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use crate::{Error, Result};
use proc_macro2::{Ident, Span, TokenStream, TokenTree};
macro_rules! decl_settings {
($($val:expr => $variant:ident),+ $(,)*) => {
#[derive(PartialEq)]
pub(crate) enum Setting {
$($variant),*
}
fn ident_to_setting(ident: Ident) -> Result<Setting> {
match &*ident.to_string() {
$($val => Ok(Setting::$variant),)*
_ => {
let possible_vals = [$($val),*]
.iter()
.map(|v| format!("`{}`", v))
.collect::<Vec<_>>()
.join(", ");
Err(Error::new(
ident.span(),
format!("unknown setting `{}`, expected one of {}", ident, possible_vals)))
}
}
}
};
}
decl_settings! {
"assert_unwind_safe" => AssertUnwindSafe,
"allow_not_macro" => AllowNotMacro,
"proc_macro_hack" => ProcMacroHack,
}
pub(crate) fn parse_settings(input: TokenStream) -> Result<Settings> {
let mut input = input.into_iter();
let mut res = Settings(Vec::new());
loop {
match input.next() {
Some(TokenTree::Ident(ident)) => {
res.0.push(ident_to_setting(ident)?);
}
None => return Ok(res),
other => {
let span = other.map_or(Span::call_site(), |tt| tt.span());
return Err(Error::new(span, "expected identifier".to_string()));
}
}
match input.next() {
Some(TokenTree::Punct(ref punct)) if punct.as_char() == ',' => {}
None => return Ok(res),
other => {
let span = other.map_or(Span::call_site(), |tt| tt.span());
return Err(Error::new(span, "expected `,`".to_string()));
}
}
}
}
pub(crate) struct Settings(Vec<Setting>);
impl Settings {
pub(crate) fn is_set(&self, setting: Setting) -> bool {
self.0.iter().any(|s| *s == setting)
}
pub(crate) fn set(&mut self, setting: Setting) {
self.0.push(setting)
}
}