Move crates under a sub folder to clean up the code

crates/milli/src/heed_codec/facet/mod.rs

@@ -0,0 +1,123 @@
+mod field_doc_id_facet_codec;
+mod ordered_f64_codec;
+
+use std::borrow::Cow;
+use std::convert::TryFrom;
+use std::marker::PhantomData;
+
+use heed::types::DecodeIgnore;
+use heed::{BoxedError, BytesDecode, BytesEncode};
+use roaring::RoaringBitmap;
+
+pub use self::field_doc_id_facet_codec::FieldDocIdFacetCodec;
+pub use self::ordered_f64_codec::OrderedF64Codec;
+use super::StrRefCodec;
+use crate::{CboRoaringBitmapCodec, BEU16};
+
+pub type FieldDocIdFacetF64Codec = FieldDocIdFacetCodec<OrderedF64Codec>;
+pub type FieldDocIdFacetStringCodec = FieldDocIdFacetCodec<StrRefCodec>;
+pub type FieldDocIdFacetIgnoreCodec = FieldDocIdFacetCodec<DecodeIgnore>;
+
+pub type FieldIdCodec = BEU16;
+
+/// Tries to split a slice in half at the given middle point,
+/// `None` if the slice is too short.
+pub fn try_split_at(slice: &[u8], mid: usize) -> Option<(&[u8], &[u8])> {
+    if slice.len() >= mid {
+        Some(slice.split_at(mid))
+    } else {
+        None
+    }
+}
+
+/// The key in the [`facet_id_string_docids` and `facet_id_f64_docids`][`Index::facet_id_string_docids`]
+/// databases.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)] // TODO: try removing PartialOrd and Ord
+pub struct FacetGroupKey<T> {
+    pub field_id: u16,
+    pub level: u8,
+    pub left_bound: T,
+}
+
+/// The value in the [`facet_id_string_docids` and `facet_id_f64_docids`][`Index::facet_id_string_docids`]
+/// databases.
+#[derive(Debug)]
+pub struct FacetGroupValue {
+    pub size: u8,
+    pub bitmap: RoaringBitmap,
+}
+
+#[derive(Debug)]
+pub struct FacetGroupLazyValue<'b> {
+    pub size: u8,
+    pub bitmap_bytes: &'b [u8],
+}
+
+pub struct FacetGroupKeyCodec<T> {
+    _phantom: PhantomData<T>,
+}
+
+impl<'a, T> heed::BytesEncode<'a> for FacetGroupKeyCodec<T>
+where
+    T: BytesEncode<'a>,
+    T::EItem: Sized,
+{
+    type EItem = FacetGroupKey<T::EItem>;
+
+    fn bytes_encode(value: &'a Self::EItem) -> Result<Cow<'a, [u8]>, BoxedError> {
+        let mut v = vec![];
+        v.extend_from_slice(&value.field_id.to_be_bytes());
+        v.extend_from_slice(&[value.level]);
+
+        let bound = T::bytes_encode(&value.left_bound)?;
+        v.extend_from_slice(&bound);
+
+        Ok(Cow::Owned(v))
+    }
+}
+
+impl<'a, T> heed::BytesDecode<'a> for FacetGroupKeyCodec<T>
+where
+    T: BytesDecode<'a>,
+{
+    type DItem = FacetGroupKey<T::DItem>;
+
+    fn bytes_decode(bytes: &'a [u8]) -> Result<Self::DItem, BoxedError> {
+        let fid = u16::from_be_bytes(<[u8; 2]>::try_from(&bytes[0..=1])?);
+        let level = bytes[2];
+        let bound = T::bytes_decode(&bytes[3..])?;
+        Ok(FacetGroupKey { field_id: fid, level, left_bound: bound })
+    }
+}
+
+pub struct FacetGroupValueCodec;
+
+impl<'a> heed::BytesEncode<'a> for FacetGroupValueCodec {
+    type EItem = FacetGroupValue;
+
+    fn bytes_encode(value: &'a Self::EItem) -> Result<Cow<'a, [u8]>, BoxedError> {
+        let mut v = vec![value.size];
+        CboRoaringBitmapCodec::serialize_into(&value.bitmap, &mut v);
+        Ok(Cow::Owned(v))
+    }
+}
+
+impl<'a> heed::BytesDecode<'a> for FacetGroupValueCodec {
+    type DItem = FacetGroupValue;
+
+    fn bytes_decode(bytes: &'a [u8]) -> Result<Self::DItem, BoxedError> {
+        let size = bytes[0];
+        let bitmap = CboRoaringBitmapCodec::deserialize_from(&bytes[1..])?;
+        Ok(FacetGroupValue { size, bitmap })
+    }
+}
+
+pub struct FacetGroupLazyValueCodec;
+
+impl<'a> heed::BytesDecode<'a> for FacetGroupLazyValueCodec {
+    type DItem = FacetGroupLazyValue<'a>;
+
+    fn bytes_decode(bytes: &'a [u8]) -> Result<Self::DItem, BoxedError> {
+        Ok(FacetGroupLazyValue { size: bytes[0], bitmap_bytes: &bytes[1..] })
+    }
+}