// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

use cstore;
use common;
use decoder;
use encoder;
use loader;

use middle::cstore::{InlinedItem, CrateStore, CrateSource, ChildItem, ExternCrate, DefLike};
use middle::cstore::{NativeLibraryKind, LinkMeta, LinkagePreference};
use rustc::hir::def;
use middle::lang_items;
use rustc::ty::{self, Ty, TyCtxt, VariantKind};
use rustc::hir::def_id::{DefId, DefIndex, CRATE_DEF_INDEX};

use rustc::dep_graph::DepNode;
use rustc::hir::map as hir_map;
use rustc::hir::map::DefKey;
use rustc::mir::repr::Mir;
use rustc::mir::mir_map::MirMap;
use rustc::util::nodemap::{FnvHashMap, NodeSet, DefIdMap};
use rustc::session::config::PanicStrategy;

use std::cell::RefCell;
use std::rc::Rc;
use std::path::PathBuf;
use syntax::ast;
use syntax::attr;
use syntax::parse::token;
use rustc::hir::svh::Svh;
use rustc_back::target::Target;
use rustc::hir;

impl<'tcx> CrateStore<'tcx> for cstore::CStore {
    fn stability(&self, def: DefId) -> Option<attr::Stability> {
        self.dep_graph.read(DepNode::MetaData(def));
        let cdata = self.get_crate_data(def.krate);
        decoder::get_stability(&cdata, def.index)
    }

    fn deprecation(&self, def: DefId) -> Option<attr::Deprecation> {
        self.dep_graph.read(DepNode::MetaData(def));
        let cdata = self.get_crate_data(def.krate);
        decoder::get_deprecation(&cdata, def.index)
    }

    fn visibility(&self, def: DefId) -> ty::Visibility {
        self.dep_graph.read(DepNode::MetaData(def));
        let cdata = self.get_crate_data(def.krate);
        decoder::get_visibility(&cdata, def.index)
    }

    fn closure_kind(&self, def_id: DefId) -> ty::ClosureKind
    {
        assert!(!def_id.is_local());
        self.dep_graph.read(DepNode::MetaData(def_id));
        let cdata = self.get_crate_data(def_id.krate);
        decoder::closure_kind(&cdata, def_id.index)
    }

    fn closure_ty<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> ty::ClosureTy<'tcx> {
        assert!(!def_id.is_local());
        self.dep_graph.read(DepNode::MetaData(def_id));
        let cdata = self.get_crate_data(def_id.krate);
        decoder::closure_ty(&cdata, def_id.index, tcx)
    }

    fn item_variances(&self, def: DefId) -> ty::ItemVariances {
        self.dep_graph.read(DepNode::MetaData(def));
        let cdata = self.get_crate_data(def.krate);
        decoder::get_item_variances(&cdata, def.index)
    }

    fn repr_attrs(&self, def: DefId) -> Vec<attr::ReprAttr> {
        self.dep_graph.read(DepNode::MetaData(def));
        let cdata = self.get_crate_data(def.krate);
        decoder::get_repr_attrs(&cdata, def.index)
    }

    fn item_type<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, def: DefId)
                     -> ty::TypeScheme<'tcx>
    {
        self.dep_graph.read(DepNode::MetaData(def));
        let cdata = self.get_crate_data(def.krate);
        decoder::get_type(&cdata, def.index, tcx)
    }

    fn item_predicates<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, def: DefId)
                           -> ty::GenericPredicates<'tcx>
    {
        self.dep_graph.read(DepNode::MetaData(def));
        let cdata = self.get_crate_data(def.krate);
        decoder::get_predicates(&cdata, def.index, tcx)
    }

    fn item_super_predicates<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, def: DefId)
                                 -> ty::GenericPredicates<'tcx>
    {
        self.dep_graph.read(DepNode::MetaData(def));
        let cdata = self.get_crate_data(def.krate);
        decoder::get_super_predicates(&cdata, def.index, tcx)
    }

    fn item_attrs(&self, def_id: DefId) -> Vec<ast::Attribute>
    {
        self.dep_graph.read(DepNode::MetaData(def_id));
        let cdata = self.get_crate_data(def_id.krate);
        decoder::get_item_attrs(&cdata, def_id.index)
    }

