improve adjustment of extmark-rgravs.

Both performance-wise, by eliding many, many adjustments, and
implementation-wise.

For example, as soon as a parent does not share an endpoint with the
node we want to focus, we don't have to touch its rgravs, since they can
only be pushed away from the inserted text, no matter their gravity.

lua/luasnip/init.lua

@@ -414,7 +414,7 @@ end
 
 local function active_update_dependents()
 	local active = session.current_nodes[vim.api.nvim_get_current_buf()]
-	-- special case for startNode, cannot enter_node on those (and they can't
+	-- special case for startNode, cannot focus on those (and they can't
 	-- have dependents)
 	-- don't update if a jump/change_choice is in progress.
 	if not session.jump_active and active and active.pos > 0 then
@@ -440,7 +440,7 @@ local function active_update_dependents()
 		end
 
 		-- 'restore' orientation of extmarks, may have been changed by some set_text or similar.
-		ok, err = pcall(active.parent.enter_node, active.parent, active.indx)
+		ok, err = pcall(active.focus, active)
 		if not ok then
 			log.warn(
 				"Error while entering node in snippet %s: %s",

lua/luasnip/nodes/choiceNode.lua

@@ -139,7 +139,7 @@ function ChoiceNode:input_enter(_, dry_run)
 	end
 
 	self.mark:update_opts(self.ext_opts.active)
-	self.parent:enter_node(self.indx)
+	self:focus()
 
 	self.prev_choice_node = session.active_choice_node
 	session.active_choice_node = self
@@ -254,9 +254,9 @@ function ChoiceNode:set_choice(choice, current_node)
 	--
 	-- active_choice has to be disabled (nilled?) to prevent reading from
 	-- cleared mark in set_mark_rgrav (which will be called in
-	-- parent:set_text(self,...) a few lines below).
+	-- self:set_text({""}) a few lines below).
 	self.active_choice = nil
-	self.parent:set_text(self, { "" })
+	self:set_text({ "" })
 
 	self.active_choice = choice
 
@@ -269,14 +269,19 @@ function ChoiceNode:set_choice(choice, current_node)
 	self:init_positions(self.absolute_position)
 	self:init_insert_positions(self.absolute_insert_position)
 
+	-- self is still focused, from `set_text`.
 	self.active_choice:put_initial(self.mark:pos_begin_raw())
+	-- adjust gravity in left side of inserted node, such that it matches the
+	-- current gravity of self.
+	local _, to = self.mark:pos_begin_end_raw()
+	self.active_choice:subtree_set_pos_rgrav(to, -1, true)
 
 	self.active_choice:update_restore()
 	self.active_choice:update_all_dependents()
 	self:update_dependents()
 
 	-- Another node may have been entered in update_dependents.
-	self.parent:enter_node(self.indx)
+	self:focus()
 	self:event(events.change_choice)
 
 	if self.restore_cursor then
@@ -339,15 +344,6 @@ function ChoiceNode:exit()
 	self.active = false
 end
 
--- val_begin/end may be nil, in this case that gravity won't be changed.
-function ChoiceNode:set_mark_rgrav(rgrav_beg, rgrav_end)
-	Node.set_mark_rgrav(self, rgrav_beg, rgrav_end)
-	-- may be set to temporarily in change_choice.
-	if self.active_choice then
-		self.active_choice:set_mark_rgrav(rgrav_beg, rgrav_end)
-	end
-end
-
 function ChoiceNode:set_ext_opts(name)
 	Node.set_ext_opts(self, name)
 
@@ -403,6 +399,20 @@ function ChoiceNode:static_init()
 	self.active_choice:static_init()
 end
 
+function ChoiceNode:subtree_set_pos_rgrav(pos, direction, rgrav)
+	self.mark:set_rgrav(-direction, rgrav)
+	if self.active_choice then
+		self.active_choice:subtree_set_pos_rgrav(pos, direction, rgrav)
+	end
+end
+
+function ChoiceNode:subtree_set_rgrav(rgrav)
+	self.mark:set_rgravs(rgrav, rgrav)
+	if self.active_choice then
+		self.active_choice:subtree_set_rgrav(rgrav)
+	end
+end
+
 return {
 	C = C,
 }

lua/luasnip/nodes/dynamicNode.lua

@@ -73,7 +73,7 @@ function DynamicNode:get_docstring()
 	return self.docstring
 end
 
