rdblue commented on code in PR #6566:
URL: https://github.com/apache/iceberg/pull/6566#discussion_r1089307147
##########
python/pyiceberg/expressions/visitors.py:
##########
@@ -881,3 +881,82 @@ def rewrite_to_dnf(expr: BooleanExpression) ->
Tuple[BooleanExpression, ...]:
# (A AND NOT(B) AND C) OR (NOT(D) AND E AND F) OR (G)
expr_without_not = rewrite_not(expr)
return visit(expr_without_not, _RewriteToDNF())
+
+
+class ExpressionToPlainFormat(BoundBooleanExpressionVisitor[List[Tuple[str,
str, Any]]]):
+ def visit_in(self, term: BoundTerm[L], literals: Set[L]) ->
List[Tuple[str, str, Any]]:
+ return [(term.ref().field.name, "in", literals)]
+
+ def visit_not_in(self, term: BoundTerm[L], literals: Set[L]) ->
List[Tuple[str, str, Any]]:
+ return [(term.ref().field.name, "not in", literals)]
+
+ def visit_is_nan(self, term: BoundTerm[L]) -> List[Tuple[str, str, Any]]:
+ return [(term.ref().field.name, "==", float("nan"))]
+
+ def visit_not_nan(self, term: BoundTerm[L]) -> List[Tuple[str, str, Any]]:
+ return [(term.ref().field.name, "!=", float("nan"))]
+
+ def visit_is_null(self, term: BoundTerm[L]) -> List[Tuple[str, str, Any]]:
+ return [(term.ref().field.name, "==", None)]
+
+ def visit_not_null(self, term: BoundTerm[L]) -> List[Tuple[str, str, Any]]:
+ return [(term.ref().field.name, "!=", None)]
+
+ def visit_equal(self, term: BoundTerm[L], literal: Literal[L]) ->
List[Tuple[str, str, Any]]:
+ return [(term.ref().field.name, "==", literal.value)]
+
+ def visit_not_equal(self, term: BoundTerm[L], literal: Literal[L]) ->
List[Tuple[str, str, Any]]:
+ return [(term.ref().field.name, "!=", literal.value)]
+
+ def visit_greater_than_or_equal(self, term: BoundTerm[L], literal:
Literal[L]) -> List[Tuple[str, str, Any]]:
+ return [(term.ref().field.name, ">=", literal.value)]
+
+ def visit_greater_than(self, term: BoundTerm[L], literal: Literal[L]) ->
List[Tuple[str, str, Any]]:
+ return [(term.ref().field.name, ">", literal.value)]
+
+ def visit_less_than(self, term: BoundTerm[L], literal: Literal[L]) ->
List[Tuple[str, str, Any]]:
+ return [(term.ref().field.name, "<", literal.value)]
+
+ def visit_less_than_or_equal(self, term: BoundTerm[L], literal:
Literal[L]) -> List[Tuple[str, str, Any]]:
+ return [(term.ref().field.name, "<=", literal.value)]
+
+ def visit_true(self) -> List[Tuple[str, str, Any]]:
+ return [] # Not supported
+
+ def visit_false(self) -> List[Tuple[str, str, Any]]:
+ raise ValueError("Not supported: AlwaysFalse")
+
+ def visit_not(self, child_result: List[Tuple[str, str, Any]]) ->
List[Tuple[str, str, Any]]:
+ raise ValueError(f"Not allowed: {child_result}")
+
+ def visit_and(
+ self, left_result: List[Tuple[str, str, Any]], right_result:
List[Tuple[str, str, Any]]
+ ) -> List[Tuple[str, str, Any]]:
+ return left_result + right_result
+
+ def visit_or(
+ self, left_result: List[Tuple[str, str, Any]], right_result:
List[Tuple[str, str, Any]]
+ ) -> List[Tuple[str, str, Any]]:
+ raise ValueError(f"Not allowed: {left_result} || {right_result}")
+
+
+def expression_to_plain_format(expressions: Tuple[BooleanExpression, ...]) ->
List[List[Tuple[str, str, Any]]]:
+ """Formats a Disjunctive Normal Form expression into the format that can
be fed into:
+
+ -
https://arrow.apache.org/docs/python/generated/pyarrow.parquet.read_table.html
+ -
https://docs.dask.org/en/stable/generated/dask.dataframe.read_parquet.html
+
+ Contrary to normal DNF that may contain Not expressions, but here they
should have
+ been rewritten. This can be done using ``rewrite_not(...)``.
+
+ Keep in mind that this is only used for page skipping, and still needs to
filter
+ on a row level.
+
+ Args:
+ expressions: Expression in Disjunctive Normal Form
+
+ Returns:
+ Formatter filter compatible with Dask and PyArrow
+ """
+ # In the form of expr1 ∨ expr2 ∨ ... ∨ exprN
+ return [visit(expression, ExpressionToPlainFormat()) for expression in
expressions]
Review Comment:
Should this reuse the `ExpressionToPlainFormat` instance?
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