swapping trunk and branch

[Ben Carbery]

Hi,
I am fairly new to version control, and have made what is probably a
newbie mistake.
I created a branch and switched to it. Later I committed changes that
were meant for trunk, forgetting that I had switched to the branch. So
I want to undo this, without losing the changes..
What is the correct way to 'swap' the branch and the trunk. I am
confused about whether I should be using copy, merge or some other
technique.
cheers!
B