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use arena::TypedArena;
use rustc::ty::{self, TyCtxt};
use std::fmt;
use std::rc::Rc;
use syntax::ast;
use rustc::hir;
use rustc::hir::itemlikevisit::ItemLikeVisitor;
use util::nodemap::NodeMap;
use self::VarianceTerm::*;
pub type VarianceTermPtr<'a> = &'a VarianceTerm<'a>;
use dep_graph::DepNode::ItemSignature as VarianceDepNode;
#[derive(Copy, Clone, Debug)]
pub struct InferredIndex(pub usize);
#[derive(Copy, Clone)]
pub enum VarianceTerm<'a> {
ConstantTerm(ty::Variance),
TransformTerm(VarianceTermPtr<'a>, VarianceTermPtr<'a>),
InferredTerm(InferredIndex),
}
impl<'a> fmt::Debug for VarianceTerm<'a> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match *self {
ConstantTerm(c1) => write!(f, "{:?}", c1),
TransformTerm(v1, v2) => write!(f, "({:?} \u{00D7} {:?})", v1, v2),
InferredTerm(id) => {
write!(f, "[{}]", {
let InferredIndex(i) = id;
i
})
}
}
}
}
pub struct TermsContext<'a, 'tcx: 'a> {
pub tcx: TyCtxt<'a, 'tcx, 'tcx>,
pub arena: &'a TypedArena<VarianceTerm<'a>>,
pub empty_variances: Rc<Vec<ty::Variance>>,
pub lang_items: Vec<(ast::NodeId, Vec<ty::Variance>)>,
pub inferred_map: NodeMap<InferredIndex>,
pub inferred_infos: Vec<InferredInfo<'a>>,
}
pub struct InferredInfo<'a> {
pub item_id: ast::NodeId,
pub index: usize,
pub param_id: ast::NodeId,
pub term: VarianceTermPtr<'a>,
pub initial_variance: ty::Variance,
}
pub fn determine_parameters_to_be_inferred<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
arena: &'a mut TypedArena<VarianceTerm<'a>>)
-> TermsContext<'a, 'tcx> {
let mut terms_cx = TermsContext {
tcx: tcx,
arena: arena,
inferred_map: NodeMap(),
inferred_infos: Vec::new(),
lang_items: lang_items(tcx),
empty_variances: Rc::new(vec![]),
};
tcx.visit_all_item_likes_in_krate(|def_id| VarianceDepNode(def_id), &mut terms_cx);
terms_cx
}
fn lang_items(tcx: TyCtxt) -> Vec<(ast::NodeId, Vec<ty::Variance>)> {
let all = vec![
(tcx.lang_items.phantom_data(), vec![ty::Covariant]),
(tcx.lang_items.unsafe_cell_type(), vec![ty::Invariant]),
(tcx.lang_items.covariant_type(), vec![ty::Covariant]),
(tcx.lang_items.contravariant_type(), vec![ty::Contravariant]),
(tcx.lang_items.invariant_type(), vec![ty::Invariant]),
(tcx.lang_items.covariant_lifetime(), vec![ty::Covariant]),
(tcx.lang_items.contravariant_lifetime(), vec![ty::Contravariant]),
(tcx.lang_items.invariant_lifetime(), vec![ty::Invariant]),
];
all.into_iter()
.filter(|&(ref d,_)| d.is_some())
.map(|(d, v)| (d.unwrap(), v))
.filter_map(|(d, v)| tcx.hir.as_local_node_id(d).map(|n| (n, v)))
.collect()
}
impl<'a, 'tcx> TermsContext<'a, 'tcx> {
fn add_inferreds_for_item(&mut self,
item_id: ast::NodeId,
has_self: bool,
generics: &hir::Generics) {
let inferreds_on_entry = self.num_inferred();
if has_self {
self.add_inferred(item_id, 0, item_id);
}
for (i, p) in generics.lifetimes.iter().enumerate() {
let id = p.lifetime.id;
let i = has_self as usize + i;
self.add_inferred(item_id, i, id);
}
for (i, p) in generics.ty_params.iter().enumerate() {
let i = has_self as usize + generics.lifetimes.len() + i;
self.add_inferred(item_id, i, p.id);
}
if self.num_inferred() == inferreds_on_entry {
let item_def_id = self.tcx.hir.local_def_id(item_id);
self.tcx.maps.variances
.borrow_mut()
.insert(item_def_id, self.empty_variances.clone());
}
}
fn add_inferred(&mut self, item_id: ast::NodeId, index: usize, param_id: ast::NodeId) {
let inf_index = InferredIndex(self.inferred_infos.len());
let term = self.arena.alloc(InferredTerm(inf_index));
let initial_variance = self.pick_initial_variance(item_id, index);
self.inferred_infos.push(InferredInfo {
item_id: item_id,
index: index,
param_id: param_id,
term: term,
initial_variance: initial_variance,
});
let newly_added = self.inferred_map.insert(param_id, inf_index).is_none();
assert!(newly_added);
debug!("add_inferred(item_path={}, \
item_id={}, \
index={}, \
param_id={}, \
inf_index={:?}, \
initial_variance={:?})",
self.tcx.item_path_str(self.tcx.hir.local_def_id(item_id)),
item_id,
index,
param_id,
inf_index,
initial_variance);
}
fn pick_initial_variance(&self, item_id: ast::NodeId, index: usize) -> ty::Variance {
match self.lang_items.iter().find(|&&(n, _)| n == item_id) {
Some(&(_, ref variances)) => variances[index],
None => ty::Bivariant,
}
}
pub fn num_inferred(&self) -> usize {
self.inferred_infos.len()
}
}
impl<'a, 'tcx, 'v> ItemLikeVisitor<'v> for TermsContext<'a, 'tcx> {
fn visit_item(&mut self, item: &hir::Item) {
debug!("add_inferreds for item {}",
self.tcx.hir.node_to_string(item.id));
match item.node {
hir::ItemEnum(_, ref generics) |
hir::ItemStruct(_, ref generics) |
hir::ItemUnion(_, ref generics) => {
self.add_inferreds_for_item(item.id, false, generics);
}
hir::ItemTrait(_, ref generics, ..) => {
self.add_inferreds_for_item(item.id, true, generics);
}
hir::ItemExternCrate(_) |
hir::ItemUse(..) |
hir::ItemDefaultImpl(..) |
hir::ItemImpl(..) |
hir::ItemStatic(..) |
hir::ItemConst(..) |
hir::ItemFn(..) |
hir::ItemMod(..) |
hir::ItemForeignMod(..) |
hir::ItemTy(..) => {}
}
}
fn visit_trait_item(&mut self, _trait_item: &hir::TraitItem) {
}
fn visit_impl_item(&mut self, _impl_item: &hir::ImplItem) {
}
}