bpo-33224: PEP 479 fix for difflib.mdiff() (GH-6381) (GH-6390)
diff --git a/Lib/difflib.py b/Lib/difflib.py
index 043a169..887c3c2 100644
--- a/Lib/difflib.py
+++ b/Lib/difflib.py
@@ -1634,14 +1634,18 @@
lines_to_write -= 1
# Now yield the context lines after the change
lines_to_write = context-1
- while(lines_to_write):
- from_line, to_line, found_diff = next(line_pair_iterator)
- # If another change within the context, extend the context
- if found_diff:
- lines_to_write = context-1
- else:
- lines_to_write -= 1
- yield from_line, to_line, found_diff
+ try:
+ while(lines_to_write):
+ from_line, to_line, found_diff = next(line_pair_iterator)
+ # If another change within the context, extend the context
+ if found_diff:
+ lines_to_write = context-1
+ else:
+ lines_to_write -= 1
+ yield from_line, to_line, found_diff
+ except StopIteration:
+ # Catch exception from next() and return normally
+ return
_file_template = """
diff --git a/Lib/test/test_difflib.py b/Lib/test/test_difflib.py
index aaefe6d..745ccbd 100644
--- a/Lib/test/test_difflib.py
+++ b/Lib/test/test_difflib.py
@@ -93,6 +93,14 @@
self.assertEqual("+ \t\tI am a bug", diff[2])
self.assertEqual("? +\n", diff[3])
+ def test_mdiff_catch_stop_iteration(self):
+ # Issue #33224
+ self.assertEqual(
+ list(difflib._mdiff(["2"], ["3"], 1)),
+ [((1, '\x00-2\x01'), (1, '\x00+3\x01'), True)],
+ )
+
+
patch914575_from1 = """
1. Beautiful is beTTer than ugly.
2. Explicit is better than implicit.
diff --git a/Misc/NEWS.d/next/Library/2018-04-04-23-41-30.bpo-33224.pyR0jB.rst b/Misc/NEWS.d/next/Library/2018-04-04-23-41-30.bpo-33224.pyR0jB.rst
new file mode 100644
index 0000000..87ff100
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2018-04-04-23-41-30.bpo-33224.pyR0jB.rst
@@ -0,0 +1,2 @@
+Update difflib.mdiff() for PEP 479. Convert an uncaught StopIteration in a
+generator into a return-statement.