enable nullable annotations in the rest of SMAPI core (#837)

1 files changed, 79 insertions, 48 deletions

diff --git a/src/SMAPI/Framework/Reflection/Reflector.cs b/src/SMAPI/Framework/Reflection/Reflector.cs
index c6fc2c79..3490ee97 100644
--- a/src/SMAPI/Framework/Reflection/Reflector.cs
+++ b/src/SMAPI/Framework/Reflection/Reflector.cs
@@ -1,5 +1,3 @@
-#nullable disable
-
 using System;
 using System.Reflection;
 using System.Runtime.Caching;
@@ -14,7 +12,7 @@ namespace StardewModdingAPI.Framework.Reflection
         ** Fields
         *********/
         /// <summary>The cached fields and methods found via reflection.</summary>
-        private readonly MemoryCache Cache = new(typeof(Reflector).FullName);
+        private readonly MemoryCache Cache = new(typeof(Reflector).FullName!);
 
         /// <summary>The sliding cache expiration time.</summary>
         private readonly TimeSpan SlidingCacheExpiry = TimeSpan.FromMinutes(5);
@@ -30,8 +28,9 @@ namespace StardewModdingAPI.Framework.Reflection
         /// <typeparam name="TValue">The field type.</typeparam>
         /// <param name="obj">The object which has the field.</param>
         /// <param name="name">The field name.</param>
-        /// <param name="required">Whether to throw an exception if the field is not found.</param>
-        /// <returns>Returns the field wrapper, or <c>null</c> if the field doesn't exist and <paramref name="required"/> is <c>false</c>.</returns>
+        /// <param name="required">Whether to throw an exception if the field isn't found. <strong>Due to limitations with nullable reference types, setting this to <c>false</c> will still mark the value non-nullable.</strong></param>
+        /// <returns>Returns the field wrapper, or <c>null</c> if <paramref name="required"/> is <c>false</c> and the field doesn't exist.</returns>
+        /// <exception cref="InvalidOperationException">The target field doesn't exist, and <paramref name="required"/> is true.</exception>
         public IReflectedField<TValue> GetField<TValue>(object obj, string name, bool required = true)
         {
             // validate
@@ -39,24 +38,26 @@ namespace StardewModdingAPI.Framework.Reflection
                 throw new ArgumentNullException(nameof(obj), "Can't get a instance field from a null object.");
 
             // get field from hierarchy
-            IReflectedField<TValue> field = this.GetFieldFromHierarchy<TValue>(obj.GetType(), obj, name, BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public);
+            IReflectedField<TValue>? field = this.GetFieldFromHierarchy<TValue>(obj.GetType(), obj, name, BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public);
             if (required && field == null)
                 throw new InvalidOperationException($"The {obj.GetType().FullName} object doesn't have a '{name}' instance field.");
-            return field;
+            return field!;
         }
 
         /// <summary>Get a static field.</summary>
         /// <typeparam name="TValue">The field type.</typeparam>
         /// <param name="type">The type which has the field.</param>
         /// <param name="name">The field name.</param>
-        /// <param name="required">Whether to throw an exception if the field is not found.</param>
+        /// <param name="required">Whether to throw an exception if the field isn't found. <strong>Due to limitations with nullable reference types, setting this to <c>false</c> will still mark the value non-nullable.</strong></param>
+        /// <returns>Returns the field wrapper, or <c>null</c> if <paramref name="required"/> is <c>false</c> and the field doesn't exist.</returns>
+        /// <exception cref="InvalidOperationException">The target field doesn't exist, and <paramref name="required"/> is true.</exception>
         public IReflectedField<TValue> GetField<TValue>(Type type, string name, bool required = true)
         {
             // get field from hierarchy
-            IReflectedField<TValue> field = this.GetFieldFromHierarchy<TValue>(type, null, name, BindingFlags.NonPublic | BindingFlags.Static | BindingFlags.Public);
+            IReflectedField<TValue>? field = this.GetFieldFromHierarchy<TValue>(type, null, name, BindingFlags.NonPublic | BindingFlags.Static | BindingFlags.Public);
             if (required && field == null)
                 throw new InvalidOperationException($"The {type.FullName} object doesn't have a '{name}' static field.");
-            return field;
+            return field!;
         }
 
