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use std::iter;
use syn::{
punctuated::Punctuated, GenericArgument, Lifetime, Path, PathArguments, ReturnType, TraitBound,
Type, TypeParamBound,
};
pub fn trait_bounds<T>(
bounds: &Punctuated<TypeParamBound, T>,
) -> impl Iterator<Item = &TraitBound> {
bounds.iter().filter_map(|b| match b {
TypeParamBound::Trait(t) => Some(t),
TypeParamBound::Lifetime(_) => None,
})
}
pub fn lifetime_bounds<T>(
bounds: &Punctuated<TypeParamBound, T>,
) -> impl Iterator<Item = &Lifetime> {
bounds.iter().filter_map(|b| match b {
TypeParamBound::Trait(_) => None,
TypeParamBound::Lifetime(l) => Some(l),
})
}
pub fn type_arguments_mut<P>(
args: &mut Punctuated<GenericArgument, P>,
) -> impl Iterator<Item = &mut Type> {
args.iter_mut().filter_map(|a| match a {
GenericArgument::Type(t) => Some(t),
_other => None,
})
}
enum IterTypes<A, B, C, D, E, F> {
Single(A),
Function(B),
Tuple(C),
ImplTrait(D),
TraitObject(E),
Path(F),
Empty,
}
impl<A, B, C, D, E, F> Iterator for IterTypes<A, B, C, D, E, F>
where
A: Iterator,
B: Iterator<Item = A::Item>,
C: Iterator<Item = A::Item>,
D: Iterator<Item = A::Item>,
E: Iterator<Item = A::Item>,
F: Iterator<Item = A::Item>,
{
type Item = A::Item;
fn next(&mut self) -> Option<Self::Item> {
match self {
IterTypes::Single(a) => a.next(),
IterTypes::Function(a) => a.next(),
IterTypes::Tuple(a) => a.next(),
IterTypes::ImplTrait(a) => a.next(),
IterTypes::TraitObject(a) => a.next(),
IterTypes::Path(a) => a.next(),
IterTypes::Empty => None,
}
}
}
pub fn iter_path(path: &Path) -> impl Iterator<Item = &Type> {
types_in_path(path).flat_map(|t| iter_type(t))
}
pub fn iter_type<'a>(t: &'a Type) -> Box<dyn Iterator<Item = &'a Type> + 'a> {
Box::new(
iter::once(t).chain(match t {
Type::Array(array) => IterTypes::Single(iter_type(&array.elem)),
Type::Group(group) => IterTypes::Single(iter_type(&group.elem)),
Type::Paren(paren) => IterTypes::Single(iter_type(&paren.elem)),
Type::Ptr(ptr) => IterTypes::Single(iter_type(&ptr.elem)),
Type::Reference(r) => IterTypes::Single(iter_type(&r.elem)),
Type::Slice(slice) => IterTypes::Single(iter_type(&slice.elem)),
Type::Tuple(tuple) => IterTypes::Tuple(tuple.elems.iter().flat_map(|i| iter_type(i))),
Type::BareFn(fun) => {
IterTypes::Function(fun.inputs.iter().flat_map(|i| iter_type(&i.ty)).chain(
match &fun.output {
ReturnType::Default => IterEnum::Left(iter::empty()),
ReturnType::Type(_, ty) => IterEnum::Right(iter_type(ty.as_ref())),
},
))
}
Type::ImplTrait(impl_trait) => IterTypes::ImplTrait(
trait_bounds(&impl_trait.bounds)
.flat_map(|b| types_in_path(&b.path))
.flat_map(|t| iter_type(t)),
),
Type::Path(path) => IterTypes::Path(iter_path(&path.path)),
Type::TraitObject(trait_obj) => IterTypes::TraitObject(
trait_bounds(&trait_obj.bounds)
.flat_map(|b| types_in_path(&b.path))
.flat_map(|t| iter_type(t)),
),
_other => IterTypes::Empty,
}),
)
}
enum IterEnum<L, R> {
Left(L),
Right(R),
}
impl<L, R> Iterator for IterEnum<L, R>
where
L: Iterator,
R: Iterator<Item = L::Item>,
{
type Item = L::Item;
fn next(&mut self) -> Option<Self::Item> {
match self {
IterEnum::Left(iter) => iter.next(),
IterEnum::Right(iter) => iter.next(),
}
}
}
fn types_in_path(p: &Path) -> impl Iterator<Item = &Type> {
p.segments.iter().flat_map(|s| match &s.arguments {
PathArguments::AngleBracketed(ang) => {
IterEnum::Left(ang.args.iter().flat_map(|a| match a {
GenericArgument::Type(t) => Some(t),
GenericArgument::Binding(b) => Some(&b.ty),
// TODO: handle GenericArgument::Constraint
_other => None,
}))
}
_other => IterEnum::Right(iter::empty()),
})
}
|
