Move specialization_graph definition in traits::types.

Author: cjgillot

src/librustc/traits/specialize/specialization_graph.rs

@@ -1,58 +1,11 @@
 use super::OverlapError;
 
-use crate::ich::{self, StableHashingContext};
 use crate::traits;
-use crate::ty::fast_reject::{self, SimplifiedType};
-use crate::ty::{self, TyCtxt, TypeFoldable};
-use rustc_data_structures::fx::FxHashMap;
-use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
-use rustc_hir::def_id::{DefId, DefIdMap};
-use syntax::ast::Ident;
-
-/// A per-trait graph of impls in specialization order. At the moment, this
-/// graph forms a tree rooted with the trait itself, with all other nodes
-/// representing impls, and parent-child relationships representing
-/// specializations.
-///
-/// The graph provides two key services:
-///
-/// - Construction. This implicitly checks for overlapping impls (i.e., impls
-///   that overlap but where neither specializes the other -- an artifact of the
-///   simple "chain" rule.
-///
-/// - Parent extraction. In particular, the graph can give you the *immediate*
-///   parents of a given specializing impl, which is needed for extracting
-///   default items amongst other things. In the simple "chain" rule, every impl
-///   has at most one parent.
-#[derive(RustcEncodable, RustcDecodable, HashStable)]
-pub struct Graph {
-    // All impls have a parent; the "root" impls have as their parent the `def_id`
-    // of the trait.
-    parent: DefIdMap<DefId>,
-
-    // The "root" impls are found by looking up the trait's def_id.
-    children: DefIdMap<Children>,
-}
+use rustc::ty::fast_reject::{self, SimplifiedType};
+use rustc::ty::{self, TyCtxt, TypeFoldable};
+use rustc_hir::def_id::DefId;
 
-/// Children of a given impl, grouped into blanket/non-blanket varieties as is
-/// done in `TraitDef`.
-#[derive(Default, RustcEncodable, RustcDecodable)]
-struct Children {
-    // Impls of a trait (or specializations of a given impl). To allow for
-    // quicker lookup, the impls are indexed by a simplified version of their
-    // `Self` type: impls with a simplifiable `Self` are stored in
-    // `nonblanket_impls` keyed by it, while all other impls are stored in
-    // `blanket_impls`.
-    //
-    // A similar division is used within `TraitDef`, but the lists there collect
-    // together *all* the impls for a trait, and are populated prior to building
-    // the specialization graph.
-    /// Impls of the trait.
-    nonblanket_impls: FxHashMap<fast_reject::SimplifiedType, Vec<DefId>>,
-
-    /// Blanket impls associated with the trait.
-    blanket_impls: Vec<DefId>,
-}
+pub use rustc::traits::types::specialization_graph::*;
 
 #[derive(Copy, Clone, Debug)]
 pub enum FutureCompatOverlapErrorKind {
@@ -269,10 +222,6 @@ where
 }
 
 impl<'tcx> Graph {
-    pub fn new() -> Graph {
-        Graph { parent: Default::default(), children: Default::default() }
-    }
-
     /// Insert a local impl into the specialization graph. If an existing impl
     /// conflicts with it (has overlap, but neither specializes the other),
     /// information about the area of overlap is returned in the `Err`.
@@ -383,145 +332,4 @@ impl<'tcx> Graph {
 
