server: extract <think> tags from qwq outputs (#12297)

* extract <think> tags from qwq outputs

* const for all static regexes in chat.cpp

common/chat.cpp

@@ -445,6 +445,7 @@ std::string common_chat_format_name(common_chat_format format) {
         case COMMON_CHAT_FORMAT_FUNCTIONARY_V3_2: return "Functionary v3.2";
         case COMMON_CHAT_FORMAT_FUNCTIONARY_V3_1_LLAMA_3_1: return "Functionary v3.1 Llama 3.1";
         case COMMON_CHAT_FORMAT_HERMES_2_PRO: return "Hermes 2 Pro";
+        case COMMON_CHAT_FORMAT_HERMES_2_PRO_EXTRACT_REASONING: return "Hermes 2 Pro (extract reasoning)";
         case COMMON_CHAT_FORMAT_COMMAND_R7B: return "Command R7B";
         case COMMON_CHAT_FORMAT_COMMAND_R7B_EXTRACT_REASONING: return "Command R7B (extract reasoning)";
         default:
@@ -878,9 +879,9 @@ static common_chat_params common_chat_params_init_command_r7b(const common_chat_
     return data;
 }
 static common_chat_msg common_chat_parse_command_r7b(const std::string & input, bool extract_reasoning) {
-    static std::regex thought_regex("(<\\|START_THINKING\\|>([\\s\\S]*?)<\\|END_THINKING\\|>)([\\s\\S]*)");
+    static const std::regex thought_regex("(<\\|START_THINKING\\|>([\\s\\S]*?)<\\|END_THINKING\\|>)([\\s\\S]*)");
-    static std::regex action_regex("<\\|START_ACTION\\|>([\\s\\S]*?)<\\|END_ACTION\\|>");
+    static const std::regex action_regex("<\\|START_ACTION\\|>([\\s\\S]*?)<\\|END_ACTION\\|>");
-    static std::regex response_regex("(?:<\\|START_RESPONSE\\|>)?([\\s\\S]*?)<\\|END_RESPONSE\\|>");
+    static const std::regex response_regex("(?:<\\|START_RESPONSE\\|>)?([\\s\\S]*?)<\\|END_RESPONSE\\|>");
 
     std::smatch match;
 
@@ -1012,10 +1013,10 @@ static common_chat_params common_chat_params_init_llama_3_1_tool_calls(const com
 }
 static common_chat_msg common_chat_parse_llama_3_1(const std::string & input, bool with_builtin_tools = false) {
     // TODO: tighten & simplify the parser, don't accept leading text context.
-    static std::regex function_regex(
+    static const std::regex function_regex(
         "\\s*\\{\\s*(?:\"type\"\\s*:\\s*\"function\"\\s*,\\s*)?\"name\"\\s*:\\s*\"([^\"]+)\"\\s*,\\s*\"parameters\"\\s*: ");
-    static std::regex close_regex("\\}\\s*");
+    static const std::regex close_regex("\\}\\s*");
-    static std::regex builtin_call_regex("<\\|python_tag\\|>\\s*([^.(]+)\\s*\\.\\s*call\\s*\\(\\s*([\\w]+)\\s*=\\s*([\\s\\S]*?)\\)");
+    static const std::regex builtin_call_regex("<\\|python_tag\\|>\\s*([^.(]+)\\s*\\.\\s*call\\s*\\(\\s*([\\w]+)\\s*=\\s*([\\s\\S]*?)\\)");
 
