Merge pull request #105 from Kerollmops/custom-ranking-field-into-hashmap

Save the custom ranking field into an HashMap

src/database/mod.rs

@@ -1,3 +1,5 @@
+use crate::DocumentId;
+use crate::database::schema::SchemaAttr;
 use std::sync::Arc;
 use std::error::Error;
 use std::ffi::OsStr;
@@ -6,12 +8,13 @@ use std::path::{Path, PathBuf};
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::ops::{Deref, DerefMut};
 
-use crossbeam::atomic::ArcCell;
-use log::{info, error, warn};
-use rocksdb::rocksdb::{Writable, Snapshot};
 use rocksdb::rocksdb_options::{DBOptions, ColumnFamilyOptions};
+use rocksdb::rocksdb::{Writable, Snapshot};
 use rocksdb::{DB, MergeOperands};
+use crossbeam::atomic::ArcCell;
 use lockfree::map::Map;
+use hashbrown::HashMap;
+use log::{info, error, warn};
 
 pub use self::document_key::{DocumentKey, DocumentKeyAttr};
 pub use self::view::{DatabaseView, DocumentIter};
@@ -19,12 +22,17 @@ pub use self::update::Update;
 pub use self::serde::SerializerError;
 pub use self::schema::Schema;
 pub use self::index::Index;
+pub use self::number::{Number, ParseNumberError};
+
+pub type RankedMap = HashMap<(DocumentId, SchemaAttr), Number>;
 
 const DATA_INDEX:      &[u8] = b"data-index";
+const DATA_RANKED_MAP: &[u8] = b"data-ranked-map";
 const DATA_SCHEMA:     &[u8] = b"data-schema";
 
 pub mod schema;
 pub(crate) mod index;
+mod number;
 mod document_key;
 mod serde;
 mod update;
@@ -61,9 +69,16 @@ where D: Deref<Target=DB>
     Ok(index)
 }
 
-fn merge_indexes(key: &[u8], existing: Option<&[u8]>, operands: &mut MergeOperands) -> Vec<u8> {
+fn retrieve_data_ranked_map<D>(snapshot: &Snapshot<D>) -> Result<RankedMap, Box<Error>>
-    assert_eq!(key, DATA_INDEX, "The merge operator only supports \"data-index\" merging");
+where D: Deref<Target=DB>,
+{
+    match snapshot.get(DATA_RANKED_MAP)? {
+        Some(vector) => Ok(bincode::deserialize(&*vector)?),
+        None => Ok(HashMap::new()),
+    }
+}
 
+fn merge_indexes(existing: Option<&[u8]>, operands: &mut MergeOperands) -> Vec<u8> {
     let mut index: Option<Index> = None;
     for bytes in existing.into_iter().chain(operands) {
         let operand = Index::from_bytes(bytes.to_vec()).unwrap();
@@ -81,6 +96,28 @@ fn merge_indexes(key: &[u8], existing: Option<&[u8]>, operands: &mut MergeOperan
     bytes
 }
 
+fn merge_ranked_maps(existing: Option<&[u8]>, operands: &mut MergeOperands) -> Vec<u8> {
+    let mut ranked_map: Option<RankedMap> = None;
+    for bytes in existing.into_iter().chain(operands) {
+        let operand: RankedMap = bincode::deserialize(bytes).unwrap();
+        match ranked_map {
+            Some(ref mut ranked_map) => ranked_map.extend(operand),
+            None => { ranked_map.replace(operand); },
+        };
+    }
+
+    let ranked_map = ranked_map.unwrap_or_default();
+    bincode::serialize(&ranked_map).unwrap()
+}
+
+fn merge_operator(key: &[u8], existing: Option<&[u8]>, operands: &mut MergeOperands) -> Vec<u8> {
+    match key {
+        DATA_INDEX      => merge_indexes(existing, operands),
+        DATA_RANKED_MAP => merge_ranked_maps(existing, operands),
+        key             => panic!("The merge operator does not support merging {:?}", key),
+    }
+}
+
 pub struct IndexUpdate {
     index: String,
     update: Update,
@@ -103,14 +140,14 @@ impl DerefMut for IndexUpdate {
 struct DatabaseIndex {
     db: Arc<DB>,
 
