FA-75571 / Text diff and three-way merge / Open access
Character diff cleanup merge: a zero-length suffix slices the whole deletion · case 01
Edits without a common suffix duplicate their deleted text into the next equality.
ROOT CAUSE
The suffix is taken with a negative slice, and dl[-0:] is the entire string.
VERIFIED REPAIR
Slice the suffix from len(dl) - s so an empty suffix stays empty.
Unsuccessful approach: Falling back to the last character when there is no suffix still invents a one-character suffix.
Case contract
Normalize a character diff of [op, text] (op -1 delete, 0 equal, 1 insert): drop empty texts, merge adjacent equalities, collect each run of edits into one deletion and one insertion (deletion first), move their common prefix into the preceding equality (creating one at the start if needed) and their common suffix into the following equality (appending one at the end if needed).
Why this case matters
Character-level diff engines normalize raw edit scripts so that the same change always renders the same way.
1 / The failure
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(diffs):
res = []
diffs = [list(d) for d in diffs if d[1] != '']
i = 0
while i < len(diffs):
if diffs[i][0] == 0:
if res and res[-1][0] == 0:
res[-1][1] += diffs[i][1]
else:
res.append([0, diffs[i][1]])
i += 1
continue
dl = ins = ''
while i < len(diffs) and diffs[i][0] != 0:
if diffs[i][0] == -1:
dl += diffs[i][1]
else:
ins += diffs[i][1]
i += 1
suffix = ''
if dl and ins:
p = 0
while p < min(len(dl), len(ins)) and dl[p] == ins[p]:
p += 1
if p:
if res and res[-1][0] == 0:
res[-1][1] += dl[:p]
else:
res.append([0, dl[:p]])
dl, ins = dl[p:], ins[p:]
s = 0
while s < min(len(dl), len(ins)) and dl[-1 - s] == ins[-1 - s]:
s += 1
suffix = dl[-s:]
dl, ins = dl[:len(dl) - s], ins[:len(ins) - s]
if dl:
res.append([-1, dl])
if ins:
res.append([1, ins])
if suffix:
if i < len(diffs) and diffs[i][0] == 0:
diffs[i] = [0, suffix + diffs[i][1]]
else:
res.append([0, suffix])
return res
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = {
1: [('adjacent equalities merge', [[[0, 'ab'], [0, 'cd']]], [[0, 'abcd']]), ('empty entries are dropped', [[[0, 'a'], [-1, ''], [1, 'b'], [0, '']]], [[0, 'a'], [1, 'b']]), ('common prefix moves into the previous equality', [[[0, 'x'], [-1, 'abc'], [1, 'abd'], [0, 'y']]], [[0, 'xab'], [-1, 'c'], [1, 'd'], [0, 'y']]), ('common suffix moves into the next equality', [[[0, 'p'], [-1, 'kz'], [1, 'mz'], [0, 'q']]], [[0, 'p'], [-1, 'k'], [1, 'm'], [0, 'zq']]), ('no common affix', [[[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'e']]], [[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'e']]), ('interleaved edits are grouped deletion first', [[[1, 'I'], [-1, 'D'], [1, 'J'], [-1, 'E']]], [[-1, 'DE'], [1, 'IJ']]), ('suffix at the end of the text', [[[0, 'st'], [-1, 'xyz1'], [1, 'uvz1']]], [[0, 'st'], [-1, 'xy'], [1, 'uv'], [0, 'z1']]), ('prefix at the start of the text', [[[-1, 'prea'], [1, 'preb'], [0, 'tail']]], [[0, 'pre'], [-1, 'a'], [1, 'b'], [0, 'tail']]), ('insertion only', [[[0, 'a'], [1, 'b'], [0, 'c']]], [[0, 'a'], [1, 'b'], [0, 'c']]), ('empty equality between edits', [[[0, 'k'], [-1, 'ab1'], [0, ''], [1, 'ac1']]], [[0, 'ka'], [-1, 'b'], [1, 'c'], [0, '1']])],
