jj/docs/templates.md
Yuya Nishihara a2a9b7decb templater: add coalesce() function that selects first non-empty content
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.
2024-03-28 10:51:47 +09:00

244 lines
7.8 KiB
Markdown

# Templates
Jujutsu supports a functional language to customize output of commands.
The language consists of literals, keywords, operators, functions, and
methods.
A couple of `jj` commands accept a template via `-T`/`--template` option.
## Keywords
Keywords represent objects of different types; the types are described in
a follow-up section. In addition to context-specific keywords, the top-level
object can be referenced as `self`.
### Commit keywords
In `jj log`/`jj obslog` templates, all 0-argument methods of [the `Commit`
type](#commit-type) are available as keywords. For example, `commit_id` is
equivalent to `self.commit_id()`.
### Operation keywords
In `jj op log` templates, all 0-argument methods of [the `Operation`
type](#operation-type) are available as keywords. For example,
`current_operation` is equivalent to `self.current_operation()`.
## Operators
The following operators are supported.
* `x.f()`: Method call.
* `-x`: Negate integer value.
* `!x`: Logical not.
* `x && y`: Logical and, short-circuiting.
* `x || y`: Logical or, short-circuiting.
* `x ++ y`: Concatenate `x` and `y` templates.
## Global functions
The following functions are defined.
* `fill(width: Integer, content: Template) -> Template`: Fill lines at
the given `width`.
* `indent(prefix: Template, content: Template) -> Template`: Indent
non-empty lines by the given `prefix`.
* `label(label: Template, content: Template) -> Template`: Apply label to
the content. The `label` is evaluated as a space-separated string.
* `if(condition: Boolean, then: Template[, else: Template]) -> Template`:
Conditionally evaluate `then`/`else` template content.
* `coalesce(content: Template...) -> Template`: Returns the first **non-empty**
content.
* `concat(content: Template...) -> Template`:
Same as `content_1 ++ ... ++ content_n`.
* `separate(separator: Template, content: Template...) -> Template`:
Insert separator between **non-empty** contents.
* `surround(prefix: Template, suffix: Template, content: Template) -> Template`:
Surround **non-empty** content with texts such as parentheses.
## Types
### Boolean type
No methods are defined. Can be constructed with `false` or `true` literal.
### Commit type
This type cannot be printed. The following methods are defined.
* `description() -> String`
* `change_id() -> ChangeId`
* `commit_id() -> CommitId`
* `parents() -> List<Commit>`
* `author() -> Signature`
* `committer() -> Signature`
* `working_copies() -> String`: For multi-workspace repository, indicate
working-copy commit as `<workspace name>@`.
* `current_working_copy() -> Boolean`: True for the working-copy commit of the
current workspace.
* `branches() -> List<RefName>`: Local and remote branches pointing to the commit.
A tracking remote branch will be included only if its target is different
from the local one.
* `local_branches() -> List<RefName>`: All local branches pointing to the commit.
* `remote_branches() -> List<RefName>`: All remote branches pointing to the commit.
* `tags() -> List<RefName>`
* `git_refs() -> List<RefName>`
* `git_head() -> Option<RefName>`
* `divergent() -> Boolean`: True if the commit's change id corresponds to multiple
visible commits.
* `hidden() -> Boolean`: True if the commit is not visible (a.k.a. abandoned).
* `immutable() -> Boolean`: True if the commit is included in [the set of
immutable commits](config.md#set-of-immutable-commits).
* `conflict() -> Boolean`: True if the commit contains merge conflicts.
* `empty() -> Boolean`: True if the commit modifies no files.
* `root() -> Boolean`: True if the commit is the root commit.
### CommitId / ChangeId type
The following methods are defined.
* `.short([len: Integer]) -> String`
* `.shortest([min_len: Integer]) -> ShortestIdPrefix`: Shortest unique prefix.
### Integer type
No methods are defined.
### List type
A list can be implicitly converted to `Boolean`. The following methods are
defined.
