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Add a mirror function-like proc-macro expander for tests

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This commit is contained in:
Lukas Wirth 2021-09-21 14:55:54 +02:00
parent 8b1e8197fe
commit ba84b91e78
4 changed files with 45 additions and 10 deletions
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34
crates/base_db/src/fixture.rs
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@ -262,6 +262,10 @@ pub fn identity(_attr: TokenStream, item: TokenStream) -> TokenStream {
pub fn input_replace(attr: TokenStream, _item: TokenStream) -> TokenStream {
attr
}
#[proc_macro]
pub fn mirror(input: TokenStream) -> TokenStream {
input
}
"#;
let proc_macros = std::array::IntoIter::new([
ProcMacro {
@ -274,6 +278,11 @@ pub fn input_replace(attr: TokenStream, _item: TokenStream) -> TokenStream {
kind: crate::ProcMacroKind::Attr,
expander: Arc::new(AttributeInputReplaceProcMacroExpander),
},
ProcMacro {
name: "mirror".into(),
kind: crate::ProcMacroKind::FuncLike,
expander: Arc::new(MirrorProcMacroExpander),
},
])
.filter(|pm| proc_macros.iter().any(|name| name == pm.name))
.collect();
@ -348,3 +357,28 @@ impl ProcMacroExpander for AttributeInputReplaceProcMacroExpander {
.ok_or_else(|| ProcMacroExpansionError::Panic("Expected attribute input".into()))
}
}
#[derive(Debug)]
struct MirrorProcMacroExpander;
impl ProcMacroExpander for MirrorProcMacroExpander {
fn expand(
&self,
input: &Subtree,
_: Option<&Subtree>,
_: &Env,
) -> Result<Subtree, ProcMacroExpansionError> {
fn traverse(input: &Subtree) -> Subtree {
let mut res = Subtree::default();
res.delimiter = input.delimiter;
for tt in input.token_trees.iter().rev() {
let tt = match tt {
tt::TokenTree::Leaf(leaf) => tt::TokenTree::Leaf(leaf.clone()),
tt::TokenTree::Subtree(sub) => tt::TokenTree::Subtree(traverse(sub)),
};
res.token_trees.push(tt);
}
res
}
Ok(traverse(input))
}
}