2: [('adjacent equalities merge', [[[0, 'ab'], [0, 'cd']]], [[0, 'abcd']]), ('empty entries are dropped', [[[0, 'a'], [-1, ''], [1, 'b'], [0, '']]], [[0, 'a'], [1, 'b']]), ('common prefix moves into the previous equality', [[[0, 'x'], [-1, 'abc'], [1, 'abd'], [0, 'y']]], [[0, 'xab'], [-1, 'c'], [1, 'd'], [0, 'y']]), ('common suffix moves into the next equality', [[[0, 'p'], [-1, 'kz'], [1, 'mz'], [0, 'q']]], [[0, 'p'], [-1, 'k'], [1, 'm'], [0, 'zq']]), ('no common affix', [[[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'e']]], [[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'e']]), ('interleaved edits are grouped deletion first', [[[1, 'I'], [-1, 'D'], [1, 'J'], [-1, 'E']]], [[-1, 'DE'], [1, 'IJ']]), ('suffix at the end of the text', [[[0, 'st'], [-1, 'xyz2'], [1, 'uvz2']]], [[0, 'st'], [-1, 'xy'], [1, 'uv'], [0, 'z2']]), ('prefix at the start of the text', [[[-1, 'preprea'], [1, 'prepreb'], [0, 'tail']]], [[0, 'prepre'], [-1, 'a'], [1, 'b'], [0, 'tail']]), ('insertion only', [[[0, 'a'], [1, 'b'], [0, 'c']]], [[0, 'a'], [1, 'b'], [0, 'c']]), ('empty equality between edits', [[[0, 'k'], [-1, 'ab2'], [0, ''], [1, 'ac2']]], [[0, 'ka'], [-1, 'b'], [1, 'c'], [0, '2']])],
3: [('adjacent equalities merge', [[[0, 'ab'], [0, 'cd']]], [[0, 'abcd']]), ('empty entries are dropped', [[[0, 'a'], [-1, ''], [1, 'b'], [0, '']]], [[0, 'a'], [1, 'b']]), ('common prefix moves into the previous equality', [[[0, 'x'], [-1, 'abc'], [1, 'abd'], [0, 'y']]], [[0, 'xab'], [-1, 'c'], [1, 'd'], [0, 'y']]), ('common suffix moves into the next equality', [[[0, 'p'], [-1, 'kz'], [1, 'mz'], [0, 'q']]], [[0, 'p'], [-1, 'k'], [1, 'm'], [0, 'zq']]), ('no common affix', [[[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'e']]], [[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'e']]), ('interleaved edits are grouped deletion first', [[[1, 'I'], [-1, 'D'], [1, 'J'], [-1, 'E']]], [[-1, 'DE'], [1, 'IJ']]), ('suffix at the end of the text', [[[0, 'st'], [-1, 'xyz3'], [1, 'uvz3']]], [[0, 'st'], [-1, 'xy'], [1, 'uv'], [0, 'z3']]), ('prefix at the start of the text', [[[-1, 'prepreprea'], [1, 'preprepreb'], [0, 'tail']]], [[0, 'preprepre'], [-1, 'a'], [1, 'b'], [0, 'tail']]), ('insertion only', [[[0, 'a'], [1, 'b'], [0, 'c']]], [[0, 'a'], [1, 'b'], [0, 'c']]), ('empty equality between edits', [[[0, 'k'], [-1, 'ab3'], [0, ''], [1, 'ac3']]], [[0, 'ka'], [-1, 'b'], [1, 'c'], [0, '3']])],
4: [('adjacent equalities merge', [[[0, 'ab'], [0, 'cd']]], [[0, 'abcd']]), ('empty entries are dropped', [[[0, 'a'], [-1, ''], [1, 'b'], [0, '']]], [[0, 'a'], [1, 'b']]), ('common prefix moves into the previous equality', [[[0, 'x'], [-1, 'abc'], [1, 'abd'], [0, 'y']]], [[0, 'xab'], [-1, 'c'], [1, 'd'], [0, 'y']]), ('common suffix moves into the next equality', [[[0, 'p'], [-1, 'kz'], [1, 'mz'], [0, 'q']]], [[0, 'p'], [-1, 'k'], [1, 'm'], [0, 'zq']]), ('no common affix', [[[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'e']]], [[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'e']]), ('interleaved edits are grouped deletion first', [[[1, 'I'], [-1, 'D'], [1, 'J'], [-1, 'E']]], [[-1, 'DE'], [1, 'IJ']]), ('suffix at the end of the text', [[[0, 'st'], [-1, 'xyz4'], [1, 'uvz4']]], [[0, 'st'], [-1, 'xy'], [1, 'uv'], [0, 'z4']]), ('prefix at the start of the text', [[[-1, 'preprepreprea'], [1, 'prepreprepreb'], [0, 'tail']]], [[0, 'prepreprepre'], [-1, 'a'], [1, 'b'], [0, 'tail']]), ('insertion only', [[[0, 'a'], [1, 'b'], [0, 'c']]], [[0, 'a'], [1, 'b'], [0, 'c']]), ('empty equality between edits', [[[0, 'k'], [-1, 'ab4'], [0, ''], [1, 'ac4']]], [[0, 'ka'], [-1, 'b'], [1, 'c'], [0, '4']])],
