diff --git a/src/type.h b/src/type.h
index 1149520..304bff4 100644
--- a/src/type.h
+++ b/src/type.h
@@ -20,6 +20,15 @@ using equal_type = typename std::integral_constant<
 	std::is_same<typename X::value_type, typename Y::value_type>::value
 >::type;
 
+template <
+	typename X,
+	typename Y
+>
+using equal_value = typename std::integral_constant<
+	bool,
+	X::value == Y::value
+>::type;
+
 }
 
 #endif  // TYPEASVALUE_SRC_TYPE_H_
diff --git a/test.cc b/test.cc
index 7f97762..06f0a17 100644
--- a/test.cc
+++ b/test.cc
@@ -10,8 +10,10 @@ TEST_F(TypeAsValueTest, Value) {
 }
 
 TEST_F(TypeAsValueTest, BasicMath) {
-	EXPECT_EQ(3, ( tav::add<tav::Int<1>, tav::Int<2>>::type::value ));
-	EXPECT_EQ(4, ( tav::substract<tav::Int<10>, tav::Int<6>>::type::value ));
+	EXPECT_EQ(3,  ( tav::add<tav::Int<1>, tav::Int<2>>::type::value ));
+	EXPECT_EQ(4,  ( tav::substract<tav::Int<10>, tav::Int<6>>::type::value ));
+	EXPECT_EQ(42, ( tav::multiply<tav::Int<2>, tav::Int<21>>::type::value ));
+	EXPECT_EQ(5, ( tav::divide<tav::Int<10>, tav::Int<2>>::type::value ));
 }
 
 int main(int argc, char **argv) {
-- 
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