syn/
tt.rs

1use proc_macro2::{Delimiter, Spacing, TokenStream, TokenTree};
2use std::hash::{Hash, Hasher};
3
4pub(crate) struct TokenTreeHelper<'a>(pub &'a TokenTree);
5
6impl<'a> PartialEq for TokenTreeHelper<'a> {
7    fn eq(&self, other: &Self) -> bool {
8        match (self.0, other.0) {
9            (TokenTree::Group(g1), TokenTree::Group(g2)) => {
10                match (g1.delimiter(), g2.delimiter()) {
11                    (Delimiter::Parenthesis, Delimiter::Parenthesis)
12                    | (Delimiter::Brace, Delimiter::Brace)
13                    | (Delimiter::Bracket, Delimiter::Bracket)
14                    | (Delimiter::None, Delimiter::None) => {}
15                    _ => return false,
16                }
17
18                TokenStreamHelper(&g1.stream()) == TokenStreamHelper(&g2.stream())
19            }
20            (TokenTree::Punct(o1), TokenTree::Punct(o2)) => {
21                o1.as_char() == o2.as_char()
22                    && match (o1.spacing(), o2.spacing()) {
23                        (Spacing::Alone, Spacing::Alone) | (Spacing::Joint, Spacing::Joint) => true,
24                        _ => false,
25                    }
26            }
27            (TokenTree::Literal(l1), TokenTree::Literal(l2)) => l1.to_string() == l2.to_string(),
28            (TokenTree::Ident(s1), TokenTree::Ident(s2)) => s1 == s2,
29            _ => false,
30        }
31    }
32}
33
34impl<'a> Hash for TokenTreeHelper<'a> {
35    fn hash<H: Hasher>(&self, h: &mut H) {
36        match self.0 {
37            TokenTree::Group(g) => {
38                0u8.hash(h);
39                match g.delimiter() {
40                    Delimiter::Parenthesis => 0u8.hash(h),
41                    Delimiter::Brace => 1u8.hash(h),
42                    Delimiter::Bracket => 2u8.hash(h),
43                    Delimiter::None => 3u8.hash(h),
44                }
45
46                for item in g.stream() {
47                    TokenTreeHelper(&item).hash(h);
48                }
49                0xFFu8.hash(h); // terminator w/ a variant we don't normally hash
50            }
51            TokenTree::Punct(op) => {
52                1u8.hash(h);
53                op.as_char().hash(h);
54                match op.spacing() {
55                    Spacing::Alone => 0u8.hash(h),
56                    Spacing::Joint => 1u8.hash(h),
57                }
58            }
59            TokenTree::Literal(lit) => (2u8, lit.to_string()).hash(h),
60            TokenTree::Ident(word) => (3u8, word).hash(h),
61        }
62    }
63}
64
65pub(crate) struct TokenStreamHelper<'a>(pub &'a TokenStream);
66
67impl<'a> PartialEq for TokenStreamHelper<'a> {
68    fn eq(&self, other: &Self) -> bool {
69        let left = self.0.clone().into_iter();
70        let mut right = other.0.clone().into_iter();
71
72        for item1 in left {
73            let item2 = match right.next() {
74                Some(item) => item,
75                None => return false,
76            };
77            if TokenTreeHelper(&item1) != TokenTreeHelper(&item2) {
78                return false;
79            }
80        }
81
82        right.next().is_none()
83    }
84}
85
86impl<'a> Hash for TokenStreamHelper<'a> {
87    fn hash<H: Hasher>(&self, state: &mut H) {
88        let tokens = self.0.clone().into_iter();
89
90        tokens.clone().count().hash(state);
91
92        for tt in tokens {
93            TokenTreeHelper(&tt).hash(state);
94        }
95    }
96}
syn/tt.rs

syn/
tt.rs
