; Update tree-sitter major mode manual

* doc/lispref/parsing.texi (Tree-sitter Major Modes): Update.
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Yuan Fu 2023-01-18 15:45:29 -08:00
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@ -1692,26 +1692,48 @@ integration for a major mode.
A major mode supporting tree-sitter features should roughly follow
this pattern:
@c FIXME: Update this part once we settle on the exact format.
@example
@group
(define-derived-mode woomy-mode prog-mode "Woomy"
"A mode for Woomy programming language."
;; Shared setup.
...
(cond
;; Tree-sitter setup.
((treesit-ready-p 'woomy)
(when (treesit-ready-p 'woomy)
(setq-local treesit-variables ...)
(treesit-major-mode-setup))
;; Non-tree-sitter setup.
(t
...)))
...
(treesit-major-mode-setup)))
@end group
@end example
First, the major mode should use @code{treesit-ready-p} to determine
whether tree-sitter can be activated in this mode.
@code{treesit-ready-p} automatically emits a warning if conditions for
enabling tree-sitter aren't met.
If a tree-sitter major mode shares setup with their ``native''
counterpart, they can create a ``base mode'' that contains the common
setup, like this:
@example
@group
(define-derived-mode woomy--base-mode prog-mode "Woomy"
"An internal mode for Woomy programming language."
(common-setup)
...)
@end group
@group
(define-derived-mode woomy-mode woomy--base-mode "Woomy"
"A mode for Woomy programming language."
(native-setup)
...)
@end group
@group
(define-derived-mode woomy-ts-mode woomy--base-mode "Woomy"
"A mode for Woomy programming language."
(when (treesit-ready-p 'woomy)
(setq-local treesit-variables ...)
...
(treesit-major-mode-setup)))
@end group
@end example
@defun treesit-ready-p language &optional quiet
This function checks for conditions for activating tree-sitter. It
@ -1722,15 +1744,12 @@ language grammar for @var{language} is available on the system
This function emits a warning if tree-sitter cannot be activated. If
@var{quiet} is @code{message}, the warning is turned into a message;
if @var{quiet} is @code{nil}, no warning or message is displayed.
if @var{quiet} is @code{t}, no warning or message is displayed.
If all the necessary conditions are met, this function returns
non-@code{nil}; otherwise it returns @code{nil}.
@end defun
Next, the major mode should set up tree-sitter variables and call
@code{treesit-major-mode-setup}.
@defun treesit-major-mode-setup
This function activates some tree-sitter features for a major mode.