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//! `TyBuilder`, a helper for building instances of `Ty` and related types.
use std::iter;
use chalk_ir::{
cast::{Cast, CastTo, Caster},
fold::Fold,
interner::HasInterner,
AdtId, BoundVar, DebruijnIndex, Scalar,
};
use hir_def::{builtin_type::BuiltinType, GenericDefId, TraitId, TypeAliasId};
use smallvec::SmallVec;
use crate::{
db::HirDatabase, primitive, to_assoc_type_id, to_chalk_trait_id, utils::generics, Binders,
CallableSig, GenericArg, Interner, ProjectionTy, Substitution, TraitRef, Ty, TyDefId, TyExt,
TyKind, ValueTyDefId,
};
/// This is a builder for `Ty` or anything that needs a `Substitution`.
pub struct TyBuilder<D> {
/// The `data` field is used to keep track of what we're building (e.g. an
/// ADT, a `TraitRef`, ...).
data: D,
vec: SmallVec<[GenericArg; 2]>,
param_count: usize,
}
impl<D> TyBuilder<D> {
fn new(data: D, param_count: usize) -> TyBuilder<D> {
TyBuilder { data, param_count, vec: SmallVec::with_capacity(param_count) }
}
fn build_internal(self) -> (D, Substitution) {
assert_eq!(self.vec.len(), self.param_count);
let subst = Substitution::from_iter(&Interner, self.vec);
(self.data, subst)
}
pub fn push(mut self, arg: impl CastTo<GenericArg>) -> Self {
self.vec.push(arg.cast(&Interner));
self
}
pub fn remaining(&self) -> usize {
self.param_count - self.vec.len()
}
pub fn fill_with_bound_vars(self, debruijn: DebruijnIndex, starting_from: usize) -> Self {
self.fill(
(starting_from..)
.map(|idx| TyKind::BoundVar(BoundVar::new(debruijn, idx)).intern(&Interner)),
)
}
pub fn fill_with_unknown(self) -> Self {
self.fill(iter::repeat(TyKind::Error.intern(&Interner)))
}
pub fn fill(mut self, filler: impl Iterator<Item = impl CastTo<GenericArg>>) -> Self {
self.vec.extend(filler.take(self.remaining()).casted(&Interner));
assert_eq!(self.remaining(), 0);
self
}
pub fn use_parent_substs(mut self, parent_substs: &Substitution) -> Self {
assert!(self.vec.is_empty());
assert!(parent_substs.len(&Interner) <= self.param_count);
self.vec.extend(parent_substs.iter(&Interner).cloned());
self
}
}
impl TyBuilder<()> {
pub fn unit() -> Ty {
TyKind::Tuple(0, Substitution::empty(&Interner)).intern(&Interner)
}
pub fn fn_ptr(sig: CallableSig) -> Ty {
TyKind::Function(sig.to_fn_ptr()).intern(&Interner)
}
pub fn builtin(builtin: BuiltinType) -> Ty {
match builtin {
BuiltinType::Char => TyKind::Scalar(Scalar::Char).intern(&Interner),
BuiltinType::Bool => TyKind::Scalar(Scalar::Bool).intern(&Interner),
BuiltinType::Str => TyKind::Str.intern(&Interner),
BuiltinType::Int(t) => {
TyKind::Scalar(Scalar::Int(primitive::int_ty_from_builtin(t))).intern(&Interner)
}
BuiltinType::Uint(t) => {
TyKind::Scalar(Scalar::Uint(primitive::uint_ty_from_builtin(t))).intern(&Interner)
}
BuiltinType::Float(t) => {
TyKind::Scalar(Scalar::Float(primitive::float_ty_from_builtin(t))).intern(&Interner)
}
}
}
pub fn type_params_subst(db: &dyn HirDatabase, def: impl Into<GenericDefId>) -> Substitution {
let params = generics(db.upcast(), def.into());
params.type_params_subst(db)
}
