| // Copyright 2020 The Bazel Authors. All rights reserved. |
| // |
| // Licensed 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 std::io::{self, prelude::*}; |
| |
| /// LineOutput tells process_output what to do when a line is processed. |
| /// If a Message is returned, it will be written to write_end, if |
| /// Skip is returned nothing will be printed and execution continues, |
| /// if Terminate is returned, process_output returns immediately. |
| /// Terminate is used to stop processing when we see an emit metadata |
| /// message. |
| #[derive(Debug)] |
| pub(crate) enum LineOutput { |
| Message(String), |
| Skip, |
| Terminate, |
| } |
| |
| /// process_output reads lines from read_end and invokes process_line on each. |
| /// Depending on the result of process_line, the modified message may be written |
| /// to write_end. |
| pub(crate) fn process_output<F>( |
| read_end: &mut dyn Read, |
| write_end: &mut dyn Write, |
| mut process_line: F, |
| ) -> io::Result<()> |
| where |
| F: FnMut(String) -> LineOutput, |
| { |
| let mut reader = io::BufReader::new(read_end); |
| let mut writer = io::LineWriter::new(write_end); |
| loop { |
| let mut line = String::new(); |
| let read_bytes = reader.read_line(&mut line)?; |
| if read_bytes == 0 { |
| break; |
| } |
| match process_line(line) { |
| LineOutput::Message(to_write) => writer.write_all(to_write.as_bytes())?, |
| LineOutput::Skip => {} |
| LineOutput::Terminate => return Ok(()), |
| }; |
| } |
| Ok(()) |
| } |