The key idea is to pass a continuation function when we call
lean-server-send-cmd function. The passed continuation function is
called by lean-server-event-handler. Until the buffer is ready, the
event handler will be called in interval (lean-server-retry-time, 0.1
sec by default). When we have 'NAY' for INFO command, it will re-send
INFO commands to lean-server until we have one without 'NAY'.
Close#123
We are using asynchronous process mechanism to communicate between
lean-server and emacs. A sender function like
lean-eldoc-documentation-function sends a command and waits until
lean-global-server-message-to-process is non-nil. When a message is
received from lean-server, a filter function lean-server-output-filter
is triggered. This filter function concatenates a received message to
the buffer until it sees the end of message markers (--
END[INFO|SET|EVAL]). When it sees a marker, it splits the buffer
messages into pre, body, and post parts. Then it assembles a message to
process and attaches the message to
lean-global-server-message-to-process variable. A sender function which
is watching for the variable will recognize it, exit the polling, and
process the message.
