Span does runtime checks of bounds (if exist) now

src/lib/container/Span.h

@@ -6,7 +6,14 @@
 
 namespace Container {
 
-    // 0 is unchecked
+/**
+ * This class implements a readonly view on a memory region of uniform type.
+ * The Span can be initialized wihout size checking by supplying 0 as size
+ * and using the one-argument constructor. Then iterators become invalid.
+ *
+ * @tparam T The type of the objects located in the memory region
+ * @tparam N The size of the memory region
+ */
 template<typename T, std::size_t N = 0>
 class Span {
 public:
@@ -17,33 +24,40 @@ namespace Container {
     const std::size_t sz = N;
 
 public:
-        Span() = default;
+    Span() = delete;
 
-        Span(T* first) : ptr(first) {}
+    explicit Span(T *first) : ptr(first) {}
 
     Span(T *first, T *last) : ptr(first), sz(last - first) {}
 
+    // TODO: Rest of constructors
+
     iterator begin() { return iterator(ptr); }
+
     iterator begin() const { return iterator(ptr); }
+
     // If size is unchecked end() is equal to begin()
-        iterator end() { return iterator(&ptr[N]); }
+    iterator end() { return iterator(&ptr[sz]); }
-        iterator end() const { return iterator(&ptr[N]); }
+
+    // If size is unchecked end() is equal to begin()
+    iterator end() const { return iterator(&ptr[sz]); }
 
     T *operator[](std::size_t i) {
-            if constexpr (N != 0) {
+        if (sz != 0) {
-                if (i < 0 || i >= N) { return nullptr; }
+            if (i >= sz) { return nullptr; }
         }
         return &ptr[i];
     }
 
     T *operator[](std::size_t i) const {
-            if constexpr (N != 0) {
+        if (sz != 0) {
-                if (i < 0 || i >= N) { return nullptr; }
+            if (i >= sz) { return nullptr; }
         }
         return &ptr[i];
     }
 
     T *data() { return ptr; }
+
     const T *data() const { return ptr; }
 
     explicit operator T *() {
@@ -51,11 +65,11 @@ namespace Container {
     }
 
     // First is inclusive, last exclusive [first, last)
-        Span& subspan(std::size_t first, std::size_t last = N) {
+    Span &subspan(std::size_t first, std::size_t last) {
         return Span(ptr + first, ptr + last - 1);
     }
 
-        std::size_t size() const {
+    [[nodiscard]] std::size_t size() const {
         return sz;
     }
 };