From e38294a62d7f37c0661273a9a26fda16d557423f Mon Sep 17 00:00:00 2001
From: Jon Skeet <skeet@pobox.com>
Date: Tue, 9 Jun 2015 19:30:44 +0100
Subject: First pass at the mutable API. Quite a bit more to do - in
 particular, it's pretty slow right now.

---
 .../FieldAccess/SingleFieldAccessor.cs             | 89 ++++++++++++++++++++++
 1 file changed, 89 insertions(+)
 create mode 100644 csharp/src/ProtocolBuffers/FieldAccess/SingleFieldAccessor.cs

(limited to 'csharp/src/ProtocolBuffers/FieldAccess/SingleFieldAccessor.cs')

diff --git a/csharp/src/ProtocolBuffers/FieldAccess/SingleFieldAccessor.cs b/csharp/src/ProtocolBuffers/FieldAccess/SingleFieldAccessor.cs
new file mode 100644
index 00000000..a352d3a2
--- /dev/null
+++ b/csharp/src/ProtocolBuffers/FieldAccess/SingleFieldAccessor.cs
@@ -0,0 +1,89 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+using System.Text;
+using Google.Protobuf;
+using Google.Protobuf.Descriptors;
+using Google.Protobuf.FieldAccess;
+
+namespace Google.Protobuf.FieldAccess
+{
+    /// <summary>
+    /// Accessor for single fields.
+    /// </summary>
+    /// <typeparam name="T">The type of message containing the field.</typeparam>
+    internal sealed class SingleFieldAccessor<T> : FieldAccessorBase<T> where T : IMessage<T>
+    {
+        // All the work here is actually done in the constructor - it creates the appropriate delegates.
+        // There are various cases to consider, based on the property type (message, string/bytes, or "genuine" primitive)
+        // and proto2 vs proto3 for non-message types, as proto3 doesn't support "full" presence detection or default
+        // values.
+
+        private readonly Action<T, object> setValueDelegate;
+        private readonly Action<T> clearDelegate;
+        private readonly Func<T, bool> hasValueDelegate;
+
+        internal SingleFieldAccessor(FieldDescriptor descriptor, string name, bool supportsFieldPresence) : base(name)
+        {
+            PropertyInfo property = typeof(T).GetProperty(name);
+            // We know there *is* such a property, or the base class constructor would have thrown. We should be able to write
+            // to it though.
+            if (!property.CanWrite)
+            {
+                throw new ArgumentException("Not all required properties/methods available");
+            }
+            setValueDelegate = ReflectionUtil.CreateDowncastDelegate<T>(property.GetSetMethod());
+
+            var clrType = property.PropertyType;
+
+            if (typeof(IMessage).IsAssignableFrom(clrType))
+            {
+                // Message types are simple - we only need to detect nullity.
+                clearDelegate = message => SetValue(message, null);
+                hasValueDelegate = message => GetValue(message) == null;
+            }
+
+            if (supportsFieldPresence)
+            {
+                // Proto2: we expect a HasFoo property and a ClearFoo method.
+                // For strings and byte arrays, setting the property to null would have the equivalent effect,
+                // but we generate the method for consistency, which makes this simpler.
+                PropertyInfo hasProperty = typeof(T).GetProperty("Has" + name);
+                MethodInfo clearMethod = typeof(T).GetMethod("Clear" + name);
+                if (hasProperty == null || clearMethod == null || !hasProperty.CanRead)
+                {
+                    throw new ArgumentException("Not all required properties/methods available");
+                }
+                hasValueDelegate = ReflectionUtil.CreateDelegateFunc<T, bool>(hasProperty.GetGetMethod());
+                clearDelegate = ReflectionUtil.CreateDelegateAction<T>(clearMethod);
+            }
+            else
+            {
+                /*
+                // TODO(jonskeet): Reimplement. We need a better way of working out default values.
+                // Proto3: for field detection, we just need the default value of the field (0, "", byte[0] etc)
+                // To clear a field, we set the value to that default.
+                object defaultValue = descriptor.DefaultValue;
+                hasValueDelegate = message => GetValue(message).Equals(defaultValue);
+                clearDelegate = message => SetValue(message, defaultValue);
+                */
+            }
+        }
+
+        public override bool HasValue(T message)
+        {
+            return hasValueDelegate(message);
+        }
+
+        public override void Clear(T message)
+        {
+            clearDelegate(message);
+        }
+
+        public override void SetValue(T message, object value)
+        {
+            setValueDelegate(message, value);
+        }
+    }
+}
-- 
cgit v1.2.3