async generator stream

src/chatgpt.ts

@@ -63,7 +63,7 @@ class Chat {
       top_p = 1,
       presence_penalty = 0,
       frequency_penalty = 0,
-    } = {}
+    } = {},
   ) {
     if (OPENAI_API_KEY === undefined) {
       throw "OPENAI_API_KEY is undefined";
@@ -95,14 +95,14 @@ class Chat {
       }
       if (msg.role === "system") {
         console.log(
-          "Warning: detected system message in the middle of history"
+          "Warning: detected system message in the middle of history",
         );
       }
     }
     for (const msg of this.messages) {
       if (msg.name && msg.role !== "system") {
         console.log(
-          "Warning: detected message where name field set but role is system"
+          "Warning: detected message where name field set but role is system",
         );
       }
     }
@@ -127,6 +127,7 @@ class Chat {
     });
   }
 
+
   async fetch(): Promise<FetchResponse> {
     const resp = await this._fetch();
     const j = await resp.json();
@@ -142,6 +143,50 @@ class Chat {
     return this.messages.slice(-1)[0].content;
   }
 
+  async *processStreamResponse(resp: Response) {
+    const reader = resp?.body?.pipeThrough(new TextDecoderStream()).getReader();
+    if (reader === undefined) {
+      console.log("reader is undefined");
+      return;
+    }
+    let receiving = true;
+    while (receiving) {
+      let lastText = "";
+      const { value, done } = await reader.read();
+      if (done) break;
+      const lines = (lastText + value)
+        .trim()
+        .split("\n")
+        .filter((line) => line.trim())
+        .map((line) => line.slice("data:".length))
+        .map((line) => line.trim())
+        .filter((i) => {
+          if (i === "[DONE]") {
+            receiving = false;
+            return false;
+          }
+          return true;
+        });
+      const jsons: ChunkMessage[] = lines
+        .map((line) => {
+          try {
+            const ret = JSON.parse(line.trim());
+            lastText = "";
+            return ret;
+          } catch (e) {
+            console.log(`Chunk parse error at: ${line}`);
+            lastText = line;
+            return null;
+          }
+        })
+        .filter((i) => i.choices[0].delta.content);
+
+      for (const j of jsons) {
+        yield j;
+      }
+    }
+  }
+
   processFetchResponse(resp: FetchResponse): string {
     if (resp.error !== undefined) {
       throw JSON.stringify(resp.error);