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richardjrossiiirichardjrossiii
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Decoupled ParseObject subclassing
Similar to the subclassing architecture used on iOS, this abstracts and cleans up all of the code relating to subclassing that currently resides inside of ParseObject.
1 parent 24b213e commit e7caf82

20 files changed

+450
-317
lines changed

‎Parse/Compat/Tuple.cs‎

100644100755
Lines changed: 5 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -4,7 +4,11 @@
44
using System.Text;
55

66
namespace System {
7-
internal static class Tuple {
7+
internal static class Tuple {
8+
// This is useful because it allows for type inference, which normally cannot be done with constructors, but can be done for static methods.
9+
public static Tuple<T1, T2> Create<T1, T2>(T1 t1, T2 t2) {
10+
return new Tuple<T1, T2>(t1, t2);
11+
}
812
}
913

1014
internal class Tuple<T1, T2> {

‎Parse/Compat/Type.cs‎

Lines changed: 18 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,18 @@
1+
using System;
2+
3+
namespace System {
4+
/// <summary>
5+
/// Unity does not have an API for GetTypeInfo(), instead they expose most of the methods
6+
/// on System.Reflection.TypeInfo on the type itself. This poses a problem for compatibility
7+
/// with the rest of the C# world, as we expect the result of GetTypeInfo() to be an actual TypeInfo,
8+
/// as well as be able to be converted back to a type using AsType().
9+
///
10+
/// This class simply implements some of the simple missing methods on Type to make it as API-compatible
11+
/// as possible to TypeInfo.
12+
/// </summary>
13+
internal static class TypeExtensions {
14+
public static Type AsType(this Type type) {
15+
return type;
16+
}
17+
}
18+
}

‎Parse/Internal/Object/Subclassing/IObjectSubclassingController.cs‎

Lines changed: 20 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,20 @@
1+
using System;
2+
using System.Collections.Generic;
3+
using System.Linq;
4+
using System.Text;
5+
using System.Threading.Tasks;
6+
7+
namespace Parse.Internal {
8+
internal interface IObjectSubclassingController {
9+
String GetClassName(Type type);
10+
Type GetType(String className);
11+
12+
bool IsTypeValid(String className, Type type);
13+
14+
void RegisterSubclass(Type t);
15+
void UnregisterSubclass(Type t);
16+
17+
ParseObject Instantiate(String className);
18+
IDictionary<String, String> GetPropertyMappings(String className);
19+
}
20+
}

‎Parse/Internal/Object/Subclassing/ObjectSubclassInfo.cs‎

Lines changed: 40 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,40 @@
1+
using System;
2+
using System.Collections.Generic;
3+
using System.Linq;
4+
using System.Text;
5+
using System.Threading;
6+
using System.Threading.Tasks;
7+
using System.Reflection;
8+
9+
#if UNITY
10+
using TypeInfo = System.Type;
11+
#endif
12+
13+
namespace Parse.Internal {
14+
internal class ObjectSubclassInfo {
15+
public ObjectSubclassInfo(Type type, ConstructorInfo constructor) {
16+
TypeInfo = type.GetTypeInfo();
17+
ClassName = GetClassName(TypeInfo);
18+
Constructor = constructor;
19+
PropertyMappings = type.GetProperties()
20+
.Select(prop => Tuple.Create(prop, prop.GetCustomAttribute<ParseFieldNameAttribute>(true)))
21+
.Where(t => t.Item2 != null)
22+
.Select(t => Tuple.Create(t.Item1, t.Item2.FieldName))
23+
.ToDictionary(t => t.Item1.Name, t => t.Item2);
24+
}
25+
26+
public TypeInfo TypeInfo { get; private set; }
27+
public String ClassName { get; private set; }
28+
private ConstructorInfo Constructor { get; private set; }
29+
public IDictionary<String, String> PropertyMappings { get; private set; }
30+
31+
public ParseObject Instantiate() {
32+
return (ParseObject)Constructor.Invoke(null);
33+
}
34+
35+
internal static String GetClassName(TypeInfo type) {
36+
var attribute = type.GetCustomAttribute<ParseClassNameAttribute>();
37+
return attribute != null ? attribute.ClassName : null;
38+
}
39+
}
40+
}

