Refactor common_chat_* functions to accept minja template + use_jinja option

Author: ochafik

common/common.cpp

@@ -74,6 +74,15 @@
 #endif
 #define LLAMA_CURL_MAX_URL_LENGTH 2084 // Maximum URL Length in Chrome: 2083
 
+const char * LLAMA_CHATML_TEMPLATE = 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 -%}
+)";
+
 //
 // CURL utils
 //
@@ -1748,86 +1757,77 @@ bool common_chat_verify_template(const std::string & tmpl, bool use_jinja) {
     return res >= 0;
 }
 
-std::string common_chat_apply_template(const struct llama_model * model,
-        const std::string & tmpl,
+std::string common_chat_apply_template(
+        const llama_chat_template & tmpl,
         const std::vector<common_chat_msg> & msgs,
-        bool add_ass) {
+        bool add_ass,
+        bool use_jinja) {
+    if (use_jinja) {
+        auto messages = json::array();
+        for (const auto & msg : msgs) {
+            messages.push_back({{"role", msg.role}, {"content", msg.content}});
+        }
+        return tmpl.apply(messages, /* tools= */ json(), add_ass);
+    }
+
     int alloc_size = 0;
-    bool fallback = false; // indicate if we must fallback to default chatml
     std::vector<llama_chat_message> chat;
     for (const auto & msg : msgs) {
         chat.push_back({msg.role.c_str(), msg.content.c_str()});
         alloc_size += (msg.role.size() + msg.content.size()) * 1.25;
     }
 
-    const char * ptr_tmpl = tmpl.empty() ? llama_model_chat_template(model, /* name */ nullptr) : tmpl.c_str();
     std::vector<char> buf(alloc_size);
 
     // run the first time to get the total output length
-    int32_t res = llama_chat_apply_template(ptr_tmpl, chat.data(), chat.size(), add_ass, buf.data(), buf.size());
+    int32_t res = llama_chat_apply_template(tmpl.source().c_str(), chat.data(), chat.size(), add_ass, buf.data(), buf.size());
 
     // error: chat template is not supported
     if (res < 0) {
-        if (ptr_tmpl != nullptr) {
-            // if the custom "tmpl" is not supported, we throw an error
-            // this is a bit redundant (for good), since we're not sure if user validated the custom template with llama_chat_verify_template()
-            throw std::runtime_error("this custom template is not supported");
-        }
-
-        // If the built-in template is not supported, we default to chatml
-        res = llama_chat_apply_template("chatml", chat.data(), chat.size(), add_ass, buf.data(), buf.size());
-        fallback = true;
+        // if the custom "tmpl" is not supported, we throw an error
+        // this is a bit redundant (for good), since we're not sure if user validated the custom template with llama_chat_verify_template()
+        throw std::runtime_error("this custom template is not supported");
     }
 
     // if it turns out that our buffer is too small, we resize it
     if ((size_t) res > buf.size()) {
         buf.resize(res);
-        res = llama_chat_apply_template(
-            fallback ? "chatml" : ptr_tmpl,
-            chat.data(), chat.size(), add_ass, buf.data(), buf.size());
+        res = llama_chat_apply_template(tmpl.source().c_str(), chat.data(), chat.size(), add_ass, buf.data(), buf.size());
     }
 
     std::string formatted_chat(buf.data(), res);
     return formatted_chat;
 }
 
-std::string common_chat_format_single(const struct llama_model * model,
-        const std::string & tmpl,
+std::string common_chat_format_single(
+        const llama_chat_template & tmpl,
         const std::vector<common_chat_msg> & past_msg,
         const common_chat_msg & new_msg,
-        bool add_ass) {
+        bool add_ass,
+        bool use_jinja) {
     std::ostringstream ss;
-    auto fmt_past_msg = past_msg.empty() ? "" : common_chat_apply_template(model, tmpl, past_msg, false);
+    auto fmt_past_msg = past_msg.empty() ? "" : common_chat_apply_template(tmpl, past_msg, false, use_jinja);
     std::vector<common_chat_msg> chat_new(past_msg);
     // if the past_msg ends with a newline, we must preserve it in the formatted version
     if (add_ass && !fmt_past_msg.empty() && fmt_past_msg.back() == '\n') {
         ss << "\n";
     };
     // format chat with new_msg
     chat_new.push_back(new_msg);
-    auto fmt_new_msg = common_chat_apply_template(model, tmpl, chat_new, add_ass);
+    auto fmt_new_msg = common_chat_apply_template(tmpl, chat_new, add_ass, use_jinja);
     // get the diff part
     ss << fmt_new_msg.substr(fmt_past_msg.size(), fmt_new_msg.size() - fmt_past_msg.size());
     return ss.str();
 }
 