     if (with_builtin_tools) {
         std::smatch match;
@@ -1105,34 +1106,42 @@ static common_chat_params common_chat_params_init_deepseek_r1(const common_chat_
     data.format = inputs.extract_reasoning ? COMMON_CHAT_FORMAT_DEEPSEEK_R1_EXTRACT_REASONING : COMMON_CHAT_FORMAT_DEEPSEEK_R1;
     return data;
 }
+static common_chat_msg handle_think_tag_prelude(const std::string & input, bool extract_reasoning, const std::function<common_chat_msg(const std::string &)> & rest_parser) {
+    std::smatch match;
+    static const std::regex reasoning_content_regex("((?:<think>)?([\\s\\S\\r\\n]*?)</think>)?([\\s\\S\\r\\n]*)");
+    if (std::regex_match(input, match, reasoning_content_regex)) {
+        auto rest = match[3].str();
+        auto msg = rest_parser(rest);
+        auto reasoning_content = string_strip(match[2].str());
+        if (extract_reasoning) {
+            msg.reasoning_content = reasoning_content;
+        } else if (!reasoning_content.empty()) {
+            std::ostringstream content;
+            content << "<think>" << reasoning_content << "</think>" << msg.content;
+            msg.content = content.str();
+        }
+        return msg;
+    }
+    return rest_parser(input);
+}
 static common_chat_msg common_chat_parse_deepseek_r1(const std::string & input, bool extract_reasoning) {
-    static std::regex function_regex("<｜tool▁call▁begin｜>function<｜tool▁sep｜>([^\n]+)\n```json\n");
+    return handle_think_tag_prelude(input, extract_reasoning, [](const std::string & input) {
-    static std::regex close_regex("```[\\s\\r\\n]*<｜tool▁call▁end｜>");
+        static const std::regex function_regex("<｜tool▁call▁begin｜>function<｜tool▁sep｜>([^\n]+)\n```json\n");
-    static std::regex reasoning_content_regex("((?:<think>)?([\\s\\S\\r\\n]*?)</think>)?([\\s\\S\\r\\n]*)");
+        static const std::regex close_regex("```[\\s\\r\\n]*<｜tool▁call▁end｜>");
-    static std::regex tool_calls_regex("[\\s\\r\\n]*(?:<｜tool▁calls▁begin｜>|<｜tool_calls_begin｜>|<｜tool calls begin｜>|<｜tool\\\\_calls\\\\_begin｜>)([\\s\\S\\r\\n]*?)<｜tool▁calls▁end｜>");
+        static const std::regex tool_calls_regex("[\\s\\r\\n]*(?:<｜tool▁calls▁begin｜>|<｜tool_calls_begin｜>|<｜tool calls begin｜>|<｜tool\\\\_calls\\\\_begin｜>)([\\s\\S\\r\\n]*?)<｜tool▁calls▁end｜>");
+
         common_chat_msg msg;
         msg.role = "assistant";
         std::smatch match;
-    if (std::regex_match(input, match, reasoning_content_regex)) {
+        if (std::regex_search(input, match, tool_calls_regex)) {
-        std::string rest;
-        if (extract_reasoning) {
-            msg.reasoning_content = string_strip(match[2].str());
-        } else {
-            msg.content = match[1].str();
-        }
-        rest = match[3].str();
-
-        if (std::regex_search(rest, match, tool_calls_regex)) {
             auto tool_calls = match[1].str();
             auto msg2 = parse_json_tool_calls(tool_calls, std::nullopt, function_regex, close_regex);
             msg.tool_calls = std::move(msg2.tool_calls);
-        } else {
-            msg.content += std::string(rest.begin() + rest.find_first_not_of(" \r\n"), rest.end());
-        }
         } else {
             msg.content = input;
         }
         return msg;
+    });
 }
 
 static common_chat_params common_chat_params_init_firefunction_v2(const common_chat_template & tmpl, const struct templates_params & inputs) {
@@ -1237,8 +1246,8 @@ static common_chat_params common_chat_params_init_functionary_v3_2(const common_
 }
 
 static common_chat_msg common_chat_parse_functionary_v3_2(const std::string & input) {
-    static std::regex function_regex(R"((?:>>>)?(?:assistant<|end_header_id|>\n)?(\w+)\n)");
+    static const std::regex function_regex(R"((?:>>>)?(?:assistant<|end_header_id|>\n)?(\w+)\n)");
-    static std::regex close_regex(R"($|(?=>>>))");
+    static const std::regex close_regex(R"($|(?=>>>))");
 