5: [('adjacent equalities merge', [[[0, 'ab'], [0, 'cd']]], [[0, 'abcd']]), ('empty entries are dropped', [[[0, 'a'], [-1, ''], [1, 'b'], [0, '']]], [[0, 'a'], [1, 'b']]), ('common prefix moves into the previous equality', [[[0, 'x'], [-1, 'abc'], [1, 'abd'], [0, 'y']]], [[0, 'xab'], [-1, 'c'], [1, 'd'], [0, 'y']]), ('common suffix moves into the next equality', [[[0, 'p'], [-1, 'kz'], [1, 'mz'], [0, 'q']]], [[0, 'p'], [-1, 'k'], [1, 'm'], [0, 'zq']]), ('no common affix', [[[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'e']]], [[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'e']]), ('interleaved edits are grouped deletion first', [[[1, 'I'], [-1, 'D'], [1, 'J'], [-1, 'E']]], [[-1, 'DE'], [1, 'IJ']]), ('suffix at the end of the text', [[[0, 'st'], [-1, 'xyz5'], [1, 'uvz5']]], [[0, 'st'], [-1, 'xy'], [1, 'uv'], [0, 'z5']]), ('prefix at the start of the text', [[[-1, 'prepreprepreprea'], [1, 'preprepreprepreb'], [0, 'tail']]], [[0, 'preprepreprepre'], [-1, 'a'], [1, 'b'], [0, 'tail']]), ('insertion only', [[[0, 'a'], [1, 'b'], [0, 'c']]], [[0, 'a'], [1, 'b'], [0, 'c']]), ('empty equality between edits', [[[0, 'k'], [-1, 'ab5'], [0, ''], [1, 'ac5']]], [[0, 'ka'], [-1, 'b'], [1, 'c'], [0, '5']])],
}[N]
for label, args, expected in cases:
check(label, solve(*args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
| Boundary fixture | Actual | Expected | Outcome |
|---|---|---|---|
| adjacent equalities merge | [[0, 'abcd']] | [[0, 'abcd']] | Passed |
| empty entries are dropped | [[0, 'a'], [1, 'b']] | [[0, 'a'], [1, 'b']] | Passed |
| common prefix moves into the previous equality | [[0, 'xab'], [-1, 'c'], [1, 'd'], [0, 'cy']] | [[0, 'xab'], [-1, 'c'], [1, 'd'], [0, 'y']] | Failed |
| common suffix moves into the next equality | [[0, 'p'], [-1, 'k'], [1, 'm'], [0, 'zq']] | [[0, 'p'], [-1, 'k'], [1, 'm'], [0, 'zq']] | Passed |
| no common affix | [[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'abe']] | [[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'e']] | Failed |
| interleaved edits are grouped deletion first | [[-1, 'DE'], [1, 'IJ'], [0, 'DE']] | [[-1, 'DE'], [1, 'IJ']] | Failed |
| suffix at the end of the text | [[0, 'st'], [-1, 'xy'], [1, 'uv'], [0, 'z1']] | [[0, 'st'], [-1, 'xy'], [1, 'uv'], [0, 'z1']] | Passed |
| prefix at the start of the text | [[0, 'pre'], [-1, 'a'], [1, 'b'], [0, 'atail']] | [[0, 'pre'], [-1, 'a'], [1, 'b'], [0, 'tail']] | Failed |
| insertion only | [[0, 'a'], [1, 'b'], [0, 'c']] | [[0, 'a'], [1, 'b'], [0, 'c']] | Passed |
| empty equality between edits | [[0, 'ka'], [-1, 'b'], [1, 'c'], [0, '1']] | [[0, 'ka'], [-1, 'b'], [1, 'c'], [0, '1']] | Passed |
SHA-256 / d189889c3caac7a76905bf191cfd66ac7c2640af9136bd5d24e2a54918598f1b
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(diffs):
res = []
diffs = [list(d) for d in diffs if d[1] != '']
i = 0
while i < len(diffs):
if diffs[i][0] == 0:
if res and res[-1][0] == 0:
res[-1][1] += diffs[i][1]
else:
res.append([0, diffs[i][1]])
i += 1
continue
dl = ins = ''
while i < len(diffs) and diffs[i][0] != 0:
if diffs[i][0] == -1:
dl += diffs[i][1]
else:
ins += diffs[i][1]
i += 1
suffix = ''
if dl and ins:
p = 0
while p < min(len(dl), len(ins)) and dl[p] == ins[p]:
p += 1
if p:
if res and res[-1][0] == 0:
res[-1][1] += dl[:p]
else:
res.append([0, dl[:p]])
dl, ins = dl[p:], ins[p:]
s = 0
