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use std::{
cmp::{Eq, PartialEq},
fmt::{self, Display, Formatter},
iter::IntoIterator,
vec::IntoIter,
};
use itertools::Itertools;
use once_cell::sync::Lazy;
use proc_macro::{Delimiter, Span, TokenStream, TokenTree};
use proc_macro2::Span as Span2;
use regex::Regex;
#[derive(Clone, Copy, Debug)]
pub(crate) struct Pos {
pub(crate) line: usize,
pub(crate) column: usize,
}
impl Pos {
fn new(line: usize, column: usize) -> Self {
Self { line, column }
}
fn left(&self) -> Self {
Self {
line: self.line,
column: self.column.saturating_sub(1),
}
}
fn right(&self) -> Self {
Self {
line: self.line,
column: self.column.saturating_add(1),
}
}
}
fn span_pos(span: &Span) -> (Pos, Pos) {
let span2: Span2 = (*span).into();
let start = span2.start();
let end = span2.end();
// In stable, line/column information is not provided
// and set to 0 (line is 1-indexed)
if start.line == 0 || end.line == 0 {
return fallback_span_pos(span);
}
(
Pos::new(start.line, start.column),
Pos::new(end.line, end.column),
)
}
fn parse_pos(span: &Span) -> Option<(usize, usize)> {
// Workaround to somehow retrieve location information in span in stable rust :(
static RE: Lazy<Regex> = Lazy::new(|| Regex::new(r"bytes\(([0-9]+)\.\.([0-9]+)\)").unwrap());
match RE.captures(&format!("{span:?}")) {
Some(caps) => match (caps.get(1), caps.get(2)) {
(Some(start), Some(end)) => Some((
match start.as_str().parse() {
Ok(v) => v,
_ => return None,
},
match end.as_str().parse() {
Ok(v) => v,
_ => return None,
},
)),
_ => None,
},
None => None,
}
}
fn fallback_span_pos(span: &Span) -> (Pos, Pos) {
let (start, end) = match parse_pos(span) {
Some(v) => v,
None => proc_macro_error::abort_call_site!(
"Cannot retrieve span information; please use nightly"
),
};
(Pos::new(1, start), Pos::new(1, end))
}
/// Attribute of token.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
enum TokenAttr {
/// No attribute
None,
/// Starts with `$`
Cap,
}
#[derive(Clone, Debug)]
pub(crate) struct Token {
source: String,
tree: TokenTree,
start: Pos,
end: Pos,
attr: TokenAttr,
}
impl PartialEq for Token {
fn eq(&self, other: &Self) -> bool {
self.source == other.source && self.attr == other.attr
}
}
impl Eq for Token {}
impl Token {
fn new(tree: TokenTree) -> Self {
let (start, end) = span_pos(&tree.span());
Self {
source: tree.to_string(),
start,
end,
tree,
attr: TokenAttr::None,
}
}
fn new_delim(source: String, tree: TokenTree, open: bool) -> Self {
let (start, end) = span_pos(&tree.span());
let (start, end) = if open {
(start, start.right())
} else {
(end.left(), end)
};
Self {
source,
tree,
start,
end,
attr: TokenAttr::None,
}
}
pub(crate) fn tree(&self) -> &TokenTree {
&self.tree
}
pub(crate) fn is_cap(&self) -> bool {
self.attr == TokenAttr::Cap
}
pub(crate) fn start(&self) -> Pos {
self.start
}
pub(crate) fn end(&self) -> Pos {
self.end
}
fn is(&self, s: &str) -> bool {
self.source == s
}
fn attr(mut self, attr: TokenAttr) -> Self {
self.attr = attr;
self
}
}
#[derive(Debug)]
pub(crate) struct Tokens(pub(crate) Vec<Token>);
impl Tokens {
pub(crate) fn retokenize(tt: TokenStream) -> Tokens {
Tokens(
tt.into_iter()
.flat_map(Tokens::from)
.peekable()
.batching(|iter| {
// Find variable tokens
let t = iter.next()?;
if t.is("$") {
// `$` + `ident` => `$ident`
let t = iter.next().expect("$ must trail an identifier");
Some(t.attr(TokenAttr::Cap))
} else {
Some(t)
}
})
.collect(),
)
}
}
impl IntoIterator for Tokens {
type Item = Token;
type IntoIter = IntoIter<Token>;
fn into_iter(self) -> Self::IntoIter {
self.0.into_iter()
}
}
impl From<TokenTree> for Tokens {
fn from(tt: TokenTree) -> Self {
let tts = match tt.clone() {
TokenTree::Group(g) => {
let (b, e) = match g.delimiter() {
Delimiter::Parenthesis => ("(", ")"),
Delimiter::Brace => ("{", "}"),
Delimiter::Bracket => ("[", "]"),
Delimiter::None => ("", ""),
};
let (b, e) = (b.into(), e.into());
vec![Token::new_delim(b, tt.clone(), true)]
.into_iter()
.chain(g.stream().into_iter().flat_map(Tokens::from))
.chain(vec![Token::new_delim(e, tt, false)])
.collect()
}
_ => vec![Token::new(tt)],
};
Tokens(tts)
}
}
impl Display for Token {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
write!(f, "{}", self.source)
}
}
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