-    // This view is updated each time the DB ingests an update
+    // This view is updated each time the DB ingests an update.
     view: ArcCell<DatabaseView<Arc<DB>>>,
 
-    // This path is the path to the mdb folder stored on disk
+    // The path of the mdb folder stored on disk.
     path: PathBuf,
 
     // must_die false by default, must be set as true when the Index is dropped.
-    // It's used to erase the folder saved on disk when the user request to delete an index
+    // It is used to erase the folder saved on disk when the user request to delete an index.
     must_die: AtomicBool,
 }
 
@@ -128,7 +165,7 @@ impl DatabaseIndex {
         // opts.error_if_exists(true); // FIXME pull request that
 
         let mut cf_opts = ColumnFamilyOptions::new();
-        cf_opts.add_merge_operator("data-index merge operator", merge_indexes);
+        cf_opts.add_merge_operator("data merge operator", merge_operator);
 
         let db = DB::open_cf(opts, &path_lossy, vec![("default", cf_opts)])?;
 
@@ -140,7 +177,6 @@ impl DatabaseIndex {
         let snapshot = Snapshot::new(db.clone());
         let view = ArcCell::new(Arc::new(DatabaseView::new(snapshot)?));
 
-
         Ok(DatabaseIndex {
             db: db,
             view: view,
@@ -156,7 +192,7 @@ impl DatabaseIndex {
         opts.create_if_missing(false);
 
         let mut cf_opts = ColumnFamilyOptions::new();
-        cf_opts.add_merge_operator("data-index merge operator", merge_indexes);
+        cf_opts.add_merge_operator("data merge operator", merge_operator);
 
         let db = DB::open_cf(opts, &path_lossy, vec![("default", cf_opts)])?;
 

src/database/number.rs

@@ -0,0 +1,98 @@
+use std::cmp::Ordering;
+use std::str::FromStr;
+use std::fmt;
+
+use serde_derive::{Serialize, Deserialize};
+
+#[derive(Serialize, Deserialize)]
+#[derive(Debug, Copy, Clone)]
+pub enum Number {
+    Unsigned(u64),
+    Signed(i64),
+    Float(f64),
+}
+
+impl FromStr for Number {
+    type Err = ParseNumberError;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        if let Ok(unsigned) = u64::from_str(s) {
+            return Ok(Number::Unsigned(unsigned))
+        }
+
+        if let Ok(signed) = i64::from_str(s) {
+            return Ok(Number::Signed(signed))
+        }
+
+        if let Ok(float) = f64::from_str(s) {
+            if float == 0.0 || float.is_normal() {
+                return Ok(Number::Float(float))
+            }
+        }
+
+        Err(ParseNumberError)
+    }
+}
+
+impl PartialOrd for Number {
+    fn partial_cmp(&self, other: &Number) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl Ord for Number {
+    fn cmp(&self, other: &Number) -> Ordering {
+        use Number::*;
+        match (self, other) {
+            (Unsigned(s), Unsigned(o)) => s.cmp(o),
+            (Unsigned(s), Signed(o)) => {
+                let s = i128::from(*s);
+                let o = i128::from(*o);
+                s.cmp(&o)
+            },
+            (Unsigned(s), Float(o)) => {
+                let s = *s as f64;
+                s.partial_cmp(&o).unwrap_or(Ordering::Equal)
+            },
+
+            (Signed(s), Unsigned(o)) => {
+                let s = i128::from(*s);
+                let o = i128::from(*o);
+                s.cmp(&o)
+            },
+            (Signed(s), Signed(o)) => s.cmp(o),
+            (Signed(s), Float(o)) => {
+                let s = *s as f64;
+                s.partial_cmp(o).unwrap_or(Ordering::Equal)
+            },
+
+            (Float(s), Unsigned(o)) => {
+                let o = *o as f64;
+                s.partial_cmp(&o).unwrap_or(Ordering::Equal)
+            },
+            (Float(s), Signed(o)) => {
+                let o = *o as f64;
+                s.partial_cmp(&o).unwrap_or(Ordering::Equal)
+            },
+            (Float(s), Float(o)) => {
+                s.partial_cmp(o).unwrap_or(Ordering::Equal)
+            },
+        }
+    }
+}
+
+impl PartialEq for Number {
+    fn eq(&self, other: &Number) -> bool {
+        self.cmp(other) == Ordering::Equal
+    }
+}
+
+impl Eq for Number { }
+
+pub struct ParseNumberError;
+
+impl fmt::Display for ParseNumberError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.write_str("can not parse number")
+    }
+}

