tt.rs

  1// SPDX-License-Identifier: Apache-2.0 OR MIT
  2
  3use proc_macro2::{Delimiter, TokenStream, TokenTree};
  4use std::hash::{Hash, Hasher};
  5
  6pub(crate) struct TokenTreeHelper<'a>(pub &'a TokenTree);
  7
  8impl<'a> PartialEq for TokenTreeHelper<'a> {
  9    fn eq(&self, other: &Self) -> bool {
 10        use proc_macro2::Spacing;
 11
 12        match (self.0, other.0) {
 13            (TokenTree::Group(g1), TokenTree::Group(g2)) => {
 14                match (g1.delimiter(), g2.delimiter()) {
 15                    (Delimiter::Parenthesis, Delimiter::Parenthesis)
 16                    | (Delimiter::Brace, Delimiter::Brace)
 17                    | (Delimiter::Bracket, Delimiter::Bracket)
 18                    | (Delimiter::None, Delimiter::None) => {}
 19                    _ => return false,
 20                }
 21
 22                let s1 = g1.stream().into_iter();
 23                let mut s2 = g2.stream().into_iter();
 24
 25                for item1 in s1 {
 26                    let item2 = match s2.next() {
 27                        Some(item) => item,
 28                        None => return false,
 29                    };
 30                    if TokenTreeHelper(&item1) != TokenTreeHelper(&item2) {
 31                        return false;
 32                    }
 33                }
 34                s2.next().is_none()
 35            }
 36            (TokenTree::Punct(o1), TokenTree::Punct(o2)) => {
 37                o1.as_char() == o2.as_char()
 38                    && match (o1.spacing(), o2.spacing()) {
 39                        (Spacing::Alone, Spacing::Alone) | (Spacing::Joint, Spacing::Joint) => true,
 40                        _ => false,
 41                    }
 42            }
 43            (TokenTree::Literal(l1), TokenTree::Literal(l2)) => l1.to_string() == l2.to_string(),
 44            (TokenTree::Ident(s1), TokenTree::Ident(s2)) => s1 == s2,
 45            _ => false,
 46        }
 47    }
 48}
 49
 50impl<'a> Hash for TokenTreeHelper<'a> {
 51    fn hash<H: Hasher>(&self, h: &mut H) {
 52        use proc_macro2::Spacing;
 53
 54        match self.0 {
 55            TokenTree::Group(g) => {
 56                0u8.hash(h);
 57                match g.delimiter() {
 58                    Delimiter::Parenthesis => 0u8.hash(h),
 59                    Delimiter::Brace => 1u8.hash(h),
 60                    Delimiter::Bracket => 2u8.hash(h),
 61                    Delimiter::None => 3u8.hash(h),
 62                }
 63
 64                for item in g.stream() {
 65                    TokenTreeHelper(&item).hash(h);
 66                }
 67                0xFFu8.hash(h); // terminator w/ a variant we don't normally hash
 68            }
 69            TokenTree::Punct(op) => {
 70                1u8.hash(h);
 71                op.as_char().hash(h);
 72                match op.spacing() {
 73                    Spacing::Alone => 0u8.hash(h),
 74                    Spacing::Joint => 1u8.hash(h),
 75                }
 76            }
 77            TokenTree::Literal(lit) => (2u8, lit.to_string()).hash(h),
 78            TokenTree::Ident(word) => (3u8, word).hash(h),
 79        }
 80    }
 81}
 82
 83pub(crate) struct TokenStreamHelper<'a>(pub &'a TokenStream);
 84
 85impl<'a> PartialEq for TokenStreamHelper<'a> {
 86    fn eq(&self, other: &Self) -> bool {
 87        let left = self.0.clone().into_iter().collect::<Vec<_>>();
 88        let right = other.0.clone().into_iter().collect::<Vec<_>>();
 89        if left.len() != right.len() {
 90            return false;
 91        }
 92        for (a, b) in left.into_iter().zip(right) {
 93            if TokenTreeHelper(&a) != TokenTreeHelper(&b) {
 94                return false;
 95            }
 96        }
 97        true
 98    }
 99}
100
101impl<'a> Hash for TokenStreamHelper<'a> {
102    fn hash<H: Hasher>(&self, state: &mut H) {
103        let tts = self.0.clone().into_iter().collect::<Vec<_>>();
104        tts.len().hash(state);
105        for tt in tts {
106            TokenTreeHelper(&tt).hash(state);
107        }
108    }
109}