--- DynamicNode's don't have static text, nop these.
+-- DynamicNode's don't have static text, only set as visible.
 function DynamicNode:put_initial(_)
 	self.visible = true
 end
@@ -136,10 +136,10 @@ function DynamicNode:update()
 		self.snip:exit()
 		self.snip = nil
 
-		-- enters node.
-		self.parent:set_text(self, { "" })
+		-- focuses node.
+		self:set_text({ "" })
 	else
-		self.parent:enter_node(self.indx)
+		self:focus()
 		if not args then
 			-- no snippet exists, set an empty one.
 			tmp = SnippetNode(nil, {})
@@ -184,8 +184,16 @@ function DynamicNode:update()
 	end
 	tmp:indent(self.parent.indentstr)
 
-	self.parent:enter_node(self.indx)
-	tmp:put_initial(self.mark:pos_begin_raw())
+	-- sets own extmarks false,true
+	self:focus()
+	local from, to = self.mark:pos_begin_end_raw()
+	-- inserts nodes with extmarks false,false
+	tmp:put_initial(from)
+	-- adjust gravity in left side of snippet, such that it matches the current
+	-- gravity of self.
+	tmp:subtree_set_pos_rgrav(to, -1, true)
+
+	self.snip = tmp
 
 	-- Update, tbh no idea how that could come in handy, but should be done.
 	-- Both are needed, because
@@ -194,7 +202,6 @@ function DynamicNode:update()
 	tmp:update()
 	tmp:update_all_dependents()
 
-	self.snip = tmp
 	self:update_dependents()
 end
 
@@ -293,13 +300,6 @@ function DynamicNode:update_static()
 	self:update_dependents_static()
 end
 
-function DynamicNode:set_mark_rgrav(val_begin, val_end)
-	Node.set_mark_rgrav(self, val_begin, val_end)
-	if self.snip then
-		self.snip:set_mark_rgrav(val_begin, val_end)
-	end
-end
-
 function DynamicNode:exit()
 	self.visible = false
 	self.mark:clear()
@@ -331,7 +331,6 @@ end
 function DynamicNode:update_restore()
 	-- only restore snippet if arg-values still match.
 	if self.stored_snip and vim.deep_equal(self:get_args(), self.last_args) then
-		-- prevent entering the uninitialized snip in enter_node in a few lines.
 		local tmp = self.stored_snip
 
 		tmp.mark =
@@ -347,8 +346,15 @@ function DynamicNode:update_restore()
 		tmp:set_dependents()
 		tmp:set_argnodes(self.parent.snippet.dependents_dict)
 
-		self.parent:enter_node(self.indx)
-		tmp:put_initial(self.mark:pos_begin_raw())
+		-- sets own extmarks false,true
+		self:focus()
+		-- inserts nodes with extmarks false,false
+		local from, to = self.mark:pos_begin_end_raw()
+		tmp:put_initial(from)
+		-- adjust gravity in left side of snippet, such that it matches the current
+		-- gravity of self.
+		tmp:subtree_set_pos_rgrav(to, -1, true)
+
 		tmp:update_restore()
 
 		self.snip = tmp
@@ -399,6 +405,20 @@ function DynamicNode:resolve_position(position)
 	return self.snip
 end
 
