1 | use proc_macro2::{Ident, Span}; |
2 | use std::cmp::Ordering; |
3 | use std::fmt::{self, Display}; |
4 | use std::hash::{Hash, Hasher}; |
5 | |
6 | #[cfg (feature = "parsing" )] |
7 | use crate::lookahead; |
8 | |
9 | /// A Rust lifetime: `'a`. |
10 | /// |
11 | /// Lifetime names must conform to the following rules: |
12 | /// |
13 | /// - Must start with an apostrophe. |
14 | /// - Must not consist of just an apostrophe: `'`. |
15 | /// - Character after the apostrophe must be `_` or a Unicode code point with |
16 | /// the XID_Start property. |
17 | /// - All following characters must be Unicode code points with the XID_Continue |
18 | /// property. |
19 | pub struct Lifetime { |
20 | pub apostrophe: Span, |
21 | pub ident: Ident, |
22 | } |
23 | |
24 | impl Lifetime { |
25 | /// # Panics |
26 | /// |
27 | /// Panics if the lifetime does not conform to the bulleted rules above. |
28 | /// |
29 | /// # Invocation |
30 | /// |
31 | /// ``` |
32 | /// # use proc_macro2::Span; |
33 | /// # use syn::Lifetime; |
34 | /// # |
35 | /// # fn f() -> Lifetime { |
36 | /// Lifetime::new("'a" , Span::call_site()) |
37 | /// # } |
38 | /// ``` |
39 | pub fn new(symbol: &str, span: Span) -> Self { |
40 | if !symbol.starts_with(' \'' ) { |
41 | panic!( |
42 | "lifetime name must start with apostrophe as in \"'a \", got {:?}" , |
43 | symbol |
44 | ); |
45 | } |
46 | |
47 | if symbol == "'" { |
48 | panic!("lifetime name must not be empty" ); |
49 | } |
50 | |
51 | if !crate::ident::xid_ok(&symbol[1..]) { |
52 | panic!(" {:?} is not a valid lifetime name" , symbol); |
53 | } |
54 | |
55 | Lifetime { |
56 | apostrophe: span, |
57 | ident: Ident::new(&symbol[1..], span), |
58 | } |
59 | } |
60 | |
61 | pub fn span(&self) -> Span { |
62 | self.apostrophe |
63 | .join(self.ident.span()) |
64 | .unwrap_or(self.apostrophe) |
65 | } |
66 | |
67 | pub fn set_span(&mut self, span: Span) { |
68 | self.apostrophe = span; |
69 | self.ident.set_span(span); |
70 | } |
71 | } |
72 | |
73 | impl Display for Lifetime { |
74 | fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result { |
75 | "'" .fmt(formatter)?; |
76 | self.ident.fmt(formatter) |
77 | } |
78 | } |
79 | |
80 | impl Clone for Lifetime { |
81 | fn clone(&self) -> Self { |
82 | Lifetime { |
83 | apostrophe: self.apostrophe, |
84 | ident: self.ident.clone(), |
85 | } |
86 | } |
87 | } |
88 | |
89 | impl PartialEq for Lifetime { |
90 | fn eq(&self, other: &Lifetime) -> bool { |
91 | self.ident.eq(&other.ident) |
92 | } |
93 | } |
94 | |
95 | impl Eq for Lifetime {} |
96 | |
97 | impl PartialOrd for Lifetime { |
98 | fn partial_cmp(&self, other: &Lifetime) -> Option<Ordering> { |
99 | Some(self.cmp(other)) |
100 | } |
101 | } |
102 | |
103 | impl Ord for Lifetime { |
104 | fn cmp(&self, other: &Lifetime) -> Ordering { |
105 | self.ident.cmp(&other.ident) |
106 | } |
107 | } |
108 | |
109 | impl Hash for Lifetime { |
110 | fn hash<H: Hasher>(&self, h: &mut H) { |
111 | self.ident.hash(state:h); |
112 | } |
113 | } |
114 | |
115 | #[cfg (feature = "parsing" )] |
116 | #[doc (hidden)] |
117 | #[allow (non_snake_case)] |
118 | pub fn Lifetime(marker: lookahead::TokenMarker) -> Lifetime { |
119 | match marker {} |
120 | } |
121 | |
122 | #[cfg (feature = "parsing" )] |
123 | pub mod parsing { |
124 | use super::*; |
125 | use crate::parse::{Parse, ParseStream, Result}; |
126 | |
127 | #[cfg_attr (doc_cfg, doc(cfg(feature = "parsing" )))] |
128 | impl Parse for Lifetime { |
129 | fn parse(input: ParseStream) -> Result<Self> { |
130 | input.step(|cursor: StepCursor<'_, '_>| { |
131 | cursor |
132 | .lifetime() |
133 | .ok_or_else(|| cursor.error(message:"expected lifetime" )) |
134 | }) |
135 | } |
136 | } |
137 | } |
138 | |
139 | #[cfg (feature = "printing" )] |
140 | mod printing { |
141 | use super::*; |
142 | use proc_macro2::{Punct, Spacing, TokenStream}; |
143 | use quote::{ToTokens, TokenStreamExt}; |
144 | |
145 | #[cfg_attr (doc_cfg, doc(cfg(feature = "printing" )))] |
146 | impl ToTokens for Lifetime { |
147 | fn to_tokens(&self, tokens: &mut TokenStream) { |
148 | let mut apostrophe: Punct = Punct::new(ch:' \'' , Spacing::Joint); |
149 | apostrophe.set_span(self.apostrophe); |
150 | tokens.append(token:apostrophe); |
151 | self.ident.to_tokens(tokens); |
152 | } |
153 | } |
154 | } |
155 | |