Mercurial > hg
diff rust/hg-core/src/config/layer.rs @ 46187:95d6f31e88db
hg-core: add basic config module
The config module exposes a `Config` struct, unused for now.
It only reads the config file local to the repository, but handles all valid
patterns and includes/unsets.
It is structured in layers instead of erasing by reverse order of precedence,
allowing us to transparently know more about the config for debugging purposes,
and potentially other things I haven't thought about yet.
This change also introduces `format_bytes!` to `hg-core`.
Differential Revision: https://phab.mercurial-scm.org/D9408
author | Raphaël Gomès <rgomes@octobus.net> |
---|---|
date | Tue, 29 Dec 2020 10:53:45 +0100 |
parents | |
children | 2e2033081274 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/rust/hg-core/src/config/layer.rs Tue Dec 29 10:53:45 2020 +0100 @@ -0,0 +1,268 @@ +// layer.rs +// +// Copyright 2020 +// Valentin Gatien-Baron, +// Raphaël Gomès <rgomes@octobus.net> +// +// This software may be used and distributed according to the terms of the +// GNU General Public License version 2 or any later version. + +use crate::utils::files::{ + get_bytes_from_path, get_path_from_bytes, read_whole_file, +}; +use format_bytes::format_bytes; +use lazy_static::lazy_static; +use regex::bytes::Regex; +use std::collections::HashMap; +use std::io; +use std::path::{Path, PathBuf}; + +lazy_static! { + static ref SECTION_RE: Regex = make_regex(r"^\[([^\[]+)\]"); + static ref ITEM_RE: Regex = make_regex(r"^([^=\s][^=]*?)\s*=\s*((.*\S)?)"); + /// Continuation whitespace + static ref CONT_RE: Regex = make_regex(r"^\s+(\S|\S.*\S)\s*$"); + static ref EMPTY_RE: Regex = make_regex(r"^(;|#|\s*$)"); + static ref COMMENT_RE: Regex = make_regex(r"^(;|#)"); + /// A directive that allows for removing previous entries + static ref UNSET_RE: Regex = make_regex(r"^%unset\s+(\S+)"); + /// A directive that allows for including other config files + static ref INCLUDE_RE: Regex = make_regex(r"^%include\s+(\S|\S.*\S)\s*$"); +} + +/// All config values separated by layers of precedence. +/// Each config source may be split in multiple layers if `%include` directives +/// are used. +/// TODO detail the general precedence +#[derive(Clone)] +pub struct ConfigLayer { + /// Mapping of the sections to their items + sections: HashMap<Vec<u8>, ConfigItem>, + /// All sections (and their items/values) in a layer share the same origin + pub origin: ConfigOrigin, + /// Whether this layer comes from a trusted user or group + pub trusted: bool, +} + +impl ConfigLayer { + pub fn new(origin: ConfigOrigin) -> Self { + ConfigLayer { + sections: HashMap::new(), + trusted: true, // TODO check + origin, + } + } + + /// Add an entry to the config, overwriting the old one if already present. + pub fn add( + &mut self, + section: Vec<u8>, + item: Vec<u8>, + value: Vec<u8>, + line: Option<usize>, + ) { + self.sections + .entry(section) + .or_insert_with(|| HashMap::new()) + .insert(item, ConfigValue { bytes: value, line }); + } + + /// Returns the config value in `<section>.<item>` if it exists + pub fn get(&self, section: &[u8], item: &[u8]) -> Option<&ConfigValue> { + Some(self.sections.get(section)?.get(item)?) + } + + pub fn is_empty(&self) -> bool { + self.sections.is_empty() + } + + /// Returns a `Vec` of layers in order of precedence (so, in read order), + /// recursively parsing the `%include` directives if any. + pub fn parse(src: &Path, data: &[u8]) -> Result<Vec<Self>, ConfigError> { + let mut layers = vec![]; + + // Discard byte order mark if any + let data = if data.starts_with(b"\xef\xbb\xbf") { + &data[3..] + } else { + data + }; + + // TODO check if it's trusted + let mut current_layer = Self::new(ConfigOrigin::File(src.to_owned())); + + let mut lines_iter = + data.split(|b| *b == b'\n').enumerate().peekable(); + let mut section = b"".to_vec(); + + while let Some((index, bytes)) = lines_iter.next() { + if let Some(m) = INCLUDE_RE.captures(&bytes) { + let