kakoune/doc/pages/command-parsing.asciidoc

= Command Parsing

Kakoune commands, either loaded from a script or written in the command prompt, are parsed according to the following rules:

== Basic parsing

- Commands are delimited by a `;` or an end of line

- Words (command names and parameters) are delimited by whitespaces

== Quoted Strings

If a word starts with `'`, `"`, or `%X` with `X` a non-nestable punctuation character (see below for nestable characters),
it is parsed as a quoted string whose delimiter is, respectively, `'`, `"`, or `X`.

A quoted string contains every character (including whitespaces).  Doubling a closing delimiter escapes it.
Thus, for example, entering two closing delimiting characters at the end of a quoted string will render one of the characters literally;
that is, it will be considered as part of the quoted string's content.

Inside double quotes, `%`-strings are processed unless the `%` is escaped by doubling it.
Double quotes inside these nested strings must still be escaped.

No other escaping takes place in quoted strings.

=== Quoted Strings Examples

- `'foo'` contains *foo*

- `foo'bar'` is read verbatim, so it contains *foo'bar'*

- `foo%|bar|` is read verbatim, so it contains *foo%|bar|*.

- `'foo''bar'` is a single word whose content is *foo'bar*

- `"baz"""` is a single word whose content is *baz"*.

- `%|foo||bar|` is a single word whose content is *foo|bar*.

- `"foo %|""bar| %%,baz,"` is a single word whose content is *foo "bar %,baz,*.

== Balanced Strings

If a word starts with `%X` with `X` a nestable punctuation character (one of `(`, `[`, `{` and `<`),
it is parsed as a balanced string
whose closing delimiter matches that of its opening delimiter (respectively `)`, `]`, `}` and `>`).

Characters may be escaped in the same manner as those for quoted strings.

=== Balanced Strings Examples

- `%{foo}` contains *foo*

- `%{foo\{bar}}` contains *foo\{bar}*

- `foo%{bar}` contains *foo%{bar}*

- `"foo %{bar}"` is a single word whose content is *foo bar*

== Non Quoted words

Other words are non-quoted.
Non-quoted words end either at a whitespace or a `;`.

If they start with a `\` followed by a `%`, `'`, or `"`,
then that leading `\` escapes those characters and is discarded.

If a whitespace or `;` is preceded by a `\`,
then the `\` is discarded, and the whitespace or `;` becomes part of the word.
Any other `\` is treated as a literal `\`.

== Typed Expansions

Quoted and Balanced strings starting with `%` might have an optional alphabetic *expansion type* between the `%` and their delimiter
(which is always a punctuation character).
This *expansion type* defines how the string's content is going to be expanded.
Rules for expanding and escaping expansion types are the same as for `%`-strings.

- If the *expansion type* is empty, the string content is used verbatim.

- If the *expansion type* is one of `sh`, `reg`, `opt`, `val` or `arg`,
  The string is expanded as described in <<expansions#,`:doc expansions`>>

- For any other *expansion type* a parsing error is raised.