pub fn subst_for_def(db: &dyn HirDatabase, def: impl Into<GenericDefId>) -> TyBuilder<()> {
let def = def.into();
let params = generics(db.upcast(), def);
let param_count = params.len();
TyBuilder::new((), param_count)
}
pub fn build(self) -> Substitution {
let ((), subst) = self.build_internal();
subst
}
}
impl TyBuilder<hir_def::AdtId> {
pub fn adt(db: &dyn HirDatabase, adt: hir_def::AdtId) -> TyBuilder<hir_def::AdtId> {
let generics = generics(db.upcast(), adt.into());
let param_count = generics.len();
TyBuilder::new(adt, param_count)
}
pub fn fill_with_defaults(
mut self,
db: &dyn HirDatabase,
mut fallback: impl FnMut() -> Ty,
) -> Self {
let defaults = db.generic_defaults(self.data.into());
for default_ty in defaults.iter().skip(self.vec.len()) {
if default_ty.skip_binders().is_unknown() {
self.vec.push(fallback().cast(&Interner));
} else {
// each default can depend on the previous parameters
let subst_so_far = Substitution::from_iter(&Interner, self.vec.clone());
self.vec
.push(default_ty.clone().substitute(&Interner, &subst_so_far).cast(&Interner));
}
}
self
}
pub fn build(self) -> Ty {
let (adt, subst) = self.build_internal();
TyKind::Adt(AdtId(adt), subst).intern(&Interner)
}
}
pub struct Tuple(usize);
impl TyBuilder<Tuple> {
pub fn tuple(size: usize) -> TyBuilder<Tuple> {
TyBuilder::new(Tuple(size), size)
}
pub fn build(self) -> Ty {
let (Tuple(size), subst) = self.build_internal();
TyKind::Tuple(size, subst).intern(&Interner)
}
}
impl TyBuilder<TraitId> {
pub fn trait_ref(db: &dyn HirDatabase, trait_id: TraitId) -> TyBuilder<TraitId> {
let generics = generics(db.upcast(), trait_id.into());
let param_count = generics.len();
TyBuilder::new(trait_id, param_count)
}
pub fn build(self) -> TraitRef {
let (trait_id, substitution) = self.build_internal();
TraitRef { trait_id: to_chalk_trait_id(trait_id), substitution }
}
}
impl TyBuilder<TypeAliasId> {
pub fn assoc_type_projection(
db: &dyn HirDatabase,
type_alias: TypeAliasId,
) -> TyBuilder<TypeAliasId> {
let generics = generics(db.upcast(), type_alias.into());
let param_count = generics.len();
TyBuilder::new(type_alias, param_count)
}
pub fn build(self) -> ProjectionTy {
let (type_alias, substitution) = self.build_internal();
ProjectionTy { associated_ty_id: to_assoc_type_id(type_alias), substitution }
}
}
impl<T: HasInterner<Interner = Interner> + Fold<Interner>> TyBuilder<Binders<T>> {
fn subst_binders(b: Binders<T>) -> Self {
let param_count = b.binders.len(&Interner);
TyBuilder::new(b, param_count)
}
pub fn build(self) -> <T as Fold<Interner>>::Result {
let (b, subst) = self.build_internal();
b.substitute(&Interner, &subst)
}
}
impl TyBuilder<Binders<Ty>> {
pub fn def_ty(db: &dyn HirDatabase, def: TyDefId) -> TyBuilder<Binders<Ty>> {
TyBuilder::subst_binders(db.ty(def))
}
pub fn impl_self_ty(db: &dyn HirDatabase, def: hir_def::ImplId) -> TyBuilder<Binders<Ty>> {
TyBuilder::subst_binders(db.impl_self_ty(def))
}
pub fn value_ty(db: &dyn HirDatabase, def: ValueTyDefId) -> TyBuilder<Binders<Ty>> {
TyBuilder::subst_binders(db.value_ty(def))
}
}
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