Math: minmax() for a pointer range.

Thanks @Squareys for unblocking my brain!

src/Magnum/Math/Functions.h

@@ -332,6 +332,39 @@ template<std::size_t size, class T> std::pair<Vector<size, T>, Vector<size, T>>
 }
 #endif
 
+namespace Implementation {
+    template<class T> inline typename std::enable_if<std::is_arithmetic<T>::value, void>::type minmax(T& min, T& max, T value) {
+        if(value < min)
+            min = value;
+        else if(value > max)
+            max = value;
+    }
+    template<std::size_t size, class T> inline void minmax(Vector<size, T>& min, Vector<size, T>& max, const Vector<size, T>& value) {
+        for(std::size_t i = 0; i != size; ++i)
+            minmax(min[i], max[i], value[i]);
+    }
+}
+
+/**
+@brief Minimum and maximum of a range
+
+If the range is empty, returns default-constructed values.
+*/
+template<class T> std::pair<T, T> minmax(Corrade::Containers::ArrayView<const T> range) {
+    if(range.empty()) return {};
+
+    T min{range[0]}, max{range[0]};
+    for(std::size_t i = 1; i != range.size(); ++i)
+        Implementation::minmax(min, max, range[i]);
+
+    return {min, max};
+}
+
+/** @overload */
+template<class T> inline std::pair<T, T> minmax(std::initializer_list<T> list) {
+    return minmax(Corrade::Containers::ArrayView<const T>{list.begin(), list.size()});
+}
+
 /**
 @brief Clamp value
 

src/Magnum/Math/Test/FunctionsTest.cpp

@@ -42,6 +42,7 @@ struct FunctionsTest: Corrade::TestSuite::Tester {
     void max();
     void maxList();
     void minmax();
+    void minmaxList();
     void clamp();
     void nanPropagation();
 
@@ -86,6 +87,7 @@ FunctionsTest::FunctionsTest() {
               &FunctionsTest::max,
               &FunctionsTest::maxList,
               &FunctionsTest::minmax,
+              &FunctionsTest::minmaxList,
               &FunctionsTest::clamp,
               &FunctionsTest::nanPropagation,
 
@@ -171,6 +173,24 @@ void FunctionsTest::minmax() {
     CORRADE_COMPARE_AS(Math::minmax(b, a), expectedVector, std::pair<Vector3, Vector3>);
 }
 
+void FunctionsTest::minmaxList() {
+    const auto expected = std::make_pair(-3.0f, 2.0f);
+    CORRADE_COMPARE(Math::minmax({-1.0f, 2.0f, -3.0f}), expected);
+    CORRADE_COMPARE(Math::minmax({-1.0f, -3.0f, 2.0f}), expected);
+    CORRADE_COMPARE(Math::minmax({2.0f, -1.0f, -3.0f}), expected);
+    CORRADE_COMPARE(Math::minmax({2.0f, -3.0f, -1.0f}), expected);
+    CORRADE_COMPARE(Math::minmax({-3.0f, 2.0f, -1.0f}), expected);
+    CORRADE_COMPARE(Math::minmax({-3.0f, -1.0f, 2.0f}), expected);
+
+    const std::pair<Vector2, Vector2> expectedVec{Vector2{-3.0f, -2.0f}, Vector2{2.0f, 3.0f}};
+    CORRADE_COMPARE(Math::minmax({Vector2{-1.0f, 3.0f}, Vector2{2.0f, 1.0f}, Vector2{-3.0f, -2.0f}}), expectedVec);
+    CORRADE_COMPARE(Math::minmax({Vector2{-1.0f, 1.0f}, Vector2{-3.0f, 3.0f}, Vector2{2.0f, -2.0f}}), expectedVec);
+    CORRADE_COMPARE(Math::minmax({Vector2{2.0f, -2.0f}, Vector2{-1.0f, 1.0f}, Vector2{-3.0f, 3.0f}}), expectedVec);
+    CORRADE_COMPARE(Math::minmax({Vector2{2.0f, 1.0f}, Vector2{-3.0f, -2.0f}, Vector2{-1.0f, 3.0f}}), expectedVec);
+    CORRADE_COMPARE(Math::minmax({Vector2{-3.0f, 3.0f}, Vector2{2.0f, -2.0f}, Vector2{-1.0f, 1.0f}}), expectedVec);
+    CORRADE_COMPARE(Math::minmax({Vector2{-3.0f, -2.0f}, Vector2{-1.0f, 3.0f}, Vector2{2.0f, 1.0f}}), expectedVec);
+}
+
 void FunctionsTest::clamp() {
     CORRADE_COMPARE(Math::clamp(0.5f, -1.0f, 5.0f), 0.5f);
     CORRADE_COMPARE(Math::clamp(-1.6f, -1.0f, 5.0f), -1.0f);