src/database/schema.rs

@@ -13,8 +13,9 @@ use crate::database::serde::find_id::FindDocumentIdSerializer;
 use crate::database::serde::SerializerError;
 use crate::DocumentId;
 
-pub const STORED: SchemaProps = SchemaProps { stored: true, indexed: false };
+pub const STORED: SchemaProps  = SchemaProps { stored: true,  indexed: false, ranked: false };
-pub const INDEXED: SchemaProps = SchemaProps { stored: false, indexed: true };
+pub const INDEXED: SchemaProps = SchemaProps { stored: false, indexed: true,  ranked: false };
+pub const RANKED: SchemaProps  = SchemaProps { stored: false, indexed: false, ranked: true  };
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq, Serialize, Deserialize)]
 pub struct SchemaProps {
@@ -23,6 +24,9 @@ pub struct SchemaProps {
 
     #[serde(default)]
     indexed: bool,
+
+    #[serde(default)]
+    ranked: bool,
 }
 
 impl SchemaProps {
@@ -33,6 +37,10 @@ impl SchemaProps {
     pub fn is_indexed(self) -> bool {
         self.indexed
     }
+
+    pub fn is_ranked(self) -> bool {
+        self.ranked
+    }
 }
 
 impl BitOr for SchemaProps {
@@ -42,6 +50,7 @@ impl BitOr for SchemaProps {
         SchemaProps {
             stored: self.stored | other.stored,
             indexed: self.indexed | other.indexed,
+            ranked: self.ranked | other.ranked,
         }
     }
 }
@@ -185,7 +194,8 @@ impl Schema {
     }
 }
 
-#[derive(Debug, Copy, Clone, PartialOrd, Ord, PartialEq, Eq)]
+#[derive(Serialize, Deserialize)]
+#[derive(Debug, Copy, Clone, PartialOrd, Ord, PartialEq, Eq, Hash)]
 pub struct SchemaAttr(pub(crate) u16);
 
 impl SchemaAttr {

src/database/serde/mod.rs

@@ -17,6 +17,7 @@ macro_rules! forward_to_unserializable_type {
 
 pub mod find_id;
 pub mod key_to_string;
+pub mod value_to_number;
 pub mod serializer;
 pub mod indexer_serializer;
 pub mod deserializer;

src/database/serde/serializer.rs

@@ -5,6 +5,7 @@ use serde::ser;
 
 use crate::database::serde::indexer_serializer::IndexerSerializer;
 use crate::database::serde::key_to_string::KeyToStringSerializer;
+use crate::database::serde::value_to_number::ValueToNumberSerializer;
 use crate::database::update::DocumentUpdate;
 use crate::database::serde::SerializerError;
 use crate::tokenizer::TokenizerBuilder;
@@ -155,8 +156,8 @@ where B: TokenizerBuilder
     {
         Ok(StructSerializer {
             schema: self.schema,
-            update: self.update,
             document_id: self.document_id,
+            update: self.update,
             tokenizer_builder: self.tokenizer_builder,
             stop_words: self.stop_words,
         })
@@ -229,6 +230,10 @@ where B: TokenizerBuilder
                 };
                 value.serialize(serializer)?;
             }
+            if props.is_ranked() {
+                let number = value.serialize(ValueToNumberSerializer)?;
+                self.update.register_ranked_attribute(attr, number)?;
+            }
         }
 
