Merge remote-tracking branch 'upstream/master' into aucmd_textputpostaucmd_textputpost

1 files changed, 405 insertions, 200 deletions

diff --git a/runtime/lua/vim/shared.lua b/runtime/lua/vim/shared.lua
index cc48e3f193..9542d93789 100644
--- a/runtime/lua/vim/shared.lua
+++ b/runtime/lua/vim/shared.lua
@@ -6,8 +6,48 @@
 -- or the test suite. (Eventually the test suite will be run in a worker process,
 -- so this wouldn't be a separate case to consider)
 
+---@diagnostic disable-next-line: lowercase-global
 vim = vim or {}
 
+local function _id(v)
+  return v
+end
+
+local deepcopy
+
+local deepcopy_funcs = {
+  table = function(orig, cache)
+    if cache[orig] then
+      return cache[orig]
+    end
+    local copy = {}
+
+    cache[orig] = copy
+    local mt = getmetatable(orig)
+    for k, v in pairs(orig) do
+      copy[deepcopy(k, cache)] = deepcopy(v, cache)
+    end
+    return setmetatable(copy, mt)
+  end,
+  number = _id,
+  string = _id,
+  ['nil'] = _id,
+  boolean = _id,
+  ['function'] = _id,
+}
+
+deepcopy = function(orig, _cache)
+  local f = deepcopy_funcs[type(orig)]
+  if f then
+    return f(orig, _cache or {})
+  else
+    if type(orig) == 'userdata' and orig == vim.NIL then
+      return vim.NIL
+    end
+    error('Cannot deepcopy object of type ' .. type(orig))
+  end
+end
+
 --- Returns a deep copy of the given object. Non-table objects are copied as
 --- in a typical Lua assignment, whereas table objects are copied recursively.
 --- Functions are naively copied, so functions in the copied table point to the
@@ -17,63 +57,60 @@ vim = vim or {}
 ---@generic T: table
 ---@param orig T Table to copy
 ---@return T Table of copied keys and (nested) values.
-function vim.deepcopy(orig) end -- luacheck: no unused
-vim.deepcopy = (function()
-  local function _id(v)
-    return v
-  end
-
-  local deepcopy_funcs = {
-    table = function(orig, cache)
-      if cache[orig] then
-        return cache[orig]
-      end
-      local copy = {}
-
-      cache[orig] = copy
-      local mt = getmetatable(orig)
-      for k, v in pairs(orig) do
-        copy[vim.deepcopy(k, cache)] = vim.deepcopy(v, cache)
-      end
-      return setmetatable(copy, mt)
-    end,
-    number = _id,
-    string = _id,
-    ['nil'] = _id,
-    boolean = _id,
-    ['function'] = _id,
-  }
+function vim.deepcopy(orig)
+  return deepcopy(orig)
+end
 
