//! Builtin derives.
use base_db::{CrateOrigin, LangCrateOrigin};
use tracing::debug;
use syntax::{
ast::{self, AstNode, HasGenericParams, HasModuleItem, HasName},
match_ast,
};
use tt::TokenId;
use crate::{db::AstDatabase, name, quote, ExpandError, ExpandResult, MacroCallId};
macro_rules! register_builtin {
( $($trait:ident => $expand:ident),* ) => {
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub enum BuiltinDeriveExpander {
$($trait),*
}
impl BuiltinDeriveExpander {
pub fn expand(
&self,
db: &dyn AstDatabase,
id: MacroCallId,
tt: &tt::Subtree,
) -> ExpandResult<tt::Subtree> {
let expander = match *self {
$( BuiltinDeriveExpander::$trait => $expand, )*
};
expander(db, id, tt)
}
fn find_by_name(name: &name::Name) -> Option<Self> {
match name {
$( id if id == &name::name![$trait] => Some(BuiltinDeriveExpander::$trait), )*
_ => None,
}
}
}
};
}
register_builtin! {
Copy => copy_expand,
Clone => clone_expand,
Default => default_expand,
Debug => debug_expand,
Hash => hash_expand,
Ord => ord_expand,
PartialOrd => partial_ord_expand,
Eq => eq_expand,
PartialEq => partial_eq_expand
}
pub fn find_builtin_derive(ident: &name::Name) -> Option<BuiltinDeriveExpander> {
BuiltinDeriveExpander::find_by_name(ident)
}
struct BasicAdtInfo {
name: tt::Ident,
type_or_const_params: usize,
}
fn parse_adt(tt: &tt::Subtree) -> Result<BasicAdtInfo, ExpandError> {
let (parsed, token_map) = mbe::token_tree_to_syntax_node(tt, mbe::TopEntryPoint::MacroItems);
let macro_items = ast::MacroItems::cast(parsed.syntax_node()).ok_or_else(|| {
debug!("derive node didn't parse");
ExpandError::Other("invalid item definition".into())
})?;
let item = macro_items.items().next().ok_or_else(|| {
debug!("no module item parsed");
ExpandError::Other("no item found".into())
})?;
let node = item.syntax();
let (name, params) = match_ast! {
match node {
ast::Struct(it) => (it.name(), it.generic_param_list()),
ast::Enum(it) => (it.name(), it.generic_param_list()),
ast::Union(it) => (it.name(), it.generic_param_list()),
_ => {
debug!("unexpected node is {:?}", node);
return Err(ExpandError::Other("expected struct, enum or union".into()))
},
}
};
let name = name.ok_or_else(|| {
debug!("parsed item has no name");
ExpandError::Other("missing name".into())
})?;
let name_token_id =
token_map.token_by_range(name.syntax().text_range()).unwrap_or_else(TokenId::unspecified);
let name_token = tt::Ident { id: name_token_id, text: name.text().into() };
let type_or_const_params =
params.map_or(0, |type_param_list| type_param_list.type_or_const_params().count());
Ok(BasicAdtInfo { name: name_token, type_or_const_params })
}
fn make_type_args(n: usize, bound: Vec<tt::TokenTree>) -> Vec<tt::TokenTree> {
let mut result = Vec::<tt::TokenTree>::with_capacity(n * 2);
result.push(
tt::Leaf::Punct(tt::Punct {
char: '<',
spacing: tt::Spacing::Alone,
id: tt::TokenId::unspecified(),
})
.into(),
);
for i in 0..n {
if i > 0 {
result.push(
tt::Leaf::Punct(tt::Punct {
char: ',',
spacing: tt::Spacing::Alone,
id: tt::TokenId::unspecified(),
})
.into(),
);
}
result.push(
tt::Leaf::Ident(tt::Ident {
id: tt::TokenId::unspecified(),
text: format!("T{}", i).into(),
})
.into(),
);
result.extend(bound.iter().cloned());
}
result.push(
tt::Leaf::Punct(tt::Punct {
char: '>',
spacing: tt::Spacing::Alone,
id: tt::TokenId::unspecified(),
})
.into(),
);
result
}
fn expand_simple_derive(tt: &tt::Subtree, trait_path: tt::Subtree) -> ExpandResult<tt::Subtree> {
let info = match parse_adt(tt) {
Ok(info) => info,
Err(e) => return ExpandResult::only_err(e),
};
let name = info.name;
let trait_path_clone = trait_path.token_trees.clone();
let bound = (quote! { : ##trait_path_clone }).token_trees;
let type_params = make_type_args(info.type_or_const_params, bound);
let type_args = make_type_args(info.type_or_const_params, Vec::new());
let trait_path = trait_path.token_trees;
let expanded = quote! {
impl ##type_params ##trait_path for #name ##type_args {}
};
ExpandResult::ok(expanded)
}
fn find_builtin_crate(db: &dyn AstDatabase, id: MacroCallId) -> tt::TokenTree {
// FIXME: make hygiene works for builtin derive macro
// such that $crate can be used here.
let cg = db.crate_graph();
let krate = db.lookup_intern_macro_call(id).krate;
let tt = if matches!(cg[krate].origin, CrateOrigin::Lang(LangCrateOrigin::Core)) {
cov_mark::hit!(test_copy_expand_in_core);
quote! { crate }
} else {
quote! { core }
};
tt.token_trees[0].clone()
}
fn copy_expand(
db: &dyn AstDatabase,
id: MacroCallId,
tt: &tt::Subtree,
) -> ExpandResult<tt::Subtree> {
let krate = find_builtin_crate(db, id);
expand_simple_derive(tt, quote! { #krate::marker::Copy })
}
fn clone_expand(
db: &dyn AstDatabase,
id: MacroCallId,
tt: &tt::Subtree,
) -> ExpandResult<tt::Subtree> {
let krate = find_builtin_crate(db, id);
expand_simple_derive(tt, quote! { #krate::clone::Clone })
}
fn default_expand(
db: &dyn AstDatabase,
id: MacroCallId,
tt: &tt::Subtree,
) -> ExpandResult<tt::Subtree> {
let krate = find_builtin_crate(db, id);
expand_simple_derive(tt, quote! { #krate::default::Default })
}
fn debug_expand(
db: &dyn AstDatabase,
id: MacroCallId,
tt: &tt::Subtree,
) -> ExpandResult<tt::Subtree> {
let krate = find_builtin_crate(db, id);
expand_simple_derive(tt, quote! { #krate::fmt::Debug })
}
fn hash_expand(
db: &dyn AstDatabase,
id: MacroCallId,
tt: &tt::Subtree,
) -> ExpandResult<tt::Subtree> {
let krate = find_builtin_crate(db, id);
expand_simple_derive(tt, quote! { #krate::hash::Hash })
}
fn eq_expand(db: &dyn AstDatabase, id: MacroCallId, tt: &tt::Subtree) -> ExpandResult<tt::Subtree> {
let krate = find_builtin_crate(db, id);
expand_simple_derive(tt, quote! { #krate::cmp::Eq })
}
fn partial_eq_expand(
db: &dyn AstDatabase,
id: MacroCallId,
tt: &tt::Subtree,
) -> ExpandResult<tt::Subtree> {
let krate = find_builtin_crate(db, id);
expand_simple_derive(tt, quote! { #krate::cmp::PartialEq })
}
fn ord_expand(
db: &dyn AstDatabase,
id: MacroCallId,
tt: &tt::Subtree,
) -> ExpandResult<tt::Subtree> {
let krate = find_builtin_crate(db, id);
expand_simple_derive(tt, quote! { #krate::cmp::Ord })
}
fn partial_ord_expand(
db: &dyn AstDatabase,
id: MacroCallId,
tt: &tt::Subtree,
) -> ExpandResult<tt::Subtree> {
let krate = find_builtin_crate(db, id);
expand_simple_derive(tt, quote! { #krate::cmp::PartialOrd })
}