Class NavigationState

xtop/core/navigation.py:156–635

Manages drill-down/back-out navigation state

class NavigationState:
    """Manages drill-down/back-out navigation state"""
    
    _PREFIX_DISPLAY = _NAV_PREFIX_DISPLAY
    _LATENCY_SUFFIX_LABELS = _NAV_LATENCY_SUFFIX_LABELS
    _UNIT_SUFFIXES = _NAV_UNIT_SUFFIXES
    _LABEL_OVERRIDES = _NAV_LABEL_OVERRIDES

    def __init__(self):
        """Initialize navigation state"""
        self.history: List[NavigationFrame] = []
        self.current_frame: Optional[NavigationFrame] = None
        self.max_history = 100  # Prevent unlimited history growth
        self.grouping_history: List[List[str]] = []  # Track grouping changes for undo

    @staticmethod
    def _canonical(column: str) -> str:
        """Normalize column keys for consistent comparisons."""
        if column is None:
            raise ValueError("Column name cannot be None")
        return str(column).strip().lower()

    @staticmethod
    def _normalize_values(values: Any) -> List[Any]:
        """Ensure filter values are stored as lists."""
        if values is None:
            return []
        if isinstance(values, list):
            return list(values)
        if isinstance(values, (tuple, set)):
            return list(values)
        return [values]

    @staticmethod
    def _format_value(value: Any) -> str:
        """Format a value for human-readable display."""
        if value is None:
            return "NULL"
        if isinstance(value, str):
            return f"'{value}'" if ' ' in value else value
        return str(value)

    @classmethod
    def _format_values_short(cls, values: List[Any]) -> str:
        """Short display for a list of values."""
        if not values:
            return "[]"
        if len(values) == 1:
            return cls._format_value(values[0])
        if len(values) <= 3:
            formatted = ", ".join(cls._format_value(v) for v in values)
            return f"[{formatted}]"
        preview = ", ".join(cls._format_value(v) for v in values[:3])
        remaining = len(values) - 3
        return f"[{preview}, ... +{remaining} more]"

    @classmethod
    def _format_label(cls, column: str) -> str: