#![deny(missing_debug_implementations)]
#![deny(rust_2018_idioms)]
use std::iter;
use proc_macro::{Delimiter, Group, Literal, Span, TokenStream, TokenTree};
#[doc(hidden)]
#[proc_macro]
pub fn __cmd(macro_arg: TokenStream) -> TokenStream {
try_cmd(macro_arg).unwrap_or_else(|msg| parse_ts(&format!("compile_error!({:?})", msg)))
}
type Result<T> = std::result::Result<T, String>;
fn try_cmd(macro_arg: TokenStream) -> Result<TokenStream> {
let (cmd, literal) = {
let mut iter = macro_arg.into_iter();
let cmd = iter.next().unwrap();
let literal = iter.next().unwrap();
assert!(iter.next().is_none());
(cmd, literal)
};
let literal = match into_literal(&literal) {
Some(it) => it,
None => return Err("expected a plain string literal".to_string()),
};
let literal_text = literal.to_string();
if !literal_text.starts_with('"') {
return Err("expected a plain string literal".to_string());
}
let mut args = shell_lex(literal_text.as_str(), literal.span());
let mut res = TokenStream::new();
{
let (_joined_to_prev, splat, program) =
args.next().ok_or_else(|| "command can't be empty".to_string())??;
if splat {
return Err("can't splat program name".to_string());
}
res.extend(Some(cmd));
res.extend(program);
}
let mut prev_spat = false;
for arg in args {
let (joined_to_prev, splat, arg) = arg?;
if prev_spat && joined_to_prev {
return Err(format!(
"can't combine splat with concatenation, add spaces around `{{{}...}}`",
trim_decorations(&res.into_iter().last().unwrap().to_string()),
));
}
prev_spat = splat;
let method = match (joined_to_prev, splat) {
(false, false) => ".arg",
(false, true) => ".args",
(true, false) => ".__extend_arg",
(true, true) => {
return Err(format!(
"can't combine splat with concatenation, add spaces around `{{{}...}}`",
trim_decorations(&arg.to_string()),
))
}
};
res.extend(parse_ts(method));
res.extend(arg);
}
Ok(res)
}
fn into_literal(ts: &TokenTree) -> Option<Literal> {
match ts {
TokenTree::Literal(l) => Some(l.clone()),
TokenTree::Group(g) => match g.delimiter() {
Delimiter::None => match g.stream().into_iter().collect::<Vec<_>>().as_slice() {
[TokenTree::Literal(l)] => Some(l.clone()),
_ => None,
},
Delimiter::Parenthesis | Delimiter::Brace | Delimiter::Bracket => None,
},
_ => None,
}
}
fn trim_decorations(s: &str) -> &str {
&s[1..s.len() - 1]
}
fn shell_lex(
cmd: &str,
call_site: Span,
) -> impl Iterator<Item = Result<(bool, bool, TokenStream)>> + '_ {
tokenize(cmd).map(move |token| {
let token = token?;
let mut splat = false;
let ts = match token.kind {
TokenKind::Word => parse_ts(&format!("(\"{}\")", token.text)),
TokenKind::String => parse_ts(&format!("(\"{}\")", trim_decorations(token.text))),
TokenKind::Interpolation { splat: s } => {
splat = s;
let text = trim_decorations(token.text);
let text = &text[..text.len() - (if splat { "...".len() } else { 0 })];
if !(text.chars().all(|c| c.is_ascii_alphanumeric() || c == '_')) {
return Err(format!(
"can only interpolate simple variables, got this expression instead: `{}`",
text
));
}
let ts = if splat { format!("({})", text) } else { format!("(&({}))", text) };
respan(parse_ts(&ts), call_site)
}
};
Ok((token.joined_to_prev, splat, ts))
})
}
fn strip_matches<'a>(s: &'a str, pattern: &str) -> &'a str {
s.strip_prefix(pattern).unwrap_or(s).strip_suffix(pattern).unwrap_or(s)
}
fn tokenize(cmd: &str) -> impl Iterator<Item = Result<Token<'_>>> + '_ {
let mut cmd = strip_matches(cmd, "\"");
iter::from_fn(move || {
let old_len = cmd.len();
cmd = cmd.trim_start();
let joined_to_prev = old_len == cmd.len();
if cmd.is_empty() {
return None;
}
let (len, kind) = match next_token(cmd) {
Ok(it) => it,
Err(err) => {
cmd = "";
return Some(Err(err));
}
};
let token = Token { joined_to_prev, text: &cmd[..len], kind };
cmd = &cmd[len..];
Some(Ok(token))
})
}
#[derive(Debug)]
struct Token<'a> {
joined_to_prev: bool,
text: &'a str,
kind: TokenKind,
}
#[derive(Debug)]
enum TokenKind {
Word,
String,
Interpolation { splat: bool },
}
fn next_token(s: &str) -> Result<(usize, TokenKind)> {
if s.starts_with('{') {
let len = s.find('}').ok_or_else(|| "unclosed `{` in command".to_string())? + 1;
let splat = s[..len].ends_with("...}");
return Ok((len, TokenKind::Interpolation { splat }));
}
if s.starts_with('\'') {
let len = s[1..].find('\'').ok_or_else(|| "unclosed `'` in command".to_string())? + 2;
return Ok((len, TokenKind::String));
}
let len =
s.find(|it: char| it.is_ascii_whitespace() || it == '\'' || it == '{').unwrap_or(s.len());
Ok((len, TokenKind::Word))
}
fn respan(ts: TokenStream, span: Span) -> TokenStream {
let mut res = TokenStream::new();
for tt in ts {
let tt = match tt {
TokenTree::Ident(mut ident) => {
ident.set_span(ident.span().resolved_at(span).located_at(span));
TokenTree::Ident(ident)
}
TokenTree::Group(group) => {
TokenTree::Group(Group::new(group.delimiter(), respan(group.stream(), span)))
}
_ => tt,
};
res.extend(Some(tt))
}
res
}
fn parse_ts(s: &str) -> TokenStream {
s.parse().unwrap()
}