while s < min(len(dl), len(ins)) and dl[-1 - s] == ins[-1 - s]:
s += 1
suffix = dl[-s:] if not dl else dl[len(dl) - s:] if s else dl[-1:]
dl, ins = dl[:len(dl) - s], ins[:len(ins) - s]
if dl:
res.append([-1, dl])
if ins:
res.append([1, ins])
if suffix:
if i < len(diffs) and diffs[i][0] == 0:
diffs[i] = [0, suffix + diffs[i][1]]
else:
res.append([0, suffix])
return res
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = {
1: [('adjacent equalities merge', [[[0, 'ab'], [0, 'cd']]], [[0, 'abcd']]), ('empty entries are dropped', [[[0, 'a'], [-1, ''], [1, 'b'], [0, '']]], [[0, 'a'], [1, 'b']]), ('common prefix moves into the previous equality', [[[0, 'x'], [-1, 'abc'], [1, 'abd'], [0, 'y']]], [[0, 'xab'], [-1, 'c'], [1, 'd'], [0, 'y']]), ('common suffix moves into the next equality', [[[0, 'p'], [-1, 'kz'], [1, 'mz'], [0, 'q']]], [[0, 'p'], [-1, 'k'], [1, 'm'], [0, 'zq']]), ('no common affix', [[[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'e']]], [[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'e']]), ('interleaved edits are grouped deletion first', [[[1, 'I'], [-1, 'D'], [1, 'J'], [-1, 'E']]], [[-1, 'DE'], [1, 'IJ']]), ('suffix at the end of the text', [[[0, 'st'], [-1, 'xyz1'], [1, 'uvz1']]], [[0, 'st'], [-1, 'xy'], [1, 'uv'], [0, 'z1']]), ('prefix at the start of the text', [[[-1, 'prea'], [1, 'preb'], [0, 'tail']]], [[0, 'pre'], [-1, 'a'], [1, 'b'], [0, 'tail']]), ('insertion only', [[[0, 'a'], [1, 'b'], [0, 'c']]], [[0, 'a'], [1, 'b'], [0, 'c']]), ('empty equality between edits', [[[0, 'k'], [-1, 'ab1'], [0, ''], [1, 'ac1']]], [[0, 'ka'], [-1, 'b'], [1, 'c'], [0, '1']])],
2: [('adjacent equalities merge', [[[0, 'ab'], [0, 'cd']]], [[0, 'abcd']]), ('empty entries are dropped', [[[0, 'a'], [-1, ''], [1, 'b'], [0, '']]], [[0, 'a'], [1, 'b']]), ('common prefix moves into the previous equality', [[[0, 'x'], [-1, 'abc'], [1, 'abd'], [0, 'y']]], [[0, 'xab'], [-1, 'c'], [1, 'd'], [0, 'y']]), ('common suffix moves into the next equality', [[[0, 'p'], [-1, 'kz'], [1, 'mz'], [0, 'q']]], [[0, 'p'], [-1, 'k'], [1, 'm'], [0, 'zq']]), ('no common affix', [[[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'e']]], [[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'e']]), ('interleaved edits are grouped deletion first', [[[1, 'I'], [-1, 'D'], [1, 'J'], [-1, 'E']]], [[-1, 'DE'], [1, 'IJ']]), ('suffix at the end of the text', [[[0, 'st'], [-1, 'xyz2'], [1, 'uvz2']]], [[0, 'st'], [-1, 'xy'], [1, 'uv'], [0, 'z2']]), ('prefix at the start of the text', [[[-1, 'preprea'], [1, 'prepreb'], [0, 'tail']]], [[0, 'prepre'], [-1, 'a'], [1, 'b'], [0, 'tail']]), ('insertion only', [[[0, 'a'], [1, 'b'], [0, 'c']]], [[0, 'a'], [1, 'b'], [0, 'c']]), ('empty equality between edits', [[[0, 'k'], [-1, 'ab2'], [0, ''], [1, 'ac2']]], [[0, 'ka'], [-1, 'b'], [1, 'c'], [0, '2']])],
3: [('adjacent equalities merge', [[[0, 'ab'], [0, 'cd']]], [[0, 'abcd']]), ('empty entries are dropped', [[[0, 'a'], [-1, ''], [1, 'b'], [0, '']]], [[0, 'a'], [1, 'b']]), ('common prefix moves into the previous equality', [[[0, 'x'], [-1, 'abc'], [1, 'abd'], [0, 'y']]], [[0, 'xab'], [-1, 'c'], [1, 'd'], [0, 'y']]), ('common suffix moves into the next equality', [[[0, 'p'], [-1, 'kz'], [1, 'mz'], [0, 'q']]], [[0, 'p'], [-1, 'k'], [1, 'm'], [0, 'zq']]), ('no common affix', [[[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'e']]], [[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'e']]), ('interleaved