Merge branch 'develop' into stable

3 files changed, 431 insertions, 0 deletions

diff --git a/src/StardewModdingAPI/Framework/Reflection/PrivateField.cs b/src/StardewModdingAPI/Framework/Reflection/PrivateField.cs
new file mode 100644
index 00000000..0bf45969
--- /dev/null
+++ b/src/StardewModdingAPI/Framework/Reflection/PrivateField.cs
@@ -0,0 +1,93 @@
+using System;
+using System.Reflection;
+
+namespace StardewModdingAPI.Framework.Reflection
+{
+    /// <summary>A private field obtained through reflection.</summary>
+    /// <typeparam name="TValue">The field value type.</typeparam>
+    internal class PrivateField<TValue> : IPrivateField<TValue>
+    {
+        /*********
+        ** Properties
+        *********/
+        /// <summary>The type that has the field.</summary>
+        private readonly Type ParentType;
+
+        /// <summary>The object that has the instance field (if applicable).</summary>
+        private readonly object Parent;
+
+        /// <summary>The display name shown in error messages.</summary>
+        private string DisplayName => $"{this.ParentType.FullName}::{this.FieldInfo.Name}";
+
+
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>The reflection metadata.</summary>
+        public FieldInfo FieldInfo { get; }
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="parentType">The type that has the field.</param>
+        /// <param name="obj">The object that has the instance field (if applicable).</param>
+        /// <param name="field">The reflection metadata.</param>
+        /// <param name="isStatic">Whether the field is static.</param>
+        /// <exception cref="ArgumentNullException">The <paramref name="parentType"/> or <paramref name="field"/> is null.</exception>
+        /// <exception cref="ArgumentException">The <paramref name="obj"/> is null for a non-static field, or not null for a static field.</exception>
+        public PrivateField(Type parentType, object obj, FieldInfo field, bool isStatic)
+        {
+            // validate
+            if (parentType == null)
+                throw new ArgumentNullException(nameof(parentType));
+            if (field == null)
+                throw new ArgumentNullException(nameof(field));
+            if (isStatic && obj != null)
+                throw new ArgumentException("A static field cannot have an object instance.");
+            if (!isStatic && obj == null)
+                throw new ArgumentException("A non-static field must have an object instance.");
+
+            // save
+            this.ParentType = parentType;
+            this.Parent = obj;
+            this.FieldInfo = field;
+        }
+
+        /// <summary>Get the field value.</summary>
+        public TValue GetValue()
+        {
+            try
+            {
+                return (TValue)this.FieldInfo.GetValue(this.Parent);
+            }
+            catch (InvalidCastException)
+            {
+                throw new InvalidCastException($"Can't convert the private {this.DisplayName} field from {this.FieldInfo.FieldType.FullName} to {typeof(TValue).FullName}.");
+            }
+            catch (Exception ex)
+            {
+                throw new Exception($"Couldn't get the value of the private {this.DisplayName} field", ex);
+            }
+        }
+
+        /// <summary>Set the field value.</summary>
+        //// <param name="value">The value to set.</param>
+        public void SetValue(TValue value)
+        {
+            try
+            {
+                this.FieldInfo.SetValue(this.Parent, value);
+            }
+            catch (InvalidCastException)
+            {
+                throw new InvalidCastException($"Can't assign the private {this.DisplayName} field a {typeof(TValue).FullName} value, must be compatible with {this.FieldInfo.FieldType.FullName}.");
+            }
+            catch (Exception ex)
+            {
+                throw new Exception($"Couldn't set the value of the private {this.DisplayName} field", ex);
+            }
+        }
+    }
+}
diff --git a/src/StardewModdingAPI/Framework/Reflection/PrivateMethod.cs b/src/StardewModdingAPI/Framework/Reflection/PrivateMethod.cs
new file mode 100644
index 00000000..ba2374f4
--- /dev/null
+++ b/src/StardewModdingAPI/Framework/Reflection/PrivateMethod.cs
@@ -0,0 +1,99 @@
+using System;
+using System.Reflection;
+
+namespace StardewModdingAPI.Framework.Reflection
+{
+    /// <summary>A private method obtained through reflection.</summary>
+    internal class PrivateMethod : IPrivateMethod
+    {
+        /*********
+        ** Properties
+        *********/
+        /// <summary>The type that has the method.</summary>
+        private readonly Type ParentType;
+
+        /// <summary>The object that has the instance method (if applicable).</summary>
+        private readonly object Parent;
+
+        /// <summary>The display name shown in error messages.</summary>
+        private string DisplayName => $"{this.ParentType.FullName}::{this.MethodInfo.Name}";
+
+
