[Python-checkins] cpython (2.7): Issue #19018: The heapq.merge() function no longer suppresses IndexError

Sun Sep 15 07:17:51 CEST 2013

http://hg.python.org/cpython/rev/56a3c0bc4634
changeset: 85711:56a3c0bc4634
branch: 2.7
parent: 85685:b90ba60c5029
user: Raymond Hettinger <python at rcn.com>
date: Sat Sep 14 22:17:39 2013 -0700
summary:
 Issue #19018: The heapq.merge() function no longer suppresses IndexError
files:
 Lib/heapq.py | 15 ++++++++++-----
 Lib/test/test_heapq.py | 9 +++++++++
 Misc/ACKS | 2 ++
 Misc/NEWS | 3 +++
 4 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/Lib/heapq.py b/Lib/heapq.py
--- a/Lib/heapq.py
+++ b/Lib/heapq.py
@@ -366,6 +366,7 @@
 
 '''
 _heappop, _heapreplace, _StopIteration = heappop, heapreplace, StopIteration
+ _len = len
 
 h = []
 h_append = h.append
@@ -377,17 +378,21 @@
 pass
 heapify(h)
 
- while 1:
+ while _len(h) > 1:
 try:
- while 1:
- v, itnum, next = s = h[0] # raises IndexError when h is empty
+ while True:
+ v, itnum, next = s = h[0]
 yield v
 s[0] = next() # raises StopIteration when exhausted
 _heapreplace(h, s) # restore heap condition
 except _StopIteration:
 _heappop(h) # remove empty iterator
- except IndexError:
- return
+ if h:
+ # fast case when only a single iterator remains
+ v, itnum, next = h[0]
+ yield v
+ for v in next.__self__:
+ yield v
 
 # Extend the implementations of nsmallest and nlargest to use a key= argument
 _nsmallest = nsmallest
diff --git a/Lib/test/test_heapq.py b/Lib/test/test_heapq.py
--- a/Lib/test/test_heapq.py
+++ b/Lib/test/test_heapq.py
@@ -158,6 +158,15 @@
 self.assertEqual(sorted(chain(*inputs)), list(self.module.merge(*inputs)))
 self.assertEqual(list(self.module.merge()), [])
 
+ def test_merge_does_not_suppress_index_error(self):
+ # Issue 19018: Heapq.merge suppresses IndexError from user generator
+ def iterable():
+ s = list(range(10))
+ for i in range(20):
+ yield s[i] # IndexError when i > 10
+ with self.assertRaises(IndexError):
+ list(self.module.merge(iterable(), iterable()))
+
 def test_merge_stability(self):
 class Int(int):
 pass
diff --git a/Misc/ACKS b/Misc/ACKS
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -110,6 +110,7 @@
 Matthew Boedicker
 Robin Boerdijk
 David Bolen
+Wouter Bolsterlee
 Gawain Bolton
 Gregory Bond
 Jurjen Bos
@@ -313,6 +314,7 @@
 Frederik Fix
 Matt Fleming
 Hernán Martínez Foffani
+Artem Fokin
 Arnaud Fontaine
 Michael Foord
 Amaury Forgeot d'Arc
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -35,6 +35,9 @@
 - Issue #17324: Fix http.server's request handling case on trailing '/'. Patch
 contributed by Vajrasky Kok.
 
+- Issue #19018: The heapq.merge() function no longer suppresses IndexError
+ in the underlying iterables.
+
 - Issue #18784: The uuid module no more attempts to load libc via ctypes.CDLL,
 if all necessary functions are already found in libuuid.
 Patch by Evgeny Sologubov.
-- 
Repository URL: http://hg.python.org/cpython
