server: fix streaming crashes (#13786)

* add preludes to content on partial regex match

* allow all parsers to parse non-tool-call content.

* tweak order of <|python_tag|> vs <function= parsing for functionary v3.1 format. still not ideal but hopefully less prone to crash

Author: ochafik

common/chat-parser.cpp

@@ -170,20 +170,23 @@ std::string common_chat_msg_parser::consume_rest() {
 }
 
 // Tries to find the regex, consumes it (pos right after it) and gives the prelude (right before it) and the groups to the callback.
-std::optional<common_chat_msg_parser::find_regex_result> common_chat_msg_parser::try_find_regex(const common_regex & regex, size_t from) {
+std::optional<common_chat_msg_parser::find_regex_result> common_chat_msg_parser::try_find_regex(const common_regex & regex, size_t from, bool add_prelude_to_content) {
     auto m = regex.search(input_, from == std::string::npos ? pos_ : from);
     if (m.type == COMMON_REGEX_MATCH_TYPE_NONE) {
         return std::nullopt;
     }
+    auto prelude = input_.substr(pos_, m.groups[0].begin - pos_);
+    pos_ = m.groups[0].end;
+
+    if (add_prelude_to_content) {
+        add_content(prelude);
+    }
     if (m.type == COMMON_REGEX_MATCH_TYPE_PARTIAL) {
         if (is_partial()) {
             throw common_chat_msg_partial_exception(regex.str());
         }
         return std::nullopt;
     }
-    auto prelude = input_.substr(pos_, m.groups[0].begin - pos_);
-    pos_ = m.groups[0].end;
-
     return find_regex_result{prelude, m.groups};
 }
 

common/chat-parser.h

@@ -30,6 +30,7 @@ class common_chat_msg_parser {
     const std::string & healing_marker() const { return healing_marker_; }
     const bool & is_partial() const { return is_partial_; }
     const common_chat_msg & result() const { return result_; }
+    const common_chat_syntax & syntax() const { return syntax_; }
 
     void move_to(size_t pos) {
         if (pos > input_.size()) {
@@ -77,7 +78,7 @@ class common_chat_msg_parser {
         std::vector<common_string_range> groups;
     };
 
-    std::optional<find_regex_result> try_find_regex(const common_regex & regex, size_t from = std::string::npos);
+    std::optional<find_regex_result> try_find_regex(const common_regex & regex, size_t from = std::string::npos, bool add_prelude_to_content = true);
 
     bool try_consume_literal(const std::string & literal);
 

common/chat.cpp

@@ -656,7 +656,6 @@ static void parse_json_tool_calls(
                 }
                 from = std::string::npos;
 
-                builder.add_content(res->prelude);
                 auto maybe_raw_python = name == "python" && allow_raw_python;
                 if (builder.input()[builder.pos()] == '{' || !maybe_raw_python) {
                     if (auto arguments = builder.try_consume_json_with_dumped_args({{}})) {
@@ -686,7 +685,6 @@ static void parse_json_tool_calls(
     };
     if (block_open) {
         if (auto res = builder.try_find_regex(*block_open)) {
-            builder.add_content(res->prelude);
             parse_tool_calls();
         } else {
             builder.add_content(builder.consume_rest());
@@ -699,7 +697,6 @@ static void parse_json_tool_calls(
 static void parse_prefixed_json_tool_call_array(common_chat_msg_parser & builder, const common_regex & prefix, size_t rstrip_prefix = 0) {
     static const std::vector<std::vector<std::string>> args_paths = {{"arguments"}};
     if (auto res = builder.try_find_regex(prefix)) {
-        builder.add_content(res->prelude);
         builder.move_back(rstrip_prefix);
         auto tool_calls = builder.consume_json_with_dumped_args(args_paths);
         if (!builder.add_tool_calls(tool_calls.value) || tool_calls.is_partial) {
@@ -835,6 +832,10 @@ static common_chat_params common_chat_params_init_generic(const common_chat_temp
     return data;
 }
 static void common_chat_parse_generic(common_chat_msg_parser & builder) {
+    if (!builder.syntax().parse_tool_calls) {
+        builder.add_content(builder.consume_rest());
+        return;
+    }
     static const std::vector<std::vector<std::string>> content_paths = {
         {"response"},
     };
@@ -907,6 +908,11 @@ static common_chat_params common_chat_params_init_mistral_nemo(const common_chat
     return data;
 }
 static void common_chat_parse_mistral_nemo(common_chat_msg_parser & builder) {
+    if (!builder.syntax().parse_tool_calls) {
+        builder.add_content(builder.consume_rest());
+        return;
+    }
+
     static const common_regex prefix(regex_escape("[TOOL_CALLS]"));
     parse_prefixed_json_tool_call_array(builder, prefix);
 }
@@ -1001,7 +1007,6 @@ static void common_chat_parse_command_r7b(common_chat_msg_parser & builder) {
 
