refactor: only fallback to approximate if tiktoken fails (#1898)

langchain-ai · Jul 9, 2023 · 3635d96 · 3635d96 · vercel · Jul 9, 2023
1 parent 99b1985
commit 3635d96
Showing 1 changed file with 4 additions and 2 deletions.
diff --git a/langchain/src/base_language/count_tokens.ts b/langchain/src/base_language/count_tokens.ts
@@ -68,15 +68,17 @@ export const calculateMaxTokens = async ({
   prompt,
   modelName,
 }: CalculateMaxTokenProps) => {
-  // fallback to approximate calculation if tiktoken is not available
-  let numTokens = Math.ceil(prompt.length / 4);
+  let numTokens;
 
   try {
     numTokens = (await encodingForModel(modelName)).encode(prompt).length;
   } catch (error) {
     console.warn(
       "Failed to calculate number of tokens, falling back to approximate count"
     );
+
+    // fallback to approximate calculation if tiktoken is not available
+    numTokens = Math.ceil(prompt.length / 4);
   }
 
   const maxTokens = getModelContextSize(modelName);