| """Write ablation variants of a unified diff: the patch minus some changed lines. |
| |
| Usage: python3 ablate_patch.py PATCH OUTDIR [NAME=I,J,... ...] |
| |
| Changed lines ('+' and '-' lines inside hunks) are numbered 1..N in patch |
| order. For each i, OUTDIR/L<i>.diff is the patch without changed line i. |
| Each NAME=I,J,... argument adds OUTDIR/<NAME>.diff without the listed |
| lines. Dropping a '+' line removes it; dropping a '-' line keeps the |
| original line as context. Hunk headers are recomputed, and hunks left with |
| no change are removed. OUTDIR/MANIFEST lists every variant and the lines |
| it drops. |
| """ |
| import re |
| import sys |
| from pathlib import Path |
|
|
| HUNK = re.compile(r"^@@ -(\d+)(?:,(\d+))? \+(\d+)(?:,(\d+))? @@(.*)$") |
|
|
|
|
| def parse(text): |
| """Return a list of files: (header_lines, [(old_start, tail, body_lines)]).""" |
| files, cur, hunk = [], None, None |
| for line in text.splitlines(): |
| m = HUNK.match(line) |
| if line.startswith("diff --git"): |
| cur = ([line], []) |
| files.append(cur) |
| hunk = None |
| elif m: |
| hunk = (int(m.group(1)), m.group(5), []) |
| cur[1].append(hunk) |
| elif hunk is None: |
| cur[0].append(line) |
| else: |
| hunk[2].append(line) |
| return files |
|
|
|
|
| def render(files, drop): |
| out, idx = [], 0 |
| for header, hunks in files: |
| body_out, delta = [], 0 |
| for old_start, tail, body in hunks: |
| lines = [] |
| for line in body: |
| if line[:1] in "+-": |
| idx += 1 |
| if idx in drop: |
| if line[0] == "-": |
| lines.append(" " + line[1:]) |
| continue |
| lines.append(line) |
| |
| while lines and lines[-1] == "": |
| lines.pop() |
| if not any(l[:1] in "+-" for l in lines): |
| continue |
| old_n = sum(1 for l in lines if l[:1] in " -" or l == "") |
| new_n = sum(1 for l in lines if l[:1] in " +" or l == "") |
| body_out.append(f"@@ -{old_start},{old_n} +{old_start + delta},{new_n} @@{tail}") |
| body_out.extend(lines) |
| delta += new_n - old_n |
| if body_out: |
| out.extend(header) |
| out.extend(body_out) |
| return "\n".join(out) + "\n" |
|
|
|
|
| def main(): |
| patch, outdir = Path(sys.argv[1]), Path(sys.argv[2]) |
| files = parse(patch.read_text()) |
| changed = [l for _, hunks in files for _, _, body in hunks for l in body if l[:1] in "+-"] |
| outdir.mkdir(parents=True, exist_ok=True) |
| variants = [(f"L{i}", {i}) for i in range(1, len(changed) + 1)] |
| for arg in sys.argv[3:]: |
| name, idx = arg.split("=", 1) |
| variants.append((name, {int(x) for x in idx.split(",")})) |
| with open(outdir / "MANIFEST", "w") as man: |
| for i, line in enumerate(changed, 1): |
| man.write(f"line {i}: {line}\n") |
| for name, drop in variants: |
| (outdir / f"{name}.diff").write_text(render(files, drop)) |
| man.write(f"{name}: drops {','.join(map(str, sorted(drop)))}\n") |
| print(f"{len(changed)} changed lines, {len(variants)} variants") |
|
|
|
|
| if __name__ == "__main__": |
| main() |
|
|
