done

lib/python3.11/site-packages/narwhals/_sql/namespace.py

@@ -0,0 +1,73 @@
+from __future__ import annotations
+
+import operator
+from functools import reduce
+from typing import TYPE_CHECKING, Any, Protocol
+
+from narwhals._compliant import LazyNamespace
+from narwhals._compliant.typing import NativeExprT, NativeFrameT_co
+from narwhals._sql.typing import SQLExprT, SQLLazyFrameT
+
+if TYPE_CHECKING:
+    from collections.abc import Iterable
+
+    from narwhals.typing import PythonLiteral
+
+
+class SQLNamespace(
+    LazyNamespace[SQLLazyFrameT, SQLExprT, NativeFrameT_co],
+    Protocol[SQLLazyFrameT, SQLExprT, NativeFrameT_co, NativeExprT],
+):
+    def _function(self, name: str, *args: NativeExprT | PythonLiteral) -> NativeExprT: ...
+    def _lit(self, value: Any) -> NativeExprT: ...
+    def _when(
+        self,
+        condition: NativeExprT,
+        value: NativeExprT,
+        otherwise: NativeExprT | None = None,
+    ) -> NativeExprT: ...
+    def _coalesce(self, *exprs: NativeExprT) -> NativeExprT: ...
+
+    # Horizontal functions
+    def any_horizontal(self, *exprs: SQLExprT, ignore_nulls: bool) -> SQLExprT:
+        def func(cols: Iterable[NativeExprT]) -> NativeExprT:
+            if ignore_nulls:
+                cols = (self._coalesce(col, self._lit(False)) for col in cols)
+            return reduce(operator.or_, cols)
+
+        return self._expr._from_elementwise_horizontal_op(func, *exprs)
+
+    def all_horizontal(self, *exprs: SQLExprT, ignore_nulls: bool) -> SQLExprT:
+        def func(cols: Iterable[NativeExprT]) -> NativeExprT:
+            if ignore_nulls:
+                cols = (self._coalesce(col, self._lit(True)) for col in cols)
+            return reduce(operator.and_, cols)
+
+        return self._expr._from_elementwise_horizontal_op(func, *exprs)
+
+    def max_horizontal(self, *exprs: SQLExprT) -> SQLExprT:
+        def func(cols: Iterable[NativeExprT]) -> NativeExprT:
+            return self._function("greatest", *cols)
+
+        return self._expr._from_elementwise_horizontal_op(func, *exprs)
+
+    def min_horizontal(self, *exprs: SQLExprT) -> SQLExprT:
+        def func(cols: Iterable[NativeExprT]) -> NativeExprT:
+            return self._function("least", *cols)
+
+        return self._expr._from_elementwise_horizontal_op(func, *exprs)
+
+    def sum_horizontal(self, *exprs: SQLExprT) -> SQLExprT:
+        def func(cols: Iterable[NativeExprT]) -> NativeExprT:
+            return reduce(
+                operator.add, (self._coalesce(col, self._lit(0)) for col in cols)
+            )
+
+        return self._expr._from_elementwise_horizontal_op(func, *exprs)
+
+    # Other
+    def coalesce(self, *exprs: SQLExprT) -> SQLExprT:
+        def func(cols: Iterable[NativeExprT]) -> NativeExprT:
+            return self._coalesce(*cols)
+
+        return self._expr._from_elementwise_horizontal_op(func, *exprs)