Update output_parser.ts (#3975)

Co-authored-by: Ben Burns <[email protected]>

Author: jmlon

langchain/src/agents/xml/output_parser.ts

@@ -38,12 +38,18 @@ export class XMLAgentOutputParser extends AgentActionOutputParser {
    */
   async parse(text: string): Promise<AgentAction | AgentFinish> {
     if (text.includes("</tool>")) {
-      const [tool, toolInput] = text.split("</tool>");
-      const _tool = tool.split("<tool>")[1];
-      const _toolInput = toolInput.split("<tool_input>")[1];
+      const _toolMatch = text.match(/<tool>([^<]*)<\/tool>/);
+      const _tool = _toolMatch ? _toolMatch[1] : "";
+      const _toolInputMatch = text.match(
+        /<tool_input>([^<]*?)(?:<\/tool_input>|$)/
+      );
+      const _toolInput = _toolInputMatch ? _toolInputMatch[1] : "";
       return { tool: _tool, toolInput: _toolInput, log: text };
     } else if (text.includes("<final_answer>")) {
-      const [, answer] = text.split("<final_answer>");
+      const answerMatch = text.match(
+        /<final_answer>([^<]*?)(?:<\/final_answer>|$)/
+      );
+      const answer = answerMatch ? answerMatch[1] : "";
       return { returnValues: { output: answer }, log: text };
     } else {
       throw new OutputParserException(`Could not parse LLM output: ${text}`);