refactor: utility methods return nilable integer instead of -1 sentinel value

lua/aerial/autocommands.lua

@@ -22,7 +22,7 @@ local function should_close_aerial(aer_win)
 
   -- Close the aerial window if its attached buffer is unsupported
   if config.close_automatic_events.unsupported then
-    if not vim.api.nvim_buf_is_valid(src_buf) or not backends.get(src_buf) then
+    if not src_buf or not vim.api.nvim_buf_is_valid(src_buf) or not backends.get(src_buf) then
       return true
     end
   end

lua/aerial/backends/init.lua

@@ -108,7 +108,9 @@ local function attach(bufnr, backend, name)
     local loading = require("aerial.loading")
     local util = require("aerial.util")
     local aer_bufnr = util.get_aerial_buffer(bufnr)
-    loading.set_loading(aer_bufnr, not data.has_received_data(bufnr))
+    if aer_bufnr then
+      loading.set_loading(aer_bufnr, not data.has_received_data(bufnr))
+    end
 
     -- On first attach, fetch symbols from ALL possible backends so that they will race and the
     -- fastest provider will display symbols (instead of just waiting for the prioritized backend
@@ -179,7 +181,10 @@ M.set_symbols = function(bufnr, items, ctx)
   end
 
   data.set_symbols(bufnr, items)
-  loading.set_loading(util.get_aerial_buffer(bufnr), false)
+  local aer_bufnr = util.get_aerial_buffer(bufnr)
+  if aer_bufnr then
+    loading.set_loading(aer_bufnr, false)
+  end
 
   render.update_aerial_buffer(bufnr)
   window.update_all_positions(bufnr, 0)

lua/aerial/data.lua

@@ -17,14 +17,13 @@ local config = require("aerial.config")
 ---@field parent? aerial.Symbol
 ---@field selection_range? aerial.Range
 ---@field children? aerial.Symbol[]
----@field scope? string
 
 ---@class aerial.BufData
 ---@field bufnr integer
 ---@field items aerial.Symbol[]
 ---@field flat_items aerial.Symbol[]
 ---@field positions any
----@field last_win integer
+---@field last_win nil|integer
 ---@field collapsed table<string, boolean>
 ---@field collapse_level integer
 ---@field max_level integer
@@ -37,7 +36,7 @@ function BufData.new(bufnr)
     items = {},
     flat_items = {},
     positions = {},
-    last_win = -1,
+    last_win = nil,
     collapsed = {},
     collapse_level = 99,
   }
@@ -148,7 +147,7 @@ function BufData:visit(callback)
   end
 end
 
----@param include_hidden boolean
+---@param opts nil|{skip_hidden: nil|boolean}
 ---@return integer
 function BufData:count(opts)
   opts = vim.tbl_extend("keep", opts or {}, {
@@ -181,6 +180,9 @@ end
 function M.get_or_create(buf)
   buf = buf or 0
   local bufnr, _ = util.get_buffers(buf)
+  if not bufnr then
+    error("Could not find source buffer")
+  end
   local bufdata = buf_to_symbols[bufnr]
   if not bufdata then
     bufdata = BufData.new(bufnr)
@@ -237,7 +239,7 @@ function M.has_received_data(bufnr)
 end
 
 ---Return true if the buffer has any symbols
----@param bufnr integer
+---@param bufnr nil|integer
 ---@return boolean
 function M.has_symbols(bufnr)
   local bufdata = M.get(bufnr)

lua/aerial/loading.lua

@@ -3,10 +3,14 @@ local M = {}
 
 local timers = {}
 
+---@param aer_bufnr integer
+---@return boolean
 M.is_loading = function(aer_bufnr)
   return timers[aer_bufnr] ~= nil
 end
 
+---@param aer_bufnr integer
+---@param is_loading boolean
 M.set_loading = function(aer_bufnr, is_loading)
   if is_loading then
     if timers[aer_bufnr] == nil then