‎Parse/Internal/Object/Subclassing/ObjectSubclassingController.cs‎

Lines changed: 119 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,119 @@
1+
using System;
2+
using System.Collections.Generic;
3+
using System.Reflection;
4+
using System.Threading;
5+
6+
#if UNITY
7+
using TypeInfo = System.Type;
8+
#endif
9+
10+
namespace Parse.Internal {
11+
internal class ObjectSubclassingController : IObjectSubclassingController {
12+
private ReaderWriterLockSlim mutex;
13+
private IDictionary<String, ObjectSubclassInfo> registeredSubclasses;
14+
15+
public ObjectSubclassingController() {
16+
mutex = new ReaderWriterLockSlim();
17+
registeredSubclasses = new Dictionary<String, ObjectSubclassInfo>();
18+
}
19+
20+
public String GetClassName(Type type) {
21+
return ObjectSubclassInfo.GetClassName(type.GetTypeInfo());
22+
}
23+
24+
public Type GetType(String className) {
25+
ObjectSubclassInfo info = null;
26+
mutex.EnterReadLock();
27+
registeredSubclasses.TryGetValue(className, out info);
28+
mutex.ExitReadLock();
29+
30+
return info != null
31+
? info.TypeInfo.AsType()
32+
: null;
33+
}
34+
35+
public bool IsTypeValid(String className, Type type) {
36+
ObjectSubclassInfo subclassInfo = null;
37+
38+
mutex.EnterReadLock();
39+
registeredSubclasses.TryGetValue(className, out subclassInfo);
40+
mutex.ExitReadLock();
41+
42+
return subclassInfo == null
43+
? type == typeof(ParseObject)
44+
: subclassInfo.TypeInfo == type.GetTypeInfo();
45+
}
46+
47+
public void RegisterSubclass(Type type) {
48+
TypeInfo typeInfo = type.GetTypeInfo();
49+
if (!typeInfo.IsSubclassOf(typeof(ParseObject))) {
50+
throw new ArgumentException("Cannot register a type that is not a subclass of ParseObject");
51+
}
52+
53+
String className = ObjectSubclassInfo.GetClassName(typeInfo);
54+
55+
try {
56+
// Perform this as a single independent transaction, so we can never get into an
57+
// intermediate state where we *theoretically* register the wrong class due to a
58+
// TOCTTOU bug.
59+
mutex.EnterWriteLock();
60+
61+
ObjectSubclassInfo previousInfo = null;
62+
if (registeredSubclasses.TryGetValue(className, out previousInfo)) {
63+
if (typeInfo.IsAssignableFrom(previousInfo.TypeInfo)) {
64+
// Previous subclass is more specific or equal to the current type, do nothing.
65+
return;
66+
} else if (previousInfo.TypeInfo.IsAssignableFrom(typeInfo)) {
67+
// Previous subclass is parent of new child, fallthrough and actually register
68+
// this class.
69+
/* Do nothing */
70+
} else {
71+
throw new ArgumentException(
72+
"Tried to register both " + previousInfo.TypeInfo.FullName + " and " + typeInfo.FullName +
73+
" as the ParseObject subclass of " + className + ". Cannot determine the right class " +
74+
"to use because neither inherits from the other."
75+
);
76+
}
77+
}
78+
79+
ConstructorInfo constructor = type.FindConstructor();
80+
if (constructor == null) {
81+
throw new ArgumentException("Cannot register a type that does not implement the default constructor!");
82+
}
83+
84+
registeredSubclasses[className] = new ObjectSubclassInfo(type, constructor);
85+
} finally {
86+
mutex.ExitWriteLock();
87+
}
88+
}
89+
90+
public void UnregisterSubclass(Type type) {
91+
mutex.EnterWriteLock();
92+
registeredSubclasses.Remove(GetClassName(type));
93+
mutex.ExitWriteLock();
94+
}
95+
96+
public ParseObject Instantiate(String className) {
97+
ObjectSubclassInfo info = null;
98+
99+
mutex.EnterReadLock();
100+
registeredSubclasses.TryGetValue(className, out info);
101+
mutex.ExitReadLock();
102+
103+
return info != null
104+
? info.Instantiate()
105+
: new ParseObject(className);
106+
}
107+
108+
public IDictionary<String, String> GetPropertyMappings(String className) {
109+
ObjectSubclassInfo info = null;
110+
mutex.EnterReadLock();
111+
registeredSubclasses.TryGetValue(className, out info);
112+
mutex.ExitReadLock();
113+
114+
return info != null
115+
? info.PropertyMappings
116+
: null;
117+
}
118+
}
119+
}

