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

tools/findit/common/utils.py

Index: tools/findit/common/utils.py
diff --git a/tools/findit/common/utils.py b/tools/findit/common/utils.py
index 363048c0796fac54225b6fd8b8c3884166ad9d4b..4b989f2ddd16cdfb006905443077df5e031a3e44 100644
--- a/tools/findit/common/utils.py
+++ b/tools/findit/common/utils.py
@@ -29,3 +29,31 @@ def IsGitHash(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)