-  return function(orig, cache)
-    local f = deepcopy_funcs[type(orig)]
-    if f then
-      return f(orig, cache or {})
-    else
-      if type(orig) == 'userdata' and orig == vim.NIL then
-        return vim.NIL
-      end
-      error('Cannot deepcopy object of type ' .. type(orig))
-    end
+--- Gets an |iterator| that splits a string at each instance of a separator, in "lazy" fashion
+--- (as opposed to |vim.split()| which is "eager").
+---
+--- Example:
+---
+--- ```lua
+--- for s in vim.gsplit(':aa::b:', ':', {plain=true}) do
+---   print(s)
+--- end
+--- ```
+---
+--- If you want to also inspect the separator itself (instead of discarding it), use
+--- |string.gmatch()|. Example:
+---
+--- ```lua
+--- for word, num in ('foo111bar222'):gmatch('([^0-9]*)(%d*)') do
+---   print(('word: %s num: %s'):format(word, num))
+--- end
+--- ```
+---
+--- @see |string.gmatch()|
+--- @see |vim.split()|
+--- @see |lua-patterns|
+--- @see https://www.lua.org/pil/20.2.html
+--- @see http://lua-users.org/wiki/StringLibraryTutorial
+---
+--- @param s string String to split
+--- @param sep string Separator or pattern
+--- @param opts (table|nil) Keyword arguments |kwargs|:
+---       - plain: (boolean) Use `sep` literally (as in string.find).
+---       - trimempty: (boolean) Discard empty segments at start and end of the sequence.
+---@return fun():string|nil (function) Iterator over the split components
+function vim.gsplit(s, sep, opts)
+  local plain
+  local trimempty = false
+  if type(opts) == 'boolean' then
+    plain = opts -- For backwards compatibility.
+  else
+    vim.validate({ s = { s, 's' }, sep = { sep, 's' }, opts = { opts, 't', true } })
+    opts = opts or {}
+    plain, trimempty = opts.plain, opts.trimempty
   end
-end)()
-
---- Splits a string at each instance of a separator.
----
----@see |vim.split()|
----@see |luaref-patterns|
----@see https://www.lua.org/pil/20.2.html
----@see http://lua-users.org/wiki/StringLibraryTutorial
----
----@param s string String to split
----@param sep string Separator or pattern
----@param plain (boolean|nil) If `true` use `sep` literally (passed to string.find)
----@return fun():string (function) Iterator over the split components
-function vim.gsplit(s, sep, plain)
-  vim.validate({ s = { s, 's' }, sep = { sep, 's' }, plain = { plain, 'b', true } })
 
   local start = 1
   local done = false
 
+  -- For `trimempty`: queue of collected segments, to be emitted at next pass.
+  local segs = {}
+  local empty_start = true -- Only empty segments seen so far.
+
   local function _pass(i, j, ...)
     if i then
       assert(j + 1 > start, 'Infinite loop detected')
@@ -87,72 +124,69 @@ function vim.gsplit(s, sep, plain)
   end
 
   return function()
-    if done or (s == '' and sep == '') then
-      return
-    end
-    if sep == '' then
+    if trimempty and #segs > 0 then
+      -- trimempty: Pop the collected segments.
+      return table.remove(segs)
+    elseif done or (s == '' and sep == '') then
+      return nil
+    elseif sep == '' then
       if start == #s then
         done = true
       end
       return _pass(start + 1, start)
     end
-    return _pass(s:find(sep, start, plain))
+
+    local seg = _pass(s:find(sep, start, plain))
+
+    -- Trim empty segments from start/end.
+    if trimempty and seg ~= '' then
+      empty_start = false
+    elseif trimempty and seg == '' then
+      while not done and seg == '' do
+        table.insert(segs, 1, '')
+        seg = _pass(s:find(sep, start, plain))
+      end
+      if done and seg == '' then
+        return nil
+      elseif empty_start then
+        empty_start = false
+        segs = {}
+        return seg
+      end
+      if seg ~= '' then
+        table.insert(segs, 1, seg)
+      end
+      return table.remove(segs)
+    end
+
+    return seg
   end
 end
 
