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|
#[derive(Debug)]
pub enum Ast {
AssignVar(AssignVar),
Pipes(Pipes),
}
#[derive(Debug)]
pub struct AssignVar {
pub to: String,
// TODO: body
}
#[derive(Debug)]
pub struct Pipes {
pub cmds: Vec<Command>,
}
#[derive(Debug)]
pub struct Command {
pub path: Vec<u8>,
pub args: Vec<Vec<u8>>,
}
#[derive(Debug)]
pub enum ParseError {
/// "clean" EOF, i.e. not in the middle of something
Eof,
/// "unclean" EOF, i.e. EOF after beginning a quoted string
Incomplete,
UnexpectedPipe,
Unknown(u8),
}
type Result<T> = std::result::Result<T, ParseError>;
pub fn do_parse(mut x: &[u8]) -> Result<Ast> {
Ast::parse(&mut x)
}
trait Parse: Sized {
fn parse(b: &mut &[u8]) -> Result<Self>;
}
#[inline(always)]
fn parse<T: Parse>(b: &mut &[u8]) -> Result<T> {
T::parse(b)
}
fn spaces(b: &mut &[u8]) {
while let Some(b' ' | b'\t') = b.get(0) {
*b = &b[1..];
}
}
#[inline(always)]
fn adv(b: &mut &[u8]) {
*b = &b[1..]
}
fn parse_quoted_string(b: &mut &[u8], delim: u8) -> Result<Vec<u8>> {
// TODO: escape sequence stuff
let mut s = Vec::new();
while b.len() > 0 {
if b[0] == delim {
adv(b);
return Ok(s);
}
s.push(b[0]);
adv(b);
}
if delim == b' ' {
Ok(s)
} else {
Err(ParseError::Incomplete)
}
}
impl Parse for Vec<u8> {
fn parse(b: &mut &[u8]) -> Result<Self> {
spaces(b);
if b.is_empty() {
return Err(ParseError::Eof);
}
let c = b[0];
if c == b'|' {
Err(ParseError::UnexpectedPipe)
} else if c == b'\'' || c == b'"' {
adv(b);
parse_quoted_string(b, c)
} else if c.is_ascii_graphic() {
parse_quoted_string(b, b' ')
} else {
Err(ParseError::Unknown(c))
}
}
}
impl Parse for Ast {
fn parse(b: &mut &[u8]) -> Result<Self> {
Ok(Self::Pipes(parse(b)?))
}
}
impl Parse for Command {
fn parse(b: &mut &[u8]) -> Result<Self> {
let path: Vec<u8> = parse(b)?;
let mut args = Vec::new();
loop {
let arg: Result<Vec<u8>> = parse(b);
match arg {
Ok(arg) => args.push(arg),
Err(ParseError::Eof | ParseError::UnexpectedPipe) => break,
Err(e) => Err(e)?,
}
}
Ok(Self { path, args })
}
}
impl Parse for Pipes {
fn parse(b: &mut &[u8]) -> Result<Self> {
let mut cmds: Vec<Command> = vec![parse(b)?];
loop {
spaces(b);
if b.is_empty() {
return Ok(Pipes { cmds });
}
let c = b[0];
if c == b'|' {
adv(b);
cmds.push(parse(b)?);
} else {
Err(ParseError::Unknown(c))?;
}
}
}
}
|