         Ok(())
@@ -276,6 +281,10 @@ where B: TokenizerBuilder
                 };
                 value.serialize(serializer)?;
             }
+            if props.is_ranked() {
+                let integer = value.serialize(ValueToNumberSerializer)?;
+                self.update.register_ranked_attribute(attr, integer)?;
+            }
         }
 
         Ok(())

src/database/serde/value_to_number.rs

@@ -0,0 +1,176 @@
+use std::str::FromStr;
+
+use serde::Serialize;
+use serde::{ser, ser::Error};
+
+use crate::database::serde::SerializerError;
+use crate::database::Number;
+
+pub struct ValueToNumberSerializer;
+
+impl ser::Serializer for ValueToNumberSerializer {
+    type Ok = Number;
+    type Error = SerializerError;
+    type SerializeSeq = ser::Impossible<Self::Ok, Self::Error>;
+    type SerializeTuple = ser::Impossible<Self::Ok, Self::Error>;
+    type SerializeTupleStruct = ser::Impossible<Self::Ok, Self::Error>;
+    type SerializeTupleVariant = ser::Impossible<Self::Ok, Self::Error>;
+    type SerializeMap = ser::Impossible<Self::Ok, Self::Error>;
+    type SerializeStruct = ser::Impossible<Self::Ok, Self::Error>;
+    type SerializeStructVariant = ser::Impossible<Self::Ok, Self::Error>;
+
+    forward_to_unserializable_type! {
+        bool => serialize_bool,
+        char => serialize_char,
+    }
+
+    fn serialize_i8(self, value: i8) -> Result<Self::Ok, Self::Error> {
+        Ok(Number::Signed(value as i64))
+    }
+
+    fn serialize_i16(self, value: i16) -> Result<Self::Ok, Self::Error> {
+        Ok(Number::Signed(value as i64))
+    }
+
+    fn serialize_i32(self, value: i32) -> Result<Self::Ok, Self::Error> {
+        Ok(Number::Signed(value as i64))
+    }
+
+    fn serialize_i64(self, value: i64) -> Result<Self::Ok, Self::Error> {
+        Ok(Number::Signed(value as i64))
+    }
+
+    fn serialize_u8(self, value: u8) -> Result<Self::Ok, Self::Error> {
+        Ok(Number::Unsigned(value as u64))
+    }
+
+    fn serialize_u16(self, value: u16) -> Result<Self::Ok, Self::Error> {
+        Ok(Number::Unsigned(value as u64))
+    }
+
+    fn serialize_u32(self, value: u32) -> Result<Self::Ok, Self::Error> {
+        Ok(Number::Unsigned(value as u64))
+    }
+
+    fn serialize_u64(self, value: u64) -> Result<Self::Ok, Self::Error> {
+        Ok(Number::Unsigned(value as u64))
+    }
+
+    fn serialize_f32(self, value: f32) -> Result<Self::Ok, Self::Error> {
+        Ok(Number::Float(value as f64))
+    }
+
+    fn serialize_f64(self, value: f64) -> Result<Self::Ok, Self::Error> {
+        Ok(Number::Float(value))
+    }
+
+    fn serialize_str(self, value: &str) -> Result<Self::Ok, Self::Error> {
+        Number::from_str(value).map_err(SerializerError::custom)
+    }
+
+    fn serialize_bytes(self, _v: &[u8]) -> Result<Self::Ok, Self::Error> {
+        Err(SerializerError::UnserializableType { name: "&[u8]" })
+    }
+
+    fn serialize_none(self) -> Result<Self::Ok, Self::Error> {
+        Err(SerializerError::UnserializableType { name: "Option" })
+    }
+
+    fn serialize_some<T: ?Sized>(self, _value: &T) -> Result<Self::Ok, Self::Error>
+    where T: Serialize,
+    {
+        Err(SerializerError::UnserializableType { name: "Option" })
+    }
+
+    fn serialize_unit(self) -> Result<Self::Ok, Self::Error> {
+        Err(SerializerError::UnserializableType { name: "()" })
+    }
+
+    fn serialize_unit_struct(self, _name: &'static str) -> Result<Self::Ok, Self::Error> {
+        Err(SerializerError::UnserializableType { name: "unit struct" })
+    }
+
+    fn serialize_unit_variant(
+        self,
+        _name: &'static str,
+        _variant_index: u32,
+        _variant: &'static str
+    ) -> Result<Self::Ok, Self::Error>
+    {
+        Err(SerializerError::UnserializableType { name: "unit variant" })
+    }
+
+    fn serialize_newtype_struct<T: ?Sized>(
+        self,
+        _name: &'static str,
+        value: &T
+    ) -> Result<Self::Ok, Self::Error>
+    where T: Serialize,
+    {
+        value.serialize(self)
+    }
+
+    fn serialize_newtype_variant<T: ?Sized>(
+        self,
+        _name: &'static str,
+        _variant_index: u32,
+        _variant: &'static str,
+        _value: &T
+    ) -> Result<Self::Ok, Self::Error>
+    where T: Serialize,
+    {
+        Err(SerializerError::UnserializableType { name: "newtype variant" })
+    }
+
+    fn serialize_seq(self, _len: Option<usize>) -> Result<Self::SerializeSeq, Self::Error> {
+        Err(SerializerError::UnserializableType { name: "sequence" })
+    }
+
+    fn serialize_tuple(self, _len: usize) -> Result<Self::SerializeTuple, Self::Error> {
+        Err(SerializerError::UnserializableType { name: "tuple" })
+    }
+
+    fn serialize_tuple_struct(
+        self,
+        _name: &'static str,
+        _len: usize
+    ) -> Result<Self::SerializeTupleStruct, Self::Error>
+    {
+        Err(SerializerError::UnserializableType { name: "tuple struct" })
+    }
+
+    fn serialize_tuple_variant(
+        self,
+        _name: &'static str,
+        _variant_index: u32,
+        _variant: &'static str,
+        _len: usize
+    ) -> Result<Self::SerializeTupleVariant, Self::Error>
+    {
+        Err(SerializerError::UnserializableType { name: "tuple variant" })
+    }
+
+    fn serialize_map(self, _len: Option<usize>) -> Result<Self::SerializeMap, Self::Error> {
+        Err(SerializerError::UnserializableType { name: "map" })
+    }
+
+    fn serialize_struct(
+        self,
+        _name: &'static str,
+        _len: usize
+    ) -> Result<Self::SerializeStruct, Self::Error>
+    {
+        Err(SerializerError::UnserializableType { name: "struct" })
+    }
+
+    fn serialize_struct_variant(
+        self,
+        _name: &'static str,
+        _variant_index: u32,
+        _variant: &'static str,
+        _len: usize
+    ) -> Result<Self::SerializeStructVariant, Self::Error>
+    {
+        Err(SerializerError::UnserializableType { name: "struct variant" })
+    }
+}

