rohitg00/ai-engineering-from-scratch · error · ValueError

malformed line: {line!r}

Error message

malformed line: {line!r}

What it means

Error "malformed line: {line!r}" thrown in rohitg00/ai-engineering-from-scratch.

Source

Thrown at phases/19-capstone-projects/86-constitutional-rules-engine/code/yaml_subset.py:120

def _parse_mapping(lines: list[str], start: int, indent: int) -> tuple[dict[str, Any], int]:
    out: dict[str, Any] = {}
    i = start
    while i < len(lines):
        line = lines[i]
        cur_indent = _indent_of(line)
        if cur_indent < indent:
            break
        if cur_indent > indent:
            i += 1
            continue
        stripped = line.lstrip()
        if stripped.startswith("- "):
            break
        m = re.match(r"^([A-Za-z_][\w-]*)\s*:\s*(.*)$", stripped)
        if not m:
            raise ValueError(f"malformed line: {line!r}")
        key = m.group(1)
        rest = m.group(2)
        if rest.strip() == "":
            if i + 1 < len(lines) and _indent_of(lines[i + 1]) > indent:
                value, i = _parse_block(lines, i + 1, _indent_of(lines[i + 1]))
                out[key] = value
                continue
            out[key] = None
            i += 1
        else:
            out[key] = _coerce(rest)
            i += 1
    return out, i


def _parse_sequence(lines: list[str], start: int, indent: int) -> tuple[list[Any], int]:
    out: list[Any] = []
    i = start

View on GitHub (pinned to 39ea8a1c6d)

When it happens

Trigger: Thrown at phases/19-capstone-projects/86-constitutional-rules-engine/code/yaml_subset.py:120 when the library encounters an invalid state.

Common situations: See trigger scenarios.

Understand the failure class

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

AI-assisted analysis of rohitg00/ai-engineering-from-scratch@39ea8a1c6d (2026-08-26). Data as JSON: /api/errors/130022c7fa4f9d81. Report an issue: GitHub.