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use arena::TypedArena;
use rustc::ty::{self, TyCtxt};
use std::fmt;
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>;
#[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 lang_items: Vec<(ast::NodeId, Vec<ty::Variance>)>,
pub inferred_starts: NodeMap<InferredIndex>,
pub inferred_terms: Vec<VarianceTermPtr<'a>>,
}
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,
arena,
inferred_starts: NodeMap(),
inferred_terms: vec![],
lang_items: lang_items(tcx),
};
tcx.hir.krate().visit_all_item_likes(&mut terms_cx);
terms_cx
}
fn lang_items(tcx: TyCtxt) -> Vec<(ast::NodeId, Vec<ty::Variance>)> {
let lang_items = tcx.lang_items();
let all = vec![
(lang_items.phantom_data(), vec![ty::Covariant]),
(lang_items.unsafe_cell_type(), 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, id: ast::NodeId) {
let tcx = self.tcx;
let def_id = tcx.hir.local_def_id(id);
let count = tcx.generics_of(def_id).count();
if count == 0 {
return;
}
let start = self.inferred_terms.len();
let newly_added = self.inferred_starts.insert(id, InferredIndex(start)).is_none();
assert!(newly_added);
let arena = self.arena;
self.inferred_terms.extend((start..start+count).map(|i| {
&*arena.alloc(InferredTerm(InferredIndex(i)))
}));
}
}
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::ItemKind::Struct(ref struct_def, _) |
hir::ItemKind::Union(ref struct_def, _) => {
self.add_inferreds_for_item(item.id);
if let hir::VariantData::Tuple(..) = *struct_def {
self.add_inferreds_for_item(struct_def.id());
}
}
hir::ItemKind::Enum(ref enum_def, _) => {
self.add_inferreds_for_item(item.id);
for variant in &enum_def.variants {
if let hir::VariantData::Tuple(..) = variant.node.data {
self.add_inferreds_for_item(variant.node.data.id());
}
}
}
hir::ItemKind::Fn(..) => {
self.add_inferreds_for_item(item.id);
}
hir::ItemKind::ForeignMod(ref foreign_mod) => {
for foreign_item in &foreign_mod.items {
if let hir::ForeignItemKind::Fn(..) = foreign_item.node {
self.add_inferreds_for_item(foreign_item.id);
}
}
}
_ => {}
}
}
fn visit_trait_item(&mut self, trait_item: &hir::TraitItem) {
if let hir::TraitItemKind::Method(..) = trait_item.node {
self.add_inferreds_for_item(trait_item.id);
}
}
fn visit_impl_item(&mut self, impl_item: &hir::ImplItem) {
if let hir::ImplItemKind::Method(..) = impl_item.node {
self.add_inferreds_for_item(impl_item.id);
}
}
}