         /****
@@ -66,7 +67,9 @@ namespace StardewModdingAPI.Framework.Reflection
         /// <typeparam name="TValue">The property type.</typeparam>
         /// <param name="obj">The object which has the property.</param>
         /// <param name="name">The property name.</param>
-        /// <param name="required">Whether to throw an exception if the property is not found.</param>
+        /// <param name="required">Whether to throw an exception if the property isn't found. <strong>Due to limitations with nullable reference types, setting this to <c>false</c> will still mark the value non-nullable.</strong></param>
+        /// <returns>Returns the property wrapper, or <c>null</c> if <paramref name="required"/> is <c>false</c> and the property doesn't exist.</returns>
+        /// <exception cref="InvalidOperationException">The target property doesn't exist, and <paramref name="required"/> is true.</exception>
         public IReflectedProperty<TValue> GetProperty<TValue>(object obj, string name, bool required = true)
         {
             // validate
@@ -74,24 +77,26 @@ namespace StardewModdingAPI.Framework.Reflection
                 throw new ArgumentNullException(nameof(obj), "Can't get a instance property from a null object.");
 
             // get property from hierarchy
-            IReflectedProperty<TValue> property = this.GetPropertyFromHierarchy<TValue>(obj.GetType(), obj, name, BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public);
+            IReflectedProperty<TValue>? property = this.GetPropertyFromHierarchy<TValue>(obj.GetType(), obj, name, BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public);
             if (required && property == null)
                 throw new InvalidOperationException($"The {obj.GetType().FullName} object doesn't have a '{name}' instance property.");
-            return property;
+            return property!;
         }
 
         /// <summary>Get a static property.</summary>
         /// <typeparam name="TValue">The property type.</typeparam>
         /// <param name="type">The type which has the property.</param>
         /// <param name="name">The property name.</param>
-        /// <param name="required">Whether to throw an exception if the property is not found.</param>
+        /// <param name="required">Whether to throw an exception if the property isn't found. <strong>Due to limitations with nullable reference types, setting this to <c>false</c> will still mark the value non-nullable.</strong></param>
+        /// <returns>Returns the property wrapper, or <c>null</c> if <paramref name="required"/> is <c>false</c> and the property doesn't exist.</returns>
+        /// <exception cref="InvalidOperationException">The target property doesn't exist, and <paramref name="required"/> is true.</exception>
         public IReflectedProperty<TValue> GetProperty<TValue>(Type type, string name, bool required = true)
         {
             // get field from hierarchy
-            IReflectedProperty<TValue> property = this.GetPropertyFromHierarchy<TValue>(type, null, name, BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Static);
+            IReflectedProperty<TValue>? property = this.GetPropertyFromHierarchy<TValue>(type, null, name, BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Static);
             if (required && property == null)
                 throw new InvalidOperationException($"The {type.FullName} object doesn't have a '{name}' static property.");
-            return property;
+            return property!;
         }
 
         /****
@@ -99,8 +104,10 @@ namespace StardewModdingAPI.Framework.Reflection
         ****/
         /// <summary>Get a instance method.</summary>
         /// <param name="obj">The object which has the method.</param>
-        /// <param name="name">The field name.</param>
-        /// <param name="required">Whether to throw an exception if the field is not found.</param>
+        /// <param name="name">The method name.</param>
+        /// <param name="required">Whether to throw an exception if the method isn't found. <strong>Due to limitations with nullable reference types, setting this to <c>false</c> will still mark the value non-nullable.</strong></param>
+        /// <returns>Returns the method wrapper, or <c>null</c> if <paramref name="required"/> is <c>false</c> and the method doesn't exist.</returns>
+        /// <exception cref="InvalidOperationException">The target method doesn't exist, and <paramref name="required"/> is true.</exception>
         public IReflectedMethod GetMethod(object obj, string name, bool required = true)
         {
             // validate
@@ -108,23 +115,25 @@ namespace StardewModdingAPI.Framework.Reflection
                 throw new ArgumentNullException(nameof(obj), "Can't get a instance method from a null object.");
 