---- Splits a string at each instance of a separator.
+--- Splits a string at each instance of a separator and returns the result as a table (unlike
+--- |vim.gsplit()|).
 ---
 --- Examples:
---- <pre>lua
----  split(":aa::b:", ":")                   --> {'','aa','','b',''}
----  split("axaby", "ab?")                   --> {'','x','y'}
----  split("x*yz*o", "*", {plain=true})      --> {'x','yz','o'}
----  split("|x|y|z|", "|", {trimempty=true}) --> {'x', 'y', 'z'}
---- </pre>
+---
+--- ```lua
+--- split(":aa::b:", ":")                   --> {'','aa','','b',''}
+--- split("axaby", "ab?")                   --> {'','x','y'}
+--- split("x*yz*o", "*", {plain=true})      --> {'x','yz','o'}
+--- split("|x|y|z|", "|", {trimempty=true}) --> {'x', 'y', 'z'}
+--- ```
 ---
 ---@see |vim.gsplit()|
+---@see |string.gmatch()|
 ---
 ---@param s string String to split
 ---@param sep string Separator or pattern
----@param kwargs (table|nil) Keyword arguments:
----       - plain: (boolean) If `true` use `sep` literally (passed to string.find)
----       - trimempty: (boolean) If `true` remove empty items from the front
----         and back of the list
+---@param opts (table|nil) Keyword arguments |kwargs| accepted by |vim.gsplit()|
 ---@return string[] List of split components
-function vim.split(s, sep, kwargs)
-  local plain
-  local trimempty = false
-  if type(kwargs) == 'boolean' then
-    -- Support old signature for backward compatibility
-    plain = kwargs
-  else
-    vim.validate({ kwargs = { kwargs, 't', true } })
-    kwargs = kwargs or {}
-    plain = kwargs.plain
-    trimempty = kwargs.trimempty
-  end
-
+function vim.split(s, sep, opts)
   local t = {}
-  local skip = trimempty
-  for c in vim.gsplit(s, sep, plain) do
-    if c ~= '' then
-      skip = false
-    end
-
-    if not skip then
-      table.insert(t, c)
-    end
-  end
-
-  if trimempty then
-    for i = #t, 1, -1 do
-      if t[i] ~= '' then
-        break
-      end
-      table.remove(t, i)
-    end
+  for c in vim.gsplit(s, sep, opts) do
+    table.insert(t, c)
   end
-
   return t
 end
 
@@ -224,12 +258,54 @@ function vim.tbl_filter(func, t)
   return rettab
 end
 
---- Checks if a list-like (vector) table contains `value`.
+--- Checks if a table contains a given value, specified either directly or via
+--- a predicate that is checked for each value.
+---
+--- Example:
+---
+--- ```lua
+--- vim.tbl_contains({ 'a', { 'b', 'c' } }, function(v)
+---   return vim.deep_equal(v, { 'b', 'c' })
+--- end, { predicate = true })
+--- -- true
+--- ```
+---
+---@see |vim.list_contains()| for checking values in list-like tables
 ---
 ---@param t table Table to check
+---@param value any Value to compare or predicate function reference
+---@param opts (table|nil) Keyword arguments |kwargs|:
+---       - predicate: (boolean) `value` is a function reference to be checked (default false)
+---@return boolean `true` if `t` contains `value`
+function vim.tbl_contains(t, value, opts)
+  vim.validate({ t = { t, 't' }, opts = { opts, 't', true } })
+
+  local pred
+  if opts and opts.predicate then
+    vim.validate({ value = { value, 'c' } })
+    pred = value
+  else
+    pred = function(v)
+      return v == value
+    end
+  end
+
+  for _, v in pairs(t) do
+    if pred(v) then
+      return true
+    end
+  end
+  return false
+end
+
+--- Checks if a list-like table (integer keys without gaps) contains `value`.
+---
+---@see |vim.tbl_contains()| for checking values in general tables
+---
+---@param t table Table to check (must be list-like, not validated)
 ---@param value any Value to compare
 ---@return boolean `true` if `t` contains `value`
-function vim.tbl_contains(t, value)
+function vim.list_contains(t, value)
   vim.validate({ t = { t, 't' } })
 
   for _, v in ipairs(t) do
@@ -251,10 +327,9 @@ function vim.tbl_isempty(t)
   return next(t) == nil
 end
 
---- We only merge empty tables or tables that are not a list
----@private
+--- We only merge empty tables or tables that are not an array (indexed by integers)
 local function can_merge(v)
-  return type(v) == 'table' and (vim.tbl_isempty(v) or not vim.tbl_islist(v))
+  return type(v) == 'table' and (vim.tbl_isempty(v) or not vim.tbl_isarray(v))
 end
 
 local function tbl_extend(behavior, deep_extend, ...)
@@ -295,7 +370,7 @@ local function tbl_extend(behavior, deep_extend, ...)
   return ret
 end
 
