We'll probably add binary comparison operators at some point, but this patch
also adds size_hint.zero() method. Otherwise, we'll have to write
"if(x.upper() && x.upper() == 0, ..)" to deal with None.
The resulting "branch list" template will look like:
```
separate(", ",
if(!ref.tracking_ahead_count().zero(),
if(ref.tracking_ahead_count().exact(),
"ahead by " ++ ref.tracking_ahead_count().exact() ++ " commits",
"ahead by at least " ++ ref.tracking_ahead_count().lower() ++ " commits")),
if(!ref.tracking_behind_count().zero(),
if(ref.tracking_behind_count().exact(),
"behind by " ++ ref.tracking_behind_count().exact() ++ " commits",
"behind by at least " ++ ref.tracking_behind_count().lower() ++ " commits")),
)
```
This is a remainder of the previous refactoring series. into_template() could be
implemented as a non-extension method, which allows us to get rid of .clone()
from Literal property extraction. However, there wasn't measurable difference.
Let's not try to overly optimize things. It's probably simpler to switch to
Rc<str> if .clone() really matters.
It's not uncommon to label the whole template output with command or template
name. If the output doesn't have to be captured, we can simply push the label
to the formatter. cmd_config_list() is an example of such cases, but it's also
migrated for consistency.
The idea is that, if .extract() succeeded in static context, it means the
property can be evaluated as constant. This will potentially eliminate
expect_string_literal_with(), though I'm not too sure if it's a good idea.
If needed, maybe we can extend the idea to suppress type/name resolution errors
by "if(some_static_config_knob, x, y)".
This allows us to propagate property evaluation error to a string property. For
instance, "s.contains(x ++ y)" will be an error if "y" failed to evaluate,
whereas bare "x ++ y" shouldn't.
The other implementation ideas:
a. add Template::into_string_property() to enable strict evaluation
=> it's tedious to implement it for each printable type
b. pass (formatter, error_handler) arguments separately
=> works, but most implementors don't need error_handler argument
c. pass strict=bool flag around build_*() functions
=> didn't tried, but it would be more complicated than this patch
Because Template trait is now implementation detail of the templater, it
should be okay to use a non-standard formatter wrapper.
This can be used to flatten nested "if()"s. It's not exactly the same as "case"
or "switch" expression, but works reasonably well in template. It's not uncommon
to show placeholder text in place of an empty content, and a nullish value
(e.g. empty string, list, option) is usually rendered as an empty text.
IntoTemplate will be cleaned up later. Perhaps, the lifetime parameter can be
removed at this point, but I'm planning to remove the IntoTemplate trait at all.
The type parameter 'C' will be removed from the Template trait, making it
represent a printable type or compiled template.
TemplateRenderer now holds Box<dyn _> template because it's unlikely that the
inner template type can be statically determined.
These two are common when implementing methods. Fortunately, the
"return-position impl Trait in traits" feature is stabilized in Rust 1.75.0,
so we don't need another variant of TemplateFunction.
Now a compiled template doesn't have a static Context type internally. A
property is basically of "Fn() -> Result<O, _>" type, and a type-erased "self"
variable will be injected as needed.
Template<C> types will be refactored separately.
The idea is basically the same as list.map(|x| ...) template. It compiles the
inner template with a placeholder variable of type 'C', and evaluate it for
each instance variable by injecting the variable through RefCell.
A runtime error will be printed inline. This simplifies error handling, and I
think it's better behavior overall. "jj log" won't be terminated just because
"gpg" crashed during signature verification for example. When property
evaluation failed, the error propagates to the closest template expression, and
the error message is printed there. Then, template output continues as long as
the output stream is open.
If we add revset() function for example, dynamic revset evaluation error will be
displayed inline. Static revset expression will still be processed at parsing
phase (to cache the evaluation result), and the error will be reported early.
One caveat: a string argument passed to e.g. .contains(needle) can be a
template, so the evaluation error would be swallowed there.
This patch also extracts format_detailed_signature() function to deduplicate
the "show" template bits.
The added placeholder templates aren't labeled as "empty". If needed, I think
the whole template can be labeled as "empty" (or "empty_commit") just like
"working_copy".
Closes#2112
Summary: In preparation for unifying all workspace dependencies across all
crates, let's go ahead and move the jj-cli crate into its own new directory.
This will also be a nicer and more uniform layout as we add new `jj-*` crates.
Signed-off-by: Austin Seipp <aseipp@pobox.com>
Change-Id: Icf94e7ae5f290dc8e181215727b38ada
