Add Buffer:extmark.

Author: Julian

lua/lean/infoview.lua

@@ -947,8 +947,7 @@ function Pin:__update_extmark_style(buffer, line, col)
       return
     end
     buffer = self.__extmark_buffer
-    local extmark_pos =
-      vim.api.nvim_buf_get_extmark_by_id(buffer.bufnr, self.__extmark_ns, self.__extmark, {})
+    local extmark_pos = buffer:extmark(self.__extmark_ns, self.__extmark, {})
     if vim.tbl_isempty(extmark_pos) then
       return
     end
@@ -996,8 +995,7 @@ function Pin:update_position()
     return
   end
 
-  local extmark_pos =
-    vim.api.nvim_buf_get_extmark_by_id(buffer.bufnr, self.__extmark_ns, extmark, {})
+  local extmark_pos = buffer:extmark(self.__extmark_ns, extmark, {})
 
   local new_pos = { line = extmark_pos[1] }
 

lua/std/nvim/buffer.lua

@@ -158,13 +158,28 @@ end
 ---See :h nvim_buf_get_extmarks for details.
 ---
 ---@param ns_id? integer
----@param start? integer| { [1]: integer, [2]: integer }
----@param end_? integer| { [1]: integer, [2]: integer }
+---@param start? integer|[integer, integer]
+---@param end_? integer|[integer, integer]
 ---@param opts? table
 function Buffer:extmarks(ns_id, start, end_, opts)
   return vim.api.nvim_buf_get_extmarks(self.bufnr, ns_id or -1, start or 0, end_ or -1, opts or {})
 end
 
+---Get a specific extmark by id from the buffer.
+---
+---See :h nvim_buf_get_extmark_by_id for details.
+---
+---Note in particular that if the extmark doesn't exist, an empty list is
+---returned.
+---
+---@param ns_id integer
+---@param id integer
+---@param opts? table
+---@return [integer, integer]|{}
+function Buffer:extmark(ns_id, id, opts)
+  return vim.api.nvim_buf_get_extmark_by_id(self.bufnr, ns_id, id, opts or {})
+end
+
 ---Set an extmark in the buffer.
 ---
 ---See :h nvim_buf_set_extmark for details.

spec/std/nvim/buffer_spec.lua

@@ -320,6 +320,23 @@ describe('Buffer', function()
     end)
   end)
 
+  describe('extmark', function()
+    it('gets a specific extmark by id', function()
+      local buffer = Buffer.create {}
+      buffer:set_lines { 'line' }
+      local ns = vim.api.nvim_create_namespace ''
+      local id = buffer:set_extmark(ns, 0, 0, {})
+      assert.are.same({ 0, 0 }, buffer:extmark(ns, id))
+      buffer:force_delete()
+    end)
+
+    it('returns empty table for a non-existent extmark', function()
+      local buffer = Buffer.create {}
+      local ns = vim.api.nvim_create_namespace ''
+      assert.are.same(buffer:extmark(ns, 99999), {})
+    end)
+  end)
+
   describe('clear_namespace', function()
     it('clears all extmarks in a namespace', function()
       local buffer = Buffer.create {}