1 files changed, 64 insertions, 1 deletions
diff --git a/runtime/lua/vim/shared.lua b/runtime/lua/vim/shared.lua
index a71e9878bb..1bf1c63fd7 100644
--- a/runtime/lua/vim/shared.lua
+++ b/runtime/lua/vim/shared.lua
@@ -20,6 +20,11 @@ vim.deepcopy = (function()
   local deepcopy_funcs = {
     table = function(orig)
       local copy = {}
+
+      if vim._empty_dict_mt ~= nil and getmetatable(orig) == vim._empty_dict_mt then
+        copy = vim.empty_dict()
+      end
+
       for k, v in pairs(orig) do
         copy[vim.deepcopy(k)] = vim.deepcopy(v)
       end
@@ -130,6 +135,36 @@ function vim.tbl_values(t)
   return values
 end
 
+--- Apply a function to all values of a table.
+---
+--@param func function or callable table
+--@param t table
+function vim.tbl_map(func, t)
+  vim.validate{func={func,'c'},t={t,'t'}}
+
+  local rettab = {}
+  for k, v in pairs(t) do
+    rettab[k] = func(v)
+  end
+  return rettab
+end
+
+--- Filter a table using a predicate function
+---
+--@param func function or callable table
+--@param t table
+function vim.tbl_filter(func, t)
+  vim.validate{func={func,'c'},t={t,'t'}}
+
+  local rettab = {}
+  for _, entry in pairs(t) do
+    if func(entry) then
+      table.insert(rettab, entry)
+    end
+  end
+  return rettab
+end
+
 --- Checks if a list-like (vector) table contains `value`.
 ---
 --@param t Table to check
@@ -169,9 +204,19 @@ function vim.tbl_extend(behavior, ...)
   if (behavior ~= 'error' and behavior ~= 'keep' and behavior ~= 'force') then
     error('invalid "behavior": '..tostring(behavior))
   end
+
+  if select('#', ...) < 2 then
+    error('wrong number of arguments (given '..tostring(1 + select('#', ...))..', expected at least 3)')
+  end
+
   local ret = {}
+  if vim._empty_dict_mt ~= nil and getmetatable(select(1, ...)) == vim._empty_dict_mt then
+    ret = vim.empty_dict()
+  end
+
   for i = 1, select('#', ...) do
     local tbl = select(i, ...)
+    vim.validate{["after the second argument"] = {tbl,'t'}}
     if tbl then
       for k, v in pairs(tbl) do
         if behavior ~= 'force' and ret[k] ~= nil then
@@ -311,6 +356,24 @@ function vim.tbl_islist(t)
   end
 end
 
+--- Counts the number of non-nil values in table `t`.
+---
+--- <pre>
+--- vim.tbl_count({ a=1, b=2 }) => 2
+--- vim.tbl_count({ 1, 2 }) => 2
+--- </pre>
+---
+--@see https://github.com/Tieske/Penlight/blob/master/lua/pl/tablex.lua
+--@param Table
+--@returns Number that is the number of the value in table
+function vim.tbl_count(t)
+  vim.validate{t={t,'t'}}
+
+  local count = 0
+  for _ in pairs(t) do count = count + 1 end
+  return count
+end
+
 --- Trim whitespace (Lua pattern "%s") from both sides of a string.
 ---
 --@see https://www.lua.org/pil/20.2.html
@@ -321,7 +384,7 @@ function vim.trim(s)
   return s:match('^%s*(.*%S)') or ''
 end
 
---- Escapes magic chars in a Lua pattern string.
+--- Escapes magic chars in a Lua pattern.
 ---
 --@see https://github.com/rxi/lume
 --@param s  String to escape