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Range diff

range_diff

Read-only commit-range measurements and disposable revision exports.

ChangedFile dataclass

A repository-relative file and its changed line intervals.

Source code in packages/axm-git/src/axm_git/core/range_diff.py
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@dataclass(frozen=True)
class ChangedFile:
    """A repository-relative file and its changed line intervals."""

    path: str
    hunks: tuple[Hunk, ...]

Hunk dataclass

Line intervals on both sides; zero count denotes an insertion/deletion.

Source code in packages/axm-git/src/axm_git/core/range_diff.py
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@dataclass(frozen=True)
class Hunk:
    """Line intervals on both sides; zero count denotes an insertion/deletion."""

    old_start: int
    old_count: int
    new_start: int
    new_count: int

export_revision(root, rev)

Export tracked regular files to a temporary tree without registering worktrees.

Symlinks and submodules are not followed. No files or refs in the source repository are modified. The export contains no executable git history.

Source code in packages/axm-git/src/axm_git/core/range_diff.py
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@contextmanager
def export_revision(root: Path, rev: str) -> Iterator[Path]:
    """Export tracked regular files to a temporary tree without registering worktrees.

    Symlinks and submodules are not followed. No files or refs in the source
    repository are modified. The export contains no executable git history.
    """
    sha = resolve_revision(root, rev)
    result = subprocess.run(
        ["git", "archive", "--format=tar", sha],
        cwd=root,
        capture_output=True,
        check=False,
        timeout=120,
    )
    if result.returncode:
        raise ValueError(result.stderr.decode(errors="replace"))
    with TemporaryDirectory(prefix="axm-revision-") as directory:
        dest = Path(directory).resolve()
        with tarfile.open(fileobj=io.BytesIO(result.stdout)) as archive:
            members = [
                member for member in archive if member.isfile() or member.isdir()
            ]
            archive.extractall(dest, members=members, filter="data")
        yield dest

range_diff(root, base, head)

Measure a pinned base..head range, independent of index/worktree state.

Source code in packages/axm-git/src/axm_git/core/range_diff.py
Python
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def range_diff(root: Path, base: str, head: str) -> tuple[ChangedFile, ...]:
    """Measure a pinned base..head range, independent of index/worktree state."""
    base, head = resolve_revision(root, base), resolve_revision(root, head)
    names = _output(
        root,
        [
            "diff",
            "--no-ext-diff",
            "--no-renames",
            "--name-only",
            "-z",
            base,
            head,
            "--",
        ],
    )
    rows: list[ChangedFile] = []
    pattern = re.compile(r"^@@ -(\d+)(?:,(\d+))? \+(\d+)(?:,(\d+))? @@")
    for name in sorted(filter(None, names.split("\0"))):
        patch = _output(
            root,
            [
                "diff",
                "--no-ext-diff",
                "--no-textconv",
                "--no-renames",
                "--unified=0",
                base,
                head,
                "--",
                name,
            ],
        )
        hunks = []
        for line in patch.splitlines():
            match = pattern.match(line)
            if match:
                a, b, c, d = match.groups()
                hunks.append(Hunk(int(a), int(b or 1), int(c), int(d or 1)))
        rows.append(ChangedFile(name, tuple(hunks)))
    return tuple(rows)

resolve_revision(root, rev)

Resolve a non-option commit ref once before measuring or exporting it.

Source code in packages/axm-git/src/axm_git/core/range_diff.py
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def resolve_revision(root: Path, rev: str) -> str:
    """Resolve a non-option commit ref once before measuring or exporting it."""
    if not rev or rev.startswith("-"):
        raise ValueError("a non-option commit revision is required")
    return _output(root, ["rev-parse", "--verify", rev + "^{commit}"]).strip()