rust-tg-bot-macros 1.0.0-rc.1

Procedural macros for the rust-tg-bot Telegram framework
Documentation 
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use proc_macro2::{Delimiter, Group, Ident, Literal, Punct, Spacing, Span, TokenStream, TokenTree};
use quote::ToTokens;

pub(crate) type Result<T, E = Error> = std::result::Result<T, E>;

#[derive(Debug)]
pub(crate) struct Error(TokenStream);

pub(crate) fn compile_error<T>(data: T) -> Error
where
    T: ToTokens,
{
    use quote::quote;
    Error(quote! { ::std::compile_error! { #data } })
}

pub(crate) fn compile_error_at(msg: &str, sp: Span) -> Error {
    // Build `compile_error! { "msg" }` with the correct span so the error
    // message points at the offending attribute / token.
    let ts = TokenStream::from_iter(vec![
        TokenTree::Ident(Ident::new("compile_error", sp)),
        TokenTree::Punct({
            let mut punct = Punct::new('!', Spacing::Alone);
            punct.set_span(sp);
            punct
        }),
        TokenTree::Group({
            let mut group = Group::new(Delimiter::Brace, {
                TokenStream::from_iter(vec![TokenTree::Literal({
                    let mut string = Literal::string(msg);
                    string.set_span(sp);
                    string
                })])
            });
            group.set_span(sp);
            group
        }),
    ]);

    Error(ts)
}

impl From<Error> for proc_macro2::TokenStream {
    fn from(Error(e): Error) -> Self {
        e
    }
}

impl From<syn::Error> for Error {
    fn from(e: syn::Error) -> Self {
        Self(e.to_compile_error())
    }
}