     if (auto res = builder.try_find_regex(start_action_regex)) {
         // If we didn't extract thoughts, prelude includes them.
-        builder.add_content(res->prelude);
         auto tool_calls = builder.consume_json_with_dumped_args({{"parameters"}});
         for (const auto & tool_call : tool_calls.value) {
             std::string name = tool_call.contains("tool_name") ? tool_call.at("tool_name") : "";
@@ -1016,11 +1021,7 @@ static void common_chat_parse_command_r7b(common_chat_msg_parser & builder) {
         }
         builder.consume_regex(end_action_regex);
     } else if (auto res = builder.try_find_regex(start_response_regex)) {
-        // If we didn't extract thoughts, prelude includes them.
-        builder.add_content(res->prelude);
-        if (auto res = builder.try_find_regex(end_response_regex)) {
-            builder.add_content(res->prelude);
-        } else {
+        if (!builder.try_find_regex(end_response_regex)) {
             builder.add_content(builder.consume_rest());
             throw common_chat_msg_partial_exception(end_response_regex.str());
         }
@@ -1128,6 +1129,11 @@ static common_chat_params common_chat_params_init_llama_3_x(const common_chat_te
     return data;
 }
 static void common_chat_parse_llama_3_1(common_chat_msg_parser & builder, bool with_builtin_tools = false) {
+    if (!builder.syntax().parse_tool_calls) {
+        builder.add_content(builder.consume_rest());
+        return;
+    }
+
     static const common_regex function_regex(
         "\\s*\\{\\s*(?:\"type\"\\s*:\\s*\"function\"\\s*,\\s*)?\"name\"\\s*:\\s*\"([^\"]+)\"\\s*,\\s*\"parameters\"\\s*: ");
     static const common_regex close_regex("\\}\\s*");
@@ -1138,8 +1144,6 @@ static void common_chat_parse_llama_3_1(common_chat_msg_parser & builder, bool w
     if (with_builtin_tools) {
         static const common_regex builtin_call_regex("<\\|python_tag\\|>");
         if (auto res = builder.try_find_regex(builtin_call_regex)) {
-            builder.add_content(res->prelude);
-
             auto fun_res = builder.consume_regex(function_name_regex);
             auto function_name = builder.str(fun_res.groups[1]);
 
@@ -1255,6 +1259,10 @@ static common_chat_params common_chat_params_init_deepseek_r1(const common_chat_
 }
 static void common_chat_parse_deepseek_r1(common_chat_msg_parser & builder) {
     builder.try_parse_reasoning("<think>", "</think>");
+    if (!builder.syntax().parse_tool_calls) {
+        builder.add_content(builder.consume_rest());
+        return;
+    }
 
     static const common_regex tool_calls_begin("(?:<｜tool▁calls▁begin｜>|<｜tool_calls_begin｜>|<｜tool calls begin｜>|<｜tool\\\\_calls\\\\_begin｜>|<｜tool▁calls｜>)");
     static const common_regex tool_calls_end("<｜tool▁calls▁end｜>");
@@ -1316,6 +1324,10 @@ static common_chat_params common_chat_params_init_firefunction_v2(const common_c
     return data;
 }
 static void common_chat_parse_firefunction_v2(common_chat_msg_parser & builder) {
+    if (!builder.syntax().parse_tool_calls) {
+        builder.add_content(builder.consume_rest());
+        return;
+    }
     static const common_regex prefix(regex_escape(" functools["));
     parse_prefixed_json_tool_call_array(builder, prefix, /* rstrip_prefix= */ 1);
 }
@@ -1457,15 +1469,12 @@ static common_chat_params common_chat_params_init_functionary_v3_1_llama_3_1(con
     return data;
 }
 static void common_chat_parse_functionary_v3_1_llama_3_1(common_chat_msg_parser & builder) {
-    // This version of Functionary still supports the llama 3.1 tool call format for the python tool.
-    static const common_regex python_tag_regex(regex_escape("<|python_tag|>"));
-
-    if (auto res = builder.try_find_regex(python_tag_regex)) {
-        builder.add_content(res->prelude);
-        auto arguments = wrap_code_as_arguments(builder, builder.consume_rest());
-        builder.add_tool_call("python", "", arguments);
+    if (!builder.syntax().parse_tool_calls) {
+        builder.add_content(builder.consume_rest());
         return;
     }
+    // This version of Functionary still supports the llama 3.1 tool call format for the python tool.
+    static const common_regex python_tag_regex(regex_escape("<|python_tag|>"));
 
