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//! Many kinds of items or constructs can have generic parameters: functions,
//! structs, impls, traits, etc. This module provides a common HIR for these
//! generic parameters. See also the `Generics` type and the `generics_of` query
//! in rustc.
use std::sync::Arc;
use ra_syntax::ast::{self, DefaultTypeParamOwner, NameOwner, TypeBoundsOwner, TypeParamsOwner};
use crate::{
db::{AstDatabase, DefDatabase, HirDatabase},
path::Path,
type_ref::TypeRef,
AdtDef, AsName, Container, Enum, EnumVariant, Function, HasSource, ImplBlock, Name, Struct,
Trait, TypeAlias, Union,
};
/// Data about a generic parameter (to a function, struct, impl, ...).
#[derive(Clone, PartialEq, Eq, Debug)]
pub struct GenericParam {
// FIXME: give generic params proper IDs
pub(crate) idx: u32,
pub(crate) name: Name,
pub(crate) default: Option<Path>,
}
/// Data about the generic parameters of a function, struct, impl, etc.
#[derive(Clone, PartialEq, Eq, Debug, Default)]
pub struct GenericParams {
pub(crate) parent_params: Option<Arc<GenericParams>>,
pub(crate) params: Vec<GenericParam>,
pub(crate) where_predicates: Vec<WherePredicate>,
}
/// A single predicate from a where clause, i.e. `where Type: Trait`. Combined
/// where clauses like `where T: Foo + Bar` are turned into multiple of these.
#[derive(Clone, PartialEq, Eq, Debug)]
pub struct WherePredicate {
pub(crate) type_ref: TypeRef,
pub(crate) trait_ref: Path,
}
// FIXME: consts can have type parameters from their parents (i.e. associated consts of traits)
#[derive(Clone, Copy, PartialEq, Eq, Debug, Hash)]
pub enum GenericDef {
Function(Function),
Struct(Struct),
Union(Union),
Enum(Enum),
Trait(Trait),
TypeAlias(TypeAlias),
ImplBlock(ImplBlock),
// enum variants cannot have generics themselves, but their parent enums
// can, and this makes some code easier to write
EnumVariant(EnumVariant),
}
impl_froms!(GenericDef: Function, Struct, Union, Enum, Trait, TypeAlias, ImplBlock, EnumVariant);
impl GenericParams {
pub(crate) fn generic_params_query(
db: &(impl DefDatabase + AstDatabase),
def: GenericDef,
) -> Arc<GenericParams> {
let mut generics = GenericParams::default();
let parent = match def {
GenericDef::Function(it) => it.container(db).map(GenericDef::from),
GenericDef::TypeAlias(it) => it.container(db).map(GenericDef::from),
GenericDef::EnumVariant(it) => Some(it.parent_enum(db).into()),
GenericDef::Struct(_)
| GenericDef::Union(_)
| GenericDef::Enum(_)
| GenericDef::Trait(_) => None,
GenericDef::ImplBlock(_) => None,
};
generics.parent_params = parent.map(|p| db.generic_params(p));
let start = generics.parent_params.as_ref().map(|p| p.params.len()).unwrap_or(0) as u32;
match def {
GenericDef::Function(it) => generics.fill(&*it.source(db).ast, start),
GenericDef::Struct(it) => generics.fill(&*it.source(db).ast, start),
GenericDef::Union(it) => generics.fill(&*it.source(db).ast, start),
GenericDef::Enum(it) => generics.fill(&*it.source(db).ast, start),
GenericDef::Trait(it) => {
// traits get the Self type as an implicit first type parameter
generics.params.push(GenericParam {
idx: start,
name: Name::self_type(),
default: None,
});
generics.fill(&*it.source(db).ast, start + 1);
}
GenericDef::TypeAlias(it) => generics.fill(&*it.source(db).ast, start),
GenericDef::ImplBlock(it) => generics.fill(&*it.source(db).ast, start),
GenericDef::EnumVariant(_) => {}
}
Arc::new(generics)
}
fn fill(&mut self, node: &impl TypeParamsOwner, start: u32) {
if let Some(params) = node.type_param_list() {
