fix: Handle multi-byte characters for change/delete. (#318)

Resolves #317.

Author: kylechui

lua/nvim-surround/buffer.lua

@@ -139,14 +139,10 @@ M.get_first_byte = function(pos)
 end
 
 -- Gets the position of the last byte of a character, according to the UTF-8 standard.
----@param pos position|nil The position of the beginning of the character.
----@return position|nil @The position of the last byte of the character.
+---@param pos position The position of the beginning of the character.
+---@return position @The position of the last byte of the character.
 ---@nodiscard
 M.get_last_byte = function(pos)
-    if not pos then
-        return nil
-    end
-
     local byte = string.byte(M.get_line(pos[1]):sub(pos[2], pos[2]))
     if not byte then
         return pos

lua/nvim-surround/init.lua

@@ -130,9 +130,6 @@ M.visual_surround = function(args)
         end
 
         last_pos = buffer.get_last_byte(last_pos)
-        if not last_pos then
-            return
-        end
         buffer.insert_text({ last_pos[1], last_pos[2] + 1 }, delimiters[2])
         buffer.insert_text(first_pos, delimiters[1])
     end
@@ -257,6 +254,7 @@ M.normal_callback = function(mode)
         buffer.set_mark("]", last_pos)
     end
     -- Move the last position to the last byte of the character, if necessary
+    ---@diagnostic disable-next-line
     buffer.set_mark("]", buffer.get_last_byte(buffer.get_mark("]")))
 
     buffer.adjust_mark("[")

lua/nvim-surround/patterns.lua

@@ -30,6 +30,16 @@ M.pos_to_index = function(pos)
     return #table.concat(buffer.get_lines(1, pos[1] - 1), "\n") + pos[2] + 1
 end
 
+-- Expands a selection to properly contain multi-byte characters.
+---@param selection selection The given selection.
+---@return selection @The adjusted selection, handling multi-byte characters.
+---@nodiscard
+M.adjust_selection = function(selection)
+    selection.first_pos = buffer.get_first_byte(selection.first_pos)
+    selection.last_pos = buffer.get_last_byte(selection.last_pos)
+    return selection
+end
+
 -- Returns a selection in the buffer based on a Lua pattern.
 ---@param find string The Lua pattern to find in the buffer.
 ---@return selection|nil @The closest selection matching the pattern, if any.
@@ -58,10 +68,10 @@ M.get_selection = function(find)
     if not b_first or not b_last then
         return a_first
             and a_last
-            and {
+            and M.adjust_selection({
                 first_pos = M.index_to_pos(a_first),
                 last_pos = M.index_to_pos(a_last),
-            }
+            })
     end
     -- Adjust the selection character-wise
     local start_col, end_col = cursor_index, b_first
@@ -83,24 +93,24 @@ M.get_selection = function(find)
     end
     -- If the cursor is inside the range then return it
     if b_last and b_first and b_last >= cursor_index then
-        return {
+        return M.adjust_selection({
             first_pos = M.index_to_pos(b_first),
             last_pos = M.index_to_pos(b_last),
-        }
+        })
     end
     -- Else if there's a range found after the cursor, return it
     if a_first and a_last then
-        return {
+        return M.adjust_selection({
             first_pos = M.index_to_pos(a_first),
             last_pos = M.index_to_pos(a_last),
-        }
+        })
     end
     -- Otherwise return the range found before the cursor, if one exists
     if b_first and b_last then
-        return {
+        return M.adjust_selection({
             first_pos = M.index_to_pos(b_first),
             last_pos = M.index_to_pos(b_last),
-        }
+        })
     end
 end
 
@@ -142,14 +152,14 @@ M.get_selections = function(selection, pattern)
     local selections = {
         ---@cast first_index integer
         ---@cast last_index integer
-        left = {
+        left = M.adjust_selection({
             first_pos = M.index_to_pos(offset + first_index - left_len - 1),
             last_pos = M.index_to_pos(offset + first_index - 2),
-        },
-        right = {
+        }),
+        right = M.adjust_selection({
             first_pos = M.index_to_pos(offset + last_index - right_len - 1),
             last_pos = M.index_to_pos(offset + last_index - 2),
-        },
+        }),
     }
     -- Handle special case where the column is invalid
     if selections.left.last_pos[2] > #buffer.get_line(selections.left.last_pos[1]) then

tests/basics_spec.lua

@@ -614,6 +614,37 @@ describe("nvim-surround", function()
             "。(。。。)。",
             "𐍈𐍈𐍈(𐍈𐍈𐍈𐍈)𐍈𐍈𐍈",
         })
+
+        require("nvim-surround").setup({
+            surrounds = {
+                ["x"] = {
+                    add = { "‘", "’" },
+                    find = "‘[^‘’]*’",
+                },
+                ["y"] = {
+                    add = { "‘‘", "’’" },
+                    find = "‘‘[^‘’]*’’",
+                    delete = "^(‘‘)().-(’’)()$",
+                },
+            },
+        })
+        set_lines({
+            "‘foo bar’",
+        })
+        set_curpos({ 1, 5 })
+        vim.cmd("normal csx_")
+        check_lines({
+            "_foo bar_",
+        })
+
+        set_lines({
+            "‘‘foo bar baz’’",
+        })
+        set_curpos({ 1, 3 })
+        vim.cmd("normal dsy")
+        check_lines({
+            "foo bar baz",
+        })
     end)
 
     it("can properly use line-wise surrounds", function()