upd: update input method

src/main.cpp

@@ -4,18 +4,42 @@
 #include "antlr4-runtime.h"
 #include <iostream>
 #include "int2048/int2048.h"
+#include "clipp/clipp.h"
 using namespace antlr4;
 // TODO: regenerating files in directory named "generated" is dangerous.
 //       if you really need to regenerate,please ask TA for help.
-int main(int argc, const char *argv[]) {
-	// TODO: please don't modify the code below the construction of ifs if you want to use visitor mode
-	ANTLRInputStream input(std::cin);
-	Python3Lexer lexer(&input);
-	CommonTokenStream tokens(&lexer);
-	tokens.fill();
-	Python3Parser parser(&tokens);
-	tree::ParseTree *tree = parser.file_input();
-	EvalVisitor visitor;
-	visitor.visit(tree);
-	return 0;
+int main(int argc, char *argv[])
+{
+  // TODO: please don't modify the code below the construction of ifs if you want to use visitor mode
+  std::string input_file;
+  bool need_help = false;
+  auto cli = (clipp::option("-h", "--help").set(need_help).doc("show help") |
+              clipp::opt_value("input file", input_file));
+  if (!clipp::parse(argc, argv, cli))
+  {
+    std::cout << clipp::make_man_page(cli, argv[0]);
+    return 0;
+  }
+  if (need_help)
+  {
+    std::cout << clipp::make_man_page(cli, argv[0]);
+    return 0;
+  }
+  ANTLRInputStream *input_p;
+  if (input_file.length() == 0)
+    input_p = new ANTLRInputStream(std::cin);
+  else
+  {
+    std::ifstream ifs(input_file);
+    input_p = new ANTLRInputStream(ifs);
+  }
+  Python3Lexer lexer(input_p);
+  CommonTokenStream tokens(&lexer);
+  tokens.fill();
+  Python3Parser parser(&tokens);
+  tree::ParseTree *tree = parser.file_input();
+  EvalVisitor visitor;
+  visitor.visit(tree);
+  delete input_p;
+  return 0;
 }