From: Mikko Rasa <tdb@tdb.fi>
Date: Sun, 2 Jun 2019 12:28:34 +0000 (+0300)
Subject: Improve Vector constructor for C++11
X-Git-Url: http://git.tdb.fi/?p=libs%2Fmath.git;a=commitdiff_plain;h=0a8781509bafe347b9c32f1106891eac18354965

Improve Vector constructor for C++11

The new overload allows vectors of any size to be constructed by passing
the component values as constructor arguments.
---

diff --git a/source/linal/vector.h b/source/linal/vector.h
index 767cc88..31597d4 100644
--- a/source/linal/vector.h
+++ b/source/linal/vector.h
@@ -84,9 +84,14 @@ public:
 	use by Matrix row accessor. */
 	Vector(const T *, unsigned);
 
+#if __cplusplus >= 201103L
+	template<typename... Args>
+	Vector(T, Args...);
+#else
 	Vector(T, T);
 	Vector(T, T, T);
 	Vector(T, T, T, T);
+#endif
 	template<typename U>
 	Vector(const Vector<U, N> &);
 
@@ -126,6 +131,18 @@ inline Vector<T, N>::Vector(const T *d, unsigned stride)
 		(*this)[i] = d[i*stride];
 }
 
+#if __cplusplus >= 201103L
+template<typename T, unsigned N>
+template<typename... Args>
+inline Vector<T, N>::Vector(T x_, Args... v)
+{
+	static_assert(1+sizeof...(v)==N, "Incorrect number of arguments in Vector constructor");
+	(*this)[0] = x_;
+	unsigned i = 1;
+	for(auto c: std::initializer_list<T> { static_cast<T>(v)... })
+		(*this)[i++] = c;
+}
+#else
 /* The compiler won't instantiate these unless they are used.  Trying to use
 them on the wrong class results in an error. */
 template<typename T, unsigned N>
@@ -151,6 +168,7 @@ inline Vector<T, N>::Vector(T x_, T y_, T z_, T w_)
 	this->VectorComponents<T, 4>::z = z_;
 	this->VectorComponents<T, 4>::w = w_;
 }
+#endif
 
 template<typename T, unsigned N>
 template<typename U>
diff --git a/tests/vector.cpp b/tests/vector.cpp
index 14aea87..cf07329 100644
--- a/tests/vector.cpp
+++ b/tests/vector.cpp
@@ -18,6 +18,7 @@ public:
 	static const char *get_name() { return "Vector"; }
 
 private:
+	void constructors();
 	void component_aliases();
 	void composition();
 	void slice();
@@ -30,6 +31,7 @@ private:
 
 VectorTests::VectorTests()
 {
+	add(&VectorTests::constructors, "Constructors");
 	add(&VectorTests::component_aliases, "Component aliases");
 	add(&VectorTests::composition, "Compose");
 	add(&VectorTests::slice, "Slice");
@@ -40,6 +42,29 @@ VectorTests::VectorTests()
 	add(&VectorTests::unit_vec, "Normalize");
 }
 
+void VectorTests::constructors()
+{
+	static int data[] = { 1, 2, 3 };
+
+	Vector2i v1(1, 2);
+	EXPECT_EQUAL(v1[0], 1);
+	EXPECT_EQUAL(v1[1], 2);
+
+	Vector3i v2(data);
+	EXPECT_EQUAL(v2[0], 1);
+	EXPECT_EQUAL(v2[1], 2);
+	EXPECT_EQUAL(v2[2], 3);
+
+#if __cplusplus >= 201103L
+	LinAl::Vector<int, 1> v3(1);
+	EXPECT_EQUAL(v3[0], 1);
+
+	LinAl::Vector<int, 5> v4(1, 2, 3, 4, 5);
+	EXPECT_EQUAL(v4[0], 1);
+	EXPECT_EQUAL(v4[4], 5);
+#endif
+}
+
 void VectorTests::component_aliases()
 {
 	Vector3i v;