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1fbde52b MO |
1 | // SPDX-License-Identifier: GPL-2.0 |
2 | ||
e957b9cd | 3 | use proc_macro::{token_stream, Group, Punct, Spacing, TokenStream, TokenTree}; |
1fbde52b MO |
4 | |
5 | pub(crate) fn try_ident(it: &mut token_stream::IntoIter) -> Option<String> { | |
6 | if let Some(TokenTree::Ident(ident)) = it.next() { | |
7 | Some(ident.to_string()) | |
8 | } else { | |
9 | None | |
10 | } | |
11 | } | |
12 | ||
13 | pub(crate) fn try_literal(it: &mut token_stream::IntoIter) -> Option<String> { | |
14 | if let Some(TokenTree::Literal(literal)) = it.next() { | |
15 | Some(literal.to_string()) | |
16 | } else { | |
17 | None | |
18 | } | |
19 | } | |
20 | ||
b13c9880 GG |
21 | pub(crate) fn try_string(it: &mut token_stream::IntoIter) -> Option<String> { |
22 | try_literal(it).and_then(|string| { | |
23 | if string.starts_with('\"') && string.ends_with('\"') { | |
24 | let content = &string[1..string.len() - 1]; | |
25 | if content.contains('\\') { | |
26 | panic!("Escape sequences in string literals not yet handled"); | |
27 | } | |
28 | Some(content.to_string()) | |
29 | } else if string.starts_with("r\"") { | |
30 | panic!("Raw string literals are not yet handled"); | |
1fbde52b MO |
31 | } else { |
32 | None | |
33 | } | |
34 | }) | |
35 | } | |
36 | ||
37 | pub(crate) fn expect_ident(it: &mut token_stream::IntoIter) -> String { | |
38 | try_ident(it).expect("Expected Ident") | |
39 | } | |
40 | ||
41 | pub(crate) fn expect_punct(it: &mut token_stream::IntoIter) -> char { | |
42 | if let TokenTree::Punct(punct) = it.next().expect("Reached end of token stream for Punct") { | |
43 | punct.as_char() | |
44 | } else { | |
45 | panic!("Expected Punct"); | |
46 | } | |
47 | } | |
48 | ||
b13c9880 GG |
49 | pub(crate) fn expect_string(it: &mut token_stream::IntoIter) -> String { |
50 | try_string(it).expect("Expected string") | |
51 | } | |
52 | ||
53 | pub(crate) fn expect_string_ascii(it: &mut token_stream::IntoIter) -> String { | |
54 | let string = try_string(it).expect("Expected string"); | |
55 | assert!(string.is_ascii(), "Expected ASCII string"); | |
56 | string | |
1fbde52b MO |
57 | } |
58 | ||
39867fec AL |
59 | pub(crate) fn expect_group(it: &mut token_stream::IntoIter) -> Group { |
60 | if let TokenTree::Group(group) = it.next().expect("Reached end of token stream for Group") { | |
61 | group | |
62 | } else { | |
63 | panic!("Expected Group"); | |
64 | } | |
65 | } | |
66 | ||
1fbde52b MO |
67 | pub(crate) fn expect_end(it: &mut token_stream::IntoIter) { |
68 | if it.next().is_some() { | |
69 | panic!("Expected end"); | |
70 | } | |
71 | } | |
e957b9cd BL |
72 | |
73 | pub(crate) struct Generics { | |
74 | pub(crate) impl_generics: Vec<TokenTree>, | |
75 | pub(crate) ty_generics: Vec<TokenTree>, | |
76 | } | |
77 | ||
78 | /// Parses the given `TokenStream` into `Generics` and the rest. | |
79 | /// | |
80 | /// The generics are not present in the rest, but a where clause might remain. | |
81 | pub(crate) fn parse_generics(input: TokenStream) -> (Generics, Vec<TokenTree>) { | |
82 | // `impl_generics`, the declared generics with their bounds. | |
83 | let mut impl_generics = vec![]; | |
84 | // Only the names of the generics, without any bounds. | |
85 | let mut ty_generics = vec![]; | |
86 | // Tokens not related to the generics e.g. the `where` token and definition. | |
87 | let mut rest = vec![]; | |
88 | // The current level of `<`. | |
89 | let mut nesting = 0; | |
90 | let mut toks = input.into_iter(); | |
91 | // If we are at the beginning of a generic parameter. | |
92 | let mut at_start = true; | |
93 | for tt in &mut toks { | |
94 | match tt.clone() { | |
95 | TokenTree::Punct(p) if p.as_char() == '<' => { | |
96 | if nesting >= 1 { | |
97 | // This is inside of the generics and part of some bound. | |
98 | impl_generics.push(tt); | |
99 | } | |
100 | nesting += 1; | |
101 | } | |
102 | TokenTree::Punct(p) if p.as_char() == '>' => { | |
103 | // This is a parsing error, so we just end it here. | |
104 | if nesting == 0 { | |
105 | break; | |
106 | } else { | |
107 | nesting -= 1; | |
108 | if nesting >= 1 { | |
109 | // We are still inside of the generics and part of some bound. | |
110 | impl_generics.push(tt); | |
111 | } | |
112 | if nesting == 0 { | |
113 | break; | |
114 | } | |
115 | } | |
116 | } | |
117 | tt => { | |
118 | if nesting == 1 { | |
119 | // Here depending on the token, it might be a generic variable name. | |
120 | match &tt { | |
121 | // Ignore const. | |
122 | TokenTree::Ident(i) if i.to_string() == "const" => {} | |
123 | TokenTree::Ident(_) if at_start => { | |
124 | ty_generics.push(tt.clone()); | |
125 | // We also already push the `,` token, this makes it easier to append | |
126 | // generics. | |
127 | ty_generics.push(TokenTree::Punct(Punct::new(',', Spacing::Alone))); | |
128 | at_start = false; | |
129 | } | |
130 | TokenTree::Punct(p) if p.as_char() == ',' => at_start = true, | |
131 | // Lifetimes begin with `'`. | |
132 | TokenTree::Punct(p) if p.as_char() == '\'' && at_start => { | |
133 | ty_generics.push(tt.clone()); | |
134 | } | |
135 | _ => {} | |
136 | } | |
137 | } | |
138 | if nesting >= 1 { | |
139 | impl_generics.push(tt); | |
140 | } else if nesting == 0 { | |
141 | // If we haven't entered the generics yet, we still want to keep these tokens. | |
142 | rest.push(tt); | |
143 | } | |
144 | } | |
145 | } | |
146 | } | |
147 | rest.extend(toks); | |
148 | ( | |
149 | Generics { | |
150 | impl_generics, | |
151 | ty_generics, | |
152 | }, | |
153 | rest, | |
154 | ) | |
155 | } |