Introduce the obkv heed codec

Cargo.lock

@@ -1021,6 +1021,7 @@ dependencies = [
  "log 0.4.11",
  "memmap",
  "near-proximity",
+ "obkv",
  "once_cell",
  "rayon",
  "ringtail",
@@ -1241,6 +1242,12 @@ version = "0.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b8f8bdf33df195859076e54ab11ee78a1b208382d3a26ec40d142ffc1ecc49ef"
 
+[[package]]
+name = "obkv"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ce30a214135d83e7250f2e8fad781f7cb987e3a3f1b4529712d891594bda311c"
+
 [[package]]
 name = "once_cell"
 version = "1.4.0"

Cargo.toml

@@ -21,6 +21,7 @@ levenshtein_automata = { version = "0.2.0", features = ["fst_automaton"] }
 linked-hash-map = "0.5.3"
 memmap = "0.7.0"
 near-proximity = { git = "https://github.com/Kerollmops/plane-sweep-proximity", rev = "6608205" }
+obkv = "0.1.0"
 once_cell = "1.4.0"
 rayon = "1.3.1"
 ringtail = "0.3.0"

src/heed_codec/mod.rs

@@ -2,6 +2,7 @@ mod beu32_str_codec;
 mod bo_roaring_bitmap_codec;
 mod cbo_roaring_bitmap_codec;
 mod csv_string_record_codec;
+mod obkv_codec;
 mod roaring_bitmap_codec;
 mod str_str_u8_codec;
 
@@ -9,5 +10,6 @@ pub use self::beu32_str_codec::BEU32StrCodec;
 pub use self::bo_roaring_bitmap_codec::BoRoaringBitmapCodec;
 pub use self::cbo_roaring_bitmap_codec::CboRoaringBitmapCodec;
 pub use self::csv_string_record_codec::CsvStringRecordCodec;
+pub use self::obkv_codec::ObkvCodec;
 pub use self::roaring_bitmap_codec::RoaringBitmapCodec;
 pub use self::str_str_u8_codec::StrStrU8Codec;

src/heed_codec/obkv_codec.rs

@@ -0,0 +1,20 @@
+use std::borrow::Cow;
+use obkv::{KvReader, KvWriter};
+
+pub struct ObkvCodec;
+
+impl<'a> heed::BytesDecode<'a> for ObkvCodec {
+    type DItem = KvReader<'a>;
+
+    fn bytes_decode(bytes: &'a [u8]) -> Option<Self::DItem> {
+        Some(KvReader::new(bytes))
+    }
+}
+
+impl heed::BytesEncode<'_> for ObkvCodec {
+    type EItem = KvWriter<Vec<u8>>;
+
+    fn bytes_encode(item: &Self::EItem) -> Option<Cow<[u8]>> {
+        item.clone().into_inner().map(Cow::Owned).ok()
+    }
+}