    fn trait_def<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, def: DefId) -> ty::TraitDef<'tcx>
    {
        self.dep_graph.read(DepNode::MetaData(def));
        let cdata = self.get_crate_data(def.krate);
        decoder::get_trait_def(&cdata, def.index, tcx)
    }

    fn adt_def<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, def: DefId) -> ty::AdtDefMaster<'tcx>
    {
        self.dep_graph.read(DepNode::MetaData(def));
        let cdata = self.get_crate_data(def.krate);
        decoder::get_adt_def(&cdata, def.index, tcx)
    }

    fn method_arg_names(&self, did: DefId) -> Vec<String>
    {
        self.dep_graph.read(DepNode::MetaData(did));
        let cdata = self.get_crate_data(did.krate);
        decoder::get_method_arg_names(&cdata, did.index)
    }

    fn item_name(&self, def: DefId) -> ast::Name {
        self.dep_graph.read(DepNode::MetaData(def));
        let cdata = self.get_crate_data(def.krate);
        decoder::get_item_name(&cdata, def.index)
    }

    fn opt_item_name(&self, def: DefId) -> Option<ast::Name> {
        self.dep_graph.read(DepNode::MetaData(def));
        let cdata = self.get_crate_data(def.krate);
        decoder::maybe_get_item_name(&cdata, def.index)
    }

    fn inherent_implementations_for_type(&self, def_id: DefId) -> Vec<DefId>
    {
        self.dep_graph.read(DepNode::MetaData(def_id));
        let mut result = vec![];
        let cdata = self.get_crate_data(def_id.krate);
        decoder::each_inherent_implementation_for_type(&cdata, def_id.index,
                                                       |iid| result.push(iid));
        result
    }

    fn implementations_of_trait(&self, def_id: DefId) -> Vec<DefId>
    {
        self.dep_graph.read(DepNode::MetaData(def_id));
        let mut result = vec![];
        self.iter_crate_data(|_, cdata| {
            decoder::each_implementation_for_trait(cdata, def_id, &mut |iid| {
                result.push(iid)
            })
        });
        result
    }

    fn provided_trait_methods<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, def: DefId)
                                  -> Vec<Rc<ty::Method<'tcx>>>
    {
        self.dep_graph.read(DepNode::MetaData(def));
        let cdata = self.get_crate_data(def.krate);
        decoder::get_provided_trait_methods(&cdata, def.index, tcx)
    }

    fn trait_item_def_ids(&self, def: DefId)
                          -> Vec<ty::ImplOrTraitItemId>
    {
        self.dep_graph.read(DepNode::MetaData(def));
        let cdata = self.get_crate_data(def.krate);
        decoder::get_trait_item_def_ids(&cdata, def.index)
    }

    fn impl_items(&self, impl_def_id: DefId) -> Vec<ty::ImplOrTraitItemId>
    {
        self.dep_graph.read(DepNode::MetaData(impl_def_id));
        let cdata = self.get_crate_data(impl_def_id.krate);
        decoder::get_impl_items(&cdata, impl_def_id.index)
    }

    fn impl_polarity(&self, def: DefId) -> Option<hir::ImplPolarity>
    {
        self.dep_graph.read(DepNode::MetaData(def));
        let cdata = self.get_crate_data(def.krate);
        decoder::get_impl_polarity(&cdata, def.index)
    }

    fn impl_trait_ref<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, def: DefId)
                          -> Option<ty::TraitRef<'tcx>>
    {
        self.dep_graph.read(DepNode::MetaData(def));
        let cdata = self.get_crate_data(def.krate);
        decoder::get_impl_trait(&cdata, def.index, tcx)
    }

    fn custom_coerce_unsized_kind(&self, def: DefId)
                                  -> Option<ty::adjustment::CustomCoerceUnsized>
    {
        self.dep_graph.read(DepNode::MetaData(def));
        let cdata = self.get_crate_data(def.krate);
        decoder::get_custom_coerce_unsized_kind(&cdata, def.index)
    }

