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.
