54 lines
1.8 KiB
Python
54 lines
1.8 KiB
Python
from __future__ import annotations
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from typing import TYPE_CHECKING, Any, Protocol
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from narwhals._compliant.dataframe import CompliantLazyFrame
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from narwhals._compliant.typing import (
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CompliantExprT_contra,
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NativeExprT,
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NativeLazyFrameT,
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)
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from narwhals._translate import ToNarwhalsT_co
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from narwhals._utils import check_columns_exist
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from narwhals.exceptions import MultiOutputExpressionError
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if TYPE_CHECKING:
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from collections.abc import Sequence
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from typing_extensions import Self, TypeAlias
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from narwhals._compliant.window import WindowInputs
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from narwhals._sql.expr import SQLExpr
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from narwhals.exceptions import ColumnNotFoundError
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Incomplete: TypeAlias = Any
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class SQLLazyFrame(
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CompliantLazyFrame[CompliantExprT_contra, NativeLazyFrameT, ToNarwhalsT_co],
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Protocol[CompliantExprT_contra, NativeLazyFrameT, ToNarwhalsT_co],
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):
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def _evaluate_window_expr(
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self,
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expr: SQLExpr[Self, NativeExprT],
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/,
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window_inputs: WindowInputs[NativeExprT],
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) -> NativeExprT:
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result = expr.window_function(self, window_inputs)
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if len(result) != 1: # pragma: no cover
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msg = "multi-output expressions not allowed in this context"
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raise MultiOutputExpressionError(msg)
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return result[0]
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def _evaluate_single_output_expr(
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self, expr: SQLExpr[Self, NativeExprT], /
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) -> NativeExprT:
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result = expr(self)
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if len(result) != 1: # pragma: no cover
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msg = "multi-output expressions not allowed in this context"
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raise MultiOutputExpressionError(msg)
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return result[0]
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def _check_columns_exist(self, subset: Sequence[str]) -> ColumnNotFoundError | None:
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return check_columns_exist(subset, available=self.columns)
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