edits are grouped deletion first', [[[1, 'I'], [-1, 'D'], [1, 'J'], [-1, 'E']]], [[-1, 'DE'], [1, 'IJ']]), ('suffix at the end of the text', [[[0, 'st'], [-1, 'xyz3'], [1, 'uvz3']]], [[0, 'st'], [-1, 'xy'], [1, 'uv'], [0, 'z3']]), ('prefix at the start of the text', [[[-1, 'prepreprea'], [1, 'preprepreb'], [0, 'tail']]], [[0, 'preprepre'], [-1, 'a'], [1, 'b'], [0, 'tail']]), ('insertion only', [[[0, 'a'], [1, 'b'], [0, 'c']]], [[0, 'a'], [1, 'b'], [0, 'c']]), ('empty equality between edits', [[[0, 'k'], [-1, 'ab3'], [0, ''], [1, 'ac3']]], [[0, 'ka'], [-1, 'b'], [1, 'c'], [0, '3']])],
4: [('adjacent equalities merge', [[[0, 'ab'], [0, 'cd']]], [[0, 'abcd']]), ('empty entries are dropped', [[[0, 'a'], [-1, ''], [1, 'b'], [0, '']]], [[0, 'a'], [1, 'b']]), ('common prefix moves into the previous equality', [[[0, 'x'], [-1, 'abc'], [1, 'abd'], [0, 'y']]], [[0, 'xab'], [-1, 'c'], [1, 'd'], [0, 'y']]), ('common suffix moves into the next equality', [[[0, 'p'], [-1, 'kz'], [1, 'mz'], [0, 'q']]], [[0, 'p'], [-1, 'k'], [1, 'm'], [0, 'zq']]), ('no common affix', [[[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'e']]], [[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'e']]), ('interleaved edits are grouped deletion first', [[[1, 'I'], [-1, 'D'], [1, 'J'], [-1, 'E']]], [[-1, 'DE'], [1, 'IJ']]), ('suffix at the end of the text', [[[0, 'st'], [-1, 'xyz4'], [1, 'uvz4']]], [[0, 'st'], [-1, 'xy'], [1, 'uv'], [0, 'z4']]), ('prefix at the start of the text', [[[-1, 'preprepreprea'], [1, 'prepreprepreb'], [0, 'tail']]], [[0, 'prepreprepre'], [-1, 'a'], [1, 'b'], [0, 'tail']]), ('insertion only', [[[0, 'a'], [1, 'b'], [0, 'c']]], [[0, 'a'], [1, 'b'], [0, 'c']]), ('empty equality between edits', [[[0, 'k'], [-1, 'ab4'], [0, ''], [1, 'ac4']]], [[0, 'ka'], [-1, 'b'], [1, 'c'], [0, '4']])],
5: [('adjacent equalities merge', [[[0, 'ab'], [0, 'cd']]], [[0, 'abcd']]), ('empty entries are dropped', [[[0, 'a'], [-1, ''], [1, 'b'], [0, '']]], [[0, 'a'], [1, 'b']]), ('common prefix moves into the previous equality', [[[0, 'x'], [-1, 'abc'], [1, 'abd'], [0, 'y']]], [[0, 'xab'], [-1, 'c'], [1, 'd'], [0, 'y']]), ('common suffix moves into the next equality', [[[0, 'p'], [-1, 'kz'], [1, 'mz'], [0, 'q']]], [[0, 'p'], [-1, 'k'], [1, 'm'], [0, 'zq']]), ('no common affix', [[[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'e']]], [[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'e']]), ('interleaved edits are grouped deletion first', [[[1, 'I'], [-1, 'D'], [1, 'J'], [-1, 'E']]], [[-1, 'DE'], [1, 'IJ']]), ('suffix at the end of the text', [[[0, 'st'], [-1, 'xyz5'], [1, 'uvz5']]], [[0, 'st'], [-1, 'xy'], [1, 'uv'], [0, 'z5']]), ('prefix at the start of the text', [[[-1, 'prepreprepreprea'], [1, 'preprepreprepreb'], [0, 'tail']]], [[0, 'preprepreprepre'], [-1, 'a'], [1, 'b'], [0, 'tail']]), ('insertion only', [[[0, 'a'], [1, 'b'], [0, 'c']]], [[0, 'a'], [1, 'b'], [0, 'c']]), ('empty equality between edits', [[[0, 'k'], [-1, 'ab5'], [0, ''], [1, 'ac5']]], [[0, 'ka'], [-1, 'b'], [1, 'c'], [0, '5']])],
}[N]
for label, args, expected in cases:
check(label, solve(*args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
| Boundary fixture | Actual | Expected | Outcome |
|---|---|---|---|
| adjacent equalities merge | [[0, 'abcd']] | [[0, 'abcd']] | Passed |
| empty entries are dropped | [[0, 'a'], [1, 'b']] | [[0, 'a'], [1, 'b']] | Passed |