src/database/update.rs

@@ -16,8 +16,9 @@ use crate::tokenizer::TokenizerBuilder;
 use crate::data::{DocIds, DocIndexes};
 use crate::database::schema::Schema;
 use crate::database::index::Index;
+use crate::database::{DATA_INDEX, DATA_RANKED_MAP};
+use crate::database::{RankedMap, Number};
 use crate::{DocumentId, DocIndex};
-use crate::database::DATA_INDEX;
 
 pub type Token = Vec<u8>; // TODO could be replaced by a SmallVec
 
@@ -78,6 +79,7 @@ use UpdateType::{Updated, Deleted};
 
 pub struct RawUpdateBuilder {
     documents_update: HashMap<DocumentId, UpdateType>,
+    documents_ranked_fields: RankedMap,
     indexed_words: BTreeMap<Token, Vec<DocIndex>>,
     batch: WriteBatch,
 }
@@ -86,6 +88,7 @@ impl RawUpdateBuilder {
     pub fn new() -> RawUpdateBuilder {
         RawUpdateBuilder {
             documents_update: HashMap::new(),
+            documents_ranked_fields: HashMap::new(),
             indexed_words: BTreeMap::new(),
             batch: WriteBatch::new(),
         }
@@ -137,9 +140,12 @@ impl RawUpdateBuilder {
         let index = Index { negative, positive };
 
