ADD a example for GPT chat completion tool_calls.

Author: karminski

examples/gpt-function-call/main.go

@@ -0,0 +1,68 @@
+package main
+
+import (
+	"fmt"
+
+	streamingjson "github.com/karminski/streaming-json-go"
+)
+
+// In GPT's chat completion stream mode, the request for tool_calls returns a structure as follows:
+//
+// {
+//     "id": "chatcmpl-?",
+//     "object": "chat.completion.chunk",
+//     "created": 1712000001,
+//     "model": "gpt-4-0125-preview",
+//     "system_fingerprint": "fp_?",
+//     "choices": [
+//         {
+//             "index": 0,
+//             "delta": {
+//                 "tool_calls": [
+//                     {
+//                         "index": 0,
+//                         "function": {
+//                             "arguments": "{\"fi"
+//                         }
+//                     }
+//                 ]
+//             },
+//             "logprobs": null,
+//             "finish_reason": null
+//         }
+//     ]
+// }
+//
+// We need extract data.choices[0].delta.tool_calls[0].function.arguments.
+// The arguments fiels is a JSON fragment, we can use steaming-json-go complete it to a syntactically correct JSON and Unmarshal it.
+
+func main() {
+	// We use string slice to simulate the arguments field in the return of GPT.
+	arguments := []string{`{"fu`, `nction`, `_name`, `"`, `:`, `"run`, `_code`, `", `, `"argu`, `ments"`, `: `, "\"print(", "\\\"hello", " world", "\\\"", ")\""}
+	lexer := streamingjson.NewLexer()
+	for _, jsonFragment := range arguments {
+		errInAppendString := lexer.AppendString(jsonFragment)
+		if errInAppendString != nil {
+			panic("invalied json string appended: " + errInAppendString.Error())
+		}
+		completedJSON := lexer.CompleteJSON()
+		fmt.Printf("%s\n", completedJSON)
+	}
+	// will print:
+	// {"fu":null}
+	// {"function":null}
+	// {"function_name":null}
+	// {"function_name":null}
+	// {"function_name":null}
+	// {"function_name":"run"}
+	// {"function_name":"run_code"}
+	// {"function_name":"run_code"}
+	// {"function_name":"run_code", "argu":null}
+	// {"function_name":"run_code", "arguments":null}
+	// {"function_name":"run_code", "arguments":null}
+	// {"function_name":"run_code", "arguments": "print("}
+	// {"function_name":"run_code", "arguments": "print(\"hello"}
+	// {"function_name":"run_code", "arguments": "print(\"hello world"}
+	// {"function_name":"run_code", "arguments": "print(\"hello world\""}
+	// {"function_name":"run_code", "arguments": "print(\"hello world\")"}
+}