experimental[patch]: Improve AutoGPT's output_parser to extract JSON …

…code block (#3656)

* Improve output_parser to extract JSON code block

Closes #3655

* Ran yarn format and lint

langchain/src/experimental/autogpt/output_parser.ts

@@ -2,18 +2,24 @@ import { BaseOutputParser } from "../../schema/output_parser.js";
 import { AutoGPTAction } from "./schema.js";
 
 /**
- * Utility function used to preprocess a string to be parsed as JSON. It
- * replaces single backslashes with double backslashes, while leaving
+ * Utility function used to preprocess a string to be parsed as JSON.
+ * It replaces single backslashes with double backslashes, while leaving
  * already escaped ones intact.
+ * It also extracts the json code if it is inside a code block
  */
 export function preprocessJsonInput(inputStr: string): string {
-  // Replace single backslashes with double backslashes,
-  // while leaving already escaped ones intact
   const correctedStr = inputStr.replace(
     /(?<!\\)\\(?!["\\/bfnrt]|u[0-9a-fA-F]{4})/g,
     "\\\\"
   );
-  return correctedStr;
+  const match = correctedStr.match(
+    /```(.*)(\r\n|\r|\n)(?<code>[\w\W\n]+)(\r\n|\r|\n)```/
+  );
+  if (match?.groups?.code) {
+    return match.groups.code.trim();
+  } else {
+    return correctedStr;
+  }
 }
 
 /**

langchain/src/experimental/autogpt/tests/output_parser.test.ts

@@ -0,0 +1,12 @@
+import { test, expect } from "@jest/globals";
+import { preprocessJsonInput } from "../output_parser.js";
+
+test("should parse outputs correctly", () => {
+  expect(preprocessJsonInput("{'escaped':'\\a'}")).toBe("{'escaped':'\\\\a'}");
+
+  expect(preprocessJsonInput("```\n{}\n```")).toBe("{}");
+  expect(preprocessJsonInput("```json\n{}\n```")).toBe("{}");
+  expect(
+    preprocessJsonInput("I will do the following:\n\n```json\n{}\n```")
+  ).toBe("{}");
+});