Merge pull request #225 from WildernessLabs/feature/PinDefinitionBase

pushed common code to PinDefinitionBase

Source/Meadow.Contracts/Hardware/PinDefinitionBase.cs

@@ -1,6 +1,7 @@
 using Meadow.Hardware;
 using System.Collections;
 using System.Collections.Generic;
+using System.Linq;
 
 namespace Meadow;
 
@@ -9,14 +10,64 @@ namespace Meadow;
 /// </summary>
 public abstract class PinDefinitionBase : IPinDefinitions
 {
-    private readonly List<IPin> _pins = new();
+    private List<IPin>? _pins;
+
     /// <inheritdoc/>
-    public IList<IPin> AllPins => _pins;
+    public virtual IList<IPin> AllPins
+    {
+        // lazy load
+        get => _pins ??= DiscoverAllPinsViaReflection();
+    }
 
     /// <inheritdoc/>
     public IPinController? Controller { get; set; }
 
+    /// <summary>
+    /// Retrieves a pin from <see cref="AllPins"/> by Name or Key
+    /// </summary>
+    public IPin this[string name]
+    {
+        get => AllPins.FirstOrDefault(p =>
+            string.Compare(p.Name, name, true) == 0
+            || string.Compare($"{p.Key}", name, true) == 0)
+            ?? throw new KeyNotFoundException();
+    }
+
+    /// <summary>
+    /// Creates a PinDefinitionBase
+    /// </summary>
+    protected PinDefinitionBase()
+    {
+    }
+
+    /// <summary>
+    /// Uses reflection to discover all IPin properties
+    /// </summary>
+    private List<IPin> DiscoverAllPinsViaReflection()
+    {
+        var list = new List<IPin>();
+
+        foreach (var prop in this.GetType()
+            .GetProperties(
+                System.Reflection.BindingFlags.Instance |
+                System.Reflection.BindingFlags.Public)
+            .Where(p => p.CanRead && p.GetIndexParameters().Length == 0 && p.PropertyType == typeof(IPin))
+            )
+        {
+            var pin = prop.GetValue(this) as IPin;
+
+            if (pin != null)
+            {
+                if (!list.Any(p => p.Name == pin.Name))
+                {
+                    list.Add(pin);
+                }
+            }
+        }
+        return list;
+    }
+
     /// <inheritdoc/>
-    public IEnumerator<IPin> GetEnumerator() => _pins.GetEnumerator();
+    public IEnumerator<IPin> GetEnumerator() => AllPins.GetEnumerator();
     IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
 }