alamb commented on code in PR #4646: URL: https://github.com/apache/arrow-datafusion/pull/4646#discussion_r1057248291
########## datafusion/optimizer/src/simplify_expressions/regex.rs: ########## @@ -0,0 +1,162 @@ +// 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 datafusion_common::{DataFusionError, ScalarValue}; +use datafusion_expr::{BinaryExpr, Expr, Like, Operator}; +use regex_syntax::hir::{Hir, HirKind, Literal}; + +/// Maximum number of regex alternations (`foo|bar|...`) that will be expanded into multiple `LIKE` expressions. +const MAX_REGEX_ALTERNATIONS_EXPENSION: usize = 4; + +pub fn simplify_regex_expr( + left: Box<Expr>, + op: Operator, + right: Box<Expr>, +) -> Result<Expr, DataFusionError> { + let mode = OperatorMode::new(&op); + + if let Expr::Literal(ScalarValue::Utf8(Some(pattern))) = right.as_ref() { + match regex_syntax::Parser::new().parse(pattern) { + Ok(hir) => { Review Comment: Relevant docs in case anyone else is looking: https://docs.rs/regex-syntax/0.6.28/regex_syntax/struct.Parser.html#method.parse ########## datafusion/optimizer/src/simplify_expressions/expr_simplifier.rs: ########## @@ -1576,17 +1589,166 @@ mod tests { assert_eq!(simplify(expr), expected) } + #[test] + fn test_simplify_regex() { + // malformed regex + assert_contains!( + try_simplify(regex_match(col("c1"), lit("foo{"))) + .unwrap_err() + .to_string(), + "regex parse error" + ); + + // unsupported cases + assert_no_change(regex_match(col("c1"), lit("foo.*"))); + assert_no_change(regex_match(col("c1"), lit("(foo)"))); + assert_no_change(regex_match(col("c1"), lit("^foo"))); + assert_no_change(regex_match(col("c1"), lit("foo$"))); + assert_no_change(regex_match(col("c1"), lit("%"))); + assert_no_change(regex_match(col("c1"), lit("_"))); + assert_no_change(regex_match(col("c1"), lit("f%o"))); + assert_no_change(regex_match(col("c1"), lit("f_o"))); + + // empty cases + assert_change(regex_match(col("c1"), lit("")), like(col("c1"), "%")); + assert_change( + regex_not_match(col("c1"), lit("")), + not_like(col("c1"), "%"), + ); + assert_change(regex_imatch(col("c1"), lit("")), ilike(col("c1"), "%")); + assert_change( + regex_not_imatch(col("c1"), lit("")), + not_ilike(col("c1"), "%"), + ); + + // single character + assert_change(regex_match(col("c1"), lit("x")), like(col("c1"), "%x%")); + + // single word + assert_change(regex_match(col("c1"), lit("foo")), like(col("c1"), "%foo%")); + + // OR-chain + assert_change( + regex_match(col("c1"), lit("foo|bar|baz")), + like(col("c1"), "%foo%") + .or(like(col("c1"), "%bar%")) + .or(like(col("c1"), "%baz%")), + ); + assert_change( + regex_match(col("c1"), lit("foo|x|baz")), + like(col("c1"), "%foo%") + .or(like(col("c1"), "%x%")) + .or(like(col("c1"), "%baz%")), + ); + assert_change( + regex_match(col("c1"), lit("foo||baz")), + like(col("c1"), "%foo%") + .or(like(col("c1"), "%")) + .or(like(col("c1"), "%baz%")), + ); + assert_change( + regex_not_match(col("c1"), lit("foo|bar|baz")), + not_like(col("c1"), "%foo%") + .and(not_like(col("c1"), "%bar%")) + .and(not_like(col("c1"), "%baz%")), + ); + } + Review Comment: I didn't see any tests here for `MAX_REGEX_ALTERNATIONS_EXPENSION` -- maybe we could add one more check for `foo|bar|baz|blarg|bozo|etc` or something to show it wasn't rewritten -- 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: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
