YAML mode tree sitter imenu

1 files changed, 72 insertions, 0 deletions

diff --git a/config/doom/config.org b/config/doom/config.org
index bec9fc0..6a2df58 100644
--- a/config/doom/config.org
+++ b/config/doom/config.org
@@ -604,6 +604,78 @@ Emacs mode for managing ledger text files
   :load-path "~/dev/emacs-lisp/emacs-libyaml/")
 
 (use-package! yaml)
+
+(after! yaml-mode
+  ;; Inspired by this blog post to use tree sitter to create a imenu list.
+  ;; https://blog.meain.io/2022/navigating-config-files-using-tree-sitter/
+  (defun on/ts-elements ()
+    "Tree sitter matches for all entries in data buffer."
+    (let ((query (thread-last
+                   (pcase major-mode
+                     ('json-mode "(object (pair (string (string_content) @key) (_)) @item)")
+                     ('yaml-mode "(block_mapping_pair (flow_node) @key (_)) @item"))
+                   (tsc-make-query tree-sitter-language)))
+          (root-node (tsc-root-node tree-sitter-tree)))
+      (tsc-query-matches query root-node #'tsc--buffer-substring-no-properties)))
+
+  (defun on/pos-items (ts-match)
+    "From a TS-MATCH get element key name and region in buffer."
+    (pcase-let ((`[(_ . ,item) (_ . ,key)] (cdr ts-match)))
+      (list
+       (tsc-node-text key)
+       (tsc-node-byte-range item)
+       ;; (destructuring-bind (s . e) (tsc-node-byte-range key)
+       ;;   (cons (byte-to-position s) (byte-to-position e)))
+       )))
+
+  (defun on/nested-item-names (items)
+    "From named ITEMS figure out the nested hierarchy for names."
+    (let ((node-stack '(("" 0)))
+          result)
+      (dolist (item items (nreverse result))
+        (pcase-let ((`(,item-name (,item-start . ,item-end)) item)
+                    (`((_ ,parent-end)) node-stack))
+          (when (< parent-end item-end)
+            (setq node-stack (seq-filter (lambda (y)
+                                           (<= item-end (cadr y)))
+                                         node-stack)))
+          (push (list item-name item-end) node-stack)
+          (push (list (nreverse (mapcar #'car node-stack))
+                      item-start)
+                result)))))
+
+  (defun on/imenu-nested-path-elements ()
+    "On a yaml or json buffer get the element positions for imenu."
+    (thread-last
+      (seq-map #'on/pos-items (on/ts-elements))
+      (on/nested-item-names)
+      (seq-map (lambda (item)
+                 (seq-let (name-chain start) item
+                   (cons (string-join name-chain ".") (byte-to-position start)))))))
+
+  (remove-hook 'yaml-mode-hook 'yaml-set-imenu-generic-expression) ;; don't use default one
+  (add-hook 'yaml-mode-hook
+            (lambda ()
+              (setq imenu-create-index-function #'on/imenu-nested-path-elements)))
+
+  (ert-deftest on/tree-sitter-imenu ()
+    "Test the imenu generation."
+    (with-temp-buffer
+      (yaml-mode)
+      (tree-sitter-mode)
+      (insert "one: Ñaño
+skills:
+  run: 3
+  jump:
+    high: 7
+    low: 2
+
+")
+      (should
+       (equal '(("one" . 1) ("skills" . 13) ("skills.run" . 23) ("skills.jump" . 32) ("skills.jump.high" . 43) ("skills.jump.low" . 55))
+              (on/imenu-nested-path-elements)))
+      ))
+  )
 #+end_src
 
 ** Databases