buffer: support attachment in hosted plugins

neovim/api/buffer.py

@@ -134,7 +134,6 @@ def update_highlights(self, src_id, hls, clear_start=0, clear_end=-1,
         lua = self._session._get_lua_private()
         lua.update_highlights(self, src_id, hls, clear_start, clear_end,
                               async_=async_)
-
     @property
     def name(self):
         """Get the buffer name."""
@@ -155,6 +154,32 @@ def number(self):
         """Get the buffer number."""
         return self.handle
 
+    def attach(self, cb):
+        sess = self._session._session
+        if self.handle not in sess.attached_buffers:
+            a = BufAttachState()
+            sess.attached_buffers[self.handle] = a
+            a.callbacks.append(cb)
+            self.api.attach(True, {})
+        else:
+            a = sess.attached_buffers[self.handle]
+            a.callbacks.append(cb)
+            cb(self, a.changedtick, a.lines)
+
+        def detach():
+            for i in range(len(a.callbacks)):
+                if a.callbacks[i] is cb:
+                    del a.callbacks[i]
+                    return
+            else:
+                raise ValueError("callback already detached")
+
+        return detach
+
+class BufAttachState(object):
+    def __init__(self):
+        self.callbacks = []
+        self.lines = []
 
 class Range(object):
     def __init__(self, buffer, start, end):

neovim/plugin/host.py

@@ -32,10 +32,17 @@ class Host(object):
     def __init__(self, nvim):
         """Set handlers for plugin_load/plugin_unload."""
         self.nvim = nvim
+        self.nvim._session.attached_buffers = {}
+        # TODO: delet this
+        self.nvim._session.elog = []
         self._specs = {}
         self._loaded = {}
         self._load_errors = {}
-        self._notification_handlers = {}
+        self._notification_handlers = {
+                'nvim_buf_lines_event': self._on_buf_lines,
+                'nvim_buf_changedtick_event': self._on_buf_changedtick,
+                'nvim_buf_detach_event': self._on_buf_detach,
+            }
         self._request_handlers = {
             'poll': lambda: 'ok',
             'specs': self._on_specs_request,
@@ -96,6 +103,7 @@ def _on_notification(self, name, args):
         """Handle a msgpack-rpc notification."""
         if IS_PYTHON3:
             name = decode_if_bytes(name)
+        self.nvim._session.elog.append([name]+args)
         handler = self._notification_handlers.get(name, None)
         if not handler:
             msg = self._missing_handler_error(name, 'notification')
@@ -220,3 +228,22 @@ def _configure_nvim_for(self, obj):
         if decode:
             nvim = nvim.with_decode(decode)
         return nvim
+
+    def _on_buf_lines(self, buf, changedtick, first, last, data, more):
+        a = self.nvim._session.attached_buffers[buf.handle]
+        a.lines[first:last] = data
+        a.changedtick = changedtick
+        if more: return
+        for cb in a.callbacks:
+            cb(buf, changedtick, a.lines)
+
+    def _on_buf_changedtick(self, buf, changedtick):
+        a = self.nvim._session.attached_buffers[buf.handle]
+        a.changedtick = changedtick
+        for cb in a.callbacks:
+            cb(buf, changedtick, a.lines)
+
+    def _on_buf_detach(self, buf, changedtick, first, last, data, more):
+        del self.nvim._session.attached_buffers[buf.handle]
+        for cb in a.callbacks:
+            cb(buf, -1, None)