Function _parse_unified_diff

code_review_graph/changes.py:136–166

Parse unified diff output into file -> line-range mappings. Handles the ``@@ -old,count +new,count @@`` hunk header format.

(diff_text: str)

def _parse_unified_diff(diff_text: str) -> dict[str, list[tuple[int, int]]]:
    """Parse unified diff output into file -> line-range mappings.

    Handles the ``@@ -old,count +new,count @@`` hunk header format.
    """
    ranges: dict[str, list[tuple[int, int]]] = {}
    current_file: str | None = None

    # Match "+++ b/path/to/file"
    file_pattern = re.compile(r"^\+\+\+ b/(.+)$")
    # Match "@@ ... +start,count @@" or "@@ ... +start @@"
    hunk_pattern = re.compile(r"^@@ .+? \+(\d+)(?:,(\d+))? @@")

    for line in diff_text.splitlines():
        file_match = file_pattern.match(line)
        if file_match:
            current_file = file_match.group(1)
            continue

        hunk_match = hunk_pattern.match(line)
        if hunk_match and current_file is not None:
            start = int(hunk_match.group(1))
            count = int(hunk_match.group(2)) if hunk_match.group(2) else 1
            if count == 0:
                # Pure deletion hunk (no lines added); still note the position.
                end = start
            else:
                end = start + count - 1
            ranges.setdefault(current_file, []).append((start, end))

    return ranges


# ---------------------------------------------------------------------------