The `heads()` revset function with one argument is the counterpart to
`roots()`. Without arguments, it returns the visible heads in the
repo, i.e. `heads(all())`. The two use cases are quite different, and
I think it would be good to clarify that the no-arg form returns the
visible heads, so let's split that out to a new `visible_heads()`
function.
This serves the role of limit() in Mercurial. Since revsets in JJ is
(conceptually) an unordered set, a "limit" predicate should define its
ordering criteria. That's why the added predicate is named as "latest".
Closes#1110
- branches has the signature branches([needle]), meaning the needle is optional (branches() is equivalent to branches("")) and it matches all branches whose name contains needle as a substring
- remote_branches has the signature remote_branches([branch_needle[, remote_needle]]), meaning it can be called with no arguments, or one argument (in which case, it's similar to branches), or two arguments where the first argument matches branch names and the second argument matches remote names (similar to branches, remote_branches(), remote_branches("") and remote_branches("", "") are all equivalent)
Because a unary negation node '~y' is more primitive than the corresponding
difference node 'x~y', '~y' is easier to deal with while rewriting the tree.
That's the main reason to add RevsetExpression::NotIn node.
As we have a NotIn node, it makes sense to add an operator for that. This
patch reuses '~' token, which I feel intuitive since the other set operators
looks like bitwise ops. Another option is '!'.
The unary '~' operator has the highest precedence among the set operators,
but they are lower than the ranges. This might be counter intuitive, but
useful because a prefix range ':x' can be negated without parens.
Maybe we can remove the redundant infix operator 'x ~ y', but it isn't
decided yet.
Function parameters are processed as local symbols while substituting
alias expression. This isn't as efficient as Mercurial which caches
a tree of fully-expanded function template, but that wouldn't matter in
practice.
Because the use of the change id is recommended, any operation should abort
if a valid change id happens to match a commit id. We still try the commit
id lookup first as the change id lookup is more costly.
Ambiguous change/commit id is reported as AmbiguousCommitIdPrefix for now.
Maybe we can merge AmbiguousCommit/ChangeIdPrefix errors into one?
Closes#799
Aliases are loaded at WorkspaceCommandHelper::new() as it's easier to warn
invalid declarations there. Not all commands use revsets, but many do, so
I think it's okay to always pay the loading cost. Parsing the declaration
part (i.e. a symbol) should be fast anyway.
The nested error message isn't super readable, but seems good enough.
Config syntax to bikeshed:
- naming: [revset-alias] vs [revset-aliases] ?
- function alias will need quotes: 'f(x)' = 'x'
The expression 'x ~ empty()' is identical to 'x & file(".")', but more
intuitive.
Note that 'x ~ empty()' is slower than 'x & file(".")' since the negative
intersection isn't optimized right now. I think that can be handled as
follows: 'x ~ filter(f)' -> 'x & filter(!f)' -> 'filter(!f, x)'
Since 'merges()' just filters the candidates set per item, it doesn't need
a candidates argument. Perhaps, 'merges(x)' could be a predicate to select
merge commits within a subgraph 'x', but I don't know if that would be
useful.
We have supported multiple workspaces for six months now, but I forgot
to remove a note in the revset doc saying that we don't support
it. Also update the text to descibe how to refer to the working-copy
commit in another workspace.
This introduces a `connected(x)` function, which is simply the same as
`x:x`. It's occasionally useful if `x` is a long expression. It's also
useful as a building block for `root(x)` (coming soon).
It makes sense to omit either of the arguments of the `..` operator,
even though `..x` is equivalent to `:x`. `x..`, with a implied right
argument of `heads()` is more useful.