+        /*********
+        ** Accessors
+        *********/
+        /// <summary>The reflection metadata.</summary>
+        public MethodInfo MethodInfo { get; }
+
+
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        /// <param name="parentType">The type that has the method.</param>
+        /// <param name="obj">The object that has the instance method(if applicable).</param>
+        /// <param name="method">The reflection metadata.</param>
+        /// <param name="isStatic">Whether the field is static.</param>
+        /// <exception cref="ArgumentNullException">The <paramref name="parentType"/> or <paramref name="method"/> is null.</exception>
+        /// <exception cref="ArgumentException">The <paramref name="obj"/> is null for a non-static method, or not null for a static method.</exception>
+        public PrivateMethod(Type parentType, object obj, MethodInfo method, bool isStatic)
+        {
+            // validate
+            if (parentType == null)
+                throw new ArgumentNullException(nameof(parentType));
+            if (method == null)
+                throw new ArgumentNullException(nameof(method));
+            if (isStatic && obj != null)
+                throw new ArgumentException("A static method cannot have an object instance.");
+            if (!isStatic && obj == null)
+                throw new ArgumentException("A non-static method must have an object instance.");
+
+            // save
+            this.ParentType = parentType;
+            this.Parent = obj;
+            this.MethodInfo = method;
+        }
+
+        /// <summary>Invoke the method.</summary>
+        /// <typeparam name="TValue">The return type.</typeparam>
+        /// <param name="arguments">The method arguments to pass in.</param>
+        public TValue Invoke<TValue>(params object[] arguments)
+        {
+            // invoke method
+            object result;
+            try
+            {
+                result = this.MethodInfo.Invoke(this.Parent, arguments);
+            }
+            catch (Exception ex)
+            {
+                throw new Exception($"Couldn't invoke the private {this.DisplayName} field", ex);
+            }
+
+            // cast return value
+            try
+            {
+                return (TValue)result;
+            }
+            catch (InvalidCastException)
+            {
+                throw new InvalidCastException($"Can't convert the return value of the private {this.DisplayName} method from {this.MethodInfo.ReturnType.FullName} to {typeof(TValue).FullName}.");
+            }
+        }
+
+        /// <summary>Invoke the method.</summary>
+        /// <param name="arguments">The method arguments to pass in.</param>
+        public void Invoke(params object[] arguments)
+        {
+            // invoke method
+            try
+            {
+                this.MethodInfo.Invoke(this.Parent, arguments);
+            }
+            catch (Exception ex)
+            {
+                throw new Exception($"Couldn't invoke the private {this.DisplayName} field", ex);
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/StardewModdingAPI/Framework/Reflection/ReflectionHelper.cs b/src/StardewModdingAPI/Framework/Reflection/ReflectionHelper.cs
new file mode 100644
index 00000000..38b4e357
--- /dev/null
+++ b/src/StardewModdingAPI/Framework/Reflection/ReflectionHelper.cs
@@ -0,0 +1,239 @@
+using System;
+using System.Linq;
+using System.Reflection;
+using System.Runtime.Caching;
+
+namespace StardewModdingAPI.Framework.Reflection
+{
+    /// <summary>Provides helper methods for accessing private game code.</summary>
+    /// <remarks>This implementation searches up the type hierarchy, and caches the reflected fields and methods with a sliding expiry (to optimise performance without unnecessary memory usage).</remarks>
+    internal class ReflectionHelper : IReflectionHelper
+    {
+        /*********
+        ** Properties
+        *********/
+        /// <summary>The cached fields and methods found via reflection.</summary>
+        private readonly MemoryCache Cache = new MemoryCache(typeof(ReflectionHelper).FullName);
+
+        /// <summary>The sliding cache expiration time.</summary>
+        private readonly TimeSpan SlidingCacheExpiry = TimeSpan.FromMinutes(5);
+
+
+        /*********
+        ** Public methods
+        *********/
+        /****
+        ** Fields
+        ****/
+        /// <summary>Get a private instance field.</summary>
+        /// <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 private 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>
+        public IPrivateField<TValue> GetPrivateField<TValue>(object obj, string name, bool required = true)
+        {
+            // validate
+            if (obj == null)
+                throw new ArgumentNullException(nameof(obj), "Can't get a private instance field from a null object.");
+
+            // get field from hierarchy