     std::string content;
     auto it = input.begin();
@@ -1327,7 +1336,7 @@ static common_chat_params common_chat_params_init_functionary_v3_1_llama_3_1(con
 }
 static common_chat_msg common_chat_parse_functionary_v3_1_llama_3_1(const std::string & input) {
     // This version of Functionary still supports the llama 3.1 tool call format for the python tool.
-    static std::regex python_tag_regex(R"(<\|python_tag\|>([\s\S\n]*)$)");
+    static const std::regex python_tag_regex(R"(<\|python_tag\|>([\s\S\n]*)$)");
     std::smatch match;
     if (std::regex_search(input, match, python_tag_regex)) {
         auto code = match[1].str();
@@ -1341,8 +1350,8 @@ static common_chat_msg common_chat_parse_functionary_v3_1_llama_3_1(const std::s
         });
         return msg;
     }
-    static std::regex function_regex(R"(<function=(\w+)>)");
+    static const std::regex function_regex(R"(<function=(\w+)>)");
-    static std::regex close_regex(R"(</function>)");
+    static const std::regex close_regex(R"(</function>)");
     // TODO: tighten & simplify.
     return parse_json_tool_calls(input, std::nullopt, function_regex, close_regex);
 }
@@ -1409,6 +1418,8 @@ static common_chat_params common_chat_params_init_hermes_2_pro(const common_chat
             "(?:```(?:json|xml)?\n\\s*)?(?:<function_call>|<tools>|<xml><json>|<response>)?\\s*\\{\\s*\"", //name\"\\s*:\\s*\"" + escaped_name + "\"",
         });
         data.preserved_tokens = {
+            "<think>",
+            "</think>",
             "<tool_call>",
             "</tool_call>",
             "<function",
@@ -1429,11 +1440,12 @@ static common_chat_params common_chat_params_init_hermes_2_pro(const common_chat
     });
 
     data.prompt = apply(tmpl, inputs.messages, inputs.tools.empty() ? json() : inputs.tools, inputs.add_generation_prompt);
-    data.format = COMMON_CHAT_FORMAT_HERMES_2_PRO;
+    data.format = inputs.extract_reasoning ? COMMON_CHAT_FORMAT_HERMES_2_PRO_EXTRACT_REASONING : COMMON_CHAT_FORMAT_HERMES_2_PRO;
     return data;
 }
-static common_chat_msg common_chat_parse_hermes_2_pro(const std::string& input) {
+static common_chat_msg common_chat_parse_hermes_2_pro(const std::string& input, bool extract_reasoning) {
-    const static std::regex open_regex(
+    return handle_think_tag_prelude(input, extract_reasoning, [](const std::string & input) {
+        static const std::regex open_regex(
             "(?:"
             "(```(?:xml|json)?\\n\\s*)?"         // match 1 (block_start)
             "(<tool_call>"                   // match 2 (open_tag)
@@ -1454,7 +1466,6 @@ static common_chat_msg common_chat_parse_hermes_2_pro(const std::string& input)
         );
 
         try {
-
             common_chat_msg msg;
             msg.role = "assistant";
 
@@ -1545,6 +1556,7 @@ static common_chat_msg common_chat_parse_hermes_2_pro(const std::string& input)
             msg.content = input;
             return msg;
         }
+    });
 }
 
 static common_chat_params common_chat_params_init_without_tools(const common_chat_template & tmpl, const struct templates_params & inputs) {
@@ -1609,6 +1621,11 @@ static common_chat_params common_chat_templates_apply_jinja(
         return common_chat_params_init_command_r7b(tmpl, params);
     }
 