filename_bytes = &m[1]; + let filename_to_include = get_path_from_bytes(&filename_bytes); + match read_include(&src, &filename_to_include) { + (include_src, Ok(data)) => { + layers.push(current_layer); + layers.extend(Self::parse(&include_src, &data)?); + current_layer = + Self::new(ConfigOrigin::File(src.to_owned())); + } + (_, Err(e)) => { + return Err(ConfigError::IncludeError { + path: filename_to_include.to_owned(), + io_error: e, + }) + } + } + } else if let Some(_) = EMPTY_RE.captures(&bytes) { + } else if let Some(m) = SECTION_RE.captures(&bytes) { + section = m[1].to_vec(); + } else if let Some(m) = ITEM_RE.captures(&bytes) { + let item = m[1].to_vec(); + let mut value = m[2].to_vec(); + loop { + match lines_iter.peek() { + None => break, + Some((_, v)) => { + if let Some(_) = COMMENT_RE.captures(&v) { + } else if let Some(_) = CONT_RE.captures(&v) { + value.extend(b"\n"); + value.extend(&m[1]); + } else { + break; + } + } + }; + lines_iter.next(); + } + current_layer.add( + section.clone(), + item, + value, + Some(index + 1), + ); + } else if let Some(m) = UNSET_RE.captures(&bytes) { + if let Some(map) = current_layer.sections.get_mut(§ion) { + map.remove(&m[1]); + } + } else { + return Err(ConfigError::Parse { + origin: ConfigOrigin::File(src.to_owned()), + line: Some(index + 1), + bytes: bytes.to_owned(), + }); + } + } + if !current_layer.is_empty() { + layers.push(current_layer); + } + Ok(layers) + } +} + +impl std::fmt::Debug for ConfigLayer { + fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { + let mut sections: Vec<_> = self.sections.iter().collect(); + sections.sort_by(|e0, e1| e0.0.cmp(e1.0)); + + for (section, items) in sections.into_iter() { + let mut items: Vec<_> = items.into_iter().collect(); + items.sort_by(|e0, e1| e0.0.cmp(e1.0)); + + for (item, config_entry) in items { + writeln!( + f, + "{}", + String::from_utf8_lossy(&format_bytes!( + b"{}.{}={} # {}", + section, + item, + &config_entry.bytes, + &self.origin.to_bytes(), + )) + )? + } + } + Ok(()) + } +} + +/// Mapping of section item to value. +/// In the following: +/// ```text +/// [ui] +/// paginate=no +/// ``` +/// "paginate" is the section item and "no" the value. +pub type ConfigItem = HashMap<Vec<u8>, ConfigValue>; + +#[derive(Clone, Debug, PartialEq)] +pub struct ConfigValue { + /// The raw bytes of the value (be it from the CLI, env or from a file) + pub bytes: Vec<u8>, + /// Only present if the value comes from a file, 1-indexed. + pub line: Option<usize>, +} + +#[derive(Clone, Debug)] +pub enum ConfigOrigin { + /// The value comes from a configuration file + File(PathBuf), + /// The value comes from the environment like `$PAGER` or `$EDITOR` + Environment(Vec<u8>), + /* TODO cli + * TODO defaults (configitems.py) + * TODO extensions + * TODO Python resources? + * Others? */ +} + +impl ConfigOrigin { + /// TODO use some kind of dedicated trait? + pub fn to_bytes(&self) -> Vec<u8> { + match self { + ConfigOrigin::File(p) => get_bytes_from_path(p), + ConfigOrigin::Environment(e) => e.to_owned(), + } + } +} + +#[derive(Debug)] +pub enum ConfigError { + Parse { + origin: ConfigOrigin, + line: Option<usize>, + bytes: Vec<u8>, + }, + /// Failed to include a sub config file + IncludeError { + path: PathBuf, + io_error: std::io::Error, + }, + /// Any IO error that isn't expected + IO(std::io::Error), +} + +impl From<std::io::Error> for ConfigError { + fn from(e: std::io::Error) -> Self { + Self::IO(e) + } +} + +fn make_regex(pattern: &'static str) -> Regex { + Regex::new(pattern).expect("expected a valid regex") +} + +/// Includes are relative to the file they're defined in, unless they're +/// absolute. +fn read_include( + old_src: &Path, + new_src: &Path, +) -> (PathBuf, io::Result<Vec<u8>>) { + if new_src.is_absolute() { + (new_src.to_path_buf(), read_whole_file(&new_src)) + } else { + let dir = old_src.parent().unwrap(); + let new_src = dir.join(&new_src); + (new_src.to_owned(), read_whole_file(&new_src)) + } +}