Add token limit for GPT models and update prompt token limit calculation

This commit adds a function to calculate the maximum token limit for a given
GPT model. It also updates the `AllowedInputTokens` and
`AllowedSubsequentInputTokens` functions to use the token limit instead of
hardcoding the value to 4096. Additionally, the `CreateMessagesWithSplit`
function is updated to use the new `AllowedInputTokens` function signature.
Finally, a new test function is added to test the `tokenLimitOfModel` function.

aichat.go

@@ -131,7 +131,8 @@ func (aiChat *AIChat) fold(prompt *Prompt, input string) error {
 		return fmt.Errorf("encode: %w", err)
 	}
 
-	firstAllowedTokens, err := prompt.AllowedInputTokens(aiChat.encoder, aiChat.options.maxTokens, aiChat.options.verbose)
+	tokenLimit := tokenLimitOfModel(aiChat.options.model)
+	firstAllowedTokens, err := prompt.AllowedInputTokens(aiChat.encoder, tokenLimit, aiChat.options.maxTokens, aiChat.options.verbose)
 	if err != nil {
 		return err
 	}
@@ -174,7 +175,7 @@ func (aiChat *AIChat) fold(prompt *Prompt, input string) error {
 		}
 
 		allowedTokens, err := prompt.AllowedSubsequentInputTokens(
-			aiChat.encoder, len(outputTokens), aiChat.options.maxTokens, aiChat.options.verbose)
+			aiChat.encoder, len(outputTokens), tokenLimit, aiChat.options.maxTokens, aiChat.options.verbose)
 		if err != nil {
 			return fmt.Errorf("allowed subsequent input tokens: %w", err)
 		}
@@ -208,14 +209,26 @@ func (aiChat *AIChat) fold(prompt *Prompt, input string) error {
 	return nil
 }
 
+// tokenLimitOfModel returns the maximum number of tokens allowed for a given model.
+func tokenLimitOfModel(model string) int {
+	switch model {
+	case gogpt.GPT4, gogpt.GPT40314:
+		return 8 * 1024
+	case gogpt.GPT432K, gogpt.GPT432K0314:
+		return 32 * 1024
+	default:
+		return 4 * 1024
+	}
+}
+
 func main() {
 	var temperature float32 = 0.5
 	var maxTokens = 0
 	var verbose = false
 	var listPrompts = false
 	var nonStreaming = false
 	var split = false
-	var model = gogpt.GPT3Dot5Turbo
+	var model = gogpt.GPT4
 	getopt.FlagLong(&temperature, "temperature", 't', "temperature")
 	getopt.FlagLong(&maxTokens, "max-tokens", 'm', "max tokens, 0 to use default")
 	getopt.FlagLong(&verbose, "verbose", 'v', "verbose output")
@@ -281,9 +294,10 @@ func main() {
 		}
 
 		var messagesSlice [][]gogpt.ChatCompletionMessage
+		tokenLimit := tokenLimitOfModel(aiChat.options.model)
 
 		if split {
-			messagesSlice, err = prompt.CreateMessagesWithSplit(aiChat.encoder, input, aiChat.options.maxTokens, aiChat.options.verbose)
+			messagesSlice, err = prompt.CreateMessagesWithSplit(aiChat.encoder, input, tokenLimit, aiChat.options.maxTokens, aiChat.options.verbose)
 			if err != nil {
 				log.Fatal(err)
 			}
@@ -320,8 +334,8 @@ func main() {
 			if verbose {
 				log.Printf("total tokens %d", cnt)
 			}
-			if cnt+maxTokens > 4096 {
-				log.Fatalf("total tokens %d exceeds 4096", cnt)
+			if cnt+maxTokens > tokenLimit {
+				log.Fatalf("total tokens %d exceeds %d", cnt, tokenLimit)
 			}
 
 			if aiChat.options.nonStreaming {

aichat_test.go

@@ -17,3 +17,19 @@ func TestCountTokens(t *testing.T) {
 		t.Errorf("CountTokens() returned %d, expected 8", count)
 	}
 }
+
+func TestTokenLimitOfModel(t *testing.T) {
+	data := []struct {
+		modelName  string
+		tokenLimit int
+	}{
+		{"gpt-3.5-turbo", 4096},
+		{"gpt-4", 8192},
+	}
+	for _, d := range data {
+		tokenLimit := tokenLimitOfModel(d.modelName)
+		if tokenLimit != d.tokenLimit {
+			t.Errorf("TokenLimitForModel(%q) returned %d, expected %d", d.modelName, tokenLimit, d.tokenLimit)
+		}
+	}
+}

prompt.go

@@ -87,14 +87,14 @@ func countMessagesTokens(encoder *tokenizer.Encoder, messages []Message) (int, e
 }
 
 // AllowedInputTokens returns the number of tokens allowed for the input
-func (p *Prompt) AllowedInputTokens(encoder *tokenizer.Encoder, maxTokensOverride int, verbose bool) (int, error) {
+func (p *Prompt) AllowedInputTokens(encoder *tokenizer.Encoder, tokenLimit, maxTokensOverride int, verbose bool) (int, error) {
 	promptTokens, err := p.CountTokens(encoder)
 	if err != nil {
 		return 0, err
 	}
 	// reserve 500 tokens for output if maxTokens is not specified
 	maxTokens := firstNonZeroInt(maxTokensOverride, p.MaxTokens, 500)
-	result := 4096 - (promptTokens + maxTokens)
+	result := tokenLimit - (promptTokens + maxTokens)
 	if verbose {
 		log.Printf("allowed tokens for input is %d", result)
 	}
@@ -104,14 +104,14 @@ func (p *Prompt) AllowedInputTokens(encoder *tokenizer.Encoder, maxTokensOverrid
 	return result, nil
 }
 
-func (p *Prompt) AllowedSubsequentInputTokens(encoder *tokenizer.Encoder, outputLen, maxTokensOverride int, verbose bool) (int, error) {
+func (p *Prompt) AllowedSubsequentInputTokens(encoder *tokenizer.Encoder, outputLen, tokenLimit, maxTokensOverride int, verbose bool) (int, error) {
 	promptTokens, err := p.CountSubsequentTokens(encoder)
 	if err != nil {
 		return 0, err
 	}
 	// reserve 500 tokens for output if maxTokens is not specified
 	maxTokens := firstNonZeroInt(maxTokensOverride, p.MaxTokens, 500)
-	result := 4096 - (promptTokens + maxTokens + outputLen)
+	result := tokenLimit - (promptTokens + maxTokens + outputLen)
 	if verbose {
 		log.Printf("allowed tokens for subsequent input is %d", result)
 	}
@@ -145,8 +145,8 @@ func splitStringWithTokensLimit(s string, tokensLimit int) ([]string, error) {
 	return parts, nil
 }
 
-func (p *Prompt) CreateMessagesWithSplit(encoder *tokenizer.Encoder, input string, maxTokensOverride int, verbose bool) ([][]gogpt.ChatCompletionMessage, error) {
-	allowedInputTokens, err := p.AllowedInputTokens(encoder, maxTokensOverride, verbose)
+func (p *Prompt) CreateMessagesWithSplit(encoder *tokenizer.Encoder, input string, tokenLimit, maxTokensOverride int, verbose bool) ([][]gogpt.ChatCompletionMessage, error) {
+	allowedInputTokens, err := p.AllowedInputTokens(encoder, tokenLimit, maxTokensOverride, verbose)
 	if err != nil {
 		return nil, err
 	}