lua/aerial/navigation.lua

@@ -6,8 +6,9 @@ local window = require("aerial.window")
 local M = {}
 
 local function _get_current_lnum(winid)
+  ---@type nil|integer
   local bufnr = vim.api.nvim_get_current_buf()
-  if data.has_symbols(bufnr) then
+  if bufnr and data.has_symbols(bufnr) then
     local bufdata = data.get_or_create(bufnr)
     local cached_lnum = bufdata.positions[winid]
     if cached_lnum then
@@ -18,7 +19,7 @@ local function _get_current_lnum(winid)
   if util.is_aerial_buffer(bufnr) then
     bufnr = util.get_source_buffer()
   end
-  if data.has_symbols(bufnr) then
+  if bufnr and data.has_symbols(bufnr) then
     return window.get_position_in_win(bufnr, winid)
   else
     return nil
@@ -197,6 +198,9 @@ M.select = function(opts)
     return
   end
   local bufnr, _ = util.get_buffers()
+  if not bufnr then
+    error("Could not find source buffer")
+  end
   M.select_symbol(item, winid, bufnr, opts)
 end
 

lua/aerial/render.lua

@@ -78,7 +78,7 @@ M.update_aerial_buffer = function(buf)
     return
   end
   local bufnr, aer_bufnr = util.get_buffers(buf)
-  if aer_bufnr == -1 or loading.is_loading(aer_bufnr) then
+  if not bufnr or not aer_bufnr or loading.is_loading(aer_bufnr) then
     resize_all_wins(aer_bufnr)
     return
   end
@@ -203,7 +203,7 @@ M.update_highlights = function(buf)
     return
   end
   local bufnr, aer_bufnr = util.get_buffers(buf)
-  if not data.has_symbols(bufnr) or aer_bufnr == -1 then
+  if not bufnr or not data.has_symbols(bufnr) or not aer_bufnr then
     return
   end
   local bufdata = data.get_or_create(bufnr)
@@ -251,17 +251,19 @@ M.update_highlights = function(buf)
     M.clear_highlights(bufnr)
     local cursor = vim.api.nvim_win_get_cursor(0)
     local item = data.get_or_create(0):item(cursor[1])
-    vim.api.nvim_buf_add_highlight(bufnr, ns, "AerialLine", item.lnum - 1, 0, -1)
+    if item then
+      vim.api.nvim_buf_add_highlight(bufnr, ns, "AerialLine", item.lnum - 1, 0, -1)
+    end
   end
 end
 
 ---@param bufnr integer
+---@return integer
 M.clear_highlights = function(bufnr)
-  if not vim.api.nvim_buf_is_valid(bufnr) then
-    return
-  end
   local ns = vim.api.nvim_create_namespace("aerial-line")
-  vim.api.nvim_buf_clear_namespace(bufnr, ns, 0, -1)
+  if vim.api.nvim_buf_is_valid(bufnr) then
+    vim.api.nvim_buf_clear_namespace(bufnr, ns, 0, -1)
+  end
   return ns
 end
 

lua/aerial/tree.lua

@@ -131,11 +131,11 @@ M.toggle = function(opts)
 end
 
 ---Set the collapse level of the symbol tree
----@param bufnr integer
+---@param bufnr nil|integer
 ---@param level integer 0 is all closed, use 99 to open all
 M.set_collapse_level = function(bufnr, level)
   bufnr = util.get_buffers(bufnr or 0)
-  if not data.has_symbols(bufnr) then
+  if not bufnr or not data.has_symbols(bufnr) then
     return
   end
   local bufdata = data.get_or_create(bufnr)
@@ -148,7 +148,7 @@ M.set_collapse_level = function(bufnr, level)
       end, vim.api.nvim_list_wins())
     else
       local source_win = util.get_winids(0)
-      if vim.api.nvim_win_get_buf(source_win) == bufnr then
+      if source_win and vim.api.nvim_win_get_buf(source_win) == bufnr then
         wins = { source_win }
       else
         wins = util.get_fixed_wins(bufnr)

lua/aerial/util.lua

@@ -141,6 +141,9 @@ M.get_source_win = function(winid)
   return M.get_winid_from_var(winid or 0, "source_win")
 end
 
+---@param bufnr nil|integer
+---@return nil|integer Source buffer
+---@return nil|integer Aerial buffer
 M.get_buffers = function(bufnr)
   if bufnr == nil or bufnr == 0 then
     bufnr = vim.api.nvim_get_current_buf()
@@ -152,18 +155,25 @@ M.get_buffers = function(bufnr)
   end
 end
 
+---@param bufnr nil|integer
+---@return nil|integer
 M.get_aerial_buffer = function(bufnr)
   return M.get_buffer_from_var(bufnr or 0, "aerial_buffer")
 end
 
+---@param bufnr nil|integer
+---@return nil|integer
 M.get_source_buffer = function(bufnr)
   return M.get_buffer_from_var(bufnr or 0, "source_buffer")
 end
 