    // FIXME: killme
    fn associated_consts<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, def: DefId)
                             -> Vec<Rc<ty::AssociatedConst<'tcx>>> {
        self.dep_graph.read(DepNode::MetaData(def));
        let cdata = self.get_crate_data(def.krate);
        decoder::get_associated_consts(&cdata, def.index, tcx)
    }

    fn impl_parent(&self, impl_def: DefId) -> Option<DefId> {
        self.dep_graph.read(DepNode::MetaData(impl_def));
        let cdata = self.get_crate_data(impl_def.krate);
        decoder::get_parent_impl(&*cdata, impl_def.index)
    }

    fn trait_of_item<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> Option<DefId>
    {
        self.dep_graph.read(DepNode::MetaData(def_id));
        let cdata = self.get_crate_data(def_id.krate);
        decoder::get_trait_of_item(&cdata, def_id.index, tcx)
    }

    fn impl_or_trait_item<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, def: DefId)
                              -> Option<ty::ImplOrTraitItem<'tcx>>
    {
        self.dep_graph.read(DepNode::MetaData(def));
        let cdata = self.get_crate_data(def.krate);
        decoder::get_impl_or_trait_item(&cdata, def.index, tcx)
    }

    fn is_const_fn(&self, did: DefId) -> bool
    {
        self.dep_graph.read(DepNode::MetaData(did));
        let cdata = self.get_crate_data(did.krate);
        decoder::is_const_fn(&cdata, did.index)
    }

    fn is_defaulted_trait(&self, trait_def_id: DefId) -> bool
    {
        self.dep_graph.read(DepNode::MetaData(trait_def_id));
        let cdata = self.get_crate_data(trait_def_id.krate);
        decoder::is_defaulted_trait(&cdata, trait_def_id.index)
    }

    fn is_impl(&self, did: DefId) -> bool
    {
        self.dep_graph.read(DepNode::MetaData(did));
        let cdata = self.get_crate_data(did.krate);
        decoder::is_impl(&cdata, did.index)
    }

    fn is_default_impl(&self, impl_did: DefId) -> bool {
        self.dep_graph.read(DepNode::MetaData(impl_did));
        let cdata = self.get_crate_data(impl_did.krate);
        decoder::is_default_impl(&cdata, impl_did.index)
    }

    fn is_extern_item<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, did: DefId) -> bool {
        self.dep_graph.read(DepNode::MetaData(did));
        let cdata = self.get_crate_data(did.krate);
        decoder::is_extern_item(&cdata, did.index, tcx)
    }

    fn is_foreign_item(&self, did: DefId) -> bool {
        let cdata = self.get_crate_data(did.krate);
        decoder::is_foreign_item(&cdata, did.index)
    }

    fn is_static_method(&self, def: DefId) -> bool
    {
        self.dep_graph.read(DepNode::MetaData(def));
        let cdata = self.get_crate_data(def.krate);
        decoder::is_static_method(&cdata, def.index)
    }

    fn is_statically_included_foreign_item(&self, id: ast::NodeId) -> bool
    {
        self.do_is_statically_included_foreign_item(id)
    }

    fn is_typedef(&self, did: DefId) -> bool {
        self.dep_graph.read(DepNode::MetaData(did));
        let cdata = self.get_crate_data(did.krate);
        decoder::is_typedef(&cdata, did.index)
    }

    fn dylib_dependency_formats(&self, cnum: ast::CrateNum)
                                -> Vec<(ast::CrateNum, LinkagePreference)>
    {
        let cdata = self.get_crate_data(cnum);
        decoder::get_dylib_dependency_formats(&cdata)
    }

    fn lang_items(&self, cnum: ast::CrateNum) -> Vec<(DefIndex, usize)>
    {
        let mut result = vec![];
        let crate_data = self.get_crate_data(cnum);
        decoder::each_lang_item(&crate_data, |did, lid| {
            result.push((did, lid)); true
        });
        result
    }

    fn missing_lang_items(&self, cnum: ast::CrateNum)
                          -> Vec<lang_items::LangItem>
    {
        let cdata = self.get_crate_data(cnum);
        decoder::get_missing_lang_items(&cdata)
    }