         // write the data-index
-        let mut bytes = Vec::new();
+        let mut bytes_index = Vec::new();
-        index.write_to_bytes(&mut bytes);
+        index.write_to_bytes(&mut bytes_index);
-        self.batch.merge(DATA_INDEX, &bytes)?;
+        self.batch.merge(DATA_INDEX, &bytes_index)?;
+
+        let bytes_ranked_map = bincode::serialize(&self.documents_ranked_fields).unwrap();
+        self.batch.merge(DATA_RANKED_MAP, &bytes_ranked_map)?;
 
         Ok(self.batch)
     }
@@ -195,4 +201,23 @@ impl<'a> DocumentUpdate<'a> {
 
         Ok(())
     }
+
+    pub fn register_ranked_attribute(
+        &mut self,
+        attr: SchemaAttr,
+        number: Number,
+    ) -> Result<(), SerializerError>
+    {
+        use serde::ser::Error;
+
+        if let Deleted = self.inner.documents_update.entry(self.document_id).or_insert(Updated) {
+            return Err(SerializerError::custom(
+                "This document has already been deleted, ranked attributes cannot be added in the same update"
+            ));
+        }
+
+        self.inner.documents_ranked_fields.insert((self.document_id, attr), number);
+
+        Ok(())
+    }
 }

src/database/view.rs

@@ -7,12 +7,13 @@ use rocksdb::rocksdb_options::{ReadOptions, EnvOptions, ColumnFamilyOptions};
 use rocksdb::rocksdb::{DB, DBVector, Snapshot, SeekKey, SstFileWriter};
 use serde::de::DeserializeOwned;
 
-use crate::database::{DocumentKey, DocumentKeyAttr};
+use crate::database::{retrieve_data_schema, retrieve_data_index, retrieve_data_ranked_map};
-use crate::database::{retrieve_data_schema, retrieve_data_index};
 use crate::database::serde::deserializer::Deserializer;
+use crate::database::{DocumentKey, DocumentKeyAttr};
+use crate::rank::{QueryBuilder, FilterFunc};
 use crate::database::schema::Schema;
 use crate::database::index::Index;
-use crate::rank::{QueryBuilder, FilterFunc};
+use crate::database::RankedMap;
 use crate::DocumentId;
 
 pub struct DatabaseView<D>
@@ -20,6 +21,7 @@ where D: Deref<Target=DB>
 {
     snapshot: Snapshot<D>,
     index: Index,
+    ranked_map: RankedMap,
     schema: Schema,
 }
 
@@ -29,7 +31,8 @@ where D: Deref<Target=DB>
     pub fn new(snapshot: Snapshot<D>) -> Result<DatabaseView<D>, Box<Error>> {
         let schema = retrieve_data_schema(&snapshot)?;
         let index = retrieve_data_index(&snapshot)?;
-        Ok(DatabaseView { snapshot, index, schema })
+        let ranked_map = retrieve_data_ranked_map(&snapshot)?;
+        Ok(DatabaseView { snapshot, index, ranked_map, schema })
     }
 
     pub fn schema(&self) -> &Schema {
@@ -40,6 +43,10 @@ where D: Deref<Target=DB>
         &self.index
     }
 
+    pub fn ranked_map(&self) -> &RankedMap {
+        &self.ranked_map
+    }
+
     pub fn into_snapshot(self) -> Snapshot<D> {
         self.snapshot
     }

src/lib.rs

@@ -7,6 +7,8 @@ pub mod rank;
 pub mod tokenizer;
 mod common_words;
 
