1 files changed, 73 insertions, 0 deletions
diff --git a/runtime/lua/vim/shared.lua b/runtime/lua/vim/shared.lua
new file mode 100644
index 0000000000..9dca51ce9a
--- /dev/null
+++ b/runtime/lua/vim/shared.lua
@@ -0,0 +1,73 @@
+--- Shared functions
+--    - Used by Nvim and tests
+--    - Can run in vanilla Lua (do not require a running instance of Nvim)
+
+
+-- Checks if a list-like (vector) table contains `value`.
+local function tbl_contains(t, value)
+  if type(t) ~= 'table' then
+    error('t must be a table')
+  end
+  for _,v in ipairs(t) do
+    if v == value then
+      return true
+    end
+  end
+  return false
+end
+
+--- Merges two or more map-like tables.
+--
+--@see |extend()|
+--
+-- behavior: Decides what to do if a key is found in more than one map:
+--           "error": raise an error
+--           "keep":  use value from the leftmost map
+--           "force": use value from the rightmost map
+local function tbl_extend(behavior, ...)
+  if (behavior ~= 'error' and behavior ~= 'keep' and behavior ~= 'force') then
+    error('invalid "behavior": '..tostring(behavior))
+  end
+  local ret = {}
+  for i = 1, select('#', ...) do
+    local tbl = select(i, ...)
+    if tbl then
+      for k, v in pairs(tbl) do
+        if behavior ~= 'force' and ret[k] ~= nil then
+          if behavior == 'error' then
+            error('key found in more than one map: '..k)
+          end  -- Else behavior is "keep".
+        else
+          ret[k] = v
+        end
+      end
+    end
+  end
+  return ret
+end
+
+-- Flattens a list-like table: unrolls and appends nested tables to table `t`.
+local function tbl_flatten(t)
+  -- From https://github.com/premake/premake-core/blob/master/src/base/table.lua
+  local result = {}
+  local function _tbl_flatten(_t)
+    local n = #_t
+    for i = 1, n do
+      local v = _t[i]
+      if type(v) == "table" then
+        _tbl_flatten(v)
+      elseif v then
+        table.insert(result, v)
+      end
+    end
+  end
+  _tbl_flatten(t)
+  return result
+end
+
+local module = {
+  tbl_contains = tbl_contains,
+  tbl_extend = tbl_extend,
+  tbl_flatten = tbl_flatten,
+}
+return module