    fn is_staged_api(&self, cnum: ast::CrateNum) -> bool
    {
        self.get_crate_data(cnum).staged_api
    }

    fn is_explicitly_linked(&self, cnum: ast::CrateNum) -> bool
    {
        self.get_crate_data(cnum).explicitly_linked.get()
    }

    fn is_allocator(&self, cnum: ast::CrateNum) -> bool
    {
        self.get_crate_data(cnum).is_allocator()
    }

    fn is_panic_runtime(&self, cnum: ast::CrateNum) -> bool
    {
        self.get_crate_data(cnum).is_panic_runtime()
    }

    fn panic_strategy(&self, cnum: ast::CrateNum) -> PanicStrategy {
        self.get_crate_data(cnum).panic_strategy()
    }

    fn crate_attrs(&self, cnum: ast::CrateNum) -> Vec<ast::Attribute>
    {
        decoder::get_crate_attributes(self.get_crate_data(cnum).data())
    }

    fn crate_name(&self, cnum: ast::CrateNum) -> token::InternedString
    {
        token::intern_and_get_ident(&self.get_crate_data(cnum).name[..])
    }

    fn original_crate_name(&self, cnum: ast::CrateNum) -> token::InternedString
    {
        token::intern_and_get_ident(&self.get_crate_data(cnum).name())
    }

    fn extern_crate(&self, cnum: ast::CrateNum) -> Option<ExternCrate>
    {
        self.get_crate_data(cnum).extern_crate.get()
    }

    fn crate_hash(&self, cnum: ast::CrateNum) -> Svh
    {
        let cdata = self.get_crate_data(cnum);
        decoder::get_crate_hash(cdata.data())
    }

    fn crate_disambiguator(&self, cnum: ast::CrateNum) -> token::InternedString
    {
        let cdata = self.get_crate_data(cnum);
        token::intern_and_get_ident(decoder::get_crate_disambiguator(cdata.data()))
    }

    fn crate_struct_field_attrs(&self, cnum: ast::CrateNum)
                                -> FnvHashMap<DefId, Vec<ast::Attribute>>
    {
        decoder::get_struct_field_attrs(&self.get_crate_data(cnum))
    }

    fn plugin_registrar_fn(&self, cnum: ast::CrateNum) -> Option<DefId>
    {
        let cdata = self.get_crate_data(cnum);
        decoder::get_plugin_registrar_fn(cdata.data()).map(|index| DefId {
            krate: cnum,
            index: index
        })
    }

    fn native_libraries(&self, cnum: ast::CrateNum) -> Vec<(NativeLibraryKind, String)>
    {
        let cdata = self.get_crate_data(cnum);
        decoder::get_native_libraries(&cdata)
    }

    fn reachable_ids(&self, cnum: ast::CrateNum) -> Vec<DefId>
    {
        let cdata = self.get_crate_data(cnum);
        decoder::get_reachable_ids(&cdata)
    }

    fn def_index_for_def_key(&self,
                             cnum: ast::CrateNum,
                             def: DefKey)
                             -> Option<DefIndex> {
        let cdata = self.get_crate_data(cnum);
        cdata.key_map.get(&def).cloned()
    }

    /// Returns the `DefKey` for a given `DefId`. This indicates the
    /// parent `DefId` as well as some idea of what kind of data the
    /// `DefId` refers to.
    fn def_key(&self, def: DefId) -> hir_map::DefKey {
        self.dep_graph.read(DepNode::MetaData(def));
        let cdata = self.get_crate_data(def.krate);
        decoder::def_key(&cdata, def.index)
    }

    fn relative_def_path(&self, def: DefId) -> hir_map::DefPath {
        self.dep_graph.read(DepNode::MetaData(def));
        let cdata = self.get_crate_data(def.krate);
        decoder::def_path(&cdata, def.index)
    }

    fn variant_kind(&self, def_id: DefId) -> Option<VariantKind> {
        self.dep_graph.read(DepNode::MetaData(def_id));
        let cdata = self.get_crate_data(def_id.krate);
        decoder::get_variant_kind(&cdata, def_id.index)
    }