| common prefix moves into the previous equality | [[0, 'xab'], [-1, 'c'], [1, 'd'], [0, 'cy']] | [[0, 'xab'], [-1, 'c'], [1, 'd'], [0, 'y']] | Failed |
| common suffix moves into the next equality | [[0, 'p'], [-1, 'k'], [1, 'm'], [0, 'zq']] | [[0, 'p'], [-1, 'k'], [1, 'm'], [0, 'zq']] | Passed |
| no common affix | [[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'be']] | [[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'e']] | Failed |
| interleaved edits are grouped deletion first | [[-1, 'DE'], [1, 'IJ'], [0, 'E']] | [[-1, 'DE'], [1, 'IJ']] | Failed |
| suffix at the end of the text | [[0, 'st'], [-1, 'xy'], [1, 'uv'], [0, 'z1']] | [[0, 'st'], [-1, 'xy'], [1, 'uv'], [0, 'z1']] | Passed |
| prefix at the start of the text | [[0, 'pre'], [-1, 'a'], [1, 'b'], [0, 'atail']] | [[0, 'pre'], [-1, 'a'], [1, 'b'], [0, 'tail']] | Failed |
| insertion only | [[0, 'a'], [1, 'b'], [0, 'c']] | [[0, 'a'], [1, 'b'], [0, 'c']] | Passed |
| empty equality between edits | [[0, 'ka'], [-1, 'b'], [1, 'c'], [0, '1']] | [[0, 'ka'], [-1, 'b'], [1, 'c'], [0, '1']] | Passed |
SHA-256 / 05a9f5a3cf09a52b3d045e41aac779fbee2cbbc9d71aa4e6d3db8431070418a6
3 / The verified repair
Exit 0"""Failure Map reference implementation. Python standard library only."""
import json
N = 1
observations = []
def solve(diffs):
res = []
diffs = [list(d) for d in diffs if d[1] != '']
i = 0
while i < len(diffs):
if diffs[i][0] == 0:
if res and res[-1][0] == 0:
res[-1][1] += diffs[i][1]
else:
res.append([0, diffs[i][1]])
i += 1
continue
dl = ins = ''
while i < len(diffs) and diffs[i][0] != 0:
if diffs[i][0] == -1:
dl += diffs[i][1]
else:
ins += diffs[i][1]
i += 1
suffix = ''
if dl and ins:
p = 0
while p < min(len(dl), len(ins)) and dl[p] == ins[p]:
p += 1
if p:
if res and res[-1][0] == 0:
res[-1][1] += dl[:p]
else:
res.append([0, dl[:p]])
dl, ins = dl[p:], ins[p:]
s = 0
while s < min(len(dl), len(ins)) and dl[-1 - s] == ins[-1 - s]:
s += 1
suffix = dl[len(dl) - s:]
dl, ins = dl[:len(dl) - s], ins[:len(ins) - s]
if dl:
res.append([-1, dl])
if ins:
res.append([1, ins])
if suffix:
if i < len(diffs) and diffs[i][0] == 0:
diffs[i] = [0, suffix + diffs[i][1]]
else:
res.append([0, suffix])
return res
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
cases = {
1: [('adjacent equalities merge', [[[0, 'ab'], [0, 'cd']]], [[0, 'abcd']]), ('empty entries are dropped', [[[0, 'a'], [-1, ''], [1, 'b'], [0, '']]], [[0, 'a'], [1, 'b']]), ('common prefix moves into the previous equality', [[[0, 'x'], [-1, 'abc'], [1, 'abd'], [0, 'y']]], [[0, 'xab'], [-1, 'c'], [1, 'd'], [0, 'y']]), ('common suffix moves into the next equality', [[[0, 'p'], [-1, 'kz'], [1, 'mz'], [0, 'q']]], [[0, 'p'], [-1, 'k'], [1, 'm'], [0, 'zq']]), ('no common affix', [[[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'e']]], [[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'e']]), ('interleaved edits are grouped deletion first', [[[1, 'I'], [-1, 'D'], [1, 'J'], [-1, 'E']]], [[-1, 'DE'], [1, 'IJ']]), ('suffix at the end of the text', [[[0, 'st'], [-1, 'xyz1'], [1, 'uvz1']]], [[0, 'st'], [-1, 'xy'], [1, 'uv'], [0, 'z1']]), ('prefix at the start of the text', [[[-1, 'prea'], [1, 'preb'], [0, 'tail']]], [[0, 'pre'], [-1, 'a'], [1, 'b'], [0, 'tail']]), ('insertion only', [[[0, 'a'], [1, 'b'], [0, 'c']]], [[0, 'a'], [1, 'b'], [0, 'c']]), ('empty equality between edits', [[[0, 'k'], [-1, 'ab1'], [0, ''], [1, 'ac1']]], [[0, 'ka'], [-1, 'b'], [1, 'c'], [0, '1']])],
