sweb commented on a change in pull request #9428: URL: https://github.com/apache/arrow/pull/9428#discussion_r602875955
########## File path: rust/arrow/src/compute/kernels/regexp.rs ########## @@ -0,0 +1,147 @@ +// 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. + +//! Defines kernel to extract substrings based on a regular +//! expression of a \[Large\]StringArray + +use crate::array::{ + ArrayRef, GenericStringArray, GenericStringBuilder, ListBuilder, + StringOffsetSizeTrait, +}; +use crate::error::{ArrowError, Result}; +use std::collections::HashMap; + +use std::sync::Arc; + +use regex::Regex; + +/// Extract all groups matched by a regular expression for a given String array. +pub fn regexp_match<OffsetSize: StringOffsetSizeTrait>( + array: &GenericStringArray<OffsetSize>, + regex_array: &GenericStringArray<OffsetSize>, + flags_array: Option<&GenericStringArray<OffsetSize>>, +) -> Result<ArrayRef> { + let mut patterns: HashMap<String, Regex> = HashMap::new(); + let builder: GenericStringBuilder<OffsetSize> = GenericStringBuilder::new(0); + let mut list_builder = ListBuilder::new(builder); + + let complete_pattern = match flags_array { + Some(flags) => Box::new(regex_array.iter().zip(flags.iter()).map( + |(pattern, flags)| { + pattern.map(|pattern| match flags { + Some(value) => format!("(?{}){}", value, pattern), + None => pattern.to_string(), + }) + }, + )) as Box<dyn Iterator<Item = Option<String>>>, + None => Box::new( + regex_array + .iter() + .map(|pattern| pattern.map(|pattern| pattern.to_string())), + ), + }; + array + .iter() + .zip(complete_pattern) + .map(|(value, pattern)| { + match (value, pattern) { + (Some(value), Some(pattern)) => { + let existing_pattern = patterns.get(&pattern); + let re = match existing_pattern { + Some(re) => re.clone(), + None => { + let re = Regex::new(pattern.as_str()).map_err(|e| { + ArrowError::ComputeError(format!( + "Regular expression did not compile: {:?}", + e + )) + })?; + patterns.insert(pattern, re.clone()); + re + } + }; + match re.captures(value) { + Some(caps) => { + for m in caps.iter().skip(1) { + if let Some(v) = m { + list_builder.values().append_value(v.as_str())?; + } + } + list_builder.append(true)? + } + None => { + list_builder.values().append_value("")?; Review comment: I changed the behavior - it returns NULL now. This was my half-thought-through attempt to address the review comment differentiating between matching on NULL and no match. -- 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. For queries about this service, please contact Infrastructure at: us...@infra.apache.org
