feat: add disable_max_lines option (#37)

README.md

@@ -213,6 +213,9 @@ vim.g.aerial = {
   -- different buffer in the way of the preferred direction
   default_direction = "prefer_right",
 
+  -- Disable aerial on files with this many lines
+  disable_max_lines = 10000,
+
   -- A list of all symbols to display. Set to false to display all symbols.
   filter_kind = {
     "Class",
@@ -225,7 +228,7 @@ vim.g.aerial = {
   },
 
   -- Enum: split_width, full_width, last, none
-  -- Determines line highlighting mode when multiple buffers are visible
+  -- Determines line highlighting mode when multiple splits are visible
   highlight_mode = "split_width",
 
   -- When jumping to a symbol, highlight the line for this many ms

lua/aerial/backends/init.lua

@@ -7,8 +7,17 @@ M.get_backend_by_name = function(name)
 end
 
 M.is_supported = function(bufnr, name)
+  local max_lines = config.disable_max_lines
+  if max_lines and max_lines > 0 and vim.api.nvim_buf_line_count(bufnr) > max_lines then
+    return false, "File exceeds disable_max_lines size"
+  end
   local backend = M.get_backend_by_name(name)
-  return backend and backend.is_supported(bufnr)
+  if backend then
+    local supported, err = backend.is_supported(bufnr)
+    return supported, err
+  else
+    return false, "No such backend"
+  end
 end
 
 local attach_callbacks = {}
@@ -20,11 +29,11 @@ local function get_best_backend(bufnr)
   if not bufnr or bufnr == 0 then
     bufnr = vim.api.nvim_get_current_buf()
   end
+
   local candidates = config.backends(bufnr)
   for _, name in ipairs(candidates) do
-    local backend = M.get_backend_by_name(name)
-    if backend and backend.is_supported(bufnr) then
-      return backend, name
+    if M.is_supported(bufnr, name) then
+      return M.get_backend_by_name(name), name
     end
   end
   return nil, nil
@@ -115,7 +124,7 @@ M.attach = function(bufnr, refresh)
 end
 
 -- Backends must provide the following methods:
--- is_supported(bufnr)
+-- is_supported(bufnr) -> bool, err
 -- fetch_symbols_sync(timeout)
 -- fetch_symbols()
 -- attach(bufnr)

lua/aerial/backends/lsp/init.lua

@@ -81,7 +81,15 @@ M.is_supported = function(bufnr)
   if not bufnr or bufnr == 0 then
     bufnr = vim.api.nvim_get_current_buf()
   end
-  return is_lsp_attached(bufnr)
+  if not is_lsp_attached(bufnr) then
+    for _, client in pairs(vim.lsp.buf_get_clients(bufnr)) do
+      if client.resolved_capabilities.document_symbol then
+        return false, "LSP client not attached (did you call aerial.on_attach?)"
+      end
+    end
+    return false, "LSP client not attached"
+  end
+  return true, nil
 end
 
 M.on_attach = function(client, bufnr, opts)

lua/aerial/backends/markdown.lua

@@ -5,7 +5,10 @@ local util = require("aerial.util")
 local M = {}
 
 M.is_supported = function(bufnr)
-  return vim.tbl_contains(util.get_filetypes(bufnr), "markdown")
+  if not vim.tbl_contains(util.get_filetypes(bufnr), "markdown") then
+    return false, "Filetype is not markdown"
+  end
+  return true, nil
 end
 
 M.fetch_symbols_sync = function(timeout)

lua/aerial/backends/treesitter/init.lua

@@ -7,14 +7,17 @@ local M = {}
 M.is_supported = function(bufnr)
   local ok, parsers = pcall(require, "nvim-treesitter.parsers")
   if not ok then
-    return false
+    return false, "nvim-treesitter not found"
   end
   local lang = parsers.get_buf_lang(bufnr)
   if not parsers.has_parser(lang) then
-    return false
+    return false, string.format("No treesitter parser for %s", lang)
   end
   local query = require("nvim-treesitter.query")
-  return query.has_query_files(lang, "aerial")
+  if not query.has_query_files(lang, "aerial") then
+    return false, string.format("No query file for '%s'", lang)
+  end
+  return true, nil
 end
 
 M.fetch_symbols_sync = function(timeout)

lua/aerial/config.lua

@@ -21,6 +21,9 @@ local default_options = {
   -- different buffer in the way of the preferred direction
   default_direction = "prefer_right",
 
+  -- Disable aerial on files with this many lines
+  disable_max_lines = 10000,
+
   -- A list of all symbols to display. Set to false to display all symbols.
   filter_kind = {
     "Class",
@@ -33,7 +36,7 @@ local default_options = {
   },
 
   -- Enum: split_width, full_width, last, none
-  -- Determines line highlighting mode when multiple buffers are visible
+  -- Determines line highlighting mode when multiple splits are visible
   highlight_mode = "split_width",
 
   -- When jumping to a symbol, highlight the line for this many ms

lua/aerial/init.lua

@@ -175,10 +175,11 @@ M.info = function()
   print("Configured backends:")
   for _, name in ipairs(config.backends(0)) do
     local line = "  " .. name
-    if backends.is_supported(0, name) then
+    local supported, err = backends.is_supported(0, name)
+    if supported then
       line = line .. " (supported)"
     else
-      line = line .. " (not supported)"
+      line = line .. " (not supported) [" .. err .. "]"
     end
     if backends.is_backend_attached(0, name) then
       line = line .. " (attached)"