rust/crates/hir-expand/src/builtin_derive_macro.rs
2023-04-16 19:20:48 +02:00

331 lines
10 KiB
Rust

//! Builtin derives.
use base_db::{CrateOrigin, LangCrateOrigin};
use std::collections::HashSet;
use tracing::debug;
use crate::tt::{self, TokenId};
use syntax::{
ast::{self, AstNode, HasGenericParams, HasModuleItem, HasName, HasTypeBounds, PathType},
match_ast,
};
use crate::{db::ExpandDatabase, 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 ExpandDatabase,
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,
/// first field is the name, and
/// second field is `Some(ty)` if it's a const param of type `ty`, `None` if it's a type param.
/// third fields is where bounds, if any
param_types: Vec<(tt::Subtree, Option<tt::Subtree>, Option<tt::Subtree>)>,
associated_types: Vec<tt::Subtree>,
}
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 mut param_type_set: HashSet<String> = HashSet::new();
let param_types = params
.into_iter()
.flat_map(|param_list| param_list.type_or_const_params())
.map(|param| {
let name = {
let this = param.name();
match this {
Some(x) => {
param_type_set.insert(x.to_string());
mbe::syntax_node_to_token_tree(x.syntax()).0
}
None => tt::Subtree::empty(),
}
};
let bounds = match &param {
ast::TypeOrConstParam::Type(x) => {
x.type_bound_list().map(|x| mbe::syntax_node_to_token_tree(x.syntax()).0)
}
ast::TypeOrConstParam::Const(_) => None,
};
let ty = if let ast::TypeOrConstParam::Const(param) = param {
let ty = param
.ty()
.map(|ty| mbe::syntax_node_to_token_tree(ty.syntax()).0)
.unwrap_or_else(tt::Subtree::empty);
Some(ty)
} else {
None
};
(name, ty, bounds)
})
.collect();
let is_associated_type = |p: &PathType| {
if let Some(p) = p.path() {
if let Some(parent) = p.qualifier() {
if let Some(x) = parent.segment() {
if let Some(x) = x.path_type() {
if let Some(x) = x.path() {
if let Some(pname) = x.as_single_name_ref() {
if param_type_set.contains(&pname.to_string()) {
// <T as Trait>::Assoc
return true;
}
}
}
}
}
if let Some(pname) = parent.as_single_name_ref() {
if param_type_set.contains(&pname.to_string()) {
// T::Assoc
return true;
}
}
}
}
false
};
let associated_types = node
.descendants()
.filter_map(PathType::cast)
.filter(is_associated_type)
.map(|x| mbe::syntax_node_to_token_tree(x.syntax()).0)
.collect::<Vec<_>>();
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 { span: name_token_id, text: name.text().into() };
Ok(BasicAdtInfo { name: name_token, param_types, associated_types })
}
/// Given that we are deriving a trait `DerivedTrait` for a type like:
///
/// ```ignore (only-for-syntax-highlight)
/// struct Struct<'a, ..., 'z, A, B: DeclaredTrait, C, ..., Z> where C: WhereTrait {
/// a: A,
/// b: B::Item,
/// b1: <B as DeclaredTrait>::Item,
/// c1: <C as WhereTrait>::Item,
/// c2: Option<<C as WhereTrait>::Item>,
/// ...
/// }
/// ```
///
/// create an impl like:
///
/// ```ignore (only-for-syntax-highlight)
/// impl<'a, ..., 'z, A, B: DeclaredTrait, C, ... Z> where
/// C: WhereTrait,
/// A: DerivedTrait + B1 + ... + BN,
/// B: DerivedTrait + B1 + ... + BN,
/// C: DerivedTrait + B1 + ... + BN,
/// B::Item: DerivedTrait + B1 + ... + BN,
/// <C as WhereTrait>::Item: DerivedTrait + B1 + ... + BN,
/// ...
/// {
/// ...
/// }
/// ```
///
/// where B1, ..., BN are the bounds given by `bounds_paths`.'. Z is a phantom type, and
/// therefore does not get bound by the derived trait.
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::new(tt::Subtree::empty(), e),
};
let mut where_block = vec![];
let (params, args): (Vec<_>, Vec<_>) = info
.param_types
.into_iter()
.map(|(ident, param_ty, bound)| {
let ident_ = ident.clone();
if let Some(b) = bound {
let ident = ident.clone();
where_block.push(quote! { #ident : #b , });
}
if let Some(ty) = param_ty {
(quote! { const #ident : #ty , }, quote! { #ident_ , })
} else {
let bound = trait_path.clone();
(quote! { #ident : #bound , }, quote! { #ident_ , })
}
})
.unzip();
where_block.extend(info.associated_types.iter().map(|x| {
let x = x.clone();
let bound = trait_path.clone();
quote! { #x : #bound , }
}));
let name = info.name;
let expanded = quote! {
impl < ##params > #trait_path for #name < ##args > where ##where_block {}
};
ExpandResult::ok(expanded)
}
fn find_builtin_crate(db: &dyn ExpandDatabase, 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 ExpandDatabase,
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 ExpandDatabase,
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 ExpandDatabase,
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 ExpandDatabase,
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 ExpandDatabase,
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 ExpandDatabase,
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 ExpandDatabase,
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 ExpandDatabase,
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 ExpandDatabase,
id: MacroCallId,
tt: &tt::Subtree,
) -> ExpandResult<tt::Subtree> {
let krate = find_builtin_crate(db, id);
expand_simple_derive(tt, quote! { #krate::cmp::PartialOrd })
}