Convert lambda expressions to SQL in an ORM?

How could I write an ORM that would convert LINQ into SQL?

I already have made an existing ORM, but I want to improve it with LINQ, so that I, for instance would be able to say:

MyORMObject.GetAll(o => o.firstName == "peter");

The idea in my head is that the system would then take that and convert it in开发者_运维知识库to a query. I guess the hard part is to read the stuff parsed into the LINQ part.

How do I do this? In other words, how would I (through Reflection or something else) read the FirstName property being used, and its desired match, "Peter"?

---

You are going to need to implement an IQueryable LINQ Provider. You won't be using reflection by the way, you'll be using Expression trees.

---

If your method is IEnumerable<T> GetAll<T>(Expression<Func<T,bool>>), then the lambda expression will be compiled as an expression tree, with an Equals sub-expression, which in turn has a MemberExpression containing the FirstName property, and a ConstantExpression containing the string.