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
4use crate::fallback;
5use crate::imp;
6use crate::marker::Marker;
7use crate::Span;
8use 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)]
15pub struct DelimSpan {
16    inner: DelimSpanEnum,
17    _marker: Marker,
18}
19
20#[derive(Copy, Clone)]
21enum 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
31impl DelimSpan {
32    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.
53    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.
62    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.
71    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
80impl Debug for DelimSpan {
81    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
82        Debug::fmt(&self.join(), f)
83    }
84}
85