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using System;
using System.Reflection;
using System.Reflection.Emit;
using UnityEngine;
namespace IPA.Utilities
{
/// <summary>
/// A utility class providing reflection helper methods.
/// </summary>
public static partial class ReflectionUtil
{
internal static readonly FieldInfo DynamicMethodReturnType =
typeof(DynamicMethod).GetField("returnType", BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.DeclaredOnly);
/// <summary>
/// Sets a field on the target object, as gotten from <typeparamref name="T"/>.
/// </summary>
/// <typeparam name="T">the type to get the field from</typeparam>
/// <typeparam name="U">the type of the field to set</typeparam>
/// <param name="obj">the object instance</param>
/// <param name="fieldName">the field to set</param>
/// <param name="value">the value to set it to</param>
/// <exception cref="MissingFieldException">if <paramref name="fieldName"/> does not exist on <typeparamref name="T"/></exception>
/// <seealso cref="FieldAccessor{T, U}.Set(ref T, string, U)"/>
public static void SetField<T, U>(this T obj, string fieldName, U value)
=> FieldAccessor<T, U>.Set(ref obj, fieldName, value);
/// <summary>
/// Gets the value of a field.
/// </summary>
/// <typeparam name="T">the type to get the field from</typeparam>
/// <typeparam name="U">the type of the field (result casted)</typeparam>
/// <param name="obj">the object instance to pull from</param>
/// <param name="fieldName">the name of the field to read</param>
/// <returns>the value of the field</returns>
/// <exception cref="MissingFieldException">if <paramref name="fieldName"/> does not exist on <typeparamref name="T"/></exception>
/// <seealso cref="FieldAccessor{T, U}.Get(ref T, string)"/>
public static U GetField<U, T>(this T obj, string fieldName)
=> FieldAccessor<T, U>.Get(ref obj, fieldName);
/// <summary>
/// Sets a property on the target object, as gotten from <typeparamref name="T"/>.
/// </summary>
/// <typeparam name="T">the type to get the property from</typeparam>
/// <typeparam name="U">the type of the property to set</typeparam>
/// <param name="obj">the object instance</param>
/// <param name="propertyName">the property to set</param>
/// <param name="value">the value to set it to</param>
/// <exception cref="MissingMemberException">if <paramref name="propertyName"/> does not exist on <typeparamref name="T"/></exception>
/// <seealso cref="PropertyAccessor{T, U}.Set(ref T, string, U)"/>
public static void SetProperty<T, U>(this T obj, string propertyName, U value)
=> PropertyAccessor<T, U>.Set(ref obj, propertyName, value);
/// <summary>
/// Gets a property on the target object, as gotten from <typeparamref name="T"/>.
/// </summary>
/// <typeparam name="T">the type to get the property from</typeparam>
/// <typeparam name="U">the type of the property to get</typeparam>
/// <param name="obj">the object instance</param>
/// <param name="propertyName">the property to get</param>
/// <returns>the value of the property</returns>
/// <exception cref="MissingMemberException">if <paramref name="propertyName"/> does not exist on <typeparamref name="T"/></exception>
/// <seealso cref="PropertyAccessor{T, U}.Get(ref T, string)"/>
public static U GetProperty<U, T>(this T obj, string propertyName)
=> PropertyAccessor<T, U>.Get(ref obj, propertyName);
/// <summary>
/// Invokes a method from <typeparamref name="T"/> on an object.
/// </summary>
/// <typeparam name="U">the type that the method returns</typeparam>
/// <typeparam name="T">the type to search for the method on</typeparam>
/// <param name="obj">the object instance</param>
/// <param name="methodName">the method's name</param>
/// <param name="args">the method arguments</param>
/// <returns>the return value</returns>
/// <exception cref="MissingMethodException">if <paramref name="methodName"/> does not exist on <typeparamref name="T"/></exception>
public static U InvokeMethod<U, T>(this T obj, string methodName, params object[] args)
{
var dynMethod = typeof(T).GetMethod(methodName, BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Instance);
if (dynMethod == null) throw new MissingMethodException($"Method {methodName} does not exist", nameof(methodName));
return (U)dynMethod?.Invoke(obj, args);
}
/// <summary>
/// Invokes a generic method from <typeparamref name="T"/> on an object.