+---@param bufnr integer
+---@param varname string
+---@return nil|integer
 M.get_buffer_from_var = function(bufnr, varname)
   local status, result_bufnr = pcall(vim.api.nvim_buf_get_var, bufnr, varname)
   if not status or result_bufnr == nil or not vim.api.nvim_buf_is_valid(result_bufnr) then
-    return -1
+    return nil
   end
   return result_bufnr
 end

lua/aerial/window.lua

@@ -112,7 +112,7 @@ local function create_aerial_window(bufnr, aer_bufnr, direction, existing_win)
     error("Expected direction to be 'left', 'right', or 'float'")
   end
 
-  if aer_bufnr == -1 then
+  if not aer_bufnr then
     aer_bufnr = create_aerial_buffer(bufnr)
   end
 
@@ -183,7 +183,7 @@ M.open_aerial_in_win = function(src_bufnr, src_winid, aer_winid)
     vim.api.nvim_win_set_var(src_winid, "aerial_win", aer_winid)
     return
   end
-  if aer_bufnr == -1 then
+  if not aer_bufnr then
     aer_bufnr = create_aerial_buffer(src_bufnr)
   end
   local my_winid = vim.api.nvim_get_current_win()
@@ -200,7 +200,7 @@ end
 ---@return integer|nil
 local function get_aerial_win_for_buf(bufnr)
   local aer_bufnr = util.get_aerial_buffer(bufnr)
-  if aer_bufnr ~= -1 then
+  if aer_bufnr then
     return util.buf_first_win_in_tabpage(aer_bufnr)
   end
 end
@@ -462,7 +462,7 @@ M.update_position = function(winids, last_focused_win)
   end
   local win_bufnr = vim.api.nvim_win_get_buf(winids[1])
   local bufnr = util.get_buffers(win_bufnr)
-  if not data.has_symbols(bufnr) then
+  if not bufnr or not data.has_symbols(bufnr) then
     return
   end
   if util.is_aerial_buffer(win_bufnr) then
@@ -498,9 +498,10 @@ M.update_position = function(winids, last_focused_win)
   end
 end
 
+---@param buffer nil|integer
 M.center_symbol_in_view = function(buffer)
   local bufnr, aer_bufnr = util.get_buffers(buffer)
-  if not data.has_symbols(bufnr) then
+  if not bufnr or not data.has_symbols(bufnr) or not aer_bufnr then
     return
   end
   local bufdata = data.get_or_create(bufnr)
@@ -512,9 +513,11 @@ M.center_symbol_in_view = function(buffer)
       local max_topline = vim.api.nvim_buf_line_count(aer_bufnr) - height
       local topline = math.max(1, math.min(max_topline, lnum - math.floor(height / 2)))
       local aerial_win = util.buf_first_win_in_tabpage(aer_bufnr)
-      vim.api.nvim_win_call(aerial_win, function()
-        vim.fn.winrestview({ lnum = lnum, topline = topline })
-      end)
+      if aerial_win then
+        vim.api.nvim_win_call(aerial_win, function()
+          vim.fn.winrestview({ lnum = lnum, topline = topline })
+        end)
+      end
     end
   end
 end

lua/resession/extensions/aerial.lua

@@ -5,14 +5,28 @@ M.on_load = function() end
 
 M.is_win_supported = function(winid, bufnr)
   local util = require("aerial.util")
-  return util.is_aerial_buffer(bufnr)
+  if not util.is_aerial_buffer(bufnr) then
+    return false
+  end
+  local source_win = util.get_source_win(winid)
+  local source_buf = util.get_source_buffer(bufnr)
+  return source_win
+    and vim.api.nvim_win_is_valid(source_win)
+    and source_buf
+    and vim.api.nvim_buf_is_valid(source_buf)
 end
 
 M.save_win = function(winid)
   local util = require("aerial.util")
   local source_win = util.get_source_win(winid)
+  if not source_win then
+    error("Source winid is nil")
+  end
   local rel_nr = vim.api.nvim_win_get_number(source_win) - vim.api.nvim_win_get_number(winid)
   local bufnr = util.get_source_buffer(vim.api.nvim_win_get_buf(winid))
+  if not bufnr or not vim.api.nvim_buf_is_valid(bufnr) then
+    error("Source buffer is nil")
+  end
   return {
     rel_nr = rel_nr,
     bufname = vim.api.nvim_buf_get_name(bufnr),