         self.children.entry(parent).or_default().insert_blindly(tcx, child);
     }
-
-    /// The parent of a given impl, which is the `DefId` of the trait when the
-    /// impl is a "specialization root".
-    pub fn parent(&self, child: DefId) -> DefId {
-        *self.parent.get(&child).unwrap_or_else(|| panic!("Failed to get parent for {:?}", child))
-    }
-}
-
-/// A node in the specialization graph is either an impl or a trait
-/// definition; either can serve as a source of item definitions.
-/// There is always exactly one trait definition node: the root.
-#[derive(Debug, Copy, Clone)]
-pub enum Node {
-    Impl(DefId),
-    Trait(DefId),
-}
-
-impl<'tcx> Node {
-    pub fn is_from_trait(&self) -> bool {
-        match *self {
-            Node::Trait(..) => true,
-            _ => false,
-        }
-    }
-
-    /// Iterate over the items defined directly by the given (impl or trait) node.
-    pub fn items(&self, tcx: TyCtxt<'tcx>) -> ty::AssocItemsIterator<'tcx> {
-        tcx.associated_items(self.def_id())
-    }
-
-    /// Finds an associated item defined in this node.
-    ///
-    /// If this returns `None`, the item can potentially still be found in
-    /// parents of this node.
-    pub fn item(
-        &self,
-        tcx: TyCtxt<'tcx>,
-        trait_item_name: Ident,
-        trait_item_kind: ty::AssocKind,
-        trait_def_id: DefId,
-    ) -> Option<ty::AssocItem> {
-        use crate::ty::AssocKind::*;
-
-        tcx.associated_items(self.def_id()).find(move |impl_item| {
-            match (trait_item_kind, impl_item.kind) {
-                | (Const, Const)
-                | (Method, Method)
-                | (Type, Type)
-                | (Type, OpaqueTy)  // assoc. types can be made opaque in impls
-                => tcx.hygienic_eq(impl_item.ident, trait_item_name, trait_def_id),
-
-                | (Const, _)
-                | (Method, _)
-                | (Type, _)
-                | (OpaqueTy, _)
-                => false,
-            }
-        })
-    }
-
-    pub fn def_id(&self) -> DefId {
-        match *self {
-            Node::Impl(did) => did,
-            Node::Trait(did) => did,
-        }
-    }
-}
-
-#[derive(Copy, Clone)]
-pub struct Ancestors<'tcx> {
-    trait_def_id: DefId,
-    specialization_graph: &'tcx Graph,
-    current_source: Option<Node>,
-}
-
-impl Iterator for Ancestors<'_> {
-    type Item = Node;
-    fn next(&mut self) -> Option<Node> {
-        let cur = self.current_source.take();
-        if let Some(Node::Impl(cur_impl)) = cur {
-            let parent = self.specialization_graph.parent(cur_impl);
-
-            self.current_source = if parent == self.trait_def_id {
-                Some(Node::Trait(parent))
-            } else {
-                Some(Node::Impl(parent))
-            };
-        }
-        cur
-    }
-}
-
-pub struct NodeItem<T> {
-    pub node: Node,
-    pub item: T,
-}
-
-impl<T> NodeItem<T> {
-    pub fn map<U, F: FnOnce(T) -> U>(self, f: F) -> NodeItem<U> {
-        NodeItem { node: self.node, item: f(self.item) }
-    }
-}
-
-impl<'tcx> Ancestors<'tcx> {
-    /// Finds the bottom-most (ie. most specialized) definition of an associated
-    /// item.
-    pub fn leaf_def(
-        mut self,
-        tcx: TyCtxt<'tcx>,
-        trait_item_name: Ident,
-        trait_item_kind: ty::AssocKind,
-    ) -> Option<NodeItem<ty::AssocItem>> {
-        let trait_def_id = self.trait_def_id;
-        self.find_map(|node| {
-            node.item(tcx, trait_item_name, trait_item_kind, trait_def_id)
-                .map(|item| NodeItem { node, item })
-        })
-    }
-}
-
-/// Walk up the specialization ancestors of a given impl, starting with that
-/// impl itself.
-pub fn ancestors(
-    tcx: TyCtxt<'tcx>,
-    trait_def_id: DefId,
-    start_from_impl: DefId,
-) -> Ancestors<'tcx> {
-    let specialization_graph = tcx.specialization_graph_of(trait_def_id);
-    Ancestors {
-        trait_def_id,
-        specialization_graph,
-        current_source: Some(Node::Impl(start_from_impl)),
-    }
-}
-
-impl<'a> HashStable<StableHashingContext<'a>> for Children {
-    fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
-        let Children { ref nonblanket_impls, ref blanket_impls } = *self;
-
-        ich::hash_stable_trait_impls(hcx, hasher, blanket_impls, nonblanket_impls);
-    }
 }

src/librustc/traits/types/mod.rs

@@ -4,6 +4,7 @@
 
 pub mod query;
 pub mod select;
+pub mod specialization_graph;
 mod structural_impls;
 
 use crate::mir::interpret::ErrorHandled;