Daniel Shahaf <[email protected]> writes: > My own answer to "how to change Ev2 to enable representing rotate(A,A/B/C)": > > I think the above means we have to modify move() to use SRC arguments > relative to the start state of the edited tree, rather than to its > current state.
> If we do that, we could represent your commit as: > mv(A/B/C, A); mv(A/B, A/B); mv(A, A/B/C);. > > While we're making changes, I wonder if we should nuke rotate(). I have > several reasons: I've been thinking of that as well. rotate was not it the first draft of Ev2, it was added when I asked how to order the moves in a swap. You have ordered these "start state" moves by depth order of the destination, which seems reasonable. I think that implies that the destination refers to the current state which is the same as the final state. So the pair mv(A, B) ; mv(X, B/Y) has to be in that order while the pair mv(A/P, A/Q) ; mv(B/S, B/T) could be in any order. The two moves that make up a swap: mv(A, B) ; mv(B, A) or mv(A/X, B/C/Y) ; mv(B/C/Y, A/X) can usually be in any order (except for the unusual case such as A/B/C above). For a swap/rotate the receiver is responsible for doing something to enable the moves to occur. I suppose different receivers could do different things. The driver knows when mv(A,B) is part of a rotate and when it is just a move. Perhaps it should distinguish the two and communicate this so the receiver knows as well? -- Philip Martin | Subversion Committer WANdisco | Non-Stop Data www.wandisco.com
