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use crate::BString;
#[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 cmd: 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(x: &[u8]) -> Result<Ast> {
Ast::parse(&mut Cursor::new(x, ParseMode::Command))
}
pub enum CompletionKind {
Command,
Argument,
None,
}
pub struct CompletionContext {
pub kind: CompletionKind,
pub partial: BString,
}
pub fn completion_context<'a>(x: &'a [u8]) -> CompletionContext {
let mut cursor = Cursor::new(x, ParseMode::Completion);
let ast = Ast::parse(&mut cursor);
match ast {
Ok(Ast::Pipes(pipes)) if cursor.spaced == false => {
if let Some(cmd) = pipes.cmds.last() {
if cmd.args.is_empty() {
CompletionContext {
kind: CompletionKind::Command,
partial: cmd.cmd.clone(),
}
} else {
CompletionContext {
kind: CompletionKind::Argument,
partial: cmd.args[cmd.args.len() - 1].clone(),
}
}
} else {
CompletionContext {
kind: CompletionKind::None,
partial: Vec::new(),
}
}
}
_ => CompletionContext {
kind: CompletionKind::None,
partial: Vec::new(),
},
}
}
trait Parse: Sized {
fn parse(b: &mut Cursor<'_>) -> Result<Self>;
}
enum ParseMode {
Command,
Completion,
}
struct Cursor<'a> {
buf: &'a [u8],
mode: ParseMode,
/// if the last byte that was consumed was whitespace or part of a word
spaced: bool,
}
impl<'a> Cursor<'a> {
fn new(buf: &'a [u8], mode: ParseMode) -> Self {
Self {
buf,
mode,
spaced: false,
}
}
// non empty
fn has(&self) -> bool {
!self.buf.is_empty()
}
fn is_empty(&self) -> bool {
self.buf.is_empty()
}
fn peek(&self) -> u8 {
self.buf[0]
}
fn adv(&mut self) -> u8 {
let out = self.buf[0];
self.buf = &self.buf[1..];
self.spaced = false;
out
}
fn spaces(&mut self) {
while let Some(b' ' | b'\t') = self.buf.first() {
self.adv();
self.spaced = true;
}
}
fn is_completion(&self) -> bool {
match self.mode {
ParseMode::Completion => true,
_ => false,
}
}
fn parse<T: Parse>(&mut self) -> Result<T> {
T::parse(self)
}
}
fn parse_quoted_string(b: &mut Cursor<'_>, delim: u8) -> Result<Vec<u8>> {
// TODO: escape sequence stuff
let mut s = Vec::new();
while b.has() {
if delim == b' ' && b.peek() == b'|' {
return if s.len() == 0 {
Err(ParseError::UnexpectedPipe)
} else {
Ok(s)
};
}
if b.peek() == delim {
b.adv();
if delim == b' ' {
b.spaced = true;
}
return Ok(s);
}
s.push(b.adv());
}
if delim == b' ' || b.is_completion() {
Ok(s)
} else {
Err(ParseError::Incomplete)
}
}
impl Parse for Vec<u8> {
fn parse(b: &mut Cursor<'_>) -> Result<Self> {
b.spaces();
if b.is_empty() {
return Err(ParseError::Eof);
}
let c = b.peek();
if c == b'|' {
Err(ParseError::UnexpectedPipe)
} else if c == b'\'' || c == b'"' {
b.adv();
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 Cursor<'_>) -> Result<Self> {
Ok(Self::Pipes(b.parse()?))
}
}
impl Parse for Command {
fn parse(b: &mut Cursor<'_>) -> Result<Self> {
let path: Vec<u8> = b.parse()?;
let mut args = Vec::new();
loop {
let arg: Result<Vec<u8>> = b.parse();
match arg {
Ok(arg) => args.push(arg),
Err(ParseError::Eof | ParseError::UnexpectedPipe) => break,
Err(e) => Err(e)?,
}
}
Ok(Self { cmd: path, args })
}
}
impl Parse for Pipes {
fn parse(b: &mut Cursor<'_>) -> Result<Self> {
let mut cmds: Vec<Command> = vec![b.parse()?];
loop {
b.spaces();
if b.is_empty() {
return Ok(Pipes { cmds });
}
let c = b.peek();
if c == b'|' {
b.adv();
cmds.push(b.parse()?);
} else {
Err(ParseError::Unknown(c))?;
}
}
}
}
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