    fn struct_ctor_def_id(&self, struct_def_id: DefId) -> Option<DefId>
    {
        self.dep_graph.read(DepNode::MetaData(struct_def_id));
        let cdata = self.get_crate_data(struct_def_id.krate);
        decoder::get_struct_ctor_def_id(&cdata, struct_def_id.index)
    }

    fn tuple_struct_definition_if_ctor(&self, did: DefId) -> Option<DefId>
    {
        self.dep_graph.read(DepNode::MetaData(did));
        let cdata = self.get_crate_data(did.krate);
        decoder::get_tuple_struct_definition_if_ctor(&cdata, did.index)
    }

    fn struct_field_names(&self, def: DefId) -> Vec<ast::Name>
    {
        self.dep_graph.read(DepNode::MetaData(def));
        let cdata = self.get_crate_data(def.krate);
        decoder::get_struct_field_names(&cdata, def.index)
    }

    fn item_children(&self, def_id: DefId) -> Vec<ChildItem>
    {
        self.dep_graph.read(DepNode::MetaData(def_id));
        let mut result = vec![];
        let crate_data = self.get_crate_data(def_id.krate);
        let get_crate_data = |cnum| self.get_crate_data(cnum);
        decoder::each_child_of_item(&crate_data, def_id.index, get_crate_data, |def, name, vis| {
            result.push(ChildItem { def: def, name: name, vis: vis });
        });
        result
    }

    fn crate_top_level_items(&self, cnum: ast::CrateNum) -> Vec<ChildItem>
    {
        let mut result = vec![];
        let crate_data = self.get_crate_data(cnum);
        let get_crate_data = |cnum| self.get_crate_data(cnum);
        decoder::each_top_level_item_of_crate(&crate_data, get_crate_data, |def, name, vis| {
            result.push(ChildItem { def: def, name: name, vis: vis });
        });
        result
    }

    fn maybe_get_item_ast<'a>(&'tcx self,
                              tcx: TyCtxt<'a, 'tcx, 'tcx>,
                              def_id: DefId)
                              -> Option<(&'tcx InlinedItem, ast::NodeId)>
    {
        self.dep_graph.read(DepNode::MetaData(def_id));

        match self.inlined_item_cache.borrow().get(&def_id) {
            Some(&None) => {
                return None; // Not inlinable
            }
            Some(&Some(ref cached_inlined_item)) => {
                // Already inline
                debug!("maybe_get_item_ast({}): already inline as node id {}",
                          tcx.item_path_str(def_id), cached_inlined_item.item_id);
                return Some((tcx.map.expect_inlined_item(cached_inlined_item.inlined_root),
                             cached_inlined_item.item_id));
            }
            None => {
                // Not seen yet
            }
        }

        debug!("maybe_get_item_ast({}): inlining item", tcx.item_path_str(def_id));

        let cdata = self.get_crate_data(def_id.krate);
        let inlined = decoder::maybe_get_item_ast(&cdata, tcx, def_id.index);

        let cache_inlined_item = |original_def_id, inlined_item_id, inlined_root_node_id| {
            let cache_entry = cstore::CachedInlinedItem {
                inlined_root: inlined_root_node_id,
                item_id: inlined_item_id,
            };
            self.inlined_item_cache
                .borrow_mut()
                .insert(original_def_id, Some(cache_entry));
            self.defid_for_inlined_node
                .borrow_mut()
                .insert(inlined_item_id, original_def_id);
        };

        let find_inlined_item_root = |inlined_item_id| {
            let mut node = inlined_item_id;
            let mut path = Vec::with_capacity(10);

            // If we can't find the inline root after a thousand hops, we can
            // be pretty sure there's something wrong with the HIR map.
            for _ in 0 .. 1000 {
                path.push(node);
                let parent_node = tcx.map.get_parent_node(node);
                if parent_node == node {
                    return node;
                }
                node = parent_node;
            }
            bug!("cycle in HIR map parent chain")
        };

