# tt.rs - source
Source of the Rust file `/home/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/syn-1.0.72/src/tt.rs`.
Keywords: rust, rustlang, rust-lang

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    use proc_macro2::{Delimiter, TokenStream, TokenTree};
    use std::hash::{Hash, Hasher};

    pub struct TokenTreeHelper<'a>(pub &'a TokenTree);

    impl<'a> PartialEq for TokenTreeHelper<'a> {
        fn eq(&self, other: &Self) -> bool {
            use proc_macro2::Spacing;

            match (self.0, other.0) {
                (TokenTree::Group(g1), TokenTree::Group(g2)) => {
                    match (g1.delimiter(), g2.delimiter()) {
                        (Delimiter::Parenthesis, Delimiter::Parenthesis)
                        | (Delimiter::Brace, Delimiter::Brace)
                        | (Delimiter::Bracket, Delimiter::Bracket)
                        | (Delimiter::None, Delimiter::None) => {}
                        _ => return false,
                    }

                    let s1 = g1.stream().into_iter();
                    let mut s2 = g2.stream().into_iter();

                    for item1 in s1 {
                        let item2 = match s2.next() {
                            Some(item) => item,
                            None => return false,
                        };
                        if TokenTreeHelper(&item1) != TokenTreeHelper(&item2) {
                            return false;
                        }
                    }
                    s2.next().is_none()
                }
                (TokenTree::Punct(o1), TokenTree::Punct(o2)) => {
                    o1.as_char() == o2.as_char()
                        && match (o1.spacing(), o2.spacing()) {
                            (Spacing::Alone, Spacing::Alone) | (Spacing::Joint, Spacing::Joint) => true,
                            _ => false,
                        }
                }
                (TokenTree::Literal(l1), TokenTree::Literal(l2)) => l1.to_string() == l2.to_string(),
                (TokenTree::Ident(s1), TokenTree::Ident(s2)) => s1 == s2,
                _ => false,
            }
        }
    }

    impl<'a> Hash for TokenTreeHelper<'a> {
        fn hash<H: Hasher>(&self, h: &mut H) {
            use proc_macro2::Spacing;

            match self.0 {
                TokenTree::Group(g) => {
                    0u8.hash(h);
                    match g.delimiter() {
                        Delimiter::Parenthesis => 0u8.hash(h),
                        Delimiter::Brace => 1u8.hash(h),
                        Delimiter::Bracket => 2u8.hash(h),
                        Delimiter::None => 3u8.hash(h),
                    }

                    for item in g.stream() {
                        TokenTreeHelper(&item).hash(h);
                    }
                    0xffu8.hash(h); // terminator w/ a variant we don't normally hash
                }
                TokenTree::Punct(op) => {
                    1u8.hash(h);
                    op.as_char().hash(h);
                    match op.spacing() {
                        Spacing::Alone => 0u8.hash(h),
                        Spacing::Joint => 1u8.hash(h),
                    }
                }
                TokenTree::Literal(lit) => (2u8, lit.to_string()).hash(h),
                TokenTree::Ident(word) => (3u8, word).hash(h),
            }
        }
    }

    pub struct TokenStreamHelper<'a>(pub &'a TokenStream);

    impl<'a> PartialEq for TokenStreamHelper<'a> {
        fn eq(&self, other: &Self) -> bool {
            let left = self.0.clone().into_iter().collect::<Vec<_>>();
            let right = other.0.clone().into_iter().collect::<Vec<_>>();
            if left.len() != right.len() {
                return false;
            }
            for (a, b) in left.into_iter().zip(right) {
                if TokenTreeHelper(&a) != TokenTreeHelper(&b) {
                    return false;
                }
            }
            true
        }
    }

    impl<'a> Hash for TokenStreamHelper<'a> {
        fn hash<H: Hasher>(&self, state: &mut H) {
            let tts = self.0.clone().into_iter().collect::<Vec<_>>();
            tts.len().hash(state);
            for tt in tts {
                TokenTreeHelper(&tt).hash(state);
            }
        }
    }