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Patch #1413711: Certain patterns of differences were making difflib

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touch the recursion limit. The applied patch inlines the recursive
__helper method in a non-recursive way.
This commit is contained in:
Gustavo Niemeyer 2006-01-31 18:34:13 +00:00
parent c81e3a63af
commit 548148810b
3 changed files with 34 additions and 17 deletions
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39
Lib/difflib.py
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@ -473,27 +473,32 @@ class SequenceMatcher:
if self.matching_blocks is not None:
return self.matching_blocks
self.matching_blocks = []
la, lb = len(self.a), len(self.b)
self.__helper(0, la, 0, lb, self.matching_blocks)
indexed_blocks = []
queue = [(0, la, 0, lb)]
while queue:
# builds list of matching blocks covering a[alo:ahi] and
# b[blo:bhi], appending them in increasing order to answer
alo, ahi, blo, bhi = queue.pop()
# a[alo:i] vs b[blo:j] unknown
# a[i:i+k] same as b[j:j+k]
# a[i+k:ahi] vs b[j+k:bhi] unknown
i, j, k = x = self.find_longest_match(alo, ahi, blo, bhi)
if k:
if alo < i and blo < j:
queue.append((alo, i, blo, j))
indexed_blocks.append((i, x))
if i+k < ahi and j+k < bhi:
queue.append((i+k, ahi, j+k, bhi))
indexed_blocks.sort()
self.matching_blocks = [elem[1] for elem in indexed_blocks]
self.matching_blocks.append( (la, lb, 0) )
return self.matching_blocks
# builds list of matching blocks covering a[alo:ahi] and
# b[blo:bhi], appending them in increasing order to answer
def __helper(self, alo, ahi, blo, bhi, answer):
i, j, k = x = self.find_longest_match(alo, ahi, blo, bhi)
# a[alo:i] vs b[blo:j] unknown
# a[i:i+k] same as b[j:j+k]
# a[i+k:ahi] vs b[j+k:bhi] unknown
if k:
if alo < i and blo < j:
self.__helper(alo, i, blo, j, answer)
answer.append(x)
if i+k < ahi and j+k < bhi:
self.__helper(i+k, ahi, j+k, bhi, answer)
def get_opcodes(self):
"""Return list of 5-tuples describing how to turn a into b.