139 lines
5 KiB
EmacsLisp
139 lines
5 KiB
EmacsLisp
;; this is not an actual cursor, just a node.
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;; It’s not super efficient, but cursors can’t be *set* to an arbitrary
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;; subnode, because they can’t access the parent otherwise.
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;; We’d need a way to reset the cursor and walk down to the node?!
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(defvar-local tree-sitter-move--cursor nil
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"the buffer-local cursor used for movement")
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(defvar-local tree-sitter-move--debug-overlay nil
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"an overlay used to visually display the region currently marked by the cursor")
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;;;;; TODO: should everything use named nodes? Only some things?
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;;;;; maybe there should be a pair of functions for everything?
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;;;;; For now restrict to named nodes.
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(defun tree-sitter-move--setup ()
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;; TODO
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(progn
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;; TODO: if tree-sitter-mode fails to load, display a better error
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(tree-sitter-mode t)
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(setq tree-sitter-move--cursor (tsc-root-node tree-sitter-tree))
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(add-variable-watcher
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'tree-sitter-move--cursor
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#'tree-sitter-move--debug-overlay-update)))
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(defun tree-sitter-move--debug-overlay-update (sym newval &rest _args)
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"variable-watcher to update the debug overlay when the cursor changes"
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(let ((start (tsc-node-start-position newval))
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(end (tsc-node-end-position newval)))
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(symbol-macrolet ((o tree-sitter-move--debug-overlay))
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(if o
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(move-overlay o start end)
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(setq o (make-overlay start end))
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(overlay-put o 'face 'highlight)
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))))
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(defun tree-sitter-move--debug-overlay-teardown ()
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"Turn of the overlay visibility and delete the overlay object"
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(when tree-sitter-move--debug-overlay
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(delete-overlay tree-sitter-move--debug-overlay)
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(setq tree-sitter-move--debug-overlay nil)))
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(defun tree-sitter-move--teardown ()
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(setq tree-sitter-move--cursor nil)
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(tree-sitter-move--debug-overlay-teardown)
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(tree-sitter-mode nil))
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;; Get the syntax node the cursor is on.
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(defun tsc-get-named-node-at-point ()
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(let ((p (point)))
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(tsc-get-named-descendant-for-position-range
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(tsc-root-node tree-sitter-tree) p p)))
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;; TODO: is this function necessary?
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;; Maybe tree-sitter always guarantees that parents are named?
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(defun tsc-get-named-parent (node)
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(when-let ((parent (tsc-get-parent node)))
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(while (and parent (not (tsc-node-named-p parent)))
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(setq parent (tsc-get-parent parent)))
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parent))
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(defun tsc-get-first-named-node-with-siblings-up (node)
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"Returns the first 'upwards' node that has siblings. That includes the current
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node, so if the given node has siblings, it is returned. Returns nil if there
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is no such node until the root"
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(when-let ((has-siblings-p
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(lambda (parent-node)
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(> (tsc-count-named-children parent-node)
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1)))
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(cur node)
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(parent (tsc-get-named-parent node)))
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(while (and parent (not (funcall has-siblings-p parent)))
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(setq cur parent)
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(setq parent (tsc-get-named-parent cur)))
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cur))
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(defun tree-sitter-move--set-cursor-to-node (node)
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(setq tree-sitter-move--cursor node))
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(defun tree-sitter-move--set-cursor-to-node-at-point ()
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(tree-sitter-move--set-cursor-to-node (tsc-get-named-node-at-point)))
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(defun tree-sitter-move--move-point-to-node (node)
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(set-window-point
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(selected-window)
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(tsc-node-start-position node)))
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;; interactive commands (“do what I expect” section)
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(defun tree-sitter-move-reset ()
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(interactive)
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(tree-sitter-move--set-cursor-to-node-at-point))
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(defun tree-sitter-move-right ()
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(interactive)
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(tree-sitter-move--move-skip-non-sibling-nodes 'tsc-get-next-named-sibling))
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(defun tree-sitter-move-left ()
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(interactive)
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(tree-sitter-move--move-skip-non-sibling-nodes 'tsc-get-prev-named-sibling))
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(defun tree-sitter-move-up ()
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(interactive)
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(tree-sitter-move--move-skip-non-sibling-nodes 'tsc-get-parent))
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;; TODO: does not skip siblings yet, because the skip function only goes up (not down)
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(defun tree-sitter-move-down ()
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(interactive)
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(tree-sitter-move--move-if-possible (lambda (n) (tsc-get-nth-named-child n 0))))
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(defun tree-sitter-move--move-skip-non-sibling-nodes (move-fn)
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"Moves to the sidewards next sibling. If the current node does not have siblings, go
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upwards until something has siblings and then move to the side (right or left)."
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(tree-sitter-move--move-if-possible
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(lambda (cur)
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(when-let ((with-siblings
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(tsc-get-first-named-node-with-siblings-up cur)))
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(funcall move-fn with-siblings)))))
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(defun tree-sitter-move--move-if-possible (dir-fn)
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(let ((next (funcall dir-fn tree-sitter-move--cursor)))
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(when next
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(tree-sitter-move--set-cursor-to-node next)
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(tree-sitter-move--move-point-to-node next))))
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; mostly stolen from tree-sitter-mode
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;;;###autoload
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(define-minor-mode tree-sitter-move-mode
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"Minor mode to do cursor movements via tree-sitter"
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:init-value nil
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:lighter " tree-sitter-move"
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(if tree-sitter-move-mode
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(tree-sitter--error-protect
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(progn
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(tree-sitter-move--setup))
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(setq tree-sitter-move-mode nil)
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(tree-sitter-move--teardown))
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(lambda ())
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(tree-sitter-move--teardown)))
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