---- Merges two or more map-like tables.
+--- Merges two or more tables.
 ---
 ---@see |extend()|
 ---
@@ -303,13 +378,13 @@ end
 ---      - "error": raise an error
 ---      - "keep":  use value from the leftmost map
 ---      - "force": use value from the rightmost map
----@param ... table Two or more map-like tables
+---@param ... table Two or more tables
 ---@return table Merged table
 function vim.tbl_extend(behavior, ...)
   return tbl_extend(behavior, false, ...)
 end
 
---- Merges recursively two or more map-like tables.
+--- Merges recursively two or more tables.
 ---
 ---@see |vim.tbl_extend()|
 ---
@@ -319,7 +394,7 @@ end
 ---      - "error": raise an error
 ---      - "keep":  use value from the leftmost map
 ---      - "force": use value from the rightmost map
----@param ... T2 Two or more map-like tables
+---@param ... T2 Two or more tables
 ---@return T1|T2 (table) Merged table
 function vim.tbl_deep_extend(behavior, ...)
   return tbl_extend(behavior, true, ...)
@@ -384,13 +459,14 @@ end
 --- Return `nil` if the key does not exist.
 ---
 --- Examples:
---- <pre>lua
----  vim.tbl_get({ key = { nested_key = true }}, 'key', 'nested_key') == true
----  vim.tbl_get({ key = {}}, 'key', 'nested_key') == nil
---- </pre>
+---
+--- ```lua
+--- vim.tbl_get({ key = { nested_key = true }}, 'key', 'nested_key') == true
+--- vim.tbl_get({ key = {}}, 'key', 'nested_key') == nil
+--- ```
 ---
 ---@param o table Table to index
----@param ... string Optional strings (0 or more, variadic) via which to index the table
+---@param ... any Optional keys (0 or more, variadic) via which to index the table
 ---
 ---@return any Nested value indexed by key (if it exists), else nil
 function vim.tbl_get(o, ...)
@@ -418,8 +494,8 @@ end
 ---@generic T: table
 ---@param dst T List which will be modified and appended to
 ---@param src table List from which values will be inserted
----@param start (number|nil) Start index on src. Defaults to 1
----@param finish (number|nil) Final index on src. Defaults to `#src`
+---@param start (integer|nil) Start index on src. Defaults to 1
+---@param finish (integer|nil) Final index on src. Defaults to `#src`
 ---@return T dst
 function vim.list_extend(dst, src, start, finish)
   vim.validate({
@@ -458,12 +534,12 @@ function vim.tbl_flatten(t)
   return result
 end
 
---- Enumerate a table sorted by its keys.
+--- Enumerates key-value pairs of a table, ordered by key.
 ---
 ---@see Based on https://github.com/premake/premake-core/blob/master/src/base/table.lua
 ---
----@param t table List-like table
----@return iterator over sorted keys and their values
+---@param t table Dict-like table
+---@return function # |for-in| iterator over sorted keys and their values
 function vim.spairs(t)
   assert(type(t) == 'table', string.format('Expected table, got %s', type(t)))
 
@@ -475,7 +551,6 @@ function vim.spairs(t)
   table.sort(keys)
 
   -- Return the iterator function.
-  -- TODO(justinmk): Return "iterator function, table {t}, and nil", like pairs()?
   local i = 0
   return function()
     i = i + 1
@@ -485,15 +560,18 @@ function vim.spairs(t)
   end
 end
 
---- Tests if a Lua table can be treated as an array.
+--- Tests if `t` is an "array": a table indexed _only_ by integers (potentially non-contiguous).
 ---
---- Empty table `{}` is assumed to be an array, unless it was created by
---- |vim.empty_dict()| or returned as a dict-like |API| or Vimscript result,
---- for example from |rpcrequest()| or |vim.fn|.
+--- If the indexes start from 1 and are contiguous then the array is also a list. |vim.tbl_islist()|
 ---
----@param t table Table
----@return boolean `true` if array-like table, else `false`
-function vim.tbl_islist(t)
+--- Empty table `{}` is an array, unless it was created by |vim.empty_dict()| or returned as
+--- a dict-like |API| or Vimscript result, for example from |rpcrequest()| or |vim.fn|.
+---
+---@see https://github.com/openresty/luajit2#tableisarray
+---
+---@param t table
+---@return boolean `true` if array-like table, else `false`.
+function vim.tbl_isarray(t)
   if type(t) ~= 'table' then
     return false
   end
@@ -501,7 +579,8 @@ function vim.tbl_islist(t)
   local count = 0
 