-std::string common_chat_format_example(const struct llama_model * model, const minja::chat_template & tmpl, bool use_jinja) {
+std::string common_chat_format_example(const llama_chat_template & tmpl, bool use_jinja) {
     std::vector<common_chat_msg> msgs = {
         {"system",    "You are a helpful assistant"},
         {"user",      "Hello"},
         {"assistant", "Hi there"},
         {"user",      "How are you?"},
     };
-    const auto add_generation_prompt = true;
-    if (use_jinja) {
-        auto messages = json::array();
-        for (const auto & msg : msgs) {
-            messages.push_back({{"role", msg.role}, {"content", msg.content}});
-        }
-        return tmpl.apply(messages, /* tools= */ json(), add_generation_prompt);
-    } else {
-        return common_chat_apply_template(model, tmpl.source(), msgs, add_generation_prompt);
-    }
+    return common_chat_apply_template(tmpl, msgs, true, use_jinja);
 }
 
 llama_chat_templates llama_chat_templates_from_model(const struct llama_model * model, const std::string & chat_template_override)
@@ -1847,14 +1847,7 @@ llama_chat_templates llama_chat_templates_from_model(const struct llama_model *
         if (!tool_use_template_src.empty()) {
             default_template_src = tool_use_template_src;
         } else {
-            default_template_src = 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 -%}
-            )";
+            default_template_src = LLAMA_CHATML_TEMPLATE;
         }
     }
     return {

common/common.h

@@ -26,6 +26,8 @@
 
 #define DEFAULT_MODEL_PATH "models/7B/ggml-model-f16.gguf"
 
+extern const char * LLAMA_CHATML_TEMPLATE;
+
 struct common_adapter_lora_info {
     std::string path;
     float scale;
@@ -602,29 +604,32 @@ struct common_chat_msg {
 // Check if the template supplied via "--chat-template" is supported or not. Returns true if it's valid
 bool common_chat_verify_template(const std::string & tmpl, bool use_jinja);
 
+typedef minja::chat_template llama_chat_template;
+
 // CPP wrapper for llama_chat_apply_template
 // If the built-in template is not supported, we default to chatml
 // If the custom "tmpl" is not supported, we throw an error
-std::string common_chat_apply_template(const struct llama_model * model,
-        const std::string & tmpl,
+std::string common_chat_apply_template(
+        const llama_chat_template & tmpl,
         const std::vector<common_chat_msg> & chat,
-        bool add_ass);
+        bool add_ass,
+        bool use_jinja);
 
 // Format single message, while taking into account the position of that message in chat history
-std::string common_chat_format_single(const struct llama_model * model,
-        const std::string & tmpl,
+std::string common_chat_format_single(
+        const llama_chat_template & tmpl,
         const std::vector<common_chat_msg> & past_msg,
         const common_chat_msg & new_msg,
-        bool add_ass);
+        bool add_ass,
+        bool use_jinja);
 
 // Returns an example of formatted chat
-std::string common_chat_format_example(const struct llama_model * model,
-    const minja::chat_template & tmpl, bool use_jinja);
-
+std::string common_chat_format_example(
+    const llama_chat_template & tmpl, bool use_jinja);
 
 struct llama_chat_templates {
-    minja::chat_template default_template;
-    std::optional<minja::chat_template> tool_use_template;
+    llama_chat_template default_template;
+    std::optional<llama_chat_template> tool_use_template;
 };
 
 llama_chat_templates llama_chat_templates_from_model(const struct llama_model * model, const std::string & chat_template_override);

examples/main/main.cpp

@@ -84,14 +84,6 @@ static void sigint_handler(int signo) {
 }
 #endif
 
-static std::string chat_add_and_format(struct llama_model * model, std::vector<common_chat_msg> & chat_msgs, const std::string & role, const std::string & content) {
-    common_chat_msg new_msg{role, content};
-    auto formatted = common_chat_format_single(model, g_params->chat_template, chat_msgs, new_msg, role == "user");
-    chat_msgs.push_back({role, content});
-    LOG_DBG("formatted: '%s'\n", formatted.c_str());
-    return formatted;
-}
-
 int main(int argc, char ** argv) {
     common_params params;
     g_params = &params;
@@ -226,7 +218,7 @@ int main(int argc, char ** argv) {
     // print chat template example in conversation mode
     if (params.conversation_mode) {
         if (params.enable_chat_template) {
-            LOG_INF("%s: chat template example:\n%s\n", __func__, common_chat_format_example(model, chat_templates.default_template, params.use_jinja).c_str());
+            LOG_INF("%s: chat template example:\n%s\n", __func__, common_chat_format_example(chat_templates.default_template, params.use_jinja).c_str());
         } else {
             LOG_INF("%s: in-suffix/prefix is specified, chat template will be disabled\n", __func__);
         }
@@ -270,10 +262,18 @@ int main(int argc, char ** argv) {
 
     std::vector<llama_token> embd_inp;
 
