Availability Attribute additions and clean-up. (#6)

* Added one more availability attribute - the Unavailable attribute for indicating runtime operating systems that might not support a particular API. 
* Updated version parsing code to use a regular expressions; some Unity builds were not deducing overloads of String.Split correctly.
* Small fixes to prevent bad input and addressing of typos.

plug-ins/Apple.Core/Apple.Core_Unity/Assets/Apple.Core/Runtime/AvailabilityAttributes.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 
 namespace Apple.Core
 {
@@ -11,25 +12,46 @@ namespace Apple.Core
     public class IntroducedAttribute : Attribute
     {
         // Access by property
-        public RuntimeVersion? iOS { get => _osVersionNumbers[(int)RuntimeOperatingSystem.iOS]; }
-        public RuntimeVersion? macOS { get => _osVersionNumbers[(int)RuntimeOperatingSystem.macOS]; }
-        public RuntimeVersion? tvOS { get => _osVersionNumbers[(int)RuntimeOperatingSystem.tvOS]; }
+        public RuntimeVersion? iOS { get => _osVersions[RuntimeOperatingSystem.iOS]; }
+        public RuntimeVersion? macOS { get => _osVersions[RuntimeOperatingSystem.macOS]; }
+        public RuntimeVersion? tvOS { get => _osVersions[RuntimeOperatingSystem.tvOS]; }
 
         // Access by OperatingSystem
         public RuntimeVersion? OperatingSystemVersion(RuntimeOperatingSystem operatingSystem)
         {
-            return _osVersionNumbers[(int)operatingSystem];
+            if (!Enum.IsDefined(typeof(RuntimeOperatingSystem), operatingSystem) || (operatingSystem == RuntimeOperatingSystem.Unknown) || (operatingSystem == RuntimeOperatingSystem.RuntimeOperatingSystemCount))
+            {
+                return null;
+            }
+
+            return _osVersions[operatingSystem];
         }
 
-        protected RuntimeVersion?[] _osVersionNumbers;
+        protected SortedList<RuntimeOperatingSystem, RuntimeVersion?> _osVersions;
 
         public IntroducedAttribute(string iOS = "", string macOS = "", string tvOS = "")
         {
-            _osVersionNumbers = new RuntimeVersion?[(int)RuntimeOperatingSystem.RuntimeOperatingSystemCount];
+            _osVersions = new SortedList<RuntimeOperatingSystem, RuntimeVersion?>();
 
-            _osVersionNumbers[(int)RuntimeOperatingSystem.iOS] = RuntimeVersion.FromString(iOS);
-            _osVersionNumbers[(int)RuntimeOperatingSystem.macOS] = RuntimeVersion.FromString(macOS);
-            _osVersionNumbers[(int)RuntimeOperatingSystem.tvOS] = RuntimeVersion.FromString(tvOS);
+            _osVersions[RuntimeOperatingSystem.iOS] = RuntimeVersion.FromString(iOS);
+            _osVersions[RuntimeOperatingSystem.macOS] = RuntimeVersion.FromString(macOS);
+            _osVersions[RuntimeOperatingSystem.tvOS] = RuntimeVersion.FromString(tvOS);
+        }
+    }
+
+    /// <summary>
+    /// UnavailableAttribute is used to indicate operating systems for which an API is *not* available.
+    /// Example: [Apple.Core.Unavailable(RuntimeOperatingSystem.tvOS)] means that a given API is not available for tvOS, but is available for all other supported OSes.
+    /// </summary>
+    [System.AttributeUsage(System.AttributeTargets.All)]
+    public class UnavailableAttribute : Attribute
+    {
+        public RuntimeOperatingSystem[] UnavailableOperatingSystems { get; protected set; }
+
+        public UnavailableAttribute(params RuntimeOperatingSystem[] unavailableOperatingSystems)
+        {
+            UnavailableOperatingSystems = new RuntimeOperatingSystem[unavailableOperatingSystems.Length];
+            unavailableOperatingSystems.CopyTo(UnavailableOperatingSystems, 0);
         }
     }
 

plug-ins/Apple.Core/Apple.Core_Unity/Assets/Apple.Core/Runtime/RuntimeEnvironment.cs

@@ -1,5 +1,7 @@
 using System;
 using System.Runtime.InteropServices;
+using System.Text.RegularExpressions;
+using UnityEngine;
 
 namespace Apple.Core
 {
@@ -26,8 +28,10 @@ public RuntimeVersion(int major, int minor)
             Minor = minor;
         }
 
-        public override string ToString() => $"{Major}.{Minor}";
+        public override string ToString() => (Minor == 0) ? $"{Major}" : $"{Major}.{Minor}";
 
+        static readonly Regex _versionStringFormat = new Regex(@"^((?:\d+)(?:\.\d+)?)$");
+
         /// <summary>
         /// Accepted string formats are "Major.Minor" or "Major" where Major and Minor are represented by integer values.
         ///   Minor value is assumed to be 0 when no Minor value is provided in the format string.
@@ -44,39 +48,35 @@ public RuntimeVersion(int major, int minor)
                 return null;
             }
 
-            string[] vStrings = versionString.Split('.', 3);
-
-            // String provided in the format: "Major.Minor"
-            if (vStrings.Length >= 2)
+            // Ensure strings are formatted as "Major.Minor" or "Major" where Major and Minor are strings of numbers, e.g. "12.5" or "14"
+            if (_versionStringFormat.IsMatch(versionString))
             {
                 int major = 0, minor = 0;
 
-                if (Int32.TryParse(vStrings[0], out major) && Int32.TryParse(vStrings[1], out minor))
-                {
-                    return new RuntimeVersion(major, minor);
-                }
-                else
-                {
-                    return null;
-                }
-            }
-            // String provided in the format: "Major"
-            else if (vStrings.Length == 1)
-            {
-                int major = 0;
-
-                if (Int32.TryParse(vStrings[0], out major))
+                // Get first string of numerals and try to parse
+                Match currMatch = Regex.Match(versionString, @"\d+");
+                if (currMatch.Success && Int32.TryParse(currMatch.Value, out major))
                 {
-                    return new RuntimeVersion(major, 0);
+                    // Get the string of numerals, if they exist, and try to parse
+                    currMatch = currMatch.NextMatch();
+                    if (currMatch.Success && Int32.TryParse(currMatch.Value, out minor))
+                    {
+                        return new RuntimeVersion(major, minor);
+                    }
+                    else
+                    {
+                        return new RuntimeVersion(major, 0);
+                    }
                 }
                 else
                 {
+                    Debug.Log($"[Apple.Core Plug-In] RuntimeEnvironment failed to parse \"{currMatch.Value}\" as Int32.");
                     return null;
                 }
             }
-            // Unsupported formatting.
-            else
+            else 
             {
+                Debug.Log($"[Apple.Core Plug-In] RuntimeEnvironment failed to recognize \"{versionString}\" as a valid version string.");
                 return null;
             }
         }