From b0cbf93b7ef77e42d6bca3c174f3a1cd4660fa6a Mon Sep 17 00:00:00 2001
From: Adrian Perez de Castro <aperez@igalia.com>
Date: Tue, 5 Jul 2016 01:09:51 +0300
Subject: [PATCH] Use a callback in client:sync() to determine when to stop the
 loop

Instead of adding more and more possible conditions on which the while-loop
inside client:sync() could stop, support passing a callback function which is
used to determine when to stop the loop.

The old "so N iterations behaviour" can be achieved with something like:

  function iterate_n_times(n)
    return function ()
      n = n - 1
      return n == 0
    end
  end
  client:sync(iterate_n_times(10))

If no function is passed, the client:sync() function loops forever.
---
 matrix/client.lua | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/matrix/client.lua b/matrix/client.lua
index 30ac5e3..0c8ae0c 100644
--- a/matrix/client.lua
+++ b/matrix/client.lua
@@ -429,12 +429,16 @@ function Client:_sync(options)
    end
 end
 
-function Client:sync(niters)
-   while niters == nil or niters > 0 do
-      self:_sync { timeout = 15000 }
-      if niters then
-         niters = niters - 1
-      end
+local function return_false()
+   return false
+end
+
+function Client:sync(stop, timeout)
+   if not stop then
+      stop = return_false
+   end
+   while not stop(self) do
+      self:_sync { timeout = timeout or 15000 }
    end
 end