use std::collections::HashSet;
use syn;
use syn::punctuated::{Pair, Punctuated};
use syn::visit::{self, Visit};
use internals::ast::{Container, Data};
use internals::attr;
use proc_macro2::Span;
pub fn without_defaults(generics: &syn::Generics) -> syn::Generics {
syn::Generics {
params: generics
.params
.iter()
.map(|param| match *param {
syn::GenericParam::Type(ref param) => syn::GenericParam::Type(syn::TypeParam {
eq_token: None,
default: None,
..param.clone()
}),
_ => param.clone(),
})
.collect(),
..generics.clone()
}
}
pub fn with_where_predicates(
generics: &syn::Generics,
predicates: &[syn::WherePredicate],
) -> syn::Generics {
let mut generics = generics.clone();
generics
.make_where_clause()
.predicates
.extend(predicates.into_iter().cloned());
generics
}
pub fn with_where_predicates_from_fields(
cont: &Container,
generics: &syn::Generics,
from_field: fn(&attr::Field) -> Option<&[syn::WherePredicate]>,
) -> syn::Generics {
let predicates = cont.data
.all_fields()
.flat_map(|field| from_field(&field.attrs))
.flat_map(|predicates| predicates.to_vec());
let mut generics = generics.clone();
generics.make_where_clause().predicates.extend(predicates);
generics
}
pub fn with_bound(
cont: &Container,
generics: &syn::Generics,
filter: fn(&attr::Field, Option<&attr::Variant>) -> bool,
bound: &syn::Path,
) -> syn::Generics {
struct FindTyParams<'ast> {
all_type_params: HashSet<syn::Ident>,
relevant_type_params: HashSet<syn::Ident>,
associated_type_usage: Vec<&'ast syn::TypePath>,
}
impl<'ast> Visit<'ast> for FindTyParams<'ast> {
fn visit_field(&mut self, field: &'ast syn::Field) {
if let syn::Type::Path(ref ty) = field.ty {
if let Some(Pair::Punctuated(ref t, _)) = ty.path.segments.first() {
if self.all_type_params.contains(&t.ident) {
self.associated_type_usage.push(ty);
}
}
}
self.visit_type(&field.ty);
}
fn visit_path(&mut self, path: &'ast syn::Path) {
if let Some(seg) = path.segments.last() {
if seg.into_value().ident == "PhantomData" {
return;
}
}
if path.leading_colon.is_none() && path.segments.len() == 1 {
let id = path.segments[0].ident;
if self.all_type_params.contains(&id) {
self.relevant_type_params.insert(id);
}
}
visit::visit_path(self, path);
}
fn visit_macro(&mut self, _mac: &'ast syn::Macro) {}
}
let all_type_params = generics.type_params().map(|param| param.ident).collect();
let mut visitor = FindTyParams {
all_type_params: all_type_params,
relevant_type_params: HashSet::new(),
associated_type_usage: Vec::new(),
};
match cont.data {
Data::Enum(ref variants) => for variant in variants.iter() {
let relevant_fields = variant
.fields
.iter()
.filter(|field| filter(&field.attrs, Some(&variant.attrs)));
for field in relevant_fields {
visitor.visit_field(field.original);
}
},
Data::Struct(_, ref fields) => {
for field in fields.iter().filter(|field| filter(&field.attrs, None)) {
visitor.visit_field(field.original);
}
}
}
let relevant_type_params = visitor.relevant_type_params;
let associated_type_usage = visitor.associated_type_usage;
let new_predicates = generics
.type_params()
.map(|param| param.ident)
.filter(|id| relevant_type_params.contains(id))
.map(|id| syn::TypePath {
qself: None,
path: id.into(),
})
.chain(associated_type_usage.into_iter().cloned())
.map(|bounded_ty| {
syn::WherePredicate::Type(syn::PredicateType {
lifetimes: None,
bounded_ty: syn::Type::Path(bounded_ty),
colon_token: Default::default(),
bounds: vec![syn::TypeParamBound::Trait(syn::TraitBound {
paren_token: None,
modifier: syn::TraitBoundModifier::None,
lifetimes: None,
path: bound.clone(),
})].into_iter()
.collect(),
})
});
let mut generics = generics.clone();
generics
.make_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
.make_where_clause()
.predicates
.push(syn::WherePredicate::Type(syn::PredicateType {
lifetimes: None,
bounded_ty: type_of_item(cont),
colon_token: Default::default(),
bounds: vec![syn::TypeParamBound::Trait(syn::TraitBound {
paren_token: None,
modifier: syn::TraitBoundModifier::None,
lifetimes: None,
path: bound.clone(),
})].into_iter()
.collect(),
}));
generics
}
pub fn with_lifetime_bound(generics: &syn::Generics, lifetime: &str) -> syn::Generics {
let bound = syn::Lifetime::new(lifetime, Span::call_site());
let def = syn::LifetimeDef {
attrs: Vec::new(),
lifetime: bound,
colon_token: None,
bounds: Punctuated::new(),
};
let params = Some(syn::GenericParam::Lifetime(def))
.into_iter()
.chain(generics.params.iter().cloned().map(|mut param| {
match param {
syn::GenericParam::Lifetime(ref mut param) => {
param.bounds.push(bound);
}
syn::GenericParam::Type(ref mut param) => {
param.bounds.push(syn::TypeParamBound::Lifetime(bound));
}
syn::GenericParam::Const(_) => {}
}
param
}))
.collect();
syn::Generics {
params: params,
..generics.clone()
}
}
fn type_of_item(cont: &Container) -> syn::Type {
syn::Type::Path(syn::TypePath {
qself: None,
path: syn::Path {
leading_colon: None,
segments: vec![syn::PathSegment {
ident: cont.ident,
arguments: syn::PathArguments::AngleBracketed(
syn::AngleBracketedGenericArguments {
colon2_token: None,
lt_token: Default::default(),
args: cont.generics
.params
.iter()
.map(|param| match *param {
syn::GenericParam::Type(ref param) => {
syn::GenericArgument::Type(syn::Type::Path(syn::TypePath {
qself: None,
path: param.ident.into(),
}))
}
syn::GenericParam::Lifetime(ref param) => {
syn::GenericArgument::Lifetime(param.lifetime)
}
syn::GenericParam::Const(_) => {
panic!("Serde does not support const generics yet");
}
})
.collect(),
gt_token: Default::default(),
},
),
}].into_iter()
.collect(),
},
})
}