syn 2.0.117

Parser for Rust source code
Documentation 
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#![allow(
    clippy::elidable_lifetime_names,
    clippy::needless_lifetimes,
    clippy::uninlined_format_args
)]

#[macro_use]
mod snapshot;

mod debug;

use proc_macro2::{Delimiter, Group, Literal, Punct, Spacing, TokenStream, TokenTree};
use syn::Expr;

#[test]
fn test_grouping() {
    let tokens: TokenStream = TokenStream::from_iter([
        TokenTree::Literal(Literal::i32_suffixed(1)),
        TokenTree::Punct(Punct::new('+', Spacing::Alone)),
        TokenTree::Group(Group::new(
            Delimiter::None,
            TokenStream::from_iter([
                TokenTree::Literal(Literal::i32_suffixed(2)),
                TokenTree::Punct(Punct::new('+', Spacing::Alone)),
                TokenTree::Literal(Literal::i32_suffixed(3)),
            ]),
        )),
        TokenTree::Punct(Punct::new('*', Spacing::Alone)),
        TokenTree::Literal(Literal::i32_suffixed(4)),
    ]);

    assert_eq!(tokens.to_string(), "1i32 + 2i32 + 3i32 * 4i32");

    snapshot!(tokens as Expr, @r#"
    Expr::Binary {
        left: Expr::Lit {
            lit: 1i32,
        },
        op: BinOp::Add,
        right: Expr::Binary {
            left: Expr::Group {
                expr: Expr::Binary {
                    left: Expr::Lit {
                        lit: 2i32,
                    },
                    op: BinOp::Add,
                    right: Expr::Lit {
                        lit: 3i32,
                    },
                },
            },
            op: BinOp::Mul,
            right: Expr::Lit {
                lit: 4i32,
            },
        },
    }
    "#);
}