lazydict

LazyDict

Bases: Mapping[K, V]

Lazily build a dictionary from an array of items.

Source code in pyiceberg/utils/lazydict.py

class LazyDict(Mapping[K, V]):
    """Lazily build a dictionary from an array of items."""

    __slots__ = ("_contents", "_dict")

    # Since Python's type system is not powerful enough to express the type of the
    # contents of the dictionary, we use specify the type as a sequence of either K or V
    # values.
    #
    # Rather than spending the runtime cost of checking the type of each item, we presume
    # that the developer has correctly used the class and that the contents are valid.
    def __init__(self, contents: Sequence[Sequence[Union[K, V]]]):
        self._contents = contents
        self._dict: Optional[Dict[K, V]] = None

    def _build_dict(self) -> Dict[K, V]:
        self._dict = {}
        for item in self._contents:
            self._dict.update(dict(zip(cast(Sequence[K], item[::2]), cast(Sequence[V], item[1::2]))))

        return self._dict

    def __getitem__(self, key: K, /) -> V:
        """Return the value for the given key."""
        source = self._dict or self._build_dict()
        return source[key]

    def __iter__(self) -> Iterator[K]:
        """Return an iterator over the keys of the dictionary."""
        source = self._dict or self._build_dict()
        return iter(source)

    def __len__(self) -> int:
        """Return the number of items in the dictionary."""
        source = self._dict or self._build_dict()
        return len(source)

__getitem__(key)

Return the value for the given key.

Source code in pyiceberg/utils/lazydict.py

def __getitem__(self, key: K, /) -> V:
    """Return the value for the given key."""
    source = self._dict or self._build_dict()
    return source[key]

__iter__()

Return an iterator over the keys of the dictionary.

Source code in pyiceberg/utils/lazydict.py

def __iter__(self) -> Iterator[K]:
    """Return an iterator over the keys of the dictionary."""
    source = self._dict or self._build_dict()
    return iter(source)

__len__()

Return the number of items in the dictionary.

Source code in pyiceberg/utils/lazydict.py

def __len__(self) -> int:
    """Return the number of items in the dictionary."""
    source = self._dict or self._build_dict()
    return len(source)