+use serde_derive::{Serialize, Deserialize};
+
 pub use rocksdb;
 
 pub use self::tokenizer::Tokenizer;
@@ -16,6 +18,7 @@ pub use self::common_words::CommonWords;
 ///
 /// It is used to inform the database the document you want to deserialize.
 /// Helpful for custom ranking.
+#[derive(Serialize, Deserialize)]
 #[derive(Debug, Copy, Clone, Eq, PartialEq, PartialOrd, Ord, Hash)]
 pub struct DocumentId(u64);
 

src/rank/criterion/mod.rs

@@ -4,7 +4,7 @@ mod words_proximity;
 mod sum_of_words_attribute;
 mod sum_of_words_position;
 mod exact;
-mod sort_by;
+mod sort_by_attr;
 mod document_id;
 
 use std::cmp::Ordering;
@@ -17,7 +17,7 @@ pub use self::{
     sum_of_words_attribute::SumOfWordsAttribute,
     sum_of_words_position::SumOfWordsPosition,
     exact::Exact,
-    sort_by::SortBy,
+    sort_by_attr::SortByAttr,
     document_id::DocumentId,
 };
 

src/rank/criterion/sort_by.rs

@@ -1,83 +0,0 @@
-use std::cmp::Ordering;
-use std::ops::Deref;
-use std::marker;
-
-use rocksdb::DB;
-use serde::de::DeserializeOwned;
-
-use crate::rank::criterion::Criterion;
-use crate::database::DatabaseView;
-use crate::rank::RawDocument;
-
-/// An helper struct that permit to sort documents by
-/// some of their stored attributes.
-///
-/// # Note
-///
-/// If a document cannot be deserialized it will be considered [`None`][].
-///
-/// Deserialized documents are compared like `Some(doc0).cmp(&Some(doc1))`,
-/// so you must check the [`Ord`] of `Option` implementation.
-///
-/// [`None`]: https://doc.rust-lang.org/std/option/enum.Option.html#variant.None
-/// [`Ord`]: https://doc.rust-lang.org/std/option/enum.Option.html#impl-Ord
-///
-/// # Example
-///
-/// ```ignore
-/// use serde_derive::Deserialize;
-/// use meilidb::rank::criterion::*;
-///
-/// #[derive(Deserialize, PartialOrd, Ord, PartialEq, Eq)]
-/// struct TimeOnly {
-///     time: String,
-/// }
-///
-/// let builder = CriteriaBuilder::with_capacity(8)
-///        .add(SumOfTypos)
-///        .add(NumberOfWords)
-///        .add(WordsProximity)
-///        .add(SumOfWordsAttribute)
-///        .add(SumOfWordsPosition)
-///        .add(Exact)
-///        .add(SortBy::<TimeOnly>::new(&view))
-///        .add(DocumentId);
-///
-/// let criterion = builder.build();
-///
-/// ```
-pub struct SortBy<'a, T, D>
-where D: Deref<Target=DB> + Send + Sync,
-      T: Send + Sync
-{
-    view: &'a DatabaseView<D>,
-    _phantom: marker::PhantomData<T>,
-}
-
-impl<'a, T, D> SortBy<'a, T, D>
-where D: Deref<Target=DB> + Send + Sync,
-      T: Send + Sync
-{
-    pub fn new(view: &'a DatabaseView<D>) -> Self {
-        SortBy { view, _phantom: marker::PhantomData }
-    }
-}
-
-impl<'a, T, D> Criterion for SortBy<'a, T, D>
-where D: Deref<Target=DB> + Send + Sync,
-      T: DeserializeOwned + Ord + Send + Sync,
-{
-    fn evaluate(&self, lhs: &RawDocument, rhs: &RawDocument) -> Ordering {
-        let lhs = match self.view.document_by_id::<T>(lhs.id) {
-            Ok(doc) => Some(doc),
-            Err(e) => { eprintln!("{}", e); None },
-        };
-
-        let rhs = match self.view.document_by_id::<T>(rhs.id) {
-            Ok(doc) => Some(doc),
-            Err(e) => { eprintln!("{}", e); None },
-        };
-
-        lhs.cmp(&rhs)
-    }
-}