2: [('adjacent equalities merge', [[[0, 'ab'], [0, 'cd']]], [[0, 'abcd']]), ('empty entries are dropped', [[[0, 'a'], [-1, ''], [1, 'b'], [0, '']]], [[0, 'a'], [1, 'b']]), ('common prefix moves into the previous equality', [[[0, 'x'], [-1, 'abc'], [1, 'abd'], [0, 'y']]], [[0, 'xab'], [-1, 'c'], [1, 'd'], [0, 'y']]), ('common suffix moves into the next equality', [[[0, 'p'], [-1, 'kz'], [1, 'mz'], [0, 'q']]], [[0, 'p'], [-1, 'k'], [1, 'm'], [0, 'zq']]), ('no common affix', [[[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'e']]], [[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'e']]), ('interleaved edits are grouped deletion first', [[[1, 'I'], [-1, 'D'], [1, 'J'], [-1, 'E']]], [[-1, 'DE'], [1, 'IJ']]), ('suffix at the end of the text', [[[0, 'st'], [-1, 'xyz2'], [1, 'uvz2']]], [[0, 'st'], [-1, 'xy'], [1, 'uv'], [0, 'z2']]), ('prefix at the start of the text', [[[-1, 'preprea'], [1, 'prepreb'], [0, 'tail']]], [[0, 'prepre'], [-1, 'a'], [1, 'b'], [0, 'tail']]), ('insertion only', [[[0, 'a'], [1, 'b'], [0, 'c']]], [[0, 'a'], [1, 'b'], [0, 'c']]), ('empty equality between edits', [[[0, 'k'], [-1, 'ab2'], [0, ''], [1, 'ac2']]], [[0, 'ka'], [-1, 'b'], [1, 'c'], [0, '2']])],
3: [('adjacent equalities merge', [[[0, 'ab'], [0, 'cd']]], [[0, 'abcd']]), ('empty entries are dropped', [[[0, 'a'], [-1, ''], [1, 'b'], [0, '']]], [[0, 'a'], [1, 'b']]), ('common prefix moves into the previous equality', [[[0, 'x'], [-1, 'abc'], [1, 'abd'], [0, 'y']]], [[0, 'xab'], [-1, 'c'], [1, 'd'], [0, 'y']]), ('common suffix moves into the next equality', [[[0, 'p'], [-1, 'kz'], [1, 'mz'], [0, 'q']]], [[0, 'p'], [-1, 'k'], [1, 'm'], [0, 'zq']]), ('no common affix', [[[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'e']]], [[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'e']]), ('interleaved edits are grouped deletion first', [[[1, 'I'], [-1, 'D'], [1, 'J'], [-1, 'E']]], [[-1, 'DE'], [1, 'IJ']]), ('suffix at the end of the text', [[[0, 'st'], [-1, 'xyz3'], [1, 'uvz3']]], [[0, 'st'], [-1, 'xy'], [1, 'uv'], [0, 'z3']]), ('prefix at the start of the text', [[[-1, 'prepreprea'], [1, 'preprepreb'], [0, 'tail']]], [[0, 'preprepre'], [-1, 'a'], [1, 'b'], [0, 'tail']]), ('insertion only', [[[0, 'a'], [1, 'b'], [0, 'c']]], [[0, 'a'], [1, 'b'], [0, 'c']]), ('empty equality between edits', [[[0, 'k'], [-1, 'ab3'], [0, ''], [1, 'ac3']]], [[0, 'ka'], [-1, 'b'], [1, 'c'], [0, '3']])],
4: [('adjacent equalities merge', [[[0, 'ab'], [0, 'cd']]], [[0, 'abcd']]), ('empty entries are dropped', [[[0, 'a'], [-1, ''], [1, 'b'], [0, '']]], [[0, 'a'], [1, 'b']]), ('common prefix moves into the previous equality', [[[0, 'x'], [-1, 'abc'], [1, 'abd'], [0, 'y']]], [[0, 'xab'], [-1, 'c'], [1, 'd'], [0, 'y']]), ('common suffix moves into the next equality', [[[0, 'p'], [-1, 'kz'], [1, 'mz'], [0, 'q']]], [[0, 'p'], [-1, 'k'], [1, 'm'], [0, 'zq']]), ('no common affix', [[[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'e']]], [[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'e']]), ('interleaved edits are grouped deletion first', [[[1, 'I'], [-1, 'D'], [1, 'J'], [-1, 'E']]], [[-1, 'DE'], [1, 'IJ']]), ('suffix at the end of the text', [[[0, 'st'], [-1, 'xyz4'], [1, 'uvz4']]], [[0, 'st'], [-1, 'xy'], [1, 'uv'], [0, 'z4']]), ('prefix at the start of the text', [[[-1, 'preprepreprea'], [1, 'prepreprepreb'], [0, 'tail']]], [[0, 'prepreprepre'], [-1, 'a'], [1, 'b'], [0, 'tail']]), ('insertion only', [[[0, 'a'], [1, 'b'], [0, 'c']]], [[0, 'a'], [1, 'b'], [0, 'c']]), ('empty equality between edits', [[[0, 'k'], [-1, 'ab4'], [0, ''], [1, 'ac4']]], [[0, 'ka'], [-1, 'b'], [1, 'c'], [0, '4']])],