   for k, _ in pairs(t) do
-    if type(k) == 'number' then
+    --- Check if the number k is an integer
+    if type(k) == 'number' and k == math.floor(k) then
       count = count + 1
     else
       return false
@@ -520,16 +599,50 @@ function vim.tbl_islist(t)
   end
 end
 
+--- Tests if `t` is a "list": a table indexed _only_ by contiguous integers starting from 1 (what
+--- |lua-length| calls a "regular array").
+---
+--- Empty table `{}` is a list, unless it was created by |vim.empty_dict()| or returned as
+--- a dict-like |API| or Vimscript result, for example from |rpcrequest()| or |vim.fn|.
+---
+---@see |vim.tbl_isarray()|
+---
+---@param t table
+---@return boolean `true` if list-like table, else `false`.
+function vim.tbl_islist(t)
+  if type(t) ~= 'table' then
+    return false
+  end
+
+  local num_elem = vim.tbl_count(t)
+
+  if num_elem == 0 then
+    -- TODO(bfredl): in the future, we will always be inside nvim
+    -- then this check can be deleted.
+    if vim._empty_dict_mt == nil then
+      return nil
+    end
+    return getmetatable(t) ~= vim._empty_dict_mt
+  else
+    for i = 1, num_elem do
+      if t[i] == nil then
+        return false
+      end
+    end
+    return true
+  end
+end
+
 --- Counts the number of non-nil values in table `t`.
 ---
---- <pre>lua
+--- ```lua
 --- 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 t table Table
----@return number Number of non-nil values in table
+---@return integer Number of non-nil values in table
 function vim.tbl_count(t)
   vim.validate({ t = { t, 't' } })
 
@@ -544,8 +657,8 @@ end
 ---
 ---@generic T
 ---@param list T[] (list) Table
----@param start number|nil Start range of slice
----@param finish number|nil End range of slice
+---@param start integer|nil Start range of slice
+---@param finish integer|nil End range of slice
 ---@return T[] (list) Copy of table sliced from start to finish (inclusive)
 function vim.list_slice(list, start, finish)
   local new_list = {}
@@ -557,7 +670,7 @@ end
 
 --- Trim whitespace (Lua pattern "%s") from both sides of a string.
 ---
----@see |luaref-patterns|
+---@see |lua-patterns|
 ---@see https://www.lua.org/pil/20.2.html
 ---@param s string String to trim
 ---@return string String with whitespace removed from its beginning and end
@@ -596,58 +709,6 @@ function vim.endswith(s, suffix)
   return #suffix == 0 or s:sub(-#suffix) == suffix
 end
 
