diff --git a/main.cpp b/main.