flink-python/pyflink/table/resolved_expression.py

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from typing import List

from pyflink.table.expression import Expression
from pyflink.table.types import DataType, _from_java_data_type
from pyflink.util.api_stability_decorators import PublicEvolving

__all__ = ["ResolvedExpression"]


@PublicEvolving()
class ResolvedExpression(Expression):
    """
    Expression that has been fully resolved and validated.

    Compared to :class:`~pyflink.table.Expression`, resolved expressions do not contain unresolved
    subexpressions anymore and provide an output data type for the computation result.

    Instances of this class describe a fully parameterized, immutable expression that can be
    serialized and persisted.

    Resolved expression are the output of the API to the planner and are pushed from the planner
    into interfaces, for example, for predicate push-down.
    """

    def __init__(self, j_resolved_expr):
        super().__init__(j_expr_or_property_name=j_resolved_expr)
        self._j_resolved_expr = j_resolved_expr

    def __str__(self):
        return self._j_resolved_expr.toString()

    def get_output_data_type(self) -> DataType:
        """
        Returns the data type of the computation result.
        """
        j_data_type = self._j_resolved_expr.getOutputDataType()
        return _from_java_data_type(j_data_type)

    def get_resolved_children(self) -> List["ResolvedExpression"]:
        j_resolved_children = self._j_resolved_expr.getResolvedChildren()
        return [ResolvedExpression(j_resolved_child) for j_resolved_child in j_resolved_children]

    def as_serializable_string(self) -> str:
        """
        Returns a string that fully serializes this instance. The serialized string can be used for
        storing the query in, for example, a :class:`~pyflink.table.catalog.Catalog` as a view.
        """
        return self._j_resolved_expr.asSerializableString()

    def as_summary_string(self) -> str:
        """
        Returns a string that summarizes this expression for printing to a console. An
        implementation might skip very specific properties.
        """
        return self._j_resolved_expr.asSummaryString()