---- Validates a parameter specification (types and values).
----
---- Usage example:
---- <pre>lua
----  function user.new(name, age, hobbies)
----    vim.validate{
----      name={name, 'string'},
----      age={age, 'number'},
----      hobbies={hobbies, 'table'},
----    }
----    ...
----  end
---- </pre>
----
---- Examples with explicit argument values (can be run directly):
---- <pre>lua
----  vim.validate{arg1={{'foo'}, 'table'}, arg2={'foo', 'string'}}
----     --> NOP (success)
----
----  vim.validate{arg1={1, 'table'}}
----     --> error('arg1: expected table, got number')
----
----  vim.validate{arg1={3, function(a) return (a % 2) == 0 end, 'even number'}}
----     --> error('arg1: expected even number, got 3')
---- </pre>
----
---- If multiple types are valid they can be given as a list.
---- <pre>lua
----  vim.validate{arg1={{'foo'}, {'table', 'string'}}, arg2={'foo', {'table', 'string'}}}
----     --> NOP (success)
----
----  vim.validate{arg1={1, {'string', table'}}}
----     --> error('arg1: expected string|table, got number')
----
---- </pre>
----
----@param opt table Names of parameters to validate. Each key is a parameter
----          name; each value is a tuple in one of these forms:
----          1. (arg_value, type_name, optional)
----             - arg_value: argument value
----             - type_name: string|table type name, one of: ("table", "t", "string",
----               "s", "number", "n", "boolean", "b", "function", "f", "nil",
----               "thread", "userdata") or list of them.
----             - optional: (optional) boolean, if true, `nil` is valid
----          2. (arg_value, fn, msg)
----             - arg_value: argument value
----             - fn: any function accepting one argument, returns true if and
----               only if the argument is valid. Can optionally return an additional
----               informative error message as the second returned value.
----             - msg: (optional) error string if validation fails
-function vim.validate(opt) end -- luacheck: no unused
-
 do
   local type_names = {
     ['table'] = 'table',
@@ -671,7 +732,6 @@ do
     return type(val) == t or (t == 'callable' and vim.is_callable(val))
   end
 
-  ---@private
   local function is_valid(opt)
     if type(opt) ~= 'table' then
       return false, string.format('opt: expected table, got %s', type(opt))
@@ -733,6 +793,59 @@ do
     return true, nil
   end
 
+  --- Validates a parameter specification (types and values).
+  ---
+  --- Usage example:
+  ---
+  --- ```lua
+  ---  function user.new(name, age, hobbies)
+  ---    vim.validate{
+  ---      name={name, 'string'},
+  ---      age={age, 'number'},
+  ---      hobbies={hobbies, 'table'},
+  ---    }
+  ---    ...
+  ---  end
+  --- ```
+  ---
+  --- Examples with explicit argument values (can be run directly):
+  ---
+  --- ```lua
+  ---  vim.validate{arg1={{'foo'}, 'table'}, arg2={'foo', 'string'}}
+  ---     --> NOP (success)
+  ---
+  ---  vim.validate{arg1={1, 'table'}}
+  ---     --> error('arg1: expected table, got number')
+  ---
+  ---  vim.validate{arg1={3, function(a) return (a % 2) == 0 end, 'even number'}}
+  ---     --> error('arg1: expected even number, got 3')
+  --- ```
+  ---
+  --- If multiple types are valid they can be given as a list.
+  ---
+  --- ```lua
+  ---  vim.validate{arg1={{'foo'}, {'table', 'string'}}, arg2={'foo', {'table', 'string'}}}
+  ---  -- NOP (success)
+  ---
+  ---  vim.validate{arg1={1, {'string', 'table'}}}
+  ---  -- error('arg1: expected string|table, got number')
+  ---
+  --- ```
+  ---
+  ---@param opt table Names of parameters to validate. Each key is a parameter
+  ---          name; each value is a tuple in one of these forms:
+  ---          1. (arg_value, type_name, optional)
+  ---             - arg_value: argument value
+  ---             - type_name: string|table type name, one of: ("table", "t", "string",
+  ---               "s", "number", "n", "boolean", "b", "function", "f", "nil",
+  ---               "thread", "userdata") or list of them.
+  ---             - optional: (optional) boolean, if true, `nil` is valid
+  ---          2. (arg_value, fn, msg)
+  ---             - arg_value: argument value
+  ---             - fn: any function accepting one argument, returns true if and
+  ---               only if the argument is valid. Can optionally return an additional
+  ---               informative error message as the second returned value.
+  ---             - msg: (optional) error string if validation fails
   function vim.validate(opt)
     local ok, err_msg = is_valid(opt)
     if not ok then
@@ -755,30 +868,122 @@ function vim.is_callable(f)
   return type(m.__call) == 'function'
 end
 
