1 //! Items which do not have a correspondence to any API in the proc_macro crate,
2 //! but are necessary to include in proc-macro2.
3 
4 use crate::fallback;
5 use crate::imp;
6 use crate::marker::Marker;
7 use crate::Span;
8 use core::fmt::{self, Debug};
9 
10 /// An object that holds a [`Group`]'s `span_open()` and `span_close()` together
11 /// (in a more compact representation than holding those 2 spans individually.
12 ///
13 /// [`Group`]: crate::Group
14 #[derive(Copy, Clone)]
15 pub struct DelimSpan {
16     inner: DelimSpanEnum,
17     _marker: Marker,
18 }
19 
20 #[derive(Copy, Clone)]
21 enum DelimSpanEnum {
22     #[cfg(wrap_proc_macro)]
23     Compiler {
24         join: proc_macro::Span,
25         open: proc_macro::Span,
26         close: proc_macro::Span,
27     },
28     Fallback(fallback::Span),
29 }
30 
31 impl DelimSpan {
new(group: &imp::Group) -> Self32     pub(crate) fn new(group: &imp::Group) -> Self {
33         #[cfg(wrap_proc_macro)]
34         let inner = match group {
35             imp::Group::Compiler(group) => DelimSpanEnum::Compiler {
36                 join: group.span(),
37                 open: group.span_open(),
38                 close: group.span_close(),
39             },
40             imp::Group::Fallback(group) => DelimSpanEnum::Fallback(group.span()),
41         };
42 
43         #[cfg(not(wrap_proc_macro))]
44         let inner = DelimSpanEnum::Fallback(group.span());
45 
46         DelimSpan {
47             inner,
48             _marker: Marker,
49         }
50     }
51 
52     /// Returns a span covering the entire delimited group.
join(&self) -> Span53     pub fn join(&self) -> Span {
54         match &self.inner {
55             #[cfg(wrap_proc_macro)]
56             DelimSpanEnum::Compiler { join, .. } => Span::_new(imp::Span::Compiler(*join)),
57             DelimSpanEnum::Fallback(span) => Span::_new_fallback(*span),
58         }
59     }
60 
61     /// Returns a span for the opening punctuation of the group only.
open(&self) -> Span62     pub fn open(&self) -> Span {
63         match &self.inner {
64             #[cfg(wrap_proc_macro)]
65             DelimSpanEnum::Compiler { open, .. } => Span::_new(imp::Span::Compiler(*open)),
66             DelimSpanEnum::Fallback(span) => Span::_new_fallback(span.first_byte()),
67         }
68     }
69 
70     /// Returns a span for the closing punctuation of the group only.
close(&self) -> Span71     pub fn close(&self) -> Span {
72         match &self.inner {
73             #[cfg(wrap_proc_macro)]
74             DelimSpanEnum::Compiler { close, .. } => Span::_new(imp::Span::Compiler(*close)),
75             DelimSpanEnum::Fallback(span) => Span::_new_fallback(span.last_byte()),
76         }
77     }
78 }
79 
80 impl Debug for DelimSpan {
fmt(&self, f: &mut fmt::Formatter) -> fmt::Result81     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
82         Debug::fmt(&self.join(), f)
83     }
84 }
85