1use proc_macro::{token_stream, Group, TokenStream, TokenTree};
4
5pub(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
13pub(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
21pub(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");
31 } else {
32 None
33 }
34 })
35}
36
37pub(crate) fn expect_ident(it: &mut token_stream::IntoIter) -> String {
38 try_ident(it).expect("Expected Ident")
39}
40
41pub(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
49pub(crate) fn expect_string(it: &mut token_stream::IntoIter) -> String {
50 try_string(it).expect("Expected string")
51}
52
53pub(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
57}
58
59pub(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
67pub(crate) fn expect_end(it: &mut token_stream::IntoIter) {
68 if it.next().is_some() {
69 panic!("Expected end");
70 }
71}
72
73pub(crate) struct Generics {
95 pub(crate) decl_generics: Vec<TokenTree>,
99 pub(crate) impl_generics: Vec<TokenTree>,
103 pub(crate) ty_generics: Vec<TokenTree>,
108}
109
110pub(crate) fn parse_generics(input: TokenStream) -> (Generics, Vec<TokenTree>) {
114 let mut decl_generics = vec![];
116 let mut impl_generics = vec![];
118 let mut ty_generics = vec![];
120 let mut rest = vec![];
122 let mut nesting = 0;
124 let mut toks = input.into_iter();
125 let mut at_start = true;
127 let mut skip_until_comma = false;
128 while let Some(tt) = toks.next() {
129 if nesting == 1 && matches!(&tt, TokenTree::Punct(p) if p.as_char() == '>') {
130 break;
132 } else if nesting >= 1 {
133 decl_generics.push(tt.clone());
134 }
135 match tt.clone() {
136 TokenTree::Punct(p) if p.as_char() == '<' => {
137 if nesting >= 1 && !skip_until_comma {
138 impl_generics.push(tt);
140 }
141 nesting += 1;
142 }
143 TokenTree::Punct(p) if p.as_char() == '>' => {
144 if nesting == 0 {
146 break;
147 } else {
148 nesting -= 1;
149 if nesting >= 1 && !skip_until_comma {
150 impl_generics.push(tt);
152 }
153 }
154 }
155 TokenTree::Punct(p) if skip_until_comma && p.as_char() == ',' => {
156 if nesting == 1 {
157 impl_generics.push(tt.clone());
158 impl_generics.push(tt);
159 skip_until_comma = false;
160 }
161 }
162 _ if !skip_until_comma => {
163 match nesting {
164 0 => rest.push(tt),
166 1 => {
167 match tt.clone() {
169 TokenTree::Ident(i) if at_start && i.to_string() == "const" => {
170 let Some(name) = toks.next() else {
171 break;
173 };
174 impl_generics.push(tt);
175 impl_generics.push(name.clone());
176 ty_generics.push(name.clone());
177 decl_generics.push(name);
178 at_start = false;
179 }
180 TokenTree::Ident(_) if at_start => {
181 impl_generics.push(tt.clone());
182 ty_generics.push(tt);
183 at_start = false;
184 }
185 TokenTree::Punct(p) if p.as_char() == ',' => {
186 impl_generics.push(tt.clone());
187 ty_generics.push(tt);
188 at_start = true;
189 }
190 TokenTree::Punct(p) if p.as_char() == '\'' && at_start => {
192 impl_generics.push(tt.clone());
193 ty_generics.push(tt);
194 }
195 TokenTree::Punct(p) if p.as_char() == '=' => {
197 skip_until_comma = true;
198 }
199 _ => impl_generics.push(tt),
200 }
201 }
202 _ => impl_generics.push(tt),
203 }
204 }
205 _ => {}
206 }
207 }
208 rest.extend(toks);
209 (
210 Generics {
211 impl_generics,
212 decl_generics,
213 ty_generics,
214 },
215 rest,
216 )
217}