self.fill_params(params, start)
}
if let Some(where_clause) = node.where_clause() {
self.fill_where_predicates(where_clause);
}
}
fn fill_params(&mut self, params: &ast::TypeParamList, start: u32) {
for (idx, type_param) in params.type_params().enumerate() {
let name = type_param.name().map(AsName::as_name).unwrap_or_else(Name::missing);
let default = type_param.default_type().and_then(|t| t.path()).and_then(Path::from_ast);
let param = GenericParam { idx: idx as u32 + start, name: name.clone(), default };
self.params.push(param);
let type_ref = TypeRef::Path(name.into());
for bound in type_param
.type_bound_list()
.iter()
.flat_map(|type_bound_list| type_bound_list.bounds())
{
self.add_where_predicate_from_bound(bound, type_ref.clone());
}
}
}
fn fill_where_predicates(&mut self, where_clause: &ast::WhereClause) {
for pred in where_clause.predicates() {
let type_ref = match pred.type_ref() {
Some(type_ref) => type_ref,
None => continue,
};
let type_ref = TypeRef::from_ast(type_ref);
for bound in pred.type_bound_list().iter().flat_map(|l| l.bounds()) {
self.add_where_predicate_from_bound(bound, type_ref.clone());
}
}
}
fn add_where_predicate_from_bound(&mut self, bound: &ast::TypeBound, type_ref: TypeRef) {
let path = bound
.type_ref()
.and_then(|tr| match tr.kind() {
ast::TypeRefKind::PathType(path) => path.path(),
_ => None,
})
.and_then(Path::from_ast);
let path = match path {
Some(p) => p,
None => return,
};
self.where_predicates.push(WherePredicate { type_ref, trait_ref: path });
}
pub(crate) fn find_by_name(&self, name: &Name) -> Option<&GenericParam> {
self.params.iter().find(|p| &p.name == name)
}
pub fn count_parent_params(&self) -> usize {
self.parent_params.as_ref().map(|p| p.count_params_including_parent()).unwrap_or(0)
}
pub fn count_params_including_parent(&self) -> usize {
let parent_count = self.count_parent_params();
parent_count + self.params.len()
}
fn for_each_param<'a>(&'a self, f: &mut impl FnMut(&'a GenericParam)) {
if let Some(parent) = &self.parent_params {
parent.for_each_param(f);
}
self.params.iter().for_each(f);
}
pub fn params_including_parent(&self) -> Vec<&GenericParam> {
let mut vec = Vec::with_capacity(self.count_params_including_parent());
self.for_each_param(&mut |p| vec.push(p));
vec
}
}
impl GenericDef {
pub(crate) fn resolver(&self, db: &impl HirDatabase) -> crate::Resolver {
match self {
GenericDef::Function(inner) => inner.resolver(db),
GenericDef::Struct(inner) => inner.resolver(db),
GenericDef::Union(inner) => inner.resolver(db),
GenericDef::Enum(inner) => inner.resolver(db),
GenericDef::Trait(inner) => inner.resolver(db),
GenericDef::TypeAlias(inner) => inner.resolver(db),
GenericDef::ImplBlock(inner) => inner.resolver(db),
GenericDef::EnumVariant(inner) => inner.parent_enum(db).resolver(db),
}
}
}
impl From<Container> for GenericDef {
fn from(c: Container) -> Self {
match c {
Container::Trait(trait_) => trait_.into(),
Container::ImplBlock(impl_block) => impl_block.into(),
}
}
}
impl From<crate::adt::AdtDef> for GenericDef {
fn from(adt: crate::adt::AdtDef) -> Self {
match adt {
AdtDef::Struct(s) => s.into(),
AdtDef::Union(u) => u.into(),
AdtDef::Enum(e) => e.into(),
}
}
}
pub trait HasGenericParams: Copy {
fn generic_params(self, db: &impl DefDatabase) -> Arc<GenericParams>;
}
impl<T> HasGenericParams for T
where
T: Into<GenericDef> + Copy,
{
fn generic_params(self, db: &impl DefDatabase) -> Arc<GenericParams> {
db.generic_params(self.into())
}
}
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