--- /dev/null
+use crate::rmeta::DecodeContext;
+use crate::rmeta::EncodeContext;
+use crate::rmeta::MetadataBlob;
+use rustc_data_structures::owning_ref::OwningRef;
+use rustc_hir::def_path_hash_map::{Config as HashMapConfig, DefPathHashMap};
+use rustc_serialize::{opaque, Decodable, Decoder, Encodable, Encoder};
+use rustc_span::def_id::{DefIndex, DefPathHash};
+
+crate enum DefPathHashMapRef<'tcx> {
+ OwnedFromMetadata(odht::HashTable<HashMapConfig, OwningRef<MetadataBlob, [u8]>>),
+ BorrowedFromTcx(&'tcx DefPathHashMap),
+}
+
+impl DefPathHashMapRef<'tcx> {
+ #[inline]
+ pub fn def_path_hash_to_def_index(&self, def_path_hash: &DefPathHash) -> DefIndex {
+ match *self {
+ DefPathHashMapRef::OwnedFromMetadata(ref map) => map.get(def_path_hash).unwrap(),
+ DefPathHashMapRef::BorrowedFromTcx(_) => {
+ panic!("DefPathHashMap::BorrowedFromTcx variant only exists for serialization")
+ }
+ }
+ }
+}
+
+impl<'a, 'tcx> Encodable<EncodeContext<'a, 'tcx>> for DefPathHashMapRef<'tcx> {
+ fn encode(&self, e: &mut EncodeContext<'a, 'tcx>) -> opaque::EncodeResult {
+ match *self {
+ DefPathHashMapRef::BorrowedFromTcx(def_path_hash_map) => {
+ let bytes = def_path_hash_map.raw_bytes();
+ e.emit_usize(bytes.len())?;
+ e.emit_raw_bytes(bytes)
+ }
+ DefPathHashMapRef::OwnedFromMetadata(_) => {
+ panic!("DefPathHashMap::OwnedFromMetadata variant only exists for deserialization")
+ }
+ }
+ }
+}
+
+impl<'a, 'tcx> Decodable<DecodeContext<'a, 'tcx>> for DefPathHashMapRef<'static> {
+ fn decode(d: &mut DecodeContext<'a, 'tcx>) -> Result<DefPathHashMapRef<'static>, String> {
+ // Import TyDecoder so we can access the DecodeContext::position() method
+ use crate::rustc_middle::ty::codec::TyDecoder;
+
+ let len = d.read_usize()?;
+ let pos = d.position();
+ let o = OwningRef::new(d.blob().clone()).map(|x| &x[pos..pos + len]);
+
+ // Although we already have the data we need via the OwningRef, we still need
+ // to advance the DecodeContext's position so it's in a valid state after
+ // the method. We use read_raw_bytes() for that.
+ let _ = d.read_raw_bytes(len);
+
+ let inner = odht::HashTable::from_raw_bytes(o).map_err(|e| format!("{}", e))?;
+ Ok(DefPathHashMapRef::OwnedFromMetadata(inner))
+ }
+}