Add interval template

Signed-off-by: Simon Rozman <simon@rozman.si>

include/stdex/interval.h

@@ -0,0 +1,55 @@
+/*
+    SPDX-License-Identifier: MIT
+    Copyright © 2023 Amebis
+*/
+
+#pragma once
+
+#include "sal.h"
+
+namespace stdex
+{
+    ///
+    /// Numerical interval
+    ///
+    template <class T>
+    struct interval
+    {
+        T start; ///< interval start
+        T end;   ///< interval end
+
+        ///
+        /// Constructs an invalid interval
+        ///
+        inline interval() noexcept : start(1), end(0) {}
+
+        ///
+        /// Constructs a zero-size interval
+        ///
+        /// \param[in] x  Interval start and end value
+        ///
+        inline interval(_In_ T x) noexcept : start(x), end(x) {}
+
+        ///
+        /// Constructs an interval
+        ///
+        /// \param[in] _start  Interval start value
+        /// \param[in] _end    Interval end value
+        ///
+        inline interval(_In_ T _start, _In_ T _end) noexcept : start(_start), end(_end) {}
+
+        ///
+        /// Returns interval size
+        ///
+        /// \returns Interval size or 0 if interval is invalid
+        ///
+        inline T size() const { return start <= end ? end - start : 0; }
+
+        ///
+        /// Is interval valid?
+        ///
+        /// \returns true if interval is valid or false otherwise
+        ///
+        inline operator bool() const { return start <= end; }
+    };
+}