Swaparound Feature

lua/treewalker/nodes.lua

@@ -176,6 +176,22 @@ function M.next_sib(node)
   return node:next_named_sibling()
 end
 
+---@param node TSNode
+---@param fn function
+---@return TSNode | nil
+function M.farthest_sibling(node, fn)
+  if not node then return nil end
+
+  ---@type TSNode | nil
+  local iter = fn(node)
+
+  while iter do
+    node = iter
+    iter = fn(iter)
+  end
+  return node
+end
+
 -- Convenience for give me back prev sibling of a potentially nil node
 ---@param node TSNode | nil
 function M.prev_sib(node)

lua/treewalker/swap.lua

@@ -121,7 +121,7 @@ function M.swap_right()
   current = strategies.get_highest_string_node(current) or current
   current = nodes.get_highest_coincident(current)
 
-  local target = nodes.next_sib(current)
+  local target = nodes.next_sib(current) or nodes.farthest_sibling(current, nodes.prev_sib)
 
   if not current or not target then return end
 
@@ -158,7 +158,7 @@ function M.swap_left()
   current = strategies.get_highest_string_node(current) or current
   current = nodes.get_highest_coincident(current)
 
-  local target = nodes.prev_sib(current)
+  local target = nodes.prev_sib(current) or nodes.farthest_sibling(current, nodes.next_sib)
 
   if not current or not target then return end
 

tests/treewalker/c_sharp_spec.lua

@@ -41,4 +41,12 @@ describe("In a C Sharp file", function()
     assert.same(first_block, lines.get_lines(30, 48))
     h.assert_cursor_at(7, 5)
   end)
+
+  it("swaparound behavior works", function()
+    vim.fn.cursor(52, 31)
+    tw.swap_left()
+    assert.same("        public static int Add(int b, int a) => a + b;", lines.get_line(52))
+    tw.swap_right()
+    assert.same("        public static int Add(int a, int b) => a + b;", lines.get_line(52))
+  end)
 end)

tests/treewalker/c_spec.lua

@@ -52,4 +52,12 @@ describe("In a c file:", function()
     assert.same(first_block, lines.get_lines(68, 72))
     assert.same(second_block, lines.get_lines(63, 66))
   end)
+
+  it("swaparound behavior works", function()
+    vim.fn.cursor(11, 24)
+    tw.swap_left()
+    assert.same("Account* createAccount(float initialBalance, int accountNumber) {", lines.get_line(11))
+    tw.swap_right()
+    assert.same("Account* createAccount(int accountNumber, float initialBalance) {", lines.get_line(11))
+  end)
 end)

tests/treewalker/haskell_spec.lua

@@ -1,6 +1,7 @@
 local load_fixture = require "tests.load_fixture"
 local tw = require 'treewalker'
 local h = require 'tests.treewalker.helpers'
+local lines = require 'treewalker.lines'
 
 describe("In a haskell file: ", function()
   before_each(function()
@@ -27,6 +28,12 @@ describe("In a haskell file: ", function()
     tw.move_out()
     h.assert_cursor_at(19, 1)
   end)
-end)
-
 
+  it("swaparound behavior works", function()
+    vim.fn.cursor(40, 15)
+    tw.swap_left()
+    assert.same("  printEvens [9, 3, 5, 7, 1]", lines.get_line(40))
+    tw.swap_right()
+    assert.same("  printEvens [1, 3, 5, 7, 9]", lines.get_line(40))
+  end)
+end)

tests/treewalker/lua_spec.lua

@@ -321,6 +321,14 @@ describe("Swapping in a regular lua file:", function()
     apply_text_edits_stub:revert()
   end)
 
+  it("swaparound behavior works", function()
+    vim.fn.cursor(38, 32)
+    tw.swap_left()
+    assert.same("local function have_same_range(node2, node1)", lines.get_line(38))
+    tw.swap_right()
+    assert.same("local function have_same_range(node1, node2)", lines.get_line(38))
+  end)
+
   -- Actually I don't think this is supposed to work. It's ambiguous what
   -- node we're on. We'd need to do the lowest coincident that is the highest string
   -- or something.
@@ -341,4 +349,3 @@ describe("Swapping in a regular lua file:", function()
     assert.same("  print('one' .. 'two' .. 'three')", lines.get_line(188))
   end)
 end)
-

tests/treewalker/python_spec.lua

@@ -76,5 +76,12 @@ describe("In a python file: ", function()
     assert.same(bottom_before, lines.get_lines(118, 131))
     assert.same(top_before, lines.get_lines(135, 136))
   end)
-end)
 
+  it("swaparound feature works", function()
+    vim.fn.cursor(14, 18)
+    tw.swap_left()
+    assert.same("    def __init__(name, self):", lines.get_line(14))
+    tw.swap_right()
+    assert.same("    def __init__(self, name):", lines.get_line(14))
+  end)
+end)

tests/treewalker/ruby_spec.lua

@@ -39,5 +39,13 @@ describe("In a ruby file: ", function()
     assert.same(first_block, lines.get_lines(15, 19))
     h.assert_cursor_at(16, 3)
   end)
+
+  it("swaparound feature works", function()
+    vim.fn.cursor(40, 27)
+    tw.swap_left()
+    assert.same("  def process_transaction(callback = nil, amount)", lines.get_line(40))
+    tw.swap_right()
+    assert.same("  def process_transaction(amount, callback = nil)", lines.get_line(40))
+  end)
 end)