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use rustc_ast as ast;
use rustc_ast::ptr::P;
use rustc_ast::token::{self, Token};
use rustc_ast::tokenstream::{TokenStream, TokenTree};
use rustc_expand::base::{self, *};
use rustc_span::symbol::{Ident, Symbol};
use rustc_span::Span;
pub fn expand_concat_idents<'cx>(
cx: &'cx mut ExtCtxt<'_>,
sp: Span,
tts: TokenStream,
) -> Box<dyn base::MacResult + 'cx> {
if tts.is_empty() {
cx.span_err(sp, "concat_idents! takes 1 or more arguments");
return DummyResult::any(sp);
}
let mut res_str = String::new();
for (i, e) in tts.into_trees().enumerate() {
if i & 1 == 1 {
match e {
TokenTree::Token(Token { kind: token::Comma, .. }, _) => {}
_ => {
cx.span_err(sp, "concat_idents! expecting comma");
return DummyResult::any(sp);
}
}
} else {
if let TokenTree::Token(token, _) = e {
if let Some((ident, _)) = token.ident() {
res_str.push_str(ident.name.as_str());
continue;
}
}
cx.span_err(sp, "concat_idents! requires ident args");
return DummyResult::any(sp);
}
}
let ident = Ident::new(Symbol::intern(&res_str), cx.with_call_site_ctxt(sp));
struct ConcatIdentsResult {
ident: Ident,
}
impl base::MacResult for ConcatIdentsResult {
fn make_expr(self: Box<Self>) -> Option<P<ast::Expr>> {
Some(P(ast::Expr {
id: ast::DUMMY_NODE_ID,
kind: ast::ExprKind::Path(None, ast::Path::from_ident(self.ident)),
span: self.ident.span,
attrs: ast::AttrVec::new(),
tokens: None,
}))
}
fn make_ty(self: Box<Self>) -> Option<P<ast::Ty>> {
Some(P(ast::Ty {
id: ast::DUMMY_NODE_ID,
kind: ast::TyKind::Path(None, ast::Path::from_ident(self.ident)),
span: self.ident.span,
tokens: None,
}))
}
}
Box::new(ConcatIdentsResult { ident })
}
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