lua: Add paths from &runtimepath to package.path and package.cpath

1 files changed, 56 insertions, 1 deletions

diff --git a/src/nvim/lua/vim.lua b/src/nvim/lua/vim.lua
index 8d1c5bdf4f..736182de11 100644
--- a/src/nvim/lua/vim.lua
+++ b/src/nvim/lua/vim.lua
@@ -1,2 +1,57 @@
 -- TODO(ZyX-I): Create compatibility layer.
-return {}
+--{{{1 package.path updater function
+-- Last inserted paths. Used to clear out items from package.[c]path when they
+-- are no longer in &runtimepath.
+local last_nvim_paths = {}
+local function _update_package_paths()
+  local cur_nvim_paths = {}
+  local rtps = vim.api.nvim_list_runtime_paths()
+  local sep = package.config:sub(1, 1)
+  for _, key in ipairs({'path', 'cpath'}) do
+    local orig_str = package[key] .. ';'
+    local pathtrails = {}
+    local pathtrails_ordered = {}
+    local orig = {}
+    -- Note: ignores trailing item without trailing `;`. Not using something
+    -- simpler in order to preserve empty items (stand for default path).
+    for s in orig_str:gmatch('[^;]*;') do
+      s = s:sub(1, -2)  -- Strip trailing semicolon
+      orig[#orig + 1] = s
+      -- Find out path patterns. pathtrail should contain something like
+      -- /?.so, /?/init.lua, /?.lua. This allows not to bother determining what
+      -- correct suffixes are.
+      local pathtrail = s:match('[/\\][^/\\]*%?.*$')
+      if pathtrail and not pathtrails[pathtrail] then
+        pathtrails[pathtrail] = true
+        pathtrails_ordered[#pathtrails_ordered + 1] = pathtrail
+      end
+    end
+    local new = {}
+    for _, rtp in ipairs(rtps) do
+      if not rtp:match(';') then
+        for _, pathtrail in pairs(pathtrails_ordered) do
+          local new_path = rtp .. sep .. 'lua' .. pathtrail
+          -- Always keep paths from &runtimepath at the start:
+          -- append them here disregarding orig possibly containing one of them.
+          new[#new + 1] = new_path
+          cur_nvim_paths[new_path] = true
+        end
+      end
+    end
+    for _, orig_path in ipairs(orig) do
+      -- Handle removing obsolete paths originating from &runtimepath: such
+      -- paths either belong to cur_nvim_paths and were already added above or
+      -- to last_nvim_paths and should not be added at all if corresponding
+      -- entry was removed from &runtimepath list.
+      if not (cur_nvim_paths[orig_path] or last_nvim_paths[orig_path]) then
+        new[#new + 1] = orig_path
+      end
+    end
+    package[key] = table.concat(new, ';')
+  end
+  last_nvim_paths = cur_nvim_paths
+end
+--{{{1 Module definition
+return {
+  _update_package_paths = _update_package_paths,
+}