---- Creates a table whose members are automatically created when accessed, if they don't already
---- exist.
----
---- They mimic defaultdict in python.
+--- Creates a table whose missing keys are provided by {createfn} (like Python's "defaultdict").
 ---
---- If {create} is `nil`, this will create a defaulttable whose constructor function is
---- this function, effectively allowing to create nested tables on the fly:
+--- If {createfn} is `nil` it defaults to defaulttable() itself, so accessing nested keys creates
+--- nested tables:
 ---
---- <pre>lua
+--- ```lua
 --- local a = vim.defaulttable()
 --- a.b.c = 1
---- </pre>
+--- ```
 ---
----@param create function|nil The function called to create a missing value.
----@return table Empty table with metamethod
-function vim.defaulttable(create)
-  create = create or vim.defaulttable
+---@param createfn function?(key:any):any Provides the value for a missing `key`.
+---@return table # Empty table with `__index` metamethod.
+function vim.defaulttable(createfn)
+  createfn = createfn or function(_)
+    return vim.defaulttable()
+  end
   return setmetatable({}, {
     __index = function(tbl, key)
-      rawset(tbl, key, create())
+      rawset(tbl, key, createfn(key))
       return rawget(tbl, key)
     end,
   })
 end
 
+do
+  ---@class vim.Ringbuf<T>
+  ---@field private _items table[]
+  ---@field private _idx_read integer
+  ---@field private _idx_write integer
+  ---@field private _size integer
+  local Ringbuf = {}
+
+  --- Clear all items
+  function Ringbuf.clear(self)
+    self._items = {}
+    self._idx_read = 0
+    self._idx_write = 0
+  end
+
+  --- Adds an item, overriding the oldest item if the buffer is full.
+  ---@generic T
+  ---@param item T
+  function Ringbuf.push(self, item)
+    self._items[self._idx_write] = item
+    self._idx_write = (self._idx_write + 1) % self._size
+    if self._idx_write == self._idx_read then
+      self._idx_read = (self._idx_read + 1) % self._size
+    end
+  end
+
+  --- Removes and returns the first unread item
+  ---@generic T
+  ---@return T?
+  function Ringbuf.pop(self)
+    local idx_read = self._idx_read
+    if idx_read == self._idx_write then
+      return nil
+    end
+    local item = self._items[idx_read]
+    self._items[idx_read] = nil
+    self._idx_read = (idx_read + 1) % self._size
+    return item
+  end
+
+  --- Returns the first unread item without removing it
+  ---@generic T
+  ---@return T?
+  function Ringbuf.peek(self)
+    if self._idx_read == self._idx_write then
+      return nil
+    end
+    return self._items[self._idx_read]
+  end
+
+  --- Create a ring buffer limited to a maximal number of items.
+  --- Once the buffer is full, adding a new entry overrides the oldest entry.
+  ---
+  --- ```lua
+  ---   local ringbuf = vim.ringbuf(4)
+  ---   ringbuf:push("a")
+  ---   ringbuf:push("b")
+  ---   ringbuf:push("c")
+  ---   ringbuf:push("d")
+  ---   ringbuf:push("e")    -- overrides "a"
+  ---   print(ringbuf:pop()) -- returns "b"
+  ---   print(ringbuf:pop()) -- returns "c"
+  ---
+  ---   -- Can be used as iterator. Pops remaining items:
+  ---   for val in ringbuf do
+  ---     print(val)
+  ---   end
+  --- ```
+  ---
+  --- Returns a Ringbuf instance with the following methods:
+  ---
+  --- - |Ringbuf:push()|
+  --- - |Ringbuf:pop()|
+  --- - |Ringbuf:peek()|
+  --- - |Ringbuf:clear()|
+  ---
+  ---@param size integer
+  ---@return vim.Ringbuf ringbuf (table)
+  function vim.ringbuf(size)
+    local ringbuf = {
+      _items = {},
+      _size = size + 1,
+      _idx_read = 0,
+      _idx_write = 0,
+    }
+    return setmetatable(ringbuf, {
+      __index = Ringbuf,
+      __call = function(self)
+        return self:pop()
+      end,
+    })
+  end
+end
+
 return vim
--- vim:sw=2 ts=2 et