feat: add strategies for building query embedding vector

crates/llm-ls/src/main.rs

@@ -33,6 +33,7 @@ use uuid::Uuid;
 use crate::backend::{build_body, build_headers, parse_generations};
 use crate::document::Document;
 use crate::error::{internal_error, Error, Result};
+use crate::retrieval::BuildFrom;
 
 mod backend;
 mod config;
@@ -238,11 +239,21 @@ async fn build_prompt(
             after_line = after_iter.next();
         }
         let before = before.into_iter().rev().collect::<Vec<_>>().join("");
+        let query = snippet_retriever
+            .read()
+            .await
+            .build_query(
+                format!("{before}{after}"),
+                BuildFrom::Cursor {
+                    cursor_position: before.len(),
+                },
+            )
+            .await?;
         let snippets = snippet_retriever
             .read()
             .await
             .search(
-                format!("{before}{after}"),
+                &query,
                 Some(FilterBuilder::new().comparison(
                     "file_url".to_owned(),
                     Compare::Neq,
@@ -281,11 +292,16 @@ async fn build_prompt(
             before.push(line);
         }
         let prompt = before.into_iter().rev().collect::<Vec<_>>().join("");
+        let query = snippet_retriever
+            .read()
+            .await
+            .build_query(prompt.clone(), BuildFrom::End)
+            .await?;
         let snippets = snippet_retriever
             .read()
             .await
             .search(
-                prompt.clone(),
+                &query,
                 Some(FilterBuilder::new().comparison(
                     "file_url".to_owned(),
                     Compare::Neq,

crates/llm-ls/src/retrieval.rs

@@ -377,29 +377,60 @@ impl SnippetRetriever {
         Ok(())
     }
 
-    pub(crate) async fn search(
+    pub(crate) async fn build_query(
         &self,
         snippet: String,
+        strategy: BuildFrom,
+    ) -> Result<Vec<f32>> {
+        match strategy {
+            BuildFrom::Start => {
+                let mut encoding = self.tokenizer.encode(snippet.clone(), true)?;
+                encoding.truncate(
+                    self.model_config.max_input_size,
+                    1,
+                    TruncationDirection::Right,
+                );
+                self.generate_embedding(encoding, self.model.clone()).await
+            }
+            BuildFrom::Cursor { cursor_position } => {
+                let (before, after) = snippet.split_at(cursor_position);
+                let mut before_encoding = self.tokenizer.encode(before, true)?;
+                let mut after_encoding = self.tokenizer.encode(after, true)?;
+                let share = self.model_config.max_input_size / 2;
+                before_encoding.truncate(share, 1, TruncationDirection::Left);
+                after_encoding.truncate(share, 1, TruncationDirection::Right);
+                before_encoding.take_overflowing();
+                after_encoding.take_overflowing();
+                before_encoding.merge_with(after_encoding, false);
+                self.generate_embedding(before_encoding, self.model.clone())
+                    .await
+            }
+            BuildFrom::End => {
+                let mut encoding = self.tokenizer.encode(snippet.clone(), true)?;
+                encoding.truncate(
+                    self.model_config.max_input_size,
+                    1,
+                    TruncationDirection::Left,
+                );
+                self.generate_embedding(encoding, self.model.clone()).await
+            }
+        }
+    }
+
+    pub(crate) async fn search(
+        &self,
+        query: &[f32],
         filter: Option<FilterBuilder>,
     ) -> Result<Vec<Snippet>> {
         let db = match self.db.as_ref() {
             Some(db) => db.clone(),
             None => return Err(Error::UninitialisedDatabase),
         };
         let col = db.get_collection(&self.collection_name).await?;
-        let mut encoding = self.tokenizer.encode(snippet.clone(), true)?;
-        encoding.truncate(
-            self.model_config.max_input_size,
-            1,
-            TruncationDirection::Right,
-        );
-        let query = self
-            .generate_embedding(encoding, self.model.clone())
-            .await?;
         let result = col
             .read()
             .await
-            .get(&query, 5, filter)
+            .get(query, 5, filter)
             .await?
             .iter()
             .map(TryInto::try_into)
@@ -537,3 +568,12 @@ impl SnippetRetriever {
         Ok(())
     }
 }
+
+pub(crate) enum BuildFrom {
+    Cursor {
+        cursor_position: usize,
+    },
+    End,
+    #[allow(dead_code)]
+    Start,
+}