/// </summary>
/// <typeparam name="U">the type that the method returns</typeparam>
/// <typeparam name="T">the type to search for the method on</typeparam>
/// <typeparam name="G">the generic type to invoke the method with</typeparam>
/// <param name="obj">the object instance</param>
/// <param name="methodName">the method's name</param>
/// <param name="args">the method arguments</param>
/// <returns>the return value</returns>
/// <exception cref="T:System.MissingMethodException">if <paramref name="methodName" /> does not exist on <typeparamref name="T" /></exception>
public static U InvokeGenericMethod<U, T, G>(this T obj, string methodName, params object[] args)
{
var dynMethod = typeof(T).GetMethod(methodName, BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Instance);
if (dynMethod == null) throw new MissingMethodException($"Method {methodName} does not exist", nameof(methodName));
var genMethod = dynMethod.MakeGenericMethod(typeof(G));
return (U)genMethod?.Invoke(obj, args);
}
/// <summary>
/// Copies a component <paramref name="original"/> to a component of <paramref name="overridingType"/> on the destination <see cref="GameObject"/>.
/// </summary>
/// <param name="original">the original component</param>
/// <param name="overridingType">the new component's type</param>
/// <param name="destination">the destination GameObject</param>
/// <param name="originalTypeOverride">overrides the source component type (for example, to a superclass)</param>
/// <returns>the copied component</returns>
public static Component CopyComponent(this Component original, Type overridingType, GameObject destination, Type originalTypeOverride = null)
{
var copy = destination.AddComponent(overridingType);
var originalType = originalTypeOverride ?? original.GetType();
Type type = originalType;
while (type != typeof(MonoBehaviour))
{
CopyForType(type, original, copy);
type = type?.BaseType;
}
return copy;
}
/// <summary>
/// A generic version of <see cref="CopyComponent(Component, Type, GameObject, Type)"/>.
/// </summary>
/// <seealso cref="CopyComponent(Component, Type, GameObject, Type)"/>
/// <typeparam name="T">the overriding type</typeparam>
/// <param name="original">the original component</param>
/// <param name="destination">the destination game object</param>
/// <param name="originalTypeOverride">overrides the source component type (for example, to a superclass)</param>
/// <returns>the copied component</returns>
public static T CopyComponent<T>(this Component original, GameObject destination, Type originalTypeOverride = null)
where T : Component
{
var copy = destination.AddComponent<T>();
var originalType = originalTypeOverride ?? original.GetType();
Type type = originalType;
while (type != typeof(MonoBehaviour))
{
CopyForType(type, original, copy);
type = type?.BaseType;
}
return copy;
}
/// <summary>
/// Converts the property name to the one of the compiler-generated backing field.
/// This can be used for the field-based reflection when you want to set the value of a get-only property
/// </summary>
/// <param name="propertyName">Name of the property</param>
/// <returns>Name of the backing field</returns>
/// <remarks>
/// Only works for properties with compiler-generated backing fields.
/// This is only a simple method and doesn't have any guarantees to work 100% of the time across different compilers/runtimes.
/// See <a href="https://github.com/dotnet/roslyn/blob/1497e87d967c5b7797edb5f782131508607139e5/src/Compilers/CSharp/Portable/Symbols/Synthesized/GeneratedNames.cs#L24-L28">this link</a> for more info.
/// </remarks>
public static string ToCompilerGeneratedBackingField(string propertyName) => $"<{propertyName}>k__BackingField";
private static void CopyForType(Type type, Component source, Component destination)
{
FieldInfo[] myObjectFields = type.GetFields(BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Instance);
foreach (FieldInfo fi in myObjectFields)
{
fi.SetValue(destination, fi.GetValue(source));
}
}
}
}