use std::collections::HashSet;
use syn::{self, visit};
use internals::ast::Container;
use internals::attr;
macro_rules! path {
($($path:tt)+) => {
syn::parse_path(stringify!($($path)+)).unwrap()
};
}
pub fn without_defaults(generics: &syn::Generics) -> syn::Generics {
syn::Generics {
ty_params: generics
.ty_params
.iter()
.map(
|ty_param| {
syn::TyParam {
default: None,
..ty_param.clone()
}
},
)
.collect(),
..generics.clone()
}
}
pub fn with_where_predicates(
generics: &syn::Generics,
predicates: &[syn::WherePredicate],
) -> syn::Generics {
let mut generics = generics.clone();
generics
.where_clause
.predicates
.extend_from_slice(predicates);
generics
}
pub fn with_where_predicates_from_fields<F>(
cont: &Container,
generics: &syn::Generics,
from_field: F,
) -> syn::Generics
where
F: Fn(&attr::Field) -> Option<&[syn::WherePredicate]>,
{
let predicates = cont.body
.all_fields()
.flat_map(|field| from_field(&field.attrs))
.flat_map(|predicates| predicates.to_vec());
let mut generics = generics.clone();
generics.where_clause.predicates.extend(predicates);
generics
}
pub fn with_bound<F>(
cont: &Container,
generics: &syn::Generics,
filter: F,
bound: &syn::Path,
) -> syn::Generics
where
F: Fn(&attr::Field) -> bool,
{
struct FindTyParams {
all_ty_params: HashSet<syn::Ident>,
relevant_ty_params: HashSet<syn::Ident>,
}
impl visit::Visitor for FindTyParams {
fn visit_path(&mut self, path: &syn::Path) {
if let Some(seg) = path.segments.last() {
if seg.ident == "PhantomData" {
return;
}
}
if !path.global && path.segments.len() == 1 {
let id = path.segments[0].ident.clone();
if self.all_ty_params.contains(&id) {
self.relevant_ty_params.insert(id);
}
}
visit::walk_path(self, path);
}
}
let all_ty_params: HashSet<_> = generics
.ty_params
.iter()
.map(|ty_param| ty_param.ident.clone())
.collect();
let relevant_tys = cont.body
.all_fields()
.filter(|&field| filter(&field.attrs))
.map(|field| &field.ty);
let mut visitor = FindTyParams {
all_ty_params: all_ty_params,
relevant_ty_params: HashSet::new(),
};
for ty in relevant_tys {
visit::walk_ty(&mut visitor, ty);
}
let new_predicates = generics
.ty_params
.iter()
.map(|ty_param| ty_param.ident.clone())
.filter(|id| visitor.relevant_ty_params.contains(id))
.map(
|id| {
syn::WherePredicate::BoundPredicate(
syn::WhereBoundPredicate {
bound_lifetimes: Vec::new(),
bounded_ty: syn::Ty::Path(None, id.into()),
bounds: vec![
syn::TyParamBound::Trait(
syn::PolyTraitRef {
bound_lifetimes: Vec::new(),
trait_ref: bound.clone(),
},
syn::TraitBoundModifier::None,
),
],
},
)
},
);
let mut generics = generics.clone();
generics.where_clause.predicates.extend(new_predicates);
generics
}
pub fn with_self_bound(
cont: &Container,
generics: &syn::Generics,
bound: &syn::Path,
) -> syn::Generics {
let mut generics = generics.clone();
generics
.where_clause
.predicates
.push(
syn::WherePredicate::BoundPredicate(
syn::WhereBoundPredicate {
bound_lifetimes: Vec::new(),
bounded_ty: type_of_item(cont),
bounds: vec![
syn::TyParamBound::Trait(
syn::PolyTraitRef {
bound_lifetimes: Vec::new(),
trait_ref: bound.clone(),
},
syn::TraitBoundModifier::None,
),
],
},
),
);
generics
}
pub fn with_lifetime_bound(generics: &syn::Generics, lifetime: &str) -> syn::Generics {
let mut generics = generics.clone();
for lifetime_def in &mut generics.lifetimes {
lifetime_def.bounds.push(syn::Lifetime::new(lifetime));
}
for ty_param in &mut generics.ty_params {
ty_param
.bounds
.push(syn::TyParamBound::Region(syn::Lifetime::new(lifetime)));
}
generics
.lifetimes
.push(
syn::LifetimeDef {
attrs: Vec::new(),
lifetime: syn::Lifetime::new(lifetime),
bounds: Vec::new(),
},
);
generics
}
fn type_of_item(cont: &Container) -> syn::Ty {
syn::Ty::Path(
None,
syn::Path {
global: false,
segments: vec![
syn::PathSegment {
ident: cont.ident.clone(),
parameters: syn::PathParameters::AngleBracketed(
syn::AngleBracketedParameterData {
lifetimes: cont.generics
.lifetimes
.iter()
.map(|def| def.lifetime.clone())
.collect(),
types: cont.generics
.ty_params
.iter()
.map(|param| syn::Ty::Path(None, param.ident.clone().into()))
.collect(),
bindings: Vec::new(),
},
),
},
],
},
)
}