Reflect.cs

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//-----------------------------------------------------------------------
// <copyright file="Reflect.cs" company="Marimer LLC">
//     Copyright (c) Marimer LLC. All rights reserved.
//     Website: https://cslanet.com
// </copyright>
// <summary>Provides strong-typed reflection of the <typeparamref name="TTarget"/> </summary>
//-----------------------------------------------------------------------
using System;
using System.Linq.Expressions;
using System.Reflection;
 
namespace Csla.Reflection
{
  public static class Reflect<TTarget>
  {
    public static System.Reflection.MethodInfo GetMethod(Expression<Action<TTarget>> method)
    {
      return GetMethodInfo(method);
    }
 
    public static System.Reflection.MethodInfo GetMethod<T1>(Expression<Action<TTarget, T1>> method)
    {
      return GetMethodInfo(method);
    }
 
    public static System.Reflection.MethodInfo GetMethod<T1, T2>(Expression<Action<TTarget, T1, T2>> method)
    {
      return GetMethodInfo(method);
    }
 
    public static System.Reflection.MethodInfo GetMethod<T1, T2, T3>(Expression<Action<TTarget, T1, T2, T3>> method)
    {
      return GetMethodInfo(method);
    }
 
    private static System.Reflection.MethodInfo GetMethodInfo(Expression method)
    {
      if (method == null) throw new ArgumentNullException("method");
 
      var lambda = method as LambdaExpression;
      if (lambda == null) throw new ArgumentException("Not a lambda expression", "method");
      if (lambda.Body.NodeType != ExpressionType.Call) throw new ArgumentException("Not a method call", "method");
 
      return ((MethodCallExpression)lambda.Body).Method;
    }
 
    public static PropertyInfo GetProperty(Expression<Func<TTarget, object>> property)
    {
      var info = GetMemberInfo(property) as PropertyInfo;
      if (info == null) throw new ArgumentException("Member is not a property");
 
      return info;
    }
 
    public static PropertyInfo GetProperty<P>(Expression<Func<TTarget, P>> property)
    {
      var info = GetMemberInfo(property) as PropertyInfo;
      if (info == null) throw new ArgumentException("Member is not a property");
 
      return info;
    }
 
    public static FieldInfo GetField(Expression<Func<TTarget, object>> field)
    {
      var info = GetMemberInfo(field) as FieldInfo;
      if (info == null) throw new ArgumentException("Member is not a field");
 
      return info;
    }
 
    private static MemberInfo GetMemberInfo(Expression member)
    {
      if (member == null) throw new ArgumentNullException("member");
 
      var lambda = member as LambdaExpression;
      if (lambda == null) throw new ArgumentException("Not a lambda expression", "member");
 
      MemberExpression memberExpr = null;
 
      // The Func<TTarget, object> we use returns an object, so first statement can be either 
      // a cast (if the field/property does not return an object) or the direct member access.
      if (lambda.Body.NodeType == ExpressionType.Convert)
      {
        // The cast is an unary expression, where the operand is the 
        // actual member access expression.
        memberExpr = ((UnaryExpression)lambda.Body).Operand as MemberExpression;
      }
      else if (lambda.Body.NodeType == ExpressionType.MemberAccess)
      {
        memberExpr = lambda.Body as MemberExpression;
      }
 
      if (memberExpr == null) throw new ArgumentException("Not a member access", "member");
 
      return memberExpr.Member;
    }
  }
}