src/rank/criterion/sort_by_attr.rs

@@ -0,0 +1,122 @@
+use std::cmp::Ordering;
+use std::error::Error;
+use std::fmt;
+
+use crate::database::schema::{Schema, SchemaAttr};
+use crate::rank::criterion::Criterion;
+use crate::database::RankedMap;
+use crate::rank::RawDocument;
+
+/// An helper struct that permit to sort documents by
+/// some of their stored attributes.
+///
+/// # Note
+///
+/// If a document cannot be deserialized it will be considered [`None`][].
+///
+/// Deserialized documents are compared like `Some(doc0).cmp(&Some(doc1))`,
+/// so you must check the [`Ord`] of `Option` implementation.
+///
+/// [`None`]: https://doc.rust-lang.org/std/option/enum.Option.html#variant.None
+/// [`Ord`]: https://doc.rust-lang.org/std/option/enum.Option.html#impl-Ord
+///
+/// # Example
+///
+/// ```ignore
+/// use serde_derive::Deserialize;
+/// use meilidb::rank::criterion::*;
+///
+/// let custom_ranking = SortByAttr::lower_is_better(&ranked_map, &schema, "published_at")?;
+///
+/// let builder = CriteriaBuilder::with_capacity(8)
+///        .add(SumOfTypos)
+///        .add(NumberOfWords)
+///        .add(WordsProximity)
+///        .add(SumOfWordsAttribute)
+///        .add(SumOfWordsPosition)
+///        .add(Exact)
+///        .add(custom_ranking)
+///        .add(DocumentId);
+///
+/// let criterion = builder.build();
+///
+/// ```
+pub struct SortByAttr<'a> {
+    ranked_map: &'a RankedMap,
+    attr: SchemaAttr,
+    reversed: bool,
+}
+
+impl<'a> SortByAttr<'a> {
+    pub fn lower_is_better(
+        ranked_map: &'a RankedMap,
+        schema: &Schema,
+        attr_name: &str,
+    ) -> Result<SortByAttr<'a>, SortByAttrError>
+    {
+        SortByAttr::new(ranked_map, schema, attr_name, false)
+    }
+
+    pub fn higher_is_better(
+        ranked_map: &'a RankedMap,
+        schema: &Schema,
+        attr_name: &str,
+    ) -> Result<SortByAttr<'a>, SortByAttrError>
+    {
+        SortByAttr::new(ranked_map, schema, attr_name, true)
+    }
+
+    fn new(
+        ranked_map: &'a RankedMap,
+        schema: &Schema,
+        attr_name: &str,
+        reversed: bool,
+    ) -> Result<SortByAttr<'a>, SortByAttrError>
+    {
+        let attr = match schema.attribute(attr_name) {
+            Some(attr) => attr,
+            None => return Err(SortByAttrError::AttributeNotFound),
+        };
+
+        if schema.props(attr).is_ranked() {
+            return Err(SortByAttrError::AttributeNotRegisteredForRanking);
+        }
+
+        Ok(SortByAttr { ranked_map, attr, reversed })
+    }
+}
+
+impl<'a> Criterion for SortByAttr<'a> {
+    fn evaluate(&self, lhs: &RawDocument, rhs: &RawDocument) -> Ordering {
+        let lhs = self.ranked_map.get(&(lhs.id, self.attr));
+        let rhs = self.ranked_map.get(&(rhs.id, self.attr));
+
+        match (lhs, rhs) {
+            (Some(lhs), Some(rhs)) => {
+                let order = lhs.cmp(&rhs);
+                if self.reversed { order.reverse() } else { order }
+            },
+            (None,    Some(_)) => Ordering::Greater,
+            (Some(_), None)    => Ordering::Less,
+            (None,    None)    => Ordering::Equal,
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum SortByAttrError {
+    AttributeNotFound,
+    AttributeNotRegisteredForRanking,
+}
+
+impl fmt::Display for SortByAttrError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        use SortByAttrError::*;
+        match self {
+            AttributeNotFound => f.write_str("attribute not found in the schema"),
+            AttributeNotRegisteredForRanking => f.write_str("attribute not registered for ranking"),
+        }
+    }
+}
+
+impl Error for SortByAttrError { }