1use proc_macro2::{Ident, Span, TokenStream};
2use quote::ToTokens;
3use syn::LitStr;
4
5use std::ops::{Deref, DerefMut};
6
7/// An entity with a span attached.
8#[derive(Debug, Copy, Clone)]
9pub struct Sp<T> {
10    val: T,
11    span: Span,
12}
13
14impl<T> Sp<T> {
15    pub fn new(val: T, span: Span) -> Self {
16        Sp { val, span }
17    }
18
19    pub fn get(&self) -> &T {
20        &self.val
21    }
22
23    pub fn span(&self) -> Span {
24        self.span
25    }
26}
27
28impl<T> Deref for Sp<T> {
29    type Target = T;
30
31    fn deref(&self) -> &T {
32        &self.val
33    }
34}
35
36impl<T> DerefMut for Sp<T> {
37    fn deref_mut(&mut self) -> &mut T {
38        &mut self.val
39    }
40}
41
42impl From<Ident> for Sp<String> {
43    fn from(ident: Ident) -> Self {
44        Sp {
45            val: ident.to_string(),
46            span: ident.span(),
47        }
48    }
49}
50
51impl From<LitStr> for Sp<String> {
52    fn from(lit: LitStr) -> Self {
53        Sp {
54            val: lit.value(),
55            span: lit.span(),
56        }
57    }
58}
59
60impl<'a> From<Sp<&'a str>> for Sp<String> {
61    fn from(sp: Sp<&'a str>) -> Self {
62        Sp::new(sp.val.into(), sp.span)
63    }
64}
65
66impl<U, T: PartialEq<U>> PartialEq<U> for Sp<T> {
67    fn eq(&self, other: &U) -> bool {
68        self.val == *other
69    }
70}
71
72impl<T: AsRef<str>> AsRef<str> for Sp<T> {
73    fn as_ref(&self) -> &str {
74        self.val.as_ref()
75    }
76}
77
78impl<T: ToTokens> ToTokens for Sp<T> {
79    fn to_tokens(&self, stream: &mut TokenStream) {
80        // this is the simplest way out of correct ones to change span on
81        // arbitrary token tree I could come up with
82        let tt = self.val.to_token_stream().into_iter().map(|mut tt| {
83            tt.set_span(self.span);
84            tt
85        });
86
87        stream.extend(tt);
88    }
89}
90