syn/
tt.rs

1use std::hash::{Hash, Hasher};
2
3use proc_macro2::{Delimiter, TokenStream, TokenTree};
4
5pub struct TokenTreeHelper<'a>(pub &'a TokenTree);
6
7impl<'a> PartialEq for TokenTreeHelper<'a> {
8    fn eq(&self, other: &Self) -> bool {
9        use proc_macro2::Spacing;
10
11        match (self.0, other.0) {
12            (TokenTree::Group(g1), TokenTree::Group(g2)) => {
13                match (g1.delimiter(), g2.delimiter()) {
14                    (Delimiter::Parenthesis, Delimiter::Parenthesis)
15                    | (Delimiter::Brace, Delimiter::Brace)
16                    | (Delimiter::Bracket, Delimiter::Bracket)
17                    | (Delimiter::None, Delimiter::None) => {}
18                    _ => return false,
19                }
20
21                let s1 = g1.stream().into_iter();
22                let mut s2 = g2.stream().into_iter();
23
24                for item1 in s1 {
25                    let item2 = match s2.next() {
26                        Some(item) => item,
27                        None => return false,
28                    };
29                    if TokenTreeHelper(&item1) != TokenTreeHelper(&item2) {
30                        return false;
31                    }
32                }
33                s2.next().is_none()
34            }
35            (TokenTree::Punct(o1), TokenTree::Punct(o2)) => {
36                o1.as_char() == o2.as_char()
37                    && match (o1.spacing(), o2.spacing()) {
38                        (Spacing::Alone, Spacing::Alone) | (Spacing::Joint, Spacing::Joint) => true,
39                        _ => false,
40                    }
41            }
42            (TokenTree::Literal(l1), TokenTree::Literal(l2)) => l1.to_string() == l2.to_string(),
43            (TokenTree::Ident(s1), TokenTree::Ident(s2)) => s1 == s2,
44            _ => false,
45        }
46    }
47}
48
49impl<'a> Hash for TokenTreeHelper<'a> {
50    fn hash<H: Hasher>(&self, h: &mut H) {
51        use proc_macro2::Spacing;
52
53        match self.0 {
54            TokenTree::Group(g) => {
55                0u8.hash(h);
56                match g.delimiter() {
57                    Delimiter::Parenthesis => 0u8.hash(h),
58                    Delimiter::Brace => 1u8.hash(h),
59                    Delimiter::Bracket => 2u8.hash(h),
60                    Delimiter::None => 3u8.hash(h),
61                }
62
63                for item in g.stream() {
64                    TokenTreeHelper(&item).hash(h);
65                }
66                0xffu8.hash(h); // terminator w/ a variant we don't normally hash
67            }
68            TokenTree::Punct(op) => {
69                1u8.hash(h);
70                op.as_char().hash(h);
71                match op.spacing() {
72                    Spacing::Alone => 0u8.hash(h),
73                    Spacing::Joint => 1u8.hash(h),
74                }
75            }
76            TokenTree::Literal(lit) => (2u8, lit.to_string()).hash(h),
77            TokenTree::Ident(word) => (3u8, word).hash(h),
78        }
79    }
80}
81
82pub struct TokenStreamHelper<'a>(pub &'a TokenStream);
83
84impl<'a> PartialEq for TokenStreamHelper<'a> {
85    fn eq(&self, other: &Self) -> bool {
86        let left = self.0.clone().into_iter().collect::<Vec<_>>();
87        let right = other.0.clone().into_iter().collect::<Vec<_>>();
88        if left.len() != right.len() {
89            return false;
90        }
91        for (a, b) in left.into_iter().zip(right) {
92            if TokenTreeHelper(&a) != TokenTreeHelper(&b) {
93                return false;
94            }
95        }
96        true
97    }
98}
99
100impl<'a> Hash for TokenStreamHelper<'a> {
101    fn hash<H: Hasher>(&self, state: &mut H) {
102        let tts = self.0.clone().into_iter().collect::<Vec<_>>();
103        tts.len().hash(state);
104        for tt in tts {
105            TokenTreeHelper(&tt).hash(state);
106        }
107    }
108}