rustversion/
attr.rs

1use crate::error::{Error, Result};
2use crate::expr::{self, Expr};
3use crate::{iter, token};
4use proc_macro::{Span, TokenStream};
5
6pub struct Args {
7    pub condition: Expr,
8    pub then: Then,
9}
10
11pub enum Then {
12    Const(Span),
13    Attribute(TokenStream),
14}
15
16pub fn parse(input: TokenStream) -> Result<Args> {
17    let ref mut input = iter::new(input);
18    let condition = expr::parse(input)?;
19
20    token::parse_punct(input, ',')?;
21    if input.peek().is_none() {
22        return Err(Error::new(Span::call_site(), "expected one or more attrs"));
23    }
24
25    let const_span = token::parse_optional_keyword(input, "const");
26    let then = if let Some(const_span) = const_span {
27        token::parse_optional_punct(input, ',');
28        token::parse_end(input)?;
29        Then::Const(const_span)
30    } else {
31        Then::Attribute(input.collect())
32    };
33
34    Ok(Args { condition, then })
35}
rustversion/attr.rs

rustversion/
attr.rs