+    auto chat_add_and_format = [&chat_msgs, &chat_templates](const std::string & role, const std::string & content) {
+        common_chat_msg new_msg{role, content};
+        auto formatted = common_chat_format_single(chat_templates.default_template, chat_msgs, new_msg, role == "user", g_params->use_jinja);
+        chat_msgs.push_back({role, content});
+        LOG_DBG("formatted: '%s'\n", formatted.c_str());
+        return formatted;
+    };
+
     {
         auto prompt = (params.conversation_mode && params.enable_chat_template)
             // format the system prompt in conversation mode (fallback to default if empty)
-            ? chat_add_and_format(model, chat_msgs, "system", params.prompt.empty() ? DEFAULT_SYSTEM_MESSAGE : params.prompt)
+            ? chat_add_and_format("system", params.prompt.empty() ? DEFAULT_SYSTEM_MESSAGE : params.prompt)
             // otherwise use the prompt as is
             : params.prompt;
         if (params.interactive_first || !params.prompt.empty() || session_tokens.empty()) {
@@ -780,7 +780,7 @@ int main(int argc, char ** argv) {
                     }
 
                     if (params.enable_chat_template) {
-                        chat_add_and_format(model, chat_msgs, "assistant", assistant_ss.str());
+                        chat_add_and_format("assistant", assistant_ss.str());
                     }
                     is_interacting = true;
                     LOG("\n");
@@ -845,7 +845,7 @@ int main(int argc, char ** argv) {
 
                     bool format_chat = params.conversation_mode && params.enable_chat_template;
                     std::string user_inp = format_chat
-                        ? chat_add_and_format(model, chat_msgs, "user", std::move(buffer))
+                        ? chat_add_and_format("user", std::move(buffer))
                         : std::move(buffer);
                     // TODO: one inconvenient of current chat template implementation is that we can't distinguish between user input and special tokens (prefix/postfix)
                     const auto line_pfx = common_tokenize(ctx, params.input_prefix, false, true);

examples/run/run.cpp

@@ -714,7 +714,7 @@ static void add_message(const char * role, const std::string & text, LlamaData &
 }
 
 // Function to apply the chat template and resize `formatted` if needed
-static int apply_chat_template(const minja::chat_template & tmpl, LlamaData & llama_data, const bool append, bool use_jinja) {
+static int apply_chat_template(const llama_chat_template & tmpl, LlamaData & llama_data, const bool append, bool use_jinja) {
     if (use_jinja) {
         json messages = json::array();
         for (const auto & msg : llama_data.messages) {
@@ -868,7 +868,7 @@ static int generate_response(LlamaData & llama_data, const std::string & prompt,
 }
 
 // Helper function to apply the chat template and handle errors
-static int apply_chat_template_with_error_handling(const minja::chat_template & tmpl, LlamaData & llama_data, const bool append, int & output_length, bool use_jinja) {
+static int apply_chat_template_with_error_handling(const llama_chat_template & tmpl, LlamaData & llama_data, const bool append, int & output_length, bool use_jinja) {
     const int new_len = apply_chat_template(tmpl, llama_data, append, use_jinja);
     if (new_len < 0) {
         printe("failed to apply the chat template\n");

examples/server/server.cpp

@@ -3869,7 +3869,7 @@ int main(int argc, char ** argv) {
         auto body = json::parse(req.body);
         const auto & templates = get_chat_templates();
         const auto & chat_template = body.contains("tools") && templates.tool_use_template ? *templates.tool_use_template : templates.default_template;
-        json data = oaicompat_completion_params_parse(ctx_server.model, body, chat_template, params.use_jinja);
+        json data = oaicompat_completion_params_parse(body, chat_template, params.use_jinja);
 
         return handle_completions_impl(
             SERVER_TASK_TYPE_COMPLETION,
@@ -4288,7 +4288,7 @@ int main(int argc, char ** argv) {
     // print sample chat example to make it clear which template is used
     LOG_INF("%s: chat template, chat_template: %s, example_format: '%s'\n", __func__,
         get_chat_templates().default_template.source().c_str(),
-        common_chat_format_example(ctx_server.model, get_chat_templates().default_template, ctx_server.params_base.use_jinja).c_str());
+        common_chat_format_example(get_chat_templates().default_template, ctx_server.params_base.use_jinja).c_str());
 