+            IPrivateField<TValue> field = this.GetFieldFromHierarchy<TValue>(obj.GetType(), obj, name, BindingFlags.Instance | BindingFlags.NonPublic);
+            if (required && field == null)
+                throw new InvalidOperationException($"The {obj.GetType().FullName} object doesn't have a private '{name}' instance field.");
+            return field;
+        }
+
+        /// <summary>Get a private static field.</summary>
+        /// <typeparam name="TValue">The field type.</typeparam>
+        /// <param name="type">The type which has the field.</param>
+        /// <param name="name">The field name.</param>
+        /// <param name="required">Whether to throw an exception if the private field is not found.</param>
+        public IPrivateField<TValue> GetPrivateField<TValue>(Type type, string name, bool required = true)
+        {
+            // get field from hierarchy
+            IPrivateField<TValue> field = this.GetFieldFromHierarchy<TValue>(type, null, name, BindingFlags.NonPublic | BindingFlags.Static);
+            if (required && field == null)
+                throw new InvalidOperationException($"The {type.FullName} object doesn't have a private '{name}' static field.");
+            return field;
+        }
+
+        /****
+        ** Field values
+        ** (shorthand since this is the most common case)
+        ****/
+        /// <summary>Get the value of a private instance field.</summary>
+        /// <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 private field is not found.</param>
+        /// <remarks>This is a shortcut for <see cref="GetPrivateField{TValue}(object,string,bool)"/> followed by <see cref="IPrivateField{TValue}.GetValue"/>.</remarks>
+        public TValue GetPrivateValue<TValue>(object obj, string name, bool required = true)
+        {
+            return this.GetPrivateField<TValue>(obj, name, required).GetValue();
+        }
+
+        /// <summary>Get the value of a private 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 private field is not found.</param>
+        /// <remarks>This is a shortcut for <see cref="GetPrivateField{TValue}(Type,string,bool)"/> followed by <see cref="IPrivateField{TValue}.GetValue"/>.</remarks>
+        public TValue GetPrivateValue<TValue>(Type type, string name, bool required = true)
+        {
+            return this.GetPrivateField<TValue>(type, name, required).GetValue();
+        }
+
+        /****
+        ** Methods
+        ****/
+        /// <summary>Get a private 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 private field is not found.</param>
+        public IPrivateMethod GetPrivateMethod(object obj, string name, bool required = true)
+        {
+            // validate
+            if (obj == null)
+                throw new ArgumentNullException(nameof(obj), "Can't get a private instance method from a null object.");
+
+            // get method from hierarchy
+            IPrivateMethod method = this.GetMethodFromHierarchy(obj.GetType(), obj, name, BindingFlags.Instance | BindingFlags.NonPublic);
+            if (required && method == null)
+                throw new InvalidOperationException($"The {obj.GetType().FullName} object doesn't have a private '{name}' instance method.");
+            return method;
+        }
+
+        /// <summary>Get a private static method.</summary>
+        /// <param name="type">The type which has the method.</param>
+        /// <param name="name">The field name.</param>
+        /// <param name="required">Whether to throw an exception if the private field is not found.</param>
+        public IPrivateMethod GetPrivateMethod(Type type, string name, bool required = true)
+        {
+            // get method from hierarchy
+            IPrivateMethod method = this.GetMethodFromHierarchy(type, null, name, BindingFlags.NonPublic | BindingFlags.Static);
+            if (required && method == null)
+                throw new InvalidOperationException($"The {type.FullName} object doesn't have a private '{name}' static method.");
+            return method;
+        }
+
+        /****
+        ** Methods by signature
+        ****/
+        /// <summary>Get a private instance method.</summary>
+        /// <param name="obj">The object which has the method.</param>
+        /// <param name="name">The field name.</param>
+        /// <param name="argumentTypes">The argument types of the method signature to find.</param>
+        /// <param name="required">Whether to throw an exception if the private field is not found.</param>
+        public IPrivateMethod GetPrivateMethod(object obj, string name, Type[] argumentTypes, bool required = true)
+        {
+            // validate parent
+            if (obj == null)
+                throw new ArgumentNullException(nameof(obj), "Can't get a private instance method from a null object.");
+
+            // get method from hierarchy
+            PrivateMethod method = this.GetMethodFromHierarchy(obj.GetType(), obj, name, BindingFlags.Instance | BindingFlags.NonPublic, argumentTypes);
+            if (required && method == null)
