vim: make gf work for lua modules

config/nvim/lua/fschauen/autocmd.lua

@@ -23,6 +23,19 @@ M.setup = function()
     pattern = '*',
     callback = function(_) vim.opt.cursorlineopt = 'both' end
   })
+
+  local lua_go_to_file = function()
+    require('fschauen.util').edit_lua_module(vim.fn.expand('<cfile>'))
+  end
+
+  vim.api.nvim_create_autocmd('FileType', {
+    desc = 'Make `gf` work for lua modules.',
+    group = group,
+    pattern = 'lua',
+    callback = function (_)
+      vim.keymap.set('n', 'gf', lua_go_to_file, { buffer = 0 })
+    end
+  })
 end
 
 return M

config/nvim/lua/fschauen/util.lua

@@ -0,0 +1,47 @@
+local M = {}
+
+M.file_exists = function(path)
+  local stat = vim.loop.fs_stat(path)
+  return stat and stat.type == 'file'
+end
+
+M.edit_file = function(path)
+  if not pcall(vim.api.nvim_command, string.format('edit %s', path)) then
+    vim.notify('Could not open ' .. path, vim.log.levels.ERROR)
+  end
+end
+
+local find_module_source = function(modname)
+  modname = modname:gsub('^%.+', ''):gsub('/', '.')
+  local base = 'lua/' .. modname:gsub('%.', '/')
+  local candidates = { base .. '.lua', base .. '/init.lua' }
+
+  local results = {}
+  for _, directory in ipairs(vim.opt.runtimepath:get()) do
+    for _, candidate in ipairs(candidates) do
+      local path = directory .. '/' .. candidate
+      if M.file_exists(path) then
+        table.insert(results, path)
+      end
+    end
+  end
+  return results
+end
+
+M.edit_lua_module = function(modname)
+  local sources = find_module_source(modname)
+  if #sources == 0 then
+    vim.notify('Not found: ' .. modname, vim.log.levels.WARN)
+  elseif #sources == 1 then
+    M.edit_file(sources[1])
+  else
+    vim.ui.select(sources, { prompt = 'Which one?' }, function(choice)
+      if choice then
+        M.edit_file(choice)
+      end
+    end)
+  end
+end
+
+return M
+