1use crate::{Error, Result};
2use proc_macro2::{Ident, Span, TokenStream, TokenTree};
3
4macro_rules! decl_settings {
5    ($($val:expr => $variant:ident),+ $(,)*) => {
6        #[derive(PartialEq)]
7        pub(crate) enum Setting {
8            $($variant),*
9        }
10
11        fn ident_to_setting(ident: Ident) -> Result<Setting> {
12            match &*ident.to_string() {
13                $($val => Ok(Setting::$variant),)*
14                _ => {
15                    let possible_vals = [$($val),*]
16                        .iter()
17                        .map(|v| format!("`{}`", v))
18                        .collect::<Vec<_>>()
19                        .join(", ");
20
21                    Err(Error::new(
22                        ident.span(),
23                        format!("unknown setting `{}`, expected one of {}", ident, possible_vals)))
24                }
25            }
26        }
27    };
28}
29
30decl_settings! {
31    "assert_unwind_safe" => AssertUnwindSafe,
32    "allow_not_macro"    => AllowNotMacro,
33    "proc_macro_hack"    => ProcMacroHack,
34}
35
36pub(crate) fn parse_settings(input: TokenStream) -> Result<Settings> {
37    let mut input = input.into_iter();
38    let mut res = Settings(Vec::new());
39    loop {
40        match input.next() {
41            Some(TokenTree::Ident(ident)) => {
42                res.0.push(ident_to_setting(ident)?);
43            }
44            None => return Ok(res),
45            other => {
46                let span = other.map_or(Span::call_site(), |tt| tt.span());
47                return Err(Error::new(span, "expected identifier".to_string()));
48            }
49        }
50
51        match input.next() {
52            Some(TokenTree::Punct(ref punct)) if punct.as_char() == ',' => {}
53            None => return Ok(res),
54            other => {
55                let span = other.map_or(Span::call_site(), |tt| tt.span());
56                return Err(Error::new(span, "expected `,`".to_string()));
57            }
58        }
59    }
60}
61
62pub(crate) struct Settings(Vec<Setting>);
63
64impl Settings {
65    pub(crate) fn is_set(&self, setting: Setting) -> bool {
66        self.0.iter().any(|s| *s == setting)
67    }
68
69    pub(crate) fn set(&mut self, setting: Setting) {
70        self.0.push(setting)
71    }
72}
73