feat: use existing add_generation_prompt variable from config in temp… (#1533)

This PR adds support to read the `add_generation_prompt` from the config
and use it in the chat template. If `add_generation_prompt` does not
exist we default to false

router/src/infer.rs

@@ -198,6 +198,7 @@ impl Infer {
                 messages,
                 eos_token: eos_token.as_deref(),
                 bos_token: bos_token.as_deref(),
+                add_generation_prompt: true,
             })
             .map_err(|e| {
                 metrics::increment_counter!("tgi_request_failure", "err" => "template");
@@ -806,21 +807,14 @@ mod tests {
             ],
             bos_token: Some("[BOS]"),
             eos_token: Some("[EOS]"),
+            add_generation_prompt: true,
         };
 
         let result = tmpl.unwrap().render(chat_template_inputs).unwrap();
 
         assert_eq!(
             result,
-            r#"### User:
+            "### User:\nHi!\n\n### Assistant:\nHello how can I help?### User:\nWhat is Deep Learning?\n\n### Assistant:\nmagic!### Assistant:\n"
-Hi!
-
-### Assistant:
-Hello how can I help?### User:
-What is Deep Learning?
-
-### Assistant:
-magic!"#
         );
     }
 
@@ -878,6 +872,7 @@ magic!"#
             ],
             bos_token: Some("[BOS]"),
             eos_token: Some("[EOS]"),
+            add_generation_prompt: true,
         };
 
         let result = tmpl.unwrap().render(chat_template_inputs); //.err().unwrap();
@@ -943,9 +938,60 @@ magic!"#
             ],
             bos_token: Some("[BOS]"),
             eos_token: Some("[EOS]"),
+            add_generation_prompt: true,
         };
 
         let result = tmpl.unwrap().render(chat_template_inputs).unwrap();
         assert_eq!(result, "[BOS][INST] Hi! [/INST]Hello how can I help?[EOS][INST] What is Deep Learning? [/INST]magic![EOS]");
     }
+
+    #[test]
+    fn test_chat_template_valid_with_add_generation_prompt() {
+        let mut env = Environment::new();
+        env.add_function("raise_exception", raise_exception);
+
+        let source = r#"
+        {% for message in messages %}
+        {{'<|im_start|>' + message['role'] + '\n' + message['content'] + '<|im_end|>' + '\n'}}
+        {% endfor %}
+        {% if add_generation_prompt %}
+            {{ '<|im_start|>assistant\n' }}
+        {% endif %}"#;
+
+        // trim all the whitespace
+        let source = source
+            .lines()
+            .map(|line| line.trim())
+            .collect::<Vec<&str>>()
+            .join("");
+
+        let tmpl = env.template_from_str(&source);
+
+        let chat_template_inputs = ChatTemplateInputs {
+            messages: vec![
+                Message {
+                    role: "user".to_string(),
+                    content: "Hi!".to_string(),
+                },
+                Message {
+                    role: "assistant".to_string(),
+                    content: "Hello how can I help?".to_string(),
+                },
+                Message {
+                    role: "user".to_string(),
+                    content: "What is Deep Learning?".to_string(),
+                },
+                Message {
+                    role: "assistant".to_string(),
+                    content: "magic!".to_string(),
+                },
+            ],
+            bos_token: Some("[BOS]"),
+            eos_token: Some("[EOS]"),
+            add_generation_prompt: true,
+        };
+
+        let result = tmpl.unwrap().render(chat_template_inputs).unwrap();
+        assert_eq!(result, "<|im_start|>user\nHi!<|im_end|>\n<|im_start|>assistant\nHello how can I help?<|im_end|>\n<|im_start|>user\nWhat is Deep Learning?<|im_end|>\n<|im_start|>assistant\nmagic!<|im_end|>\n<|im_start|>assistant\n");
+    }
 }

router/src/lib.rs

@@ -398,6 +398,7 @@ pub(crate) struct ChatTemplateInputs<'a> {
     messages: Vec<Message>,
     bos_token: Option<&'a str>,
     eos_token: Option<&'a str>,
+    add_generation_prompt: bool,
 }
 
 #[derive(Clone, Deserialize, ToSchema, Serialize)]