implement nvim.exec_lua and nvim.lua.function

Author: bfredl

neovim/api/nvim.py

@@ -92,6 +92,7 @@ def __init__(self, session, channel_id, metadata, types,
         self.current = Current(self)
         self.session = CompatibilitySession(self)
         self.funcs = Funcs(self)
+        self.lua = LuaFuncs(self)
         self.error = NvimError
         self._decode = decode
         self._err_cb = err_cb
@@ -253,6 +254,27 @@ def call(self, name, *args, **kwargs):
         """Call a vimscript function."""
         return self.request('nvim_call_function', name, args, **kwargs)
 
+    def exec_lua(self, code, *args, **kwargs):
+        """Execute lua code.
+
+        Additional parameters are available as `...` inside the lua chunk.
+        Only statements are executed.  To evaluate an expression, prefix it
+        with `return`: `return my_function(...)`
+
+        There is a shorthand syntax to call lua functions with arguments:
+
+            nvim.lua.func(1,2)
+            nvim.lua.mymod.myfunction(data, async_=True)
+
+        is equivalent to
+
+            nvim.exec_lua("return func(...)", 1, 2)
+            nvim.exec_lua("mymod.myfunction(...)", data, async_=True)
+
+        Note that with `async_=True` there is no return value.
+        """
+        return self.request('nvim_execute_lua', code, args, **kwargs)
+
     def strwidth(self, string):
         """Return the number of display cells `string` occupies.
 
@@ -467,5 +489,29 @@ def __getattr__(self, name):
         return partial(self._nvim.call, name)
 
 
+class LuaFuncs(object):
+
+    """Wrapper to allow lua functions to be called like python methods."""
+
+    def __init__(self, nvim, name=""):
+        self._nvim = nvim
+        self.name = name
+
+    def __getattr__(self, name):
+        """Return wrapper to named api method."""
+        prefix = self.name + "." if self.name else ""
+        return LuaFuncs(self._nvim, prefix + name)
+
+    def __call__(self, *args, **kwargs):
+        # first new function after keyword rename, be a bit noisy
+        if 'async' in kwargs:
+            raise ValueError('"async" argument is not allowed. '
+                             'Use "async_" instead.')
+        async_ = kwargs.get('async_', False)
+        pattern = "return {}(...)" if not async_ else "{}(...)"
+        code = pattern.format(self.name)
+        return self._nvim.exec_lua(code, *args, **kwargs)
+
+
 class NvimError(Exception):
     pass

test/test_vim.py

@@ -168,3 +168,32 @@ def test_cwd(vim, tmpdir):
     cwd_python = vim.command_output('{} print(os.getcwd())'.format(pycmd))
     assert cwd_python == cwd_vim
     assert cwd_python != cwd_before
+
+lua_code = """
+local a = vim.api
+local y = ...
+function pynvimtest_func(x)
+    return x+y
+end
+
+local function setbuf(buf,lines)
+   a.nvim_buf_set_lines(buf, 0, -1, true, lines)
+end
+
+
+local function getbuf(buf)
+   return a.nvim_buf_line_count(buf)
+end
+
+pynvimtest = {setbuf=setbuf,getbuf=getbuf}
+
+return "eggspam"
+"""
+
+def test_lua(vim):
+  assert vim.exec_lua(lua_code, 7) == "eggspam"
+  assert vim.lua.pynvimtest_func(3) == 10
+  testmod = vim.lua.pynvimtest
+  buf = vim.current.buffer
+  testmod.setbuf(buf, ["a", "b", "c", "d"], async_=True)
+  assert testmod.getbuf(buf) == 4