tustvold commented on code in PR #2578: URL: https://github.com/apache/arrow-datafusion/pull/2578#discussion_r884797982
########## datafusion/core/src/datasource/listing/path.rs: ########## @@ -0,0 +1,304 @@ +// 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::datasource::object_store::ObjectStoreUrl; +use datafusion_common::{DataFusionError, Result}; +use datafusion_data_access::object_store::ObjectStore; +use datafusion_data_access::FileMeta; +use futures::stream::BoxStream; +use futures::{StreamExt, TryStreamExt}; +use glob::Pattern; +use itertools::Itertools; +use std::path::is_separator; +use url::Url; + +/// A parsed URL identifying files for a listing table, see [`ListingTableUrl::parse`] +/// for more information on the supported expressions +#[derive(Debug, Clone)] +pub struct ListingTableUrl { + /// A URL that identifies a file or directory to list files from + url: Url, + /// An optional glob expression used to filter files + glob: Option<Pattern>, +} + +impl ListingTableUrl { + /// Parse a provided string as a `ListingTableUrl` + /// + /// # Paths without a Scheme + /// + /// If no scheme is provided, or the string is an absolute filesystem path + /// as determined [`std::path::Path::is_absolute`], the string will be + /// interpreted as a path on the local filesystem using the operating + /// system's standard path delimiter, i.e. `\` on Windows, `/` on Unix. + /// + /// If the path contains any of `'?', '*', '['`, it will be considered + /// a glob expression and resolved as described in the section below. + /// + /// Otherwise, the path will be resolved to an absolute path, returning + /// an error if it does not exist, and converted to a [file URI] + /// + /// If you wish to specify a path that does not exist on the local + /// machine you must provide it as a fully-qualified [file URI] + /// e.g. `file:///myfile.txt` + /// + /// ## Glob Paths + /// + /// If no scheme is provided, and the path contains a glob expression, it will + /// be resolved as follows. + /// + /// The string up to the first path segment containing a glob expression will be extracted, + /// and resolved in the same manner as a normal scheme-less path. That is, resolved to + /// an absolute path on the local filesystem, returning an error if it does not exist, + /// and converted to a [file URI] + /// + /// The remaining string will be interpreted as a [`glob::Pattern`] and used as a + /// filter when listing files from object storage + /// + /// [file URI]: https://en.wikipedia.org/wiki/File_URI_scheme + pub fn parse(s: impl AsRef<str>) -> Result<Self> { + let s = s.as_ref(); + + // This is necessary to handle the case of a path starting with a drive letter + if std::path::Path::new(s).is_absolute() { + return Self::parse_path(s); + } + + match Url::parse(s) { + Ok(url) => Ok(Self { url, glob: None }), + Err(url::ParseError::RelativeUrlWithoutBase) => Self::parse_path(s), + Err(e) => Err(DataFusionError::External(Box::new(e))), + } + } + + /// Creates a new [`ListingTableUrl`] interpreting `s` as a filesystem path + fn parse_path(s: &str) -> Result<Self> { Review Comment: I think I'd rather keep it private until such a use-case comes along. There's enough funky here, that I'm loathe to introduce more potential for strangeness :sweat_smile: -- 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]