        match inlined {
            decoder::FoundAst::NotFound => {
                self.inlined_item_cache
                    .borrow_mut()
                    .insert(def_id, None);
            }
            decoder::FoundAst::Found(&InlinedItem::Item(ref item)) => {
                let inlined_root_node_id = find_inlined_item_root(item.id);
                cache_inlined_item(def_id, item.id, inlined_root_node_id);
            }
            decoder::FoundAst::Found(&InlinedItem::Foreign(ref item)) => {
                let inlined_root_node_id = find_inlined_item_root(item.id);
                cache_inlined_item(def_id, item.id, inlined_root_node_id);
            }
            decoder::FoundAst::FoundParent(parent_did, item) => {
                let inlined_root_node_id = find_inlined_item_root(item.id);
                cache_inlined_item(parent_did, item.id, inlined_root_node_id);

                match item.node {
                    hir::ItemEnum(ref ast_def, _) => {
                        let ast_vs = &ast_def.variants;
                        let ty_vs = &tcx.lookup_adt_def(parent_did).variants;
                        assert_eq!(ast_vs.len(), ty_vs.len());
                        for (ast_v, ty_v) in ast_vs.iter().zip(ty_vs.iter()) {
                            cache_inlined_item(ty_v.did,
                                               ast_v.node.data.id(),
                                               inlined_root_node_id);
                        }
                    }
                    hir::ItemStruct(ref struct_def, _) => {
                        if struct_def.is_struct() {
                            bug!("instantiate_inline: called on a non-tuple struct")
                        } else {
                            cache_inlined_item(def_id,
                                               struct_def.id(),
                                               inlined_root_node_id);
                        }
                    }
                    _ => bug!("instantiate_inline: item has a \
                               non-enum, non-struct parent")
                }
            }
            decoder::FoundAst::Found(&InlinedItem::TraitItem(_, ref trait_item)) => {
                let inlined_root_node_id = find_inlined_item_root(trait_item.id);
                cache_inlined_item(def_id, trait_item.id, inlined_root_node_id);

                // Associated consts already have to be evaluated in `typeck`, so
                // the logic to do that already exists in `middle`. In order to
                // reuse that code, it needs to be able to look up the traits for
                // inlined items.
                let ty_trait_item = tcx.impl_or_trait_item(def_id).clone();
                let trait_item_def_id = tcx.map.local_def_id(trait_item.id);
                tcx.impl_or_trait_items.borrow_mut()
                   .insert(trait_item_def_id, ty_trait_item);
            }
            decoder::FoundAst::Found(&InlinedItem::ImplItem(_, ref impl_item)) => {
                let inlined_root_node_id = find_inlined_item_root(impl_item.id);
                cache_inlined_item(def_id, impl_item.id, inlined_root_node_id);
            }
        }

        // We can be sure to hit the cache now
        return self.maybe_get_item_ast(tcx, def_id);
    }

    fn local_node_for_inlined_defid(&'tcx self, def_id: DefId) -> Option<ast::NodeId> {
        assert!(!def_id.is_local());
        match self.inlined_item_cache.borrow().get(&def_id) {
            Some(&Some(ref cached_inlined_item)) => {
                Some(cached_inlined_item.item_id)
            }
            Some(&None) => {
                None
            }
            _ => {
                bug!("Trying to lookup inlined NodeId for unexpected item");
            }
        }
    }

    fn defid_for_inlined_node(&'tcx self, node_id: ast::NodeId) -> Option<DefId> {
        self.defid_for_inlined_node.borrow().get(&node_id).map(|x| *x)
    }

    fn maybe_get_item_mir<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, def: DefId)
                              -> Option<Mir<'tcx>> {
        self.dep_graph.read(DepNode::MetaData(def));
        let cdata = self.get_crate_data(def.krate);
        decoder::maybe_get_item_mir(&cdata, tcx, def.index)
    }

    fn is_item_mir_available(&self, def: DefId) -> bool {
        self.dep_graph.read(DepNode::MetaData(def));
        let cdata = self.get_crate_data(def.krate);
        decoder::is_item_mir_available(&cdata, def.index)
    }

    fn crates(&self) -> Vec<ast::CrateNum>
    {
        let mut result = vec![];
        self.iter_crate_data(|cnum, _| result.push(cnum));
        result
    }

    fn used_libraries(&self) -> Vec<(String, NativeLibraryKind)>
    {
        self.get_used_libraries().borrow().clone()
    }

