Fokko commented on code in PR #320: URL: https://github.com/apache/iceberg-rust/pull/320#discussion_r1565645549
########## crates/iceberg/src/expr/visitors/bound_predicate_visitor.rs: ########## @@ -0,0 +1,317 @@ +// Licensed to the Apache Software Foundation (ASF) under one +// or more contributor license agreements. See the NOTICE file +// distributed with this work for additional information +// regarding copyright ownership. The ASF licenses this file +// to you under the Apache License, Version 2.0 (the +// "License"); you may not use this file except in compliance +// with the License. You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, +// software distributed under the License is distributed on an +// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +// KIND, either express or implied. See the License for the +// specific language governing permissions and limitations +// under the License. + +use crate::expr::{BoundPredicate, BoundReference, PredicateOperator}; +use crate::spec::Datum; +use crate::Result; +use fnv::FnvHashSet; + +pub(crate) enum OpLiteral<'a> { + Single(&'a Datum), + Set(&'a FnvHashSet<Datum>), +} + +/// A visitor for [`BoundPredicate`]s. Visits in post-order. +pub trait BoundPredicateVisitor { + /// The return type of this visitor + type T; + + /// Called after an `AlwaysTrue` predicate is visited + fn always_true(&mut self) -> Result<Self::T>; + + /// Called after an `AlwaysFalse` predicate is visited + fn always_false(&mut self) -> Result<Self::T>; + + /// Called after an `And` predicate is visited + fn and(&mut self, lhs: Self::T, rhs: Self::T) -> Result<Self::T>; + + /// Called after an `Or` predicate is visited + fn or(&mut self, lhs: Self::T, rhs: Self::T) -> Result<Self::T>; + + /// Called after a `Not` predicate is visited + fn not(&mut self, inner: Self::T) -> Result<Self::T>; + + /// Called after visiting a UnaryPredicate, BinaryPredicate, + /// or SetPredicate. Passes the predicate's operator in all cases, + /// as well as the term and literals in the case of binary and aet + /// predicates. + fn op( + &mut self, + op: PredicateOperator, + reference: &BoundReference, + literal: Option<OpLiteral>, + predicate: &BoundPredicate, + ) -> Result<Self::T>; +} + +/// Visits a [`BoundPredicate`] with the provided visitor, +/// in post-order +pub(crate) fn visit<V: BoundPredicateVisitor>( + visitor: &mut V, + predicate: &BoundPredicate, +) -> Result<V::T> { + match predicate { + BoundPredicate::AlwaysTrue => visitor.always_true(), + BoundPredicate::AlwaysFalse => visitor.always_false(), + BoundPredicate::And(expr) => { + let [left_pred, right_pred] = expr.inputs(); + + let left_result = visit(visitor, left_pred)?; + let right_result = visit(visitor, right_pred)?; + + visitor.and(left_result, right_result) + } + BoundPredicate::Or(expr) => { + let [left_pred, right_pred] = expr.inputs(); + + let left_result = visit(visitor, left_pred)?; + let right_result = visit(visitor, right_pred)?; + + visitor.or(left_result, right_result) + } + BoundPredicate::Not(expr) => { + let [inner_pred] = expr.inputs(); + + let inner_result = visit(visitor, inner_pred)?; + + visitor.not(inner_result) + } + BoundPredicate::Unary(expr) => visitor.op(expr.op(), expr.term(), None, predicate), Review Comment: In PyIceberg we've split out the operator in a per-operator basis: https://github.com/apache/iceberg-python/blob/4b911057f13491f30f89f133544c063133133fa5/pyiceberg/expressions/visitors.py#L256 The InclusiveMetricsEvaluator is already quite a beefy visitor, and by having it on this level, 95% will fall in a the `op` method: https://github.com/apache/iceberg-python/blob/4b911057f13491f30f89f133544c063133133fa5/pyiceberg/expressions/visitors.py#L1137 I think this is the nicest way since it leverages the visitor pattern as much as possible, but I also saw the discussion of having this on the `{unary,binary,set}` level. ########## crates/iceberg/src/expr/predicate.rs: ########## @@ -217,6 +249,10 @@ impl<T: Display + Debug> Display for SetExpression<T> { /// Unbound predicate expression before binding to a schema. #[derive(Debug, PartialEq)] pub enum Predicate { + /// AlwaysTrue predicate, for example, `TRUE`. + AlwaysTrue, + /// AlwaysFalse predicate, for example, `FALSE`. + AlwaysFalse, Review Comment: To add here, when we bind an `isNull` expression to a required field, then we know that that isn't possible :) ########## crates/iceberg/src/expr/visitors/bound_predicate_visitor.rs: ########## @@ -0,0 +1,317 @@ +// Licensed to the Apache Software Foundation (ASF) under one +// or more contributor license agreements. See the NOTICE file +// distributed with this work for additional information +// regarding copyright ownership. The ASF licenses this file +// to you under the Apache License, Version 2.0 (the +// "License"); you may not use this file except in compliance +// with the License. You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, +// software distributed under the License is distributed on an +// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +// KIND, either express or implied. See the License for the +// specific language governing permissions and limitations +// under the License. + +use crate::expr::{BoundPredicate, BoundReference, PredicateOperator}; +use crate::spec::Datum; +use crate::Result; +use fnv::FnvHashSet; + +pub(crate) enum OpLiteral<'a> { + Single(&'a Datum), + Set(&'a FnvHashSet<Datum>), +} + +/// A visitor for [`BoundPredicate`]s. Visits in post-order. +pub trait BoundPredicateVisitor { + /// The return type of this visitor + type T; + + /// Called after an `AlwaysTrue` predicate is visited + fn always_true(&mut self) -> Result<Self::T>; + + /// Called after an `AlwaysFalse` predicate is visited + fn always_false(&mut self) -> Result<Self::T>; + + /// Called after an `And` predicate is visited + fn and(&mut self, lhs: Self::T, rhs: Self::T) -> Result<Self::T>; + + /// Called after an `Or` predicate is visited + fn or(&mut self, lhs: Self::T, rhs: Self::T) -> Result<Self::T>; + + /// Called after a `Not` predicate is visited + fn not(&mut self, inner: Self::T) -> Result<Self::T>; + + /// Called after visiting a UnaryPredicate, BinaryPredicate, + /// or SetPredicate. Passes the predicate's operator in all cases, + /// as well as the term and literals in the case of binary and aet Review Comment: ```suggestion /// as well as the term and literals in the case of binary and set ``` ########## crates/iceberg/src/expr/visitors/bound_predicate_visitor.rs: ########## @@ -0,0 +1,317 @@ +// Licensed to the Apache Software Foundation (ASF) under one +// or more contributor license agreements. See the NOTICE file +// distributed with this work for additional information +// regarding copyright ownership. The ASF licenses this file +// to you under the Apache License, Version 2.0 (the +// "License"); you may not use this file except in compliance +// with the License. You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, +// software distributed under the License is distributed on an +// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +// KIND, either express or implied. See the License for the +// specific language governing permissions and limitations +// under the License. + +use crate::expr::{BoundPredicate, BoundReference, PredicateOperator}; +use crate::spec::Datum; +use crate::Result; +use fnv::FnvHashSet; + +pub(crate) enum OpLiteral<'a> { + Single(&'a Datum), + Set(&'a FnvHashSet<Datum>), +} + +/// A visitor for [`BoundPredicate`]s. Visits in post-order. +pub trait BoundPredicateVisitor { + /// The return type of this visitor + type T; + + /// Called after an `AlwaysTrue` predicate is visited + fn always_true(&mut self) -> Result<Self::T>; + + /// Called after an `AlwaysFalse` predicate is visited + fn always_false(&mut self) -> Result<Self::T>; + + /// Called after an `And` predicate is visited + fn and(&mut self, lhs: Self::T, rhs: Self::T) -> Result<Self::T>; + + /// Called after an `Or` predicate is visited + fn or(&mut self, lhs: Self::T, rhs: Self::T) -> Result<Self::T>; + + /// Called after a `Not` predicate is visited + fn not(&mut self, inner: Self::T) -> Result<Self::T>; + + /// Called after visiting a UnaryPredicate, BinaryPredicate, + /// or SetPredicate. Passes the predicate's operator in all cases, + /// as well as the term and literals in the case of binary and aet + /// predicates. + fn op( + &mut self, + op: PredicateOperator, + reference: &BoundReference, + literal: Option<OpLiteral>, + predicate: &BoundPredicate, + ) -> Result<Self::T>; +} + +/// Visits a [`BoundPredicate`] with the provided visitor, +/// in post-order +pub(crate) fn visit<V: BoundPredicateVisitor>( + visitor: &mut V, + predicate: &BoundPredicate, +) -> Result<V::T> { + match predicate { + BoundPredicate::AlwaysTrue => visitor.always_true(), + BoundPredicate::AlwaysFalse => visitor.always_false(), + BoundPredicate::And(expr) => { + let [left_pred, right_pred] = expr.inputs(); + + let left_result = visit(visitor, left_pred)?; + let right_result = visit(visitor, right_pred)?; + + visitor.and(left_result, right_result) + } + BoundPredicate::Or(expr) => { + let [left_pred, right_pred] = expr.inputs(); + + let left_result = visit(visitor, left_pred)?; + let right_result = visit(visitor, right_pred)?; + + visitor.or(left_result, right_result) + } + BoundPredicate::Not(expr) => { + let [inner_pred] = expr.inputs(); + + let inner_result = visit(visitor, inner_pred)?; + + visitor.not(inner_result) + } + BoundPredicate::Unary(expr) => visitor.op(expr.op(), expr.term(), None, predicate), Review Comment: With Python it is easy to have a cache-all where if nothing matches, it just goes to that one, and then we raise an exception that we've encountered an unknown predicate. This way it is possible to add new expressions, but I don't think that would happen too often. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: issues-unsubscr...@iceberg.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@iceberg.apache.org For additional commands, e-mail: issues-h...@iceberg.apache.org
