1 // Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 use hir::def_id::DefId;
13 use traits::specialization_graph;
15 use ty::fold::TypeFoldable;
20 /// A trait's definition with type information.
24 pub unsafety: hir::Unsafety,
26 /// If `true`, then this trait had the `#[rustc_paren_sugar]`
27 /// attribute, indicating that it should be used with `Foo()`
28 /// sugar. This is a temporary thing -- eventually any trait will
29 /// be usable with the sugar (or without it).
30 pub paren_sugar: bool,
32 pub has_default_impl: bool,
34 /// The ICH of this trait's DefPath, cached here so it doesn't have to be
35 /// recomputed all the time.
36 pub def_path_hash: Fingerprint,
39 // We don't store the list of impls in a flat list because each cached list of
40 // `relevant_impls_for` we would then duplicate all blanket impls. By keeping
41 // blanket and non-blanket impls separate, we can share the list of blanket
44 pub struct TraitImpls {
45 blanket_impls: Rc<Vec<DefId>>,
46 non_blanket_impls: Rc<Vec<DefId>>,
50 pub fn iter(&self) -> TraitImplsIter {
52 blanket_impls: self.blanket_impls.clone(),
53 non_blanket_impls: self.non_blanket_impls.clone(),
60 pub struct TraitImplsIter {
61 blanket_impls: Rc<Vec<DefId>>,
62 non_blanket_impls: Rc<Vec<DefId>>,
66 impl Iterator for TraitImplsIter {
69 fn next(&mut self) -> Option<DefId> {
70 if self.index < self.blanket_impls.len() {
71 let bi_index = self.index;
73 Some(self.blanket_impls[bi_index])
75 let nbi_index = self.index - self.blanket_impls.len();
76 if nbi_index < self.non_blanket_impls.len() {
78 Some(self.non_blanket_impls[nbi_index])
85 fn size_hint(&self) -> (usize, Option<usize>) {
86 let items_left = (self.blanket_impls.len() + self.non_blanket_impls.len()) - self.index;
87 (items_left, Some(items_left))
91 impl ExactSizeIterator for TraitImplsIter {}
93 impl<'a, 'gcx, 'tcx> TraitDef {
94 pub fn new(def_id: DefId,
95 unsafety: hir::Unsafety,
97 has_default_impl: bool,
98 def_path_hash: Fingerprint)
109 pub fn ancestors(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>,
111 -> specialization_graph::Ancestors {
112 specialization_graph::ancestors(tcx, self.def_id, of_impl)
115 pub fn for_each_impl<F: FnMut(DefId)>(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, mut f: F) {
116 for impl_def_id in tcx.trait_impls_of(self.def_id).iter() {
121 /// Iterate over every impl that could possibly match the
122 /// self-type `self_ty`.
123 pub fn for_each_relevant_impl<F: FnMut(DefId)>(&self,
124 tcx: TyCtxt<'a, 'gcx, 'tcx>,
128 // simplify_type(.., false) basically replaces type parameters and
129 // projections with infer-variables. This is, of course, done on
130 // the impl trait-ref when it is instantiated, but not on the
131 // predicate trait-ref which is passed here.
133 // for example, if we match `S: Copy` against an impl like
134 // `impl<T:Copy> Copy for Option<T>`, we replace the type variable
135 // in `Option<T>` with an infer variable, to `Option<_>` (this
136 // doesn't actually change fast_reject output), but we don't
137 // replace `S` with anything - this impl of course can't be
138 // selected, and as there are hundreds of similar impls,
139 // considering them would significantly harm performance.
140 let relevant_impls = if let Some(simplified_self_ty) =
141 fast_reject::simplify_type(tcx, self_ty, true) {
142 tcx.relevant_trait_impls_for((self.def_id, simplified_self_ty))
144 tcx.trait_impls_of(self.def_id)
147 for impl_def_id in relevant_impls.iter() {
153 // Query provider for `trait_impls_of`.
154 pub(super) fn trait_impls_of_provider<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
157 let remote_impls = if trait_id.is_local() {
158 // Traits defined in the current crate can't have impls in upstream
159 // crates, so we don't bother querying the cstore.
162 tcx.sess.cstore.implementations_of_trait(Some(trait_id))
165 let mut blanket_impls = Vec::new();
166 let mut non_blanket_impls = Vec::new();
168 let local_impls = tcx.hir
169 .trait_impls(trait_id)
171 .map(|&node_id| tcx.hir.local_def_id(node_id));
173 for impl_def_id in local_impls.chain(remote_impls.into_iter()) {
174 let impl_self_ty = tcx.type_of(impl_def_id);
175 if impl_def_id.is_local() && impl_self_ty.references_error() {
179 if fast_reject::simplify_type(tcx, impl_self_ty, false).is_some() {
180 non_blanket_impls.push(impl_def_id);
182 blanket_impls.push(impl_def_id);
187 blanket_impls: Rc::new(blanket_impls),
188 non_blanket_impls: Rc::new(non_blanket_impls),
192 // Query provider for `relevant_trait_impls_for`.
193 pub(super) fn relevant_trait_impls_provider<'a, 'tcx>(
194 tcx: TyCtxt<'a, 'tcx, 'tcx>,
195 (trait_id, self_ty): (DefId, fast_reject::SimplifiedType))
198 let all_trait_impls = tcx.trait_impls_of(trait_id);
200 let relevant: Vec<DefId> = all_trait_impls
204 .filter(|&impl_def_id| {
205 let impl_self_ty = tcx.type_of(impl_def_id);
206 let impl_simple_self_ty = fast_reject::simplify_type(tcx,
209 impl_simple_self_ty == self_ty
213 if all_trait_impls.non_blanket_impls.len() == relevant.len() {
214 // If we didn't filter anything out, re-use the existing vec.
218 blanket_impls: all_trait_impls.blanket_impls.clone(),
219 non_blanket_impls: Rc::new(relevant),