    fn used_link_args(&self) -> Vec<String>
    {
        self.get_used_link_args().borrow().clone()
    }

    fn metadata_filename(&self) -> &str
    {
        loader::METADATA_FILENAME
    }

    fn metadata_section_name(&self, target: &Target) -> &str
    {
        loader::meta_section_name(target)
    }
    fn encode_type<'a>(&self,
                       tcx: TyCtxt<'a, 'tcx, 'tcx>,
                       ty: Ty<'tcx>,
                       def_id_to_string: for<'b> fn(TyCtxt<'b, 'tcx, 'tcx>, DefId) -> String)
                       -> Vec<u8>
    {
        encoder::encoded_ty(tcx, ty, def_id_to_string)
    }

    fn used_crates(&self, prefer: LinkagePreference) -> Vec<(ast::CrateNum, Option<PathBuf>)>
    {
        self.do_get_used_crates(prefer)
    }

    fn used_crate_source(&self, cnum: ast::CrateNum) -> CrateSource
    {
        self.opt_used_crate_source(cnum).unwrap()
    }

    fn extern_mod_stmt_cnum(&self, emod_id: ast::NodeId) -> Option<ast::CrateNum>
    {
        self.do_extern_mod_stmt_cnum(emod_id)
    }

    fn encode_metadata<'a>(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>,
                           reexports: &def::ExportMap,
                           link_meta: &LinkMeta,
                           reachable: &NodeSet,
                           mir_map: &MirMap<'tcx>,
                           krate: &hir::Crate) -> Vec<u8>
    {
        let ecx = encoder::EncodeContext {
            diag: tcx.sess.diagnostic(),
            tcx: tcx,
            reexports: reexports,
            link_meta: link_meta,
            cstore: self,
            reachable: reachable,
            mir_map: mir_map,
            type_abbrevs: RefCell::new(FnvHashMap()),
        };
        encoder::encode_metadata(ecx, krate)

    }

    fn metadata_encoding_version(&self) -> &[u8]
    {
        common::metadata_encoding_version
    }

    /// Returns a map from a sufficiently visible external item (i.e. an external item that is
    /// visible from at least one local module) to a sufficiently visible parent (considering
    /// modules that re-export the external item to be parents).
    fn visible_parent_map<'a>(&'a self) -> ::std::cell::RefMut<'a, DefIdMap<DefId>> {
        let mut visible_parent_map = self.visible_parent_map.borrow_mut();
        if !visible_parent_map.is_empty() { return visible_parent_map; }

        use rustc::middle::cstore::ChildItem;
        use std::collections::vec_deque::VecDeque;
        use std::collections::hash_map::Entry;
        for cnum in 1 .. self.next_crate_num() {
            let cdata = self.get_crate_data(cnum);

            match cdata.extern_crate.get() {
                // Ignore crates without a corresponding local `extern crate` item.
                Some(extern_crate) if !extern_crate.direct => continue,
                _ => {},
            }

            let mut bfs_queue = &mut VecDeque::new();
            let mut add_child = |bfs_queue: &mut VecDeque<_>, child: ChildItem, parent: DefId| {
                let child = match child.def {
                    DefLike::DlDef(def) if child.vis == ty::Visibility::Public => def.def_id(),
                    _ => return,
                };

                match visible_parent_map.entry(child) {
                    Entry::Occupied(mut entry) => {
                        // If `child` is defined in crate `cnum`, ensure
                        // that it is mapped to a parent in `cnum`.
                        if child.krate == cnum && entry.get().krate != cnum {
                            entry.insert(parent);
                        }
                    }
                    Entry::Vacant(entry) => {
                        entry.insert(parent);
                        bfs_queue.push_back(child);
                    }
                }
            };

            let croot = DefId { krate: cnum, index: CRATE_DEF_INDEX };
            for child in self.crate_top_level_items(cnum) {
                add_child(bfs_queue, child, croot);
            }
            while let Some(def) = bfs_queue.pop_front() {
                for child in self.item_children(def) {
                    add_child(bfs_queue, child, def);
                }
            }
        }

        visible_parent_map
    }
}