+function DynamicNode:subtree_set_pos_rgrav(pos, direction, rgrav)
+	self.mark:set_rgrav(-direction, rgrav)
+	if self.snip then
+		self.snip:subtree_set_pos_rgrav(pos, direction, rgrav)
+	end
+end
+
+function DynamicNode:subtree_set_rgrav(rgrav)
+	self.mark:set_rgravs(rgrav, rgrav)
+	if self.snip then
+		self.snip:subtree_set_rgrav(rgrav)
+	end
+end
+
 return {
 	D = D,
 }

lua/luasnip/nodes/functionNode.lua

@@ -48,8 +48,9 @@ function FunctionNode:update()
 	if vim.bo.expandtab then
 		util.expand_tabs(text, util.tab_width(), #self.parent.indentstr)
 	end
+
 	-- don't expand tabs in parent.indentstr, use it as-is.
-	self.parent:set_text(self, util.indent(text, self.parent.indentstr))
+	self:set_text(util.indent(text, self.parent.indentstr))
 	self:update_dependents()
 end
 
@@ -89,13 +90,13 @@ end
 function FunctionNode:update_restore()
 	-- only if args still match.
 	if self.static_text and vim.deep_equal(self:get_args(), self.last_args) then
-		self.parent:set_text(self, self.static_text)
+		self:set_text(self.static_text)
 	else
 		self:update()
 	end
 end
 
--- FunctionNode's don't have static text, nop these.
+-- FunctionNode's don't have static text, only set visibility.
 function FunctionNode:put_initial(_)
 	self.visible = true
 end

lua/luasnip/nodes/insertNode.lua

@@ -1,4 +1,5 @@
-local InsertNode = require("luasnip.nodes.node").Node:new()
+local Node = require("luasnip.nodes.node")
+local InsertNode = Node.Node:new()
 local ExitNode = InsertNode:new()
 local util = require("luasnip.util.util")
 local types = require("luasnip.util.types")
@@ -42,26 +43,46 @@ function ExitNode:input_enter(no_move, dry_run)
 		InsertNode.input_enter(self, no_move, dry_run)
 	else
 		-- -1-node:
-		self:set_mark_rgrav(true, true)
-		if not no_move then
-			local mark_begin_pos = self.mark:pos_begin_raw()
+		-- set rgrav true on left side of snippet. Text inserted now pushes the
+		-- snippet, and is not contained in it.
+		local begin_pos = self.mark:pos_begin_raw()
+		self.parent:subtree_set_pos_rgrav(begin_pos, 1, true)
 
+		if not no_move then
 			if vim.fn.mode() == "i" then
-				util.insert_move_on(mark_begin_pos)
+				util.insert_move_on(begin_pos)
 			else
 				vim.api.nvim_feedkeys(
 					vim.api.nvim_replace_termcodes("<Esc>", true, false, true),
 					"n",
 					true
 				)
-				util.normal_move_on_insert(mark_begin_pos)
+				util.normal_move_on_insert(begin_pos)
 			end
 		end
 
 		self:event(events.enter)
 	end
 end
 
+function ExitNode:focus()
+	local lrgrav, rrgrav
+	local snippet = self.parent
+	-- if last of first node of the snippet, make inserted text move out of snippet.
+	if snippet.nodes[#snippet.nodes] == self then
+		lrgrav = false
+		rrgrav = false
+	elseif snippet.nodes[1] == self then
+		lrgrav = true
+		rrgrav = true
+	else
+		lrgrav = false
+		rrgrav = true
+	end
+
+	Node.focus_node(self, lrgrav, rrgrav)
+end
+
 function ExitNode:input_leave(no_move, dry_run)
 	if dry_run then
 		return
@@ -111,9 +132,11 @@ function InsertNode:input_enter(no_move, dry_run)
 	self.visited = true
 	self.mark:update_opts(self.ext_opts.active)
 
-	if not no_move then
-		self.parent:enter_node(self.indx)
+	-- no_move only prevents moving the cursor, but the active node should
+	-- still be focused.
+	self:focus()
 
+	if not no_move then
 		-- SELECT snippet text only when there is text to select (more oft than not there isnt).
 		local mark_begin_pos, mark_end_pos = self.mark:pos_begin_end_raw()
 		if not util.pos_equal(mark_begin_pos, mark_end_pos) then
@@ -132,8 +155,6 @@ function InsertNode:input_enter(no_move, dry_run)
 				util.normal_move_on_insert(mark_begin_pos)
 			end
 		end
-	else
-		self.parent:enter_node(self.indx)
 	end
 
 	self:event(events.enter)