     ctx_server.queue_tasks.on_new_task(std::bind(
                 &server_context::process_single_task, &ctx_server, std::placeholders::_1));

examples/server/utils.hpp

@@ -351,7 +351,7 @@ static llama_tokens format_infill(
 }
 
 // Format given chat. If tmpl is empty, we take the template from model metadata
-inline std::string format_chat(const struct llama_model * model, const std::string & tmpl, const std::vector<json> & messages) {
+inline std::string format_chat(const llama_chat_template & tmpl, const std::vector<json> & messages) {
     std::vector<common_chat_msg> chat;
 
     for (size_t i = 0; i < messages.size(); ++i) {
@@ -379,7 +379,7 @@ inline std::string format_chat(const struct llama_model * model, const std::stri
         chat.push_back({role, content});
     }
 
-    const auto formatted_chat = common_chat_apply_template(model, tmpl, chat, true);
+    const auto formatted_chat = common_chat_apply_template(tmpl, chat, true, /* use_jinja= */ false);
     LOG_DBG("formatted_chat: '%s'\n", formatted_chat.c_str());
 
     return formatted_chat;
@@ -579,9 +579,8 @@ static json oaicompat_completion_params_parse(const json & body) {
 }
 
 static json oaicompat_completion_params_parse(
-    const struct llama_model * model,
     const json & body, /* openai api json semantics */
-    const minja::chat_template & tmpl,
+    const llama_chat_template & tmpl,
     bool use_jinja)
 {
     json llama_params;
@@ -622,7 +621,7 @@ static json oaicompat_completion_params_parse(
     if (use_jinja) {
         llama_params["prompt"] = tmpl.apply(body.at("messages"), tools, /* add_generation_prompt= */ true);
     } else {
-        llama_params["prompt"] = format_chat(model, tmpl.source(), body.at("messages"));
+        llama_params["prompt"] = format_chat(tmpl, body.at("messages"));
     }
 
     // Handle "n" field

tests/test-chat-template.cpp

@@ -8,6 +8,7 @@
 #include "llama.h"
 #include "common.h"
 #include "chat-template.hpp"
+#include "llama-chat.h"
 
 int main(void) {
     std::vector<llama_chat_message> conversation {
@@ -319,9 +320,10 @@ int main(void) {
     std::vector<common_chat_msg> chat2;
     common_chat_msg sys_msg{"system", "You are a helpful assistant"};
 
-    auto fmt_sys = [&](std::string tmpl) {
-        auto output = common_chat_format_single(nullptr, tmpl, chat2, sys_msg, false);
-        printf("fmt_sys(%s) : %s\n", tmpl.c_str(), output.c_str());
+    auto fmt_sys = [&](std::string tmpl_str) {
+        minja::chat_template tmpl(tmpl_str, "", "");
+        auto output = common_chat_format_single(tmpl, chat2, sys_msg, false, /* use_jinja= */ false);
+        printf("fmt_sys(%s) : %s\n", tmpl_str.c_str(), output.c_str());
         printf("-------------------------\n");
         return output;
     };
@@ -345,9 +347,10 @@ int main(void) {
     chat2.push_back({"assistant", "I am assistant"});
     common_chat_msg new_msg{"user", "How are you"};
 
-    auto fmt_single = [&](std::string tmpl) {
-        auto output = common_chat_format_single(nullptr, tmpl, chat2, new_msg, true);
-        printf("fmt_single(%s) : %s\n", tmpl.c_str(), output.c_str());
+    auto fmt_single = [&](std::string tmpl_str) {
+        minja::chat_template tmpl(tmpl_str, "", "");
+        auto output = common_chat_format_single(tmpl, chat2, new_msg, true, /* use_jinja= */ false);
+        printf("fmt_single(%s) : %s\n", tmpl_str.c_str(), output.c_str());
         printf("-------------------------\n");
         return output;
     };
@@ -362,5 +365,7 @@ int main(void) {
     assert(fmt_single("llama3") == "<|start_header_id|>user<|end_header_id|>\n\nHow are you<|eot_id|><|start_header_id|>assistant<|end_header_id|>\n\n");
     assert(fmt_single("gigachat") == "user<|role_sep|>How are you<|message_sep|>available functions<|role_sep|>[]<|message_sep|>assistant<|role_sep|>");
 
+    assert(llm_chat_detect_template(LLAMA_CHATML_TEMPLATE) == LLM_CHAT_TEMPLATE_CHATML);
+
     return 0;
 }