Moving the selection with syntax-aware motions
Alt-p
, Alt-o
, Alt-i
, and Alt-n
(or Alt
and arrow keys) allow you to move the
selection according to its location in the syntax tree. For example, many languages have the
following syntax for function calls:
func(arg1, arg2, arg3);
A function call might be parsed by tree-sitter into a tree like the following.
(call
function: (identifier) ; func
arguments:
(arguments ; (arg1, arg2, arg3)
(identifier) ; arg1
(identifier) ; arg2
(identifier))) ; arg3
Use :tree-sitter-subtree
to view the syntax tree of the primary selection. In
a more intuitive tree format:
┌────┐
│call│
┌─────┴────┴─────┐
│ │
┌─────▼────┐ ┌────▼────┐
│identifier│ │arguments│
│ "func" │ ┌────┴───┬─────┴───┐
└──────────┘ │ │ │
│ │ │
┌─────────▼┐ ┌────▼─────┐ ┌▼─────────┐
│identifier│ │identifier│ │identifier│
│ "arg1" │ │ "arg2" │ │ "arg3" │
└──────────┘ └──────────┘ └──────────┘
If you have a selection that wraps arg1
(see the tree above), and you use
Alt-n
, it will select the next sibling in the syntax tree: arg2
.
// before
func([arg1], arg2, arg3)
// after
func(arg1, [arg2], arg3);
Similarly, Alt-o
will expand the selection to the parent node, in this case, the
arguments node.
func[(arg1, arg2, arg3)];
There is also some nuanced behavior that prevents you from getting stuck on a
node with no sibling. When using Alt-p
with a selection on arg1
, the previous
child node will be selected. In the event that arg1
does not have a previous
sibling, the selection will move up the syntax tree and select the previous
element. As a result, using Alt-p
with a selection on arg1
will move the
selection to the "func" identifier
.