[Findit] Improve output format and cherry-pick bugs fix.

tools/findit/common/utils.py

 # Copyright (c) 2011 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import re
 import sys
 
 from http_client_local import HttpClientLocal
 
 
@@ skipping 11 matching lines @@
     return platform_name
 
 
 def IsGitHash(revision):
   return GIT_HASH_PATTERN.match(str(revision))
 
 
 def GetHttpClient():
   # TODO(stgao): return implementation for appengine when running on appengine.
   return HttpClientLocal
+
+
+def JoinLineNumbers(line_numbers, accepted_gap=1):

[aarya, 2014/08/26 02:13:53]

Please don't use accepted_gap. When someone modifies a long section, it will
still cause lots of x-y pairs. I know you passed 4, but we want to club as many
as possible. Just go through the loop

5,6,7,8,9,10,11,12,14,15,16,17,18 should be

5-12,14-18 and not groups of 4.

[stgao, 2014/08/26 18:35:24]

I think I didn't make it clear for the meaning of gap.
I added a more detail comment with example.

If |accepted_gap| = 1, the result of your example is 5-12, 14-18 as you
expected. If |accepted_gap| = 4, the result is 5-18 instead.

The reason I use |accepted_gap| = 4 is: for the testcase we discussed in the
email, the line number sequence is 1120, 1121, 1123, 1124, 1126, 1127, 1128,
1132, 1134, 1135, 1136, 1176, 1170, 1173, 1174, 1175

with gap=1, the result is 1120-1124, 1126-1128, 1132, 1134-1136, 1176, 1170,
1173-1175
with gap=4, the result looks better: 1120-1136, 1170-1174

+  """Join line numbers into line blocks."""
+  if not line_numbers:
+    return ''
+
+  line_numbers = map(int, line_numbers)
+  line_numbers.sort()
+
+  block = []
+  start_line_number = line_numbers[0]
+  last_line_number = start_line_number
+  for current_line_number in line_numbers[1:]:
+    if last_line_number + accepted_gap < current_line_number:
+      if start_line_number == last_line_number:
+        block.append('%d' % start_line_number)
+      else:
+        block.append('%d-%d' % (start_line_number, last_line_number))
+      start_line_number = current_line_number
+    last_line_number = current_line_number
+  else:
+    if start_line_number == last_line_number:
+      block.append('%d' % start_line_number)
+    else:
+      block.append('%d-%d' % (start_line_number, last_line_number))
+
+  return ', '.join(block)