‎Parse/Internal/ParseCorePlugins.cs‎

100644100755
Lines changed: 16 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -28,7 +28,8 @@ public static ParseCorePlugins Instance {
2828
private IParseSessionController sessionController;
2929
private IParseUserController userController;
3030
private IParsePushController pushController;
31-
private IParsePushChannelsController pushChannelsController;
31+
private IParsePushChannelsController pushChannelsController;
32+
private IObjectSubclassingController subclassingController;
3233

3334
#endregion
3435

@@ -242,6 +243,20 @@ internal set {
242243
currentUserController = value;
243244
}
244245
}
246+
}
247+
248+
public IObjectSubclassingController SubclassingController {
249+
get {
250+
lock (mutex) {
251+
subclassingController = subclassingController ?? new ObjectSubclassingController();
252+
return subclassingController;
253+
}
254+
}
255+
internal set {
256+
lock (mutex) {
257+
subclassingController = value;
258+
}
259+
}
245260
}
246261
}
247262
}

‎Parse/Internal/ReflectionHelpers.cs‎

100644100755
Lines changed: 4 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -50,8 +50,9 @@ internal static bool IsConstructedGenericType(this Type type) {
5050
internal static IEnumerable<ConstructorInfo> GetConstructors(this Type type) {
5151
#if UNITY
5252
return type.GetConstructors();
53-
#else
54-
return type.GetTypeInfo().DeclaredConstructors;
53+
#else
54+
return type.GetTypeInfo().DeclaredConstructors
55+
.Where(c => (c.Attributes & MethodAttributes.Static) == 0);
5556
#endif
5657
}
5758

@@ -78,7 +79,7 @@ from constructor in self.GetConstructors()
7879
let types = from p in parameters select p.ParameterType
7980
where types.SequenceEqual(parameterTypes)
8081
select constructor;
81-
return constructors.Single();
82+
return constructors.SingleOrDefault();
8283
}
8384

8485
internal static PropertyInfo GetProperty(this Type type, string name) {

‎Parse/Parse.Android.csproj‎

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -73,6 +73,9 @@
7373
<Compile Include="Internal\Object\Controller\ParseObjectController.cs" />
7474
<Compile Include="Internal\Object\State\IObjectState.cs" />
7575
<Compile Include="Internal\Object\State\MutableObjectState.cs" />
76+
<Compile Include="Internal\Object\Subclassing\IObjectSubclassingController.cs" />
77+
<Compile Include="Internal\Object\Subclassing\ObjectSubclassInfo.cs" />
78+
<Compile Include="Internal\Object\Subclassing\ObjectSubclassingController.cs" />
7679
<Compile Include="Internal\ParseCorePlugins.cs" />
7780
<Compile Include="Internal\ParseDecoder.cs" />
7881
<Compile Include="Internal\ParseEncoder.cs" />

‎Parse/Parse.Unity.csproj‎

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Original file line numberDiff line numberDiff line change
@@ -56,6 +56,7 @@
5656
<Compile Include="Compat\Progress.cs" />
5757
<Compile Include="Compat\ThreadLocal.cs" />
5858
<Compile Include="Compat\Tuple.cs" />
59+
<Compile Include="Compat\Type.cs" />
5960
<Compile Include="Internal\Analytics\Controller\IParseAnalyticsController.cs" />
6061
<Compile Include="Internal\Analytics\Controller\ParseAnalyticsController.cs" />
6162
<Compile Include="Internal\Cloud\Controller\IParseCloudCodeController.cs" />
@@ -90,6 +91,9 @@
9091
<Compile Include="Internal\Object\Controller\ParseObjectController.cs" />
9192
<Compile Include="Internal\Object\State\IObjectState.cs" />
9293
<Compile Include="Internal\Object\State\MutableObjectState.cs" />
94+
<Compile Include="Internal\Object\Subclassing\IObjectSubclassingController.cs" />
95+
<Compile Include="Internal\Object\Subclassing\ObjectSubclassInfo.cs" />
96+
<Compile Include="Internal\Object\Subclassing\ObjectSubclassingController.cs" />
9397
<Compile Include="Internal\ParseAddOperation.cs" />
9498
<Compile Include="Internal\ParseAddUniqueOperation.cs" />
9599
<Compile Include="Internal\ParseCorePlugins.cs" />

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