             // get method from hierarchy
-            IReflectedMethod method = this.GetMethodFromHierarchy(obj.GetType(), obj, name, BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public);
+            IReflectedMethod? method = this.GetMethodFromHierarchy(obj.GetType(), obj, name, BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public);
             if (required && method == null)
                 throw new InvalidOperationException($"The {obj.GetType().FullName} object doesn't have a '{name}' instance method.");
-            return method;
+            return method!;
         }
 
         /// <summary>Get a static method.</summary>
         /// <param name="type">The type which has the method.</param>
-        /// <param name="name">The field name.</param>
-        /// <param name="required">Whether to throw an exception if the field is not found.</param>
+        /// <param name="name">The method name.</param>
+        /// <param name="required">Whether to throw an exception if the method isn't found. <strong>Due to limitations with nullable reference types, setting this to <c>false</c> will still mark the value non-nullable.</strong></param>
+        /// <returns>Returns the method wrapper, or <c>null</c> if <paramref name="required"/> is <c>false</c> and the method doesn't exist.</returns>
+        /// <exception cref="InvalidOperationException">The target method doesn't exist, and <paramref name="required"/> is true.</exception>
         public IReflectedMethod GetMethod(Type type, string name, bool required = true)
         {
             // get method from hierarchy
-            IReflectedMethod method = this.GetMethodFromHierarchy(type, null, name, BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Static);
+            IReflectedMethod? method = this.GetMethodFromHierarchy(type, null, name, BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Static);
             if (required && method == null)
                 throw new InvalidOperationException($"The {type.FullName} object doesn't have a '{name}' static method.");
-            return method;
+            return method!;
         }
 
 
@@ -134,18 +143,25 @@ namespace StardewModdingAPI.Framework.Reflection
         /// <summary>Get a field from the type hierarchy.</summary>
         /// <typeparam name="TValue">The expected field type.</typeparam>
         /// <param name="type">The type which has the field.</param>
-        /// <param name="obj">The object which has the field.</param>
+        /// <param name="obj">The object which has the field, or <c>null</c> for a static field.</param>
         /// <param name="name">The field name.</param>
         /// <param name="bindingFlags">The reflection binding which flags which indicates what type of field to find.</param>
-        private IReflectedField<TValue> GetFieldFromHierarchy<TValue>(Type type, object obj, string name, BindingFlags bindingFlags)
+        private IReflectedField<TValue>? GetFieldFromHierarchy<TValue>(Type type, object? obj, string name, BindingFlags bindingFlags)
         {
             bool isStatic = bindingFlags.HasFlag(BindingFlags.Static);
-            FieldInfo field = this.GetCached<FieldInfo>($"field::{isStatic}::{type.FullName}::{name}", () =>
+            FieldInfo? field = this.GetCached($"field::{isStatic}::{type.FullName}::{name}", () =>
             {
-                FieldInfo fieldInfo = null;
-                for (; type != null && fieldInfo == null; type = type.BaseType)
-                    fieldInfo = type.GetField(name, bindingFlags);
-                return fieldInfo;
+                for (Type? curType = type; curType != null; curType = curType.BaseType)
+                {
+                    FieldInfo? fieldInfo = type.GetField(name, bindingFlags);
+                    if (fieldInfo != null)
+                    {
+                        type = curType;
+                        return fieldInfo;
+                    }
+                }
+
+                return null;
             });
 