     static const common_regex function_regex(R"(<function=(\w+)>)");
     static const common_regex close_regex(R"(</function>)");
@@ -1477,6 +1486,12 @@ static void common_chat_parse_functionary_v3_1_llama_3_1(common_chat_msg_parser
         function_regex,
         close_regex,
         std::nullopt);
+
+    if (auto res = builder.try_find_regex(python_tag_regex)) {
+        auto arguments = wrap_code_as_arguments(builder, builder.consume_rest());
+        builder.add_tool_call("python", "", arguments);
+        return;
+    }
 }
 
 static common_chat_params common_chat_params_init_hermes_2_pro(const common_chat_template & tmpl, const struct templates_params & inputs) {
@@ -1595,6 +1610,10 @@ static common_chat_params common_chat_params_init_hermes_2_pro(const common_chat
 }
 static void common_chat_parse_hermes_2_pro(common_chat_msg_parser & builder) {
     builder.try_parse_reasoning("<think>", "</think>");
+    if (!builder.syntax().parse_tool_calls) {
+        builder.add_content(builder.consume_rest());
+        return;
+    }
 
     static const common_regex open_regex(
         "(?:"
@@ -1616,8 +1635,6 @@ static void common_chat_parse_hermes_2_pro(common_chat_msg_parser & builder) {
     );
 
     if (auto res = builder.try_find_regex(open_regex)) {
-        builder.add_content(res->prelude);
-
         const auto & block_start = res->groups[1];
         std::string block_end = block_start.empty() ? "" : "```";
 
@@ -1853,10 +1870,10 @@ static void common_chat_parse_content_only(common_chat_msg_parser & builder) {
     builder.add_content(builder.consume_rest());
 }
 
-static void common_chat_parse(common_chat_msg_parser & builder, common_chat_format format) {
-    LOG_DBG("Parsing input with format %s: %s\n", common_chat_format_name(format), builder.input().c_str());
+static void common_chat_parse(common_chat_msg_parser & builder) {
+    LOG_DBG("Parsing input with format %s: %s\n", common_chat_format_name(builder.syntax().format), builder.input().c_str());
 
-    switch (format) {
+    switch (builder.syntax().format) {
         case COMMON_CHAT_FORMAT_CONTENT_ONLY:
             common_chat_parse_content_only(builder);
             break;
@@ -1891,15 +1908,15 @@ static void common_chat_parse(common_chat_msg_parser & builder, common_chat_form
             common_chat_parse_command_r7b(builder);
             break;
         default:
-            throw std::runtime_error(std::string("Unsupported format: ") + common_chat_format_name(format));
+            throw std::runtime_error(std::string("Unsupported format: ") + common_chat_format_name(builder.syntax().format));
     }
     builder.finish();
 }
 
 common_chat_msg common_chat_parse(const std::string & input, bool is_partial, const common_chat_syntax & syntax) {
     common_chat_msg_parser builder(input, is_partial, syntax);
     try {
-        common_chat_parse(builder, syntax.format);
+        common_chat_parse(builder);
     } catch (const common_chat_msg_partial_exception & ex) {
         LOG_DBG("Partial parse: %s\n", ex.what());
         if (!is_partial) {

common/chat.h

@@ -144,6 +144,7 @@ struct common_chat_syntax {
     // Whether reasoning_content should be inlined in the content (e.g. for reasoning_format=deepseek in stream mode)
     bool                     reasoning_in_content  = false;
     bool                     thinking_forced_open  = false;
+    bool                     parse_tool_calls      = true;
 };
 
 // Check if the template supplied via "--chat-template" is supported or not. Returns true if it's valid