jj/docs/templates.md

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 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 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.
• 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.
• .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.

New keywords and functions can be defined as aliases, by using any combination of the predefined keywords/functions and other aliases.

For example:

[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"'