tree 254ddf2d9b250035b7da5c458050f4b4d02ca6fc
parent e0dd0334143cb31b1b563704fe3001d11a506a95
author Lei Zhang <antiagainst@google.com> 1472853978 -0400
committer Lei Zhang <antiagainst@google.com> 1473957348 -0400

Add a callback mechanism for communicating messages to callers.

Every time an event happens in the library that the user should be
aware of, the callback will be invoked.

The existing diagnostic mechanism is hijacked internally by a
callback that creates an diagnostic object each time an event
happens.