* `.len() -> Integer`: Number of elements in the list.
* `.join(separator: Template) -> Template`: Concatenate elements with
the given `separator`.
* `.map(|item| expression) -> ListTemplate`: Apply template `expression`
to each element. Example: `parents.map(|c| c.commit_id().short())`
### ListTemplate type
The following methods are defined. See also the `List` type.
* `.join(separator: Template) -> Template`
### Operation type
This type cannot be printed. The following methods are defined.
* `current_operation() -> Boolean`
* `description() -> String`
* `id() -> OperationId`
* `tags() -> String`
* `time() -> TimestampRange`
* `user() -> String`
* `root() -> Boolean`: True if the commit is the root commit.
### OperationId type
The following methods are defined.
* `.short([len: Integer]) -> String`
### Option type
An option can be implicitly converted to `Boolean` denoting whether the
contained value is set. If set, all methods of the contained value can be
invoked. If not set, an error will be reported inline on method call.
### RefName type
The following methods are defined.
* `.name() -> String`: Local branch or tag name.
* `.remote() -> String`: Remote name or empty if this is a local ref.
### ShortestIdPrefix type
The following methods are defined.
* `.prefix() -> String`
* `.rest() -> String`
* `.upper() -> ShortestIdPrefix`
* `.lower() -> ShortestIdPrefix`
### Signature type
The following methods are defined.
* `.name() -> String`
* `.email() -> String`
* `.username() -> String`
* `.timestamp() -> Timestamp`
### String type
A string can be implicitly converted to `Boolean`. The following methods are
defined.
* `.len() -> Integer`: Length in UTF-8 bytes.
* `.contains(needle: Template) -> Boolean`
* `.first_line() -> String`
* `.lines() -> List<String>`: Split into lines excluding newline characters.
* `.upper() -> String`
* `.lower() -> String`
* `.starts_with(needle: Template) -> Boolean`
* `.ends_with(needle: Template) -> Boolean`
* `.remove_prefix(needle: Template) -> String`: Removes the passed prefix, if present
* `.remove_suffix(needle: Template) -> String`: Removes the passed suffix, if present
* `.substr(start: Integer, end: Integer) -> String`: Extract substring. The
`start`/`end` indices should be specified in UTF-8 bytes. Negative values
count from the end of the string.
#### String literals
String literals must be surrounded by double quotes (`"`). The following escape
sequences starting with a backslash have their usual meaning: `\"`, `\\`, `\n`,
`\r`, `\t`, `\0`. Other escape sequences are not supported. Any UTF-8 characters
are allowed inside a string literal, with two exceptions: unescaped `"`-s and
uses of `\` that don't form a valid escape sequence.
### Template type
Most types can be implicitly converted to `Template`. No methods are defined.
### Timestamp type
The following methods are defined.
* `.ago() -> String`: Format as relative timestamp.
* `.format(format: String) -> String`: Format with [the specified strftime-like
format string](https://docs.rs/chrono/latest/chrono/format/strftime/).
* `.utc() -> Timestamp`: Convert timestamp into UTC timezone.
* `.local() -> Timestamp`: Convert timestamp into local timezone.
### TimestampRange type
The following methods are defined.
* `.start() -> Timestamp`
* `.end() -> Timestamp`
* `.duration() -> String`
## Configuration
The default templates and aliases() are defined in the `[templates]` and
`[template-aliases]` sections of the config respectively. The exact definitions
can be seen in the `cli/src/config/templates.toml` file in jj's source tree.
<!--- TODO: Find a way to embed the default config files in the docs -->
New keywords and functions can be defined as aliases, by using any
combination of the predefined keywords/functions and other aliases.
For example:
```toml
[template-aliases]
'commit_change_ids' = '''
concat(
format_field("Commit ID", commit_id),
format_field("Change ID", commit_id),
)
'''
'format_field(key, value)' = 'key ++ ": " ++ value ++ "\n"'
```