             return field != null
@@ -156,18 +172,25 @@ namespace StardewModdingAPI.Framework.Reflection
         /// <summary>Get a property from the type hierarchy.</summary>
         /// <typeparam name="TValue">The expected property type.</typeparam>
         /// <param name="type">The type which has the property.</param>
-        /// <param name="obj">The object which has the property.</param>
+        /// <param name="obj">The object which has the property, or <c>null</c> for a static property.</param>
         /// <param name="name">The property name.</param>
         /// <param name="bindingFlags">The reflection binding which flags which indicates what type of property to find.</param>
-        private IReflectedProperty<TValue> GetPropertyFromHierarchy<TValue>(Type type, object obj, string name, BindingFlags bindingFlags)
+        private IReflectedProperty<TValue>? GetPropertyFromHierarchy<TValue>(Type type, object? obj, string name, BindingFlags bindingFlags)
         {
             bool isStatic = bindingFlags.HasFlag(BindingFlags.Static);
-            PropertyInfo property = this.GetCached<PropertyInfo>($"property::{isStatic}::{type.FullName}::{name}", () =>
+            PropertyInfo? property = this.GetCached<PropertyInfo>($"property::{isStatic}::{type.FullName}::{name}", () =>
             {
-                PropertyInfo propertyInfo = null;
-                for (; type != null && propertyInfo == null; type = type.BaseType)
-                    propertyInfo = type.GetProperty(name, bindingFlags);
-                return propertyInfo;
+                for (Type? curType = type; curType != null; curType = curType.BaseType)
+                {
+                    PropertyInfo? propertyInfo = type.GetProperty(name, bindingFlags);
+                    if (propertyInfo != null)
+                    {
+                        type = curType;
+                        return propertyInfo;
+                    }
+                }
+
+                return null;
             });
 
             return property != null
@@ -177,18 +200,25 @@ namespace StardewModdingAPI.Framework.Reflection
 
         /// <summary>Get a method from the type hierarchy.</summary>
         /// <param name="type">The type which has the method.</param>
-        /// <param name="obj">The object which has the method.</param>
+        /// <param name="obj">The object which has the method, or <c>null</c> for a static method.</param>
         /// <param name="name">The method name.</param>
         /// <param name="bindingFlags">The reflection binding which flags which indicates what type of method to find.</param>
-        private IReflectedMethod GetMethodFromHierarchy(Type type, object obj, string name, BindingFlags bindingFlags)
+        private IReflectedMethod? GetMethodFromHierarchy(Type type, object? obj, string name, BindingFlags bindingFlags)
         {
             bool isStatic = bindingFlags.HasFlag(BindingFlags.Static);
-            MethodInfo method = this.GetCached($"method::{isStatic}::{type.FullName}::{name}", () =>
+            MethodInfo? method = this.GetCached($"method::{isStatic}::{type.FullName}::{name}", () =>
             {
-                MethodInfo methodInfo = null;
-                for (; type != null && methodInfo == null; type = type.BaseType)
-                    methodInfo = type.GetMethod(name, bindingFlags);
-                return methodInfo;
+                for (Type? curType = type; curType != null; curType = curType.BaseType)
+                {
+                    MethodInfo? methodInfo = type.GetMethod(name, bindingFlags);
+                    if (methodInfo != null)
+                    {
+                        type = curType;
+                        return methodInfo;
+                    }
+                }
+
+                return null;
             });
 
             return method != null
@@ -200,7 +230,8 @@ namespace StardewModdingAPI.Framework.Reflection
         /// <typeparam name="TMemberInfo">The expected <see cref="MemberInfo"/> type.</typeparam>
         /// <param name="key">The cache key.</param>
         /// <param name="fetch">Fetches a new value to cache.</param>
-        private TMemberInfo GetCached<TMemberInfo>(string key, Func<TMemberInfo> fetch) where TMemberInfo : MemberInfo
+        private TMemberInfo? GetCached<TMemberInfo>(string key, Func<TMemberInfo?> fetch)
+            where TMemberInfo : MemberInfo
         {
             // get from cache
             if (this.Cache.Contains(key))
@@ -212,8 +243,8 @@ namespace StardewModdingAPI.Framework.Reflection
             }
 
             // fetch & cache new value
-            TMemberInfo result = fetch();
-            CacheEntry cacheEntry = new(result != null, result);
+            TMemberInfo? result = fetch();
+            CacheEntry cacheEntry = new(result);
             this.Cache.Add(key, cacheEntry, new CacheItemPolicy { SlidingExpiration = this.SlidingCacheExpiry });
             return result;
         }