+    // Hermes 2/3 Pro, Qwen 2.5 Instruct (w/ tools)
+    if (src.find("<tool_call>") != std::string::npos && params.json_schema.is_null()) {
+        return common_chat_params_init_hermes_2_pro(tmpl, params);
+    }
+
     // Use generic handler when mixing tools + JSON schema.
     // TODO: support that mix in handlers below.
     if ((params.tools.is_array() && params.json_schema.is_object())) {
@@ -1630,11 +1647,6 @@ static common_chat_params common_chat_templates_apply_jinja(
         return common_chat_params_init_without_tools(tmpl, params);
     }
 
-    // Hermes 2/3 Pro, Qwen 2.5 Instruct (w/ tools)
-    if (src.find("<tool_call>") != std::string::npos) {
-        return common_chat_params_init_hermes_2_pro(tmpl, params);
-    }
-
     // Functionary v3.1 (w/ tools)
     if (src.find("<|start_header_id|>") != std::string::npos
         && src.find("<function=") != std::string::npos) {
@@ -1752,7 +1764,9 @@ common_chat_msg common_chat_parse(const std::string & input, common_chat_format
         case COMMON_CHAT_FORMAT_FUNCTIONARY_V3_1_LLAMA_3_1:
             return common_chat_parse_functionary_v3_1_llama_3_1(input);
         case COMMON_CHAT_FORMAT_HERMES_2_PRO:
-            return common_chat_parse_hermes_2_pro(input);
+            return common_chat_parse_hermes_2_pro(input, /* extract_reasoning= */ false);
+        case COMMON_CHAT_FORMAT_HERMES_2_PRO_EXTRACT_REASONING:
+            return common_chat_parse_hermes_2_pro(input, /* extract_reasoning= */ true);
         case COMMON_CHAT_FORMAT_FIREFUNCTION_V2:
             return common_chat_parse_firefunction_v2(input);
         case COMMON_CHAT_FORMAT_COMMAND_R7B:

common/chat.h

@@ -53,6 +53,7 @@ enum common_chat_format {
     COMMON_CHAT_FORMAT_FUNCTIONARY_V3_2,
     COMMON_CHAT_FORMAT_FUNCTIONARY_V3_1_LLAMA_3_1,
     COMMON_CHAT_FORMAT_HERMES_2_PRO,
+    COMMON_CHAT_FORMAT_HERMES_2_PRO_EXTRACT_REASONING,
     COMMON_CHAT_FORMAT_COMMAND_R7B,
     COMMON_CHAT_FORMAT_COMMAND_R7B_EXTRACT_REASONING,
 

tests/test-chat.cpp

@@ -766,6 +766,19 @@ static void test_template_output_parsers() {
             "{\n  \"name\": \"special_function\", \"arguments\": {\"arg1\": 1}}",
             COMMON_CHAT_FORMAT_HERMES_2_PRO));
 
+        assert_msg_equals(message_assist_thoughts_unparsed_think,
+            common_chat_parse("<think>I'm thinking</think>Hello, world!\nWhat's up?",
+            COMMON_CHAT_FORMAT_HERMES_2_PRO));
+        assert_msg_equals(message_assist_thoughts_unparsed_think,
+            common_chat_parse("I'm thinking</think>Hello, world!\nWhat's up?",
+            COMMON_CHAT_FORMAT_HERMES_2_PRO));
+        assert_msg_equals(message_assist_thoughts,
+            common_chat_parse("<think>I'm thinking</think>Hello, world!\nWhat's up?",
+            COMMON_CHAT_FORMAT_HERMES_2_PRO_EXTRACT_REASONING));
+        assert_msg_equals(message_assist_thoughts,
+            common_chat_parse("I'm thinking</think>Hello, world!\nWhat's up?",
+            COMMON_CHAT_FORMAT_HERMES_2_PRO_EXTRACT_REASONING));
+
         test_templates(tmpls.get(), end_tokens, message_assist, tools, "Hello, world!\nWhat's up?", /* expect_grammar_triggered= */ false);
         test_templates(tmpls.get(), end_tokens, message_assist_call, tools,
                       "<tool_call>\n"