Auto merge of ycm-core#305 - oblitum:extended-prepared-triggers, r=vheon

Extends PreparedTriggers.

Allows one to obtain the current trigger regex from inside semantic
completers, enabling customized completions based on it, like normal
code completion or argument hints.

<!-- Reviewable:start -->
[<img src="https://reviewable.io/review_button.png" height=40 alt="Review on Reviewable"/>](https://reviewable.io/reviews/valloric/ycmd/305)
<!-- Reviewable:end -->

ycmd/completers/completer_utils.py

@@ -36,12 +36,18 @@ def __init__( self,  user_trigger_map = None, filetype_set = None ):
     self._filetype_to_prepared_triggers = final_triggers
 
 
-  def MatchesForFiletype( self, current_line, start_column, filetype ):
+  def MatchingTriggerForFiletype( self, current_line, start_column, filetype ):
     try:
       triggers = self._filetype_to_prepared_triggers[ filetype ]
     except KeyError:
-      return False
-    return _MatchesSemanticTrigger( current_line, start_column, triggers )
+      return None
+    return _MatchingSemanticTrigger( current_line, start_column, triggers )
+
+
+  def MatchesForFiletype( self, current_line, start_column, filetype ):
+    return self.MatchingTriggerForFiletype( current_line,
+                                            start_column,
+                                            filetype ) is not None
 
 
 def _FiletypeTriggerDictFromSpec( trigger_dict_spec ):
@@ -78,18 +84,24 @@ def _RegexTriggerMatches( trigger, line_value, start_column ):
 
 
 # start_column is 0-based
-def _MatchesSemanticTrigger( line_value, start_column, trigger_list ):
+def _MatchingSemanticTrigger( line_value, start_column, trigger_list ):
   line_length = len( line_value )
   if not line_length or start_column > line_length:
-    return False
+    return None
 
   # ignore characters after user's caret column
   line_value = line_value[ :start_column ]
 
   for trigger in trigger_list:
     if _RegexTriggerMatches( trigger, line_value, start_column ):
-      return True
-  return False
+      return trigger
+  return None
+
+
+def _MatchesSemanticTrigger( line_value, start_column, trigger_list ):
+  return _MatchingSemanticTrigger( line_value,
+                                   start_column,
+                                   trigger_list ) is not None
 
 
 def _PrepareTrigger( trigger ):

ycmd/completers/completer_utils_test.py

@@ -17,6 +17,7 @@
 # You should have received a copy of the GNU General Public License
 # along with YouCompleteMe.  If not, see <http://www.gnu.org/licenses/>.
 
+import re
 from collections import defaultdict
 from nose.tools import eq_, ok_
 from ycmd.completers import completer_utils as cu
@@ -122,21 +123,40 @@ def MatchesSemanticTrigger_RegexTrigger_test():
                                        [ cu._PrepareTrigger( r're!\w+\.' ) ] ) )
 
 
+def MatchingSemanticTrigger_Basic_test():
+  triggers = [ cu._PrepareTrigger( '.' ), cu._PrepareTrigger( ';' ),
+               cu._PrepareTrigger( '::' ) ]
+  eq_( cu._MatchingSemanticTrigger( 'foo->bar', 5,  triggers ),
+       None )
+  eq_( cu._MatchingSemanticTrigger( 'foo::bar', 5,  triggers ).pattern,
+       re.escape( '::' ) )
+
+
 def PreparedTriggers_Basic_test():
   triggers = cu.PreparedTriggers()
   ok_( triggers.MatchesForFiletype( 'foo.bar', 4, 'c' ) )
+  eq_( triggers.MatchingTriggerForFiletype( 'foo.bar', 4, 'c' ).pattern,
+       re.escape( '.' ) )
   ok_( triggers.MatchesForFiletype( 'foo->bar', 5, 'cpp' ) )
+  eq_( triggers.MatchingTriggerForFiletype( 'foo->bar', 5, 'cpp' ).pattern,
+       re.escape( '->' ) )
 
 
 def PreparedTriggers_OnlySomeFiletypesSelected_test():
   triggers = cu.PreparedTriggers( filetype_set = set( 'c' ) )
   ok_( triggers.MatchesForFiletype( 'foo.bar', 4, 'c' ) )
+  eq_( triggers.MatchingTriggerForFiletype( 'foo.bar', 4, 'c' ).pattern,
+       re.escape( '.' ) )
   ok_( not triggers.MatchesForFiletype( 'foo->bar', 5, 'cpp' ) )
+  eq_( triggers.MatchingTriggerForFiletype( 'foo->bar', 5, 'cpp' ),
+       None )
 
 
 def PreparedTriggers_UserTriggers_test():
   triggers = cu.PreparedTriggers( user_trigger_map = { 'c': ['->'] } )
   ok_( triggers.MatchesForFiletype( 'foo->bar', 5, 'c' ) )
+  eq_( triggers.MatchingTriggerForFiletype( 'foo->bar', 5, 'c' ).pattern,
+       re.escape( '->' ) )
 
 
 def PreparedTriggers_ObjectiveC_test():