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Use defconst for a defvar & a constant predicate function. Allow toggling format on save. #53

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Use defconst for a defvar & a constant predicate function. Allow toggling format on save. #53

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7838919
Use defconst for a defvar and a predicate function.
pierre-rouleau Oct 6, 2025
46346ed
Add ability to toggle format on save inside an Emacs session.
pierre-rouleau Oct 6, 2025
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34 changes: 24 additions & 10 deletions gleam-ts-mode.el
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Original file line number Diff line number Diff line change
Expand Up @@ -83,19 +83,21 @@ A change to this setting only takes effect the next time the
'((t (:inherit font-lock-variable-name-face)))
"Font used for highlighting Gleam modules.")

(defvar gleam-ts--grammar-revision
(defconst gleam-ts--grammar-revision
(if (and (treesit-available-p) (< (treesit-library-abi-version) 15))
"v1.0.0"
"main")
"Treesitter grammar (gleam-lang/tree-sitter-gleam repo) revision.")

(defun gleam-ts--grammar-supports-echo-keyword-p ()
"Determines whether grammar library version supports the `echo' keyword."
(defconst gleam-ts--grammar-supports-echo-keyword-p
(let ((version-p (string-match-p "^v?[0-9]+\\(\\.[0-9]+\\)*$" gleam-ts--grammar-revision)))
(if version-p
(let ((version (string-trim-left gleam-ts--grammar-revision "v")))
(not (version< version "1.1.0")))
t)))
t))
"Grammar library version supports the `echo' keyword when t.
Does not otherwise.
The grammar library version is held in `gleam-ts--grammar-revision'.")

(defvar gleam-ts--font-lock-settings
(treesit-font-lock-rules
Expand Down Expand Up @@ -176,7 +178,7 @@ A change to this setting only takes effect the next time the
"type"
"use"
])
(keywords (if (gleam-ts--grammar-supports-echo-keyword-p)
(keywords (if gleam-ts--grammar-supports-echo-keyword-p
(append basic-keywords '("echo"))
basic-keywords)))
(list keywords '@font-lock-keyword-face))
Expand Down Expand Up @@ -232,7 +234,8 @@ A change to this setting only takes effect the next time the
"}"
"<<"
">>"
] @font-lock-bracket-face)
]
@font-lock-bracket-face)

:feature 'delimiter
:language 'gleam
Expand All @@ -247,7 +250,8 @@ A change to this setting only takes effect the next time the
".."
"-"
"<-"
] @font-lock-delimiter-face)))
]
@font-lock-delimiter-face)))

(defvar gleam-ts--indent-rules
(let ((offset 'gleam-ts-indent-offset))
Expand Down Expand Up @@ -419,6 +423,15 @@ Please update `gleam-ts-gleam-executable' customizable user-option"
node
(lambda (child) (equal (treesit-node-type child) "type_name"))))))

(defun gleam-ts--format-on-save-maybe ()
"Run gleam format on save if currently requested.
Check the current value of `gleam-ts-format-on-save' and format only when it
currently is non-nil. This extra checking allows the user to dynamically turn
this on and off, regardless of the persistent value of
`gleam-ts-format-on-save' user-option."
(when gleam-ts-format-on-save
(gleam-ts-format)))


;;; Major mode definition
;;;###autoload
Expand Down Expand Up @@ -468,9 +481,10 @@ Please update `gleam-ts-gleam-executable' customizable user-option"
(rx (* (syntax whitespace))
(group (or (syntax comment-end) "\n"))))

;; Activate format on save if requested by customization.
(when gleam-ts-format-on-save
(add-hook 'before-save-hook #'gleam-ts-format nil 'local))
;; Activate format on save if *currently* requested by customization.
;; Always add the hook; the hooked function checks the current value of
;; `gleam-ts-format-on-save' to decide whether formatting should be done.
(add-hook 'before-save-hook #'gleam-ts--format-on-save-maybe nil 'local)

(treesit-major-mode-setup))
(t
Expand Down