public static Expression <Func <T, T, bool> > comparisonGenerator <T>()
{
var ourType = typeof(T);
var members = ourType.GetMembers(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance).Where(x => x.CustomAttributes.Any(ca => ca.AttributeType == typeof(EquatableItemAttribute)));
var exprList = new List <BinaryExpression>(members.Count());
var param1 = Expression.Parameter(ourType);
var param2 = Expression.Parameter(ourType);
foreach (MemberInfo element in members)
{
BinaryExpression eq1 = null;
var accessor1 = Expression.PropertyOrField(param1, element.Name);
var accessor2 = Expression.PropertyOrField(param2, element.Name);
if (isString(element))
{
var compVal = Expression.Constant(element.GetCustomAttribute <EquatableItemAttribute>().StringComparison);
var stringCompare = typeof(string).GetMethod("Equals", BindingFlags.Static | BindingFlags.Public, null, new Type[] { typeof(string), typeof(string), typeof(StringComparison) }, null);
eq1 = Expression.Equal(Expression.Call(stringCompare, accessor1, accessor2, compVal), Expression.Constant(true));
}
else if (isEasyEquatable(element))
{
//Call our EasyEquatable method.
eq1 = Expression.Equal(Expression.Call(typeof(IEasyEquatableExtensions), "CompareEasyEquatable", new[] { MemberInfoHelpers.getType(element) }, accessor1, accessor2), Expression.Constant(true));
}
else if (isEquatable(element) && !isPrimitive(element))
{
//If here, we have Equatable
//(And aren't dealing with something so simple we should just fall-through.)
eq1 = Expression.Equal(Expression.Call(typeof(IEasyEquatableExtensions), "CompareEquatable", new[] { MemberInfoHelpers.getType(element) }, accessor1, accessor2), Expression.Constant(true));
}
//Default case: We just do Expression.Equals.
if (eq1 == null)
{
eq1 = Expression.Equal(accessor1, accessor2);
}
exprList.Add(eq1);
}
var currentExpr = exprList[0];
if (exprList.Count > 1)
{
for (int i = 1; i < exprList.Count; i++)
{
currentExpr = Expression.AndAlso(currentExpr, exprList[i]);
}
}
var compFunc = Expression.Lambda <Func <T, T, bool> >(currentExpr, param1, param2);
return(compFunc);
}
private static bool isPrimitive(MemberInfo element)
{
return(MemberInfoHelpers.getType(element).IsPrimitive);
}