+                throw new InvalidOperationException($"The {obj.GetType().FullName} object doesn't have a private '{name}' instance method with that signature.");
+            return method;
+        }
+
+        /// <summary>Get a private static method.</summary>
+        /// <param name="type">The type which has the method.</param>
+        /// <param name="name">The field name.</param>
+        /// <param name="argumentTypes">The argument types of the method signature to find.</param>
+        /// <param name="required">Whether to throw an exception if the private field is not found.</param>
+        public IPrivateMethod GetPrivateMethod(Type type, string name, Type[] argumentTypes, bool required = true)
+        {
+            // get field from hierarchy
+            PrivateMethod method = this.GetMethodFromHierarchy(type, null, name, BindingFlags.NonPublic | BindingFlags.Static, argumentTypes);
+            if (required && method == null)
+                throw new InvalidOperationException($"The {type.FullName} object doesn't have a private '{name}' static method with that signature.");
+            return method;
+        }
+
+
+        /*********
+        ** Private methods
+        *********/
+        /// <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="name">The field name.</param>
+        /// <param name="bindingFlags">The reflection binding which flags which indicates what type of field to find.</param>
+        private IPrivateField<TValue> GetFieldFromHierarchy<TValue>(Type type, object obj, string name, BindingFlags bindingFlags)
+        {
+            bool isStatic = bindingFlags.HasFlag(BindingFlags.Static);
+            FieldInfo field = this.GetCached<FieldInfo>($"field::{isStatic}::{type.FullName}::{name}", () =>
+            {
+                FieldInfo fieldInfo = null;
+                for (; type != null && fieldInfo == null; type = type.BaseType)
+                    fieldInfo = type.GetField(name, bindingFlags);
+                return fieldInfo;
+            });
+
+            return field != null
+                ? new PrivateField<TValue>(type, obj, field, isStatic)
+                : null;
+        }
+
+        /// <summary>Get a method from the type hierarchy.</summary>
+        /// <param name="type">The type which has the method.</param>
+        /// <param name="obj">The object which has the method.</param>
+        /// <param name="name">The method name.</param>
+        /// <param name="bindingFlags">The reflection binding which flags which indicates what type of method to find.</param>
+        private IPrivateMethod GetMethodFromHierarchy(Type type, object obj, string name, BindingFlags bindingFlags)
+        {
+            bool isStatic = bindingFlags.HasFlag(BindingFlags.Static);
+            MethodInfo method = this.GetCached($"method::{isStatic}::{type.FullName}::{name}", () =>
+            {
+                MethodInfo methodInfo = null;
+                for (; type != null && methodInfo == null; type = type.BaseType)
+                    methodInfo = type.GetMethod(name, bindingFlags);
+                return methodInfo;
+            });
+
+            return method != null
+                ? new PrivateMethod(type, obj, method, isStatic: bindingFlags.HasFlag(BindingFlags.Static))
+                : null;
+        }
+
+        /// <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="name">The method name.</param>
+        /// <param name="bindingFlags">The reflection binding which flags which indicates what type of method to find.</param>
+        /// <param name="argumentTypes">The argument types of the method signature to find.</param>
+        private PrivateMethod GetMethodFromHierarchy(Type type, object obj, string name, BindingFlags bindingFlags, Type[] argumentTypes)
+        {
+            bool isStatic = bindingFlags.HasFlag(BindingFlags.Static);
+            MethodInfo method = this.GetCached($"method::{isStatic}::{type.FullName}::{name}({string.Join(",", argumentTypes.Select(p => p.FullName))})", () =>
+            {
+                MethodInfo methodInfo = null;
+                for (; type != null && methodInfo == null; type = type.BaseType)
+                    methodInfo = type.GetMethod(name, bindingFlags, null, argumentTypes, null);
+                return methodInfo;
+            });
+            return method != null
+                ? new PrivateMethod(type, obj, method, isStatic)
+                : null;
+        }
+
+        /// <summary>Get a method or field through the cache.</summary>
+        /// <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
+        {
+            // get from cache
+            if (this.Cache.Contains(key))
+                return (TMemberInfo)this.Cache[key];
+
+            // fetch & cache new value
+            TMemberInfo result = fetch();
+            this.Cache.Add(key, result, new CacheItemPolicy { SlidingExpiration = this.SlidingCacheExpiry });
+            return result;
+        }
+    }
+}
\ No newline at end of file