add xbasic interpreter implementation

Signed-off-by: Avinal Kumar <avinal.xlvii@gmail.com>

src/main.cc

@@ -0,0 +1,19 @@
+#include <memory>
+
+#include "xbasic/xbasic_interpreter.hpp"
+#include "xeus/xkernel.hpp"
+#include "xeus/xkernel_configuration.hpp"
+int main(int argc, char const *argv[]) {
+  // Load configuration file
+  std::string file_name = (argc == 1) ? "connection.json" : argv[2];
+  xeus::xconfiguration config = xeus::load_configuration(file_name);
+
+  // Create interpreter instance
+  using interpreter_ptr = std::unique_ptr<xbasic::xbasic_interpreter>;
+  interpreter_ptr interpreter = std::make_unique<xbasic::xbasic_interpreter>();
+
+  // Create kernel instance and start it
+  xeus::xkernel kernel(config, xeus::get_user_name(), std::move(interpreter));
+  kernel.start();
+  return 0;
+}

src/xbasic_interpreter.cpp

@@ -0,0 +1,90 @@
+#include "xbasic/xbasic_interpreter.hpp"
+
+std::string basic::output = "";
+
+namespace xbasic {
+
+  nl::json xbasic_interpreter::execute_request_impl(int execution_counter, const std::string &code,
+                                                    bool silent, bool store_history,
+                                                    nl::json user_expressions, bool allow_stdin) {
+    auto ok = []() {
+      nl::json result;
+      result["status"] = "ok";
+      return result;
+    };
+
+    std::vector<std::string> traceback;
+    auto handle_exception = [&](std::string what) {
+      nl::json result;
+      result["status"] = "error";
+      result["ename"] = "Error";
+      result["evalue"] = what;
+      traceback.push_back((std::string)result["ename"] + ": " + what);
+      publish_execution_error(result["ename"], result["evalue"], traceback);
+      traceback.clear();
+      return result;
+    };
+
+    nl::json pub_data;
+    try {
+      if (code_runner.evaluate_line(code)) {
+        pub_data["text/plain"] = code_runner.run();
+        code_runner.clear_output();
+        publish_execution_result(execution_counter, std::move(pub_data), nl::json::object());
+        return ok();
+      } else {
+        throw(code_runner.get_error());
+      }
+    } catch (const std::exception &err) {
+      return handle_exception(err.what());
+    }
+    return ok();
+  }
+
+  nl::json xbasic_interpreter::complete_request_impl(const std::string &code, int cursor_pos) {
+    nl::json result;
+    result["status"] = "ok";
+    return result;
+  }
+
+  nl::json xbasic_interpreter::inspect_request_impl(const std::string &code, int cursor_pos,
+                                                    int detail_level) {
+    nl::json result;
+    result["status"] = "ok";
+    return result;
+  }
+
+  nl::json xbasic_interpreter::is_complete_request_impl(const std::string &code) {
+    nl::json result;
+    result["status"] = "complete";
+    return result;
+  }
+
+  void xbasic_interpreter::configure_impl() {}
+
+  nl::json xbasic_interpreter::kernel_info_request_impl() {
+    nl::json info;
+    info["implementation"] = "xbasic";
+    info["implementation_version"] = "0.1.0";
+    std::string banner = R"V0G0N(
+                `7MM***Yy.     db       .M***by. `7MMF'  .g8***bg.
+                  MM    Yb    ;MM:     ,MI    `Y   MM  .dP'     `M
+     `7M'   `MF'  MM    .P   ,V^MM.    `MMb.       MM  dM'       `
+       `VA ,V'    MMooon*   ,M  `MM      `YMMNq.   MM  MM
+         XMX      MM    `Y. AbmmmqMA   .     `MM   MM  MM.        
+       ,V' VA.    MM    ,9 A'     VML  Mb     dM   MM  `Mb.     .'
+     .AM.   .MA..JMMonal.AMA.   .AMMA.`*Ybmmd*  .JMML.  `*bMond^
+                                                                   
+      xeus-basic: a Jupyter Kernel for BASIC Language
+      xBASIC Version: 0.1.0")V0G0N";
+    info["banner"] = banner;
+    info["language_info"]["name"] = "basic";
+    info["langauge_info"]["codemirror_mode"] = "vb";
+    info["language_info"]["version"] = "0.1.0";
+    info["language_info"]["mimetype"] = "text/x-vb";
+    info["language_info"]["file_extension"] = ".bas";
+    return info;
+  }
+
+  void xbasic_interpreter::shutdown_request_impl() {}
+}  // namespace xbasic