From 18736bdcd0fb5e7444f724595204ac8ff7b13b44 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20Renault?= <renault.cle@gmail.com>
Date: Thu, 13 Jun 2019 16:20:01 +0200
Subject: [PATCH] feat: Introduce the synonyms concept to the Store trait

---
 meilidb-core/src/query_builder.rs | 66 +++++++++++++++++++++++++++----
 meilidb-core/src/store.rs         | 11 ++++++
 2 files changed, 69 insertions(+), 8 deletions(-)

diff --git a/meilidb-core/src/query_builder.rs b/meilidb-core/src/query_builder.rs
index 6e8194e2f..7c089c8dc 100644
--- a/meilidb-core/src/query_builder.rs
+++ b/meilidb-core/src/query_builder.rs
@@ -349,7 +349,7 @@ mod tests {
     use std::iter::FromIterator;
 
     use sdset::SetBuf;
-    use fst::Set;
+    use fst::{Set, IntoStreamer};
 
     use crate::DocIndex;
     use crate::store::Store;
@@ -357,18 +357,46 @@ mod tests {
     #[derive(Default)]
     struct InMemorySetStore {
         set: Set,
+        synonyms: Set,
         indexes: HashMap<Vec<u8>, SetBuf<DocIndex>>,
+        alternatives: HashMap<Vec<u8>, Set>,
     }
 
-    impl Store for InMemorySetStore {
-        type Error = std::io::Error;
+    fn set_from_stream<'f, I, S>(stream: I) -> Set
+    where
+        I: for<'a> fst::IntoStreamer<'a, Into=S, Item=&'a [u8]>,
+        S: 'f + for<'a> fst::Streamer<'a, Item=&'a [u8]>,
+    {
+        let mut builder = fst::SetBuilder::memory();
+        builder.extend_stream(stream);
+        builder.into_inner().and_then(Set::from_bytes).unwrap()
+    }
 
-        fn words(&self) -> Result<&Set, Self::Error> {
-            Ok(&self.set)
-        }
+    fn insert_key(set: &Set, key: &[u8]) -> Set {
+        let unique_key = {
+            let mut builder = fst::SetBuilder::memory();
+            builder.insert(key);
+            builder.into_inner().and_then(Set::from_bytes).unwrap()
+        };
 
-        fn word_indexes(&self, word: &[u8]) -> Result<Option<SetBuf<DocIndex>>, Self::Error> {
-            Ok(self.indexes.get(word).cloned())
+        let union_ = set.op().add(unique_key.into_stream()).r#union();
+
+        set_from_stream(union_)
+    }
+
+    fn sdset_into_fstset(set: &sdset::Set<&str>) -> Set {
+        let mut builder = fst::SetBuilder::memory();
+        builder.extend_iter(set.into_iter());
+        builder.into_inner().and_then(Set::from_bytes).unwrap()
+    }
+
+    impl InMemorySetStore {
+        pub fn add_synonym(&mut self, word: &str, new: SetBuf<&str>) {
+            let alternatives = self.alternatives.entry(word.as_bytes().to_vec()).or_default();
+            let new = sdset_into_fstset(&new);
+            *alternatives = set_from_stream(alternatives.op().add(new.into_stream()).r#union());
+
+            self.synonyms = insert_key(&self.synonyms, word.as_bytes());
         }
     }
 
@@ -384,11 +412,33 @@ mod tests {
 
             InMemorySetStore {
                 set: Set::from_iter(tree).unwrap(),
+                synonyms: Set::default(),
                 indexes: map,
+                alternatives: HashMap::new(),
             }
         }
     }
 
+    impl Store for InMemorySetStore {
+        type Error = std::io::Error;
+
+        fn words(&self) -> Result<&Set, Self::Error> {
+            Ok(&self.set)
+        }
+
+        fn word_indexes(&self, word: &[u8]) -> Result<Option<SetBuf<DocIndex>>, Self::Error> {
+            Ok(self.indexes.get(word).cloned())
+        }
+
+        fn synonyms(&self) -> Result<&Set, Self::Error> {
+            Ok(&self.synonyms)
+        }
+
+        fn alternatives_to(&self, word: &[u8]) -> Result<Option<Set>, Self::Error> {
+            Ok(self.alternatives.get(word).map(|s| Set::from_bytes(s.as_fst().to_vec()).unwrap()))
+        }
+    }
+
     const fn doc_index(document_id: u64, word_index: u16) -> DocIndex {
         DocIndex {
             document_id: DocumentId(document_id),
diff --git a/meilidb-core/src/store.rs b/meilidb-core/src/store.rs
index 14e95f0cc..6e429a1b4 100644
--- a/meilidb-core/src/store.rs
+++ b/meilidb-core/src/store.rs
@@ -8,6 +8,9 @@ pub trait Store {
 
     fn words(&self) -> Result<&Set, Self::Error>;
     fn word_indexes(&self, word: &[u8]) -> Result<Option<SetBuf<DocIndex>>, Self::Error>;
+
+    fn synonyms(&self) -> Result<&Set, Self::Error>;
+    fn alternatives_to(&self, word: &[u8]) -> Result<Option<Set>, Self::Error>;
 }
 
 impl<T> Store for &'_ T where T: Store {
@@ -20,4 +23,12 @@ impl<T> Store for &'_ T where T: Store {
     fn word_indexes(&self, word: &[u8]) -> Result<Option<SetBuf<DocIndex>>, Self::Error> {
         (*self).word_indexes(word)
     }
+
+    fn synonyms(&self) -> Result<&Set, Self::Error> {
+        (*self).synonyms()
+    }
+
+    fn alternatives_to(&self, word: &[u8]) -> Result<Option<Set>, Self::Error> {
+        (*self).alternatives_to(word)
+    }
 }