bug#60407: [PATCH] Update go-ts-mode to use Imenu facility

[Evgeni Kolev]

To illustrate the change, here's a comparison before VS after (VS eglot).

I'm using a sample .go file (at the bottom of this mail).

Before:
     4 candidates:
         Function: measure
         Type: geometry
         Type: rect
         Type: circle

After:
     8 candidates:
         Function: measure
         Type: geometry
         Type: rect
         Type: circle
         Method: area
         Method: perim
         Method: area
         Method: perim

For comparison, here's eglot's Imenu (using Go's gopls language server):
     13 candidates:
         Interface: geometry
         Struct: rect
         Struct: circle
         Field.rect: width
         Field.rect: height
         Field.circle: radius
         Method.geometry: area
         Method.geometry: perim
         Method: (rect).area
         Method: (rect).perim
         Method: (circle).area
         Method: (circle).perim
         Function: measure

Sample .go file:

> type geometry interface {
>     area() float64
>     perim() float64
> }
>
> type rect struct {
>     width, height float64
> }
>
> type circle struct {
>     radius float64
> }
>
> func (r rect) area() float64 {
>     return r.width * r.height
> }
>
> func (r rect) perim() float64 {
>     return 2*r.width + 2*r.height
> }
>
> func (c circle) area() float64 {
>     return math.Pi * c.radius * c.radius
> }
>
> func (c circle) perim() float64 {
>     return 2 * math.Pi * c.radius
> }
>
> func measure(g geometry) {
>     fmt.Println(g)
>     fmt.Println(g.area())
>     fmt.Println(g.perim())
> }

On Sun, Jan 1, 2023 at 11:07 AM Eli Zaretskii <eliz@gnu.org> wrote:
>
> > From: Evgeni Kolev <evgenysw@gmail.com>
> > Date: Thu, 29 Dec 2022 18:05:49 +0200
> >
> > This patch updates go-ts-mode to use Imenu facility added in
> > https://git.savannah.gnu.org/cgit/emacs.git/commit/?h=emacs-29&id=b39dc7ab27a696a8607ab859aeff3c71509231f5
> >
> > The Imenu items are extended to support "Method", in addition to
> > "Function" and "Type".
> >
> > The current Imenu approach uses "type_spec" to identify "Type" which
> > acts as a catch-all for many Go constructs, for example struct and
> > interface definitions. This catch-all approach is not optimal because
> > structs and interfaces are put in the same "Type" bucket. In a
> > follow-up patch I'll try to change the approach and have separate
> > "Interface" and "Struct" types.
> >
> > The patch is below.
>
> Randy, Yuan, are you looking into this?
>
> > commit 71ff7b21fe92167313bd1761b68b6e6fd879b09f
> > Author: Evgeni Kolev <evgenysw@gmail.com>
> > Date:   Thu Dec 29 17:49:40 2022 +0200
> >
> >     Update go-ts-mode to use Imenu facility
> >
> >     go-ts-mode is updated to use the Imenu facility added in commit
> >     b39dc7ab27a696a8607ab859aeff3c71509231f5.
> >
> >     The Imenu items are extended to support "Method", in addition to
> >     "Function" and "Type".
> >
> >     * lisp/progmodes/go-ts-mode.el (go-ts-mode--imenu-1) 
> > (go-ts-mode--imenu):
> >     Remove functions.
> >     (go-ts-mode--defun-name): New function.
> >
> > diff --git a/lisp/progmodes/go-ts-mode.el b/lisp/progmodes/go-ts-mode.el
> > index 124d9b044a2..c6c1c61d9f4 100644
> > --- a/lisp/progmodes/go-ts-mode.el
> > +++ b/lisp/progmodes/go-ts-mode.el
> > @@ -173,44 +173,6 @@ go-ts-mode--font-lock-settings
> >     '((ERROR) @font-lock-warning-face))
> >    "Tree-sitter font-lock settings for `go-ts-mode'.")
> >
> > -(defun go-ts-mode--imenu ()
> > -  "Return Imenu alist for the current buffer."
> > -  (let* ((node (treesit-buffer-root-node))
> > -         (func-tree (treesit-induce-sparse-tree
> > -                     node "function_declaration" nil 1000))
> > -         (type-tree (treesit-induce-sparse-tree
> > -                     node "type_spec" nil 1000))
> > -         (func-index (go-ts-mode--imenu-1 func-tree))
> > -         (type-index (go-ts-mode--imenu-1 type-tree)))
> > -    (append
> > -     (when func-index `(("Function" . ,func-index)))
> > -     (when type-index `(("Type" . ,type-index))))))
> > -
> > -(defun go-ts-mode--imenu-1 (node)
> > -  "Helper for `go-ts-mode--imenu'.
> > -Find string representation for NODE and set marker, then recurse
> > -the subtrees."
> > -  (let* ((ts-node (car node))
> > -         (children (cdr node))
> > -         (subtrees (mapcan #'go-ts-mode--imenu-1
> > -                           children))
> > -         (name (when ts-node
> > -                 (treesit-node-text
> > -                  (pcase (treesit-node-type ts-node)
> > -                    ("function_declaration"
> > -                     (treesit-node-child-by-field-name ts-node "name"))
> > -                    ("type_spec"
> > -                     (treesit-node-child-by-field-name ts-node "name"))))))
> > -         (marker (when ts-node
> > -                   (set-marker (make-marker)
> > -                               (treesit-node-start ts-node)))))
> > -    (cond
> > -     ((or (null ts-node) (null name)) subtrees)
> > -     (subtrees
> > -      `((,name ,(cons name marker) ,@subtrees)))
> > -     (t
> > -      `((,name . ,marker))))))
> > -
> >  ;;;###autoload
> >  (add-to-list 'auto-mode-alist '("\\.go\\'" . go-ts-mode))
> >
> > @@ -228,9 +190,18 @@ go-ts-mode
> >      (setq-local comment-end "")
> >      (setq-local comment-start-skip (rx "//" (* (syntax whitespace))))
> >
> > +    ;; Navigation.
> > +    (setq-local treesit-defun-type-regexp
> > +                (regexp-opt '("method_declaration"
> > +                              "function_declaration"
> > +                              "type_spec")))
> > +    (setq-local treesit-defun-name-function #'go-ts-mode--defun-name)
> > +
> >      ;; Imenu.
> > -    (setq-local imenu-create-index-function #'go-ts-mode--imenu)
> > -    (setq-local which-func-functions nil)
> > +    (setq-local treesit-simple-imenu-settings
> > +                `(("Function" "\\`function_declaration\\'" nil nil)
> > +                  ("Type" "\\`type_spec\\'" nil nil)
> > +                  ("Method" "\\`method_declaration\\'" nil nil)))
> >
> >      ;; Indent.
> >      (setq-local indent-tabs-mode t
> > @@ -247,6 +218,18 @@ go-ts-mode
> >
> >      (treesit-major-mode-setup)))
> >
> > +(defun go-ts-mode--defun-name (node)
> > +  "Return the defun name of NODE.
> > +Return nil if there is no name or if NODE is not a defun node."
> > +  (pcase (treesit-node-type node)
> > +    ((or "function_declaration"
> > +         "method_declaration"
> > +         "type_spec")
> > +     (treesit-node-text
> > +      (treesit-node-child-by-field-name
> > +       node "name")
> > +      t))))
> > +
> >  ;; go.mod support.
> >
> >  (defvar go-mod-ts-mode--syntax-table
> >
> >
> >
> >