This prepares for adding method arguments support. Since a method argument
should be evaluated in the surrounding scope, its type will be
'TemplateProperty<I>', not 'TemplateProperty<J>' for the receiver type 'J'.
Then, the receiver of type 'TemplateProperty<I, Output = J>', and arguments
of type 'TemplateProperty<I, Output = Pn>' will be composed to an input of
type 'TemplateProperty<I, Output = (J, Pn...)>'.
wrap_fn() is removed since it's only useful for nullary methods, and we
no longer need Box<dyn> to abstract the return value.
We'll probably need a better abstraction, but a parameterized keyword
function is a good first step. This unblocks the use of parse_term() for
context-less properties (or literals). I'm going to add a proper support
for context-aware method arguments, but literals can be parsed without it.
parse_keyword() closure is passed by reference to avoid infinite expansion.
I believe this isn't a good abstraction, but I need to add one more variant
for "at least n arguments" error. A stringified count like "2 to 3" could be
embedded in an error variant, but I don't think it's good idea to build error
message in that way.
Maybe I didn't make this change before because the closure needs to capture
WorkspaceId by value. Since the inlined version looks pretty simple, let's
go forward to do that.
Even though the template syntax is experimental, panicking parser makes
it difficult to write tests. So let's add minimal error handling. The error
types are basically copied from the revset module.
I made write_commit_summary() fall back to the default template if user
template had syntax error. It should be better than reporting parse error
after e.g. "jj abandon" finished successfully.
I have no idea whether or not any template expressions are intentionally
allowed as a label, but it makes sense to write something like
'label("phase-" phase, ...)' (if we had a phase keyword.) So I decided to
add .into_plain_text() instead of stricter .try_into_string().
Perhaps, non-trivial keywords can be extracted to free functions, and both
parsing and property functions can be eventually moved to a commit templater
module?
This allows us to merge parse_boolean_commit_property() into
parse_commit_term(). We'll probably need similar type coercion methods
for the other basic types.
I considered adding something like Property::Template(), which could be
reused for map operation (e.g. 'revset().map(commit_id).join(" ")'.)
However, a mapped commit template would be different from the top-level
commit template regarding the lifetime of the context.
"Expression::<Commit>::Template()" takes "for<'b> &'b Commit" as an argument,
whereas a mapped template property would capture Commit object somewhere.
Many template keywords and methods are one liners, and I think that's actually
good because writing tests for templater would be more involved than for pure
functions.
This patch introduces a wrapper for such one-line functions, and migrates
method parser to that. Some of the commit keyword structs can also be ported
to this wrapper.
Before, "f()" was parsed as a function call with one empty argument. In
practice, this change means "if(divergent,,false_template)" is no longer
valid.
Suppose "template" is a sequence of "term"s, it makes more sense to handle
an empty sequence there. It might be even better to disallow empty template
other than the top-level one.
A "list" is a sequence of more than one "term" nodes, so it shouldn't contain
a single parenthesized node.
Also, a parenthesized "term" rule wasn't handled.
A method call is typically parsed as (obj.meth)(), not as obj.(meth()),
but the latter is good enough for our needs. It's unlikely we'll add a
first-class function support.
.into_inner().next().unwrap() mess will be cleaned up by the next commit.
This basically removes 'a lifetime from these wrappers, and add trait bounds
instead. I have no idea which version would look less scary, but let's see.
I also added trait bounds to constructor functions. They aren't strictly
required, but help type inference of closure (and will probably improve
an error message.)
When implementing FormattablePropertyTemplate, I tried a generic 'property: P'
first, and I couldn't figure out how to constrain the output type.
impl<C, O, P> Template<C> for FormattablePropertyTemplate<P>
where
P: TemplateProperty<C, O>, // 'O' isn't constrained by type
O: Template<()>,
According to the book, the problem is that we can add multiple implementations
of 'TemplateProperty<C, *>'. Since TemplateProperty is basically a function
to extract data from 'C', I think the output parameter shouldn't be freely
chosen.
https://doc.rust-lang.org/book/ch19-03-advanced-traits.html
With this change, I can express the type constraint as follows:
impl<C, P> Template<C> for FormattablePropertyTemplate<P>
where
P: TemplateProperty<C>,
P::Output: Template<()>,
Now we have 'impl Template<()> for String', 'LiteralTemplate(String)' is
a bit redundant. Let's generalize it for any 'Template<()>'. I noticed
'ConstantTemplateProperty' serves as a similar role, so unified these.
I think this is a remainder of 68ad712e12 "Templater: Combine Change and
Commit id templates." It doesn't make sense that description.short() prints
the first 12 characters.
This creates a templater function `short_underscore_prefix` for commit and
change ids. It is similar to `short` function, but shows one fewer hexadecimal
digit and inserts an underscore after the shortest unique prefix.
Highlighting with an underline and perhaps color/bold will be in a follow-up
PR.
The implementation is quadratic, a simple comparison of each id with every
other id. It is replaced in a subsequent commit. The problem with it is that,
while it works fine for a `jj`-sized repo, it becomes is painfully slow with a
repo the size of git/git.
Still, this naive implemenation is included here since it's simple, and could
be used as a reference implementation.
The `shortest_unique_prefix_length` function goes into `repo.rs` since that's
convenient for follow-up commits in this PR to have nicer diffs.
