A Glimpse of the Revset Language

Important

You learn to describe sets of Changes, and how rebase couldn’t care less about their position.

With Git, you typically rebase entire branches. Jujutsu’s rebase makes no assumptions about what you want to move.

You saw how to move a single Change. You can just as easily move multiple Changes, by specifying them:

jj rebase -r X -r Y -o O

This moves both X and Y onto O. It doesn’t matter where they are: they can even be sparse!

Instead of listing Changes one by one, use the Revset Language. Here’s a taste:

X and Y don’t have to be single Changes; they can be sets themselves. Each expression returns a set, and you can recursively combine them. This expressiveness, along with custom functions, makes Revsets immensely more powerful than Git’s revspecs.

Moving Sets of Changes

Here’s a silly exercise: can you move sparse Changes too? Sure, why not! In fact, rebase works with whatever set of Changes you pass it.

Say that for some (odd) reason you want to move v, and yz on top of rt:

  m        ▢
○  qn       Add the CSS file **css***
○  rt       Link to CSS                        <-- here
│ ○  o        Play instructions **manual***
│ ○  kx       Play manual
├─╯
│ ○  zx       Click alternates Xs and Os **dev***
│ ○  v        Click sets a X                   <-- v
│ ○  s        Square has state
├─╯
○  qq       Fix
○  n        Square is interactive
○    ru       Board() invokes Square()
├─╮
○ │  ym       fix name: Square -> Board
○ │  ws       A board full of X
├─╯
○  kk       Displays X X **main***
○  wx       Fails
○  rx       Scaffold application
○  yz       LICENSE                            <-- yz
◆  zz   🔒  ▢

Warning

How would you do that in one shot?

Tip

Using a revset expression:

jj rebase -r 'yz | v' -o rt

@  m        ▢
○  qn       Add the CSS file css*
│ ○  v        Click sets a X                     <-- v
│ ○  yz       LICENSE                            <-- yz
├─╯
○  rt       Link to CSS                          <-- new base
│ ○  o        Play instructions manual*
│ ○  kx       Play manual
├─╯
~

Before the next page, undo that move:

jj undo

Feel free to spend some time moving sets of Changes around. Then pause and think how you’d do the same move in Git. it will always be technically possible just rarely this straightforward.