added json parsing support

added fall back json parsing support,
not stable yet, testing complex scenarios.

Author: dhandhalyabhavik

common/chat.cpp

@@ -1337,13 +1337,15 @@ static common_chat_params common_chat_params_init_glm_4_5(const common_chat_temp
 }
 
 static void common_chat_parse_glm_4_5(common_chat_msg_parser & builder) {
+    // consume initial spaces
     builder.consume_spaces();
     builder.try_parse_reasoning("<think>", "</think>");
     if (!builder.syntax().parse_tool_calls) {
         builder.add_content(builder.consume_rest());
         return;
     }
 
+    // GLM's XML tool calling, we also need fall back json parsing
     // GLM 4.5 uses format: <tool_call>function_name\n<arg_key>key</arg_key>\n<arg_value>value</arg_value>\n</tool_call>
     static const common_regex tool_call_start("<tool_call>([^\n<]+)");
     static const common_regex arg_key_regex("<arg_key>([^<]+)</arg_key>");
@@ -1384,6 +1386,75 @@ static void common_chat_parse_glm_4_5(common_chat_msg_parser & builder) {
         }
     }
 
+    // If XML fails, fall back to JSON parsing.
+    static const common_regex json_tool_calls_start("\\{[^}]*\"tool_calls\"\\s*:\\s*\\[");
+
+    if (auto res = builder.try_find_regex(json_tool_calls_start)) {
+        // Move to start of JSON and consume it
+        builder.move_to(res->groups[0].begin);
+        
+        // Define paths for extracting tool call data
+        static const std::vector<std::vector<std::string>> args_paths = {{"tool_calls", "arguments"}};
+        static const std::vector<std::vector<std::string>> content_paths = {{"content"}};
+        
+        auto json_result = builder.try_consume_json_with_dumped_args(args_paths, content_paths);
+        
+        if (json_result) {
+            // if partial skip
+            if (json_result->is_partial) {
+                throw common_chat_msg_partial_exception("incomplete tool call");
+            }
+            
+            // Handle content field if present
+            if (json_result->value.contains("content") && json_result->value.at("content").is_string()) {
+                std::string content = json_result->value.at("content");
+                builder.add_content(content);
+            }
+            
+            // Handle tool_calls array if present
+            if (json_result->value.contains("tool_calls") && json_result->value.at("tool_calls").is_array()) {
+                const auto& tool_calls_array = json_result->value.at("tool_calls");
+                
+                for (size_t i = 0; i < tool_calls_array.size(); i++) {
+                    const auto& tool_call = tool_calls_array[i];
+                    
+                    if (!tool_call.is_object()) {
+                        continue;
+                    }
+                    
+                    // Extract tool call fields
+                    std::string name = tool_call.contains("name") && tool_call.at("name").is_string() 
+                                     ? tool_call.at("name").get<std::string>() 
+                                     : "";
+                    std::string id = tool_call.contains("id") && tool_call.at("id").is_string() 
+                                   ? tool_call.at("id").get<std::string>() 
+                                   : "";
+                    std::string arguments = tool_call.contains("arguments") 
+                                          ? tool_call.at("arguments").dump()
+                                          : "{}";
+                    
+                    if (name.empty()) {
+                        continue;
+                    }
+                    
+                    // Add the tool call
+                    if (!builder.add_tool_call(name, id, arguments)) {
+                        if (json_result->is_partial) {
+                            throw common_chat_msg_partial_exception("incomplete JSON tool call");
+                        }
+                    }
+                }
+                
+                return; // Exit function after successful JSON parsing
+            }
+            
+            // If partial JSON without complete structure, throw exception
+            if (json_result->is_partial) {
+                throw common_chat_msg_partial_exception("incomplete JSON response");
+            }
+        }
+    }
+    
     builder.add_content(builder.consume_rest());
 }