5: [('adjacent equalities merge', [[[0, 'ab'], [0, 'cd']]], [[0, 'abcd']]), ('empty entries are dropped', [[[0, 'a'], [-1, ''], [1, 'b'], [0, '']]], [[0, 'a'], [1, 'b']]), ('common prefix moves into the previous equality', [[[0, 'x'], [-1, 'abc'], [1, 'abd'], [0, 'y']]], [[0, 'xab'], [-1, 'c'], [1, 'd'], [0, 'y']]), ('common suffix moves into the next equality', [[[0, 'p'], [-1, 'kz'], [1, 'mz'], [0, 'q']]], [[0, 'p'], [-1, 'k'], [1, 'm'], [0, 'zq']]), ('no common affix', [[[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'e']]], [[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'e']]), ('interleaved edits are grouped deletion first', [[[1, 'I'], [-1, 'D'], [1, 'J'], [-1, 'E']]], [[-1, 'DE'], [1, 'IJ']]), ('suffix at the end of the text', [[[0, 'st'], [-1, 'xyz5'], [1, 'uvz5']]], [[0, 'st'], [-1, 'xy'], [1, 'uv'], [0, 'z5']]), ('prefix at the start of the text', [[[-1, 'prepreprepreprea'], [1, 'preprepreprepreb'], [0, 'tail']]], [[0, 'preprepreprepre'], [-1, 'a'], [1, 'b'], [0, 'tail']]), ('insertion only', [[[0, 'a'], [1, 'b'], [0, 'c']]], [[0, 'a'], [1, 'b'], [0, 'c']]), ('empty equality between edits', [[[0, 'k'], [-1, 'ab5'], [0, ''], [1, 'ac5']]], [[0, 'ka'], [-1, 'b'], [1, 'c'], [0, '5']])],
}[N]
for label, args, expected in cases:
check(label, solve(*args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
| Boundary fixture | Actual | Expected | Outcome |
|---|---|---|---|
| adjacent equalities merge | [[0, 'abcd']] | [[0, 'abcd']] | Passed |
| empty entries are dropped | [[0, 'a'], [1, 'b']] | [[0, 'a'], [1, 'b']] | Passed |
| common prefix moves into the previous equality | [[0, 'xab'], [-1, 'c'], [1, 'd'], [0, 'y']] | [[0, 'xab'], [-1, 'c'], [1, 'd'], [0, 'y']] | Passed |
| common suffix moves into the next equality | [[0, 'p'], [-1, 'k'], [1, 'm'], [0, 'zq']] | [[0, 'p'], [-1, 'k'], [1, 'm'], [0, 'zq']] | Passed |
| no common affix | [[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'e']] | [[0, 'h'], [-1, 'ab'], [1, 'cd'], [0, 'e']] | Passed |
| interleaved edits are grouped deletion first | [[-1, 'DE'], [1, 'IJ']] | [[-1, 'DE'], [1, 'IJ']] | Passed |
| suffix at the end of the text | [[0, 'st'], [-1, 'xy'], [1, 'uv'], [0, 'z1']] | [[0, 'st'], [-1, 'xy'], [1, 'uv'], [0, 'z1']] | Passed |
| prefix at the start of the text | [[0, 'pre'], [-1, 'a'], [1, 'b'], [0, 'tail']] | [[0, 'pre'], [-1, 'a'], [1, 'b'], [0, 'tail']] | Passed |
| insertion only | [[0, 'a'], [1, 'b'], [0, 'c']] | [[0, 'a'], [1, 'b'], [0, 'c']] | Passed |
| empty equality between edits | [[0, 'ka'], [-1, 'b'], [1, 'c'], [0, '1']] | [[0, 'ka'], [-1, 'b'], [1, 'c'], [0, '1']] | Passed |
SHA-256 / ef74d16deb1fb8eefd5809e2832497e8e9b4b810fb3a90fc851295b7626bdcf3
Verification & scope
A deterministic, bounded teaching model of one diff, patch or merge rule with stipulated conventions; it is not a production diff or version-control implementation and makes no claim of conformance to any specific tool. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.
Observations recorded using Python 3.12.14 at 2026-09-29T14:49:07.969292+00:00.
Case digest / fcaf68611fd01b0ded5e04603259f478e6455485f992847b713856034e961465