1 // SPDX-License-Identifier: GPL-2.0 2 3 use proc_macro::{token_stream, Group, Punct, Spacing, TokenStream, TokenTree}; 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 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"); 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 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 57 } 58 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 67 pub(crate) fn expect_end(it: &mut token_stream::IntoIter) { 68 if it.next().is_some() { 69 panic!("Expected end"); 70 } 71 } 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 } 156