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|
use pest::Parser as _;
#[derive(pest_derive::Parser)]
#[grammar = "shell.pest"]
struct Shell;
#[derive(Debug, Clone)]
pub enum RedirectTarget {
Fd(std::os::unix::io::RawFd),
File(std::path::PathBuf),
}
#[derive(Debug, Clone, Copy)]
pub enum Direction {
In,
Out,
}
impl Direction {
fn parse(c: u8) -> Option<Self> {
Some(match c {
b'>' => Self::Out,
b'<' => Self::In,
_ => return None,
})
}
pub fn open(
self,
path: &std::path::Path,
) -> nix::Result<std::os::unix::io::RawFd> {
use nix::fcntl::OFlag;
use nix::sys::stat::Mode;
Ok(match self {
crate::parse::Direction::In => nix::fcntl::open(
path,
OFlag::O_NOCTTY | OFlag::O_RDONLY,
Mode::empty(),
)?,
crate::parse::Direction::Out => nix::fcntl::open(
path,
OFlag::O_CREAT
| OFlag::O_NOCTTY
| OFlag::O_WRONLY
| OFlag::O_TRUNC,
Mode::S_IRUSR
| Mode::S_IWUSR
| Mode::S_IRGRP
| Mode::S_IWGRP
| Mode::S_IROTH
| Mode::S_IWOTH,
)?,
})
}
}
#[derive(Debug, Clone)]
pub struct Redirect {
pub from: std::os::unix::io::RawFd,
pub to: RedirectTarget,
pub dir: Direction,
}
impl Redirect {
fn parse(s: &str) -> Self {
let (from, to) = s.split_once(&['<', '>'][..]).unwrap();
let dir = Direction::parse(s.as_bytes()[from.len()]).unwrap();
let from = if from.is_empty() {
match dir {
Direction::In => 0,
Direction::Out => 1,
}
} else {
from.parse().unwrap()
};
let to = to.strip_prefix('&').map_or_else(
|| RedirectTarget::File(to.into()),
|fd| RedirectTarget::Fd(fd.parse().unwrap()),
);
Self { from, to, dir }
}
}
#[derive(Debug)]
pub struct Word {
word: String,
interpolate: bool,
quoted: bool,
}
impl Word {
fn build_ast(pair: pest::iterators::Pair<Rule>) -> Self {
assert!(matches!(pair.as_rule(), Rule::word));
let word = pair.into_inner().next().unwrap();
assert!(matches!(
word.as_rule(),
Rule::bareword | Rule::single_string | Rule::double_string
));
Self {
word: word.as_str().to_string(),
interpolate: matches!(
word.as_rule(),
Rule::bareword | Rule::double_string
),
quoted: matches!(
word.as_rule(),
Rule::single_string | Rule::double_string
),
}
}
}
#[derive(Debug)]
pub struct Exe {
exe: Word,
args: Vec<Word>,
redirects: Vec<Redirect>,
}
impl Exe {
fn build_ast(pair: pest::iterators::Pair<Rule>) -> Self {
assert!(matches!(pair.as_rule(), Rule::exe));
let mut iter = pair.into_inner();
let exe = Word::build_ast(iter.next().unwrap());
let (args, redirects): (_, Vec<_>) =
iter.map(Word::build_ast).partition(|word| {
word.quoted || !word.word.contains(&['<', '>'][..])
});
let redirects =
redirects.iter().map(|r| Redirect::parse(&r.word)).collect();
Self {
exe,
args,
redirects,
}
}
pub fn exe(&self) -> &str {
&self.exe.word
}
pub fn args(&self) -> impl Iterator<Item = &str> {
self.args.iter().map(|arg| arg.word.as_ref())
}
pub fn redirects(&self) -> &[Redirect] {
&self.redirects
}
pub fn shift(&mut self) {
self.exe = self.args.remove(0);
}
}
#[derive(Debug)]
pub struct Pipeline {
exes: Vec<Exe>,
input_string: String,
}
impl Pipeline {
pub fn parse(pipeline: &str) -> Result<Self, Error> {
Ok(Self::build_ast(
Shell::parse(Rule::pipeline, pipeline)
.map_err(|e| Error::new(pipeline, anyhow::anyhow!(e)))?
.next()
.unwrap(),
))
}
pub fn into_exes(self) -> impl Iterator<Item = Exe> {
self.exes.into_iter()
}
pub fn input_string(&self) -> &str {
&self.input_string
}
fn build_ast(pipeline: pest::iterators::Pair<Rule>) -> Self {
assert!(matches!(pipeline.as_rule(), Rule::pipeline));
let input_string = pipeline.as_str().to_string();
Self {
exes: pipeline.into_inner().map(Exe::build_ast).collect(),
input_string,
}
}
}
#[derive(Debug)]
pub struct Commands {
pipelines: Vec<Pipeline>,
input_string: String,
}
impl Commands {
pub fn parse(full_cmd: &str) -> Result<Self, Error> {
Ok(Self::build_ast(
Shell::parse(Rule::line, full_cmd)
.map_err(|e| Error::new(full_cmd, anyhow::anyhow!(e)))?
.next()
.unwrap()
.into_inner()
.next()
.unwrap(),
))
}
pub fn pipelines(&self) -> &[Pipeline] {
&self.pipelines
}
pub fn input_string(&self) -> &str {
&self.input_string
}
fn build_ast(commands: pest::iterators::Pair<Rule>) -> Self {
assert!(matches!(commands.as_rule(), Rule::commands));
let input_string = commands.as_str().to_string();
Self {
pipelines: commands
.into_inner()
.map(Pipeline::build_ast)
.collect(),
input_string,
}
}
}
#[derive(Debug)]
pub struct Error {
input: String,
e: anyhow::Error,
}
impl Error {
fn new(input: &str, e: anyhow::Error) -> Self {
Self {
input: input.to_string(),
e,
}
}
pub fn into_input(self) -> String {
self.input
}
}
impl std::fmt::Display for Error {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
write!(f, "failed to parse {}: {}", self.input, self.e)
}
}
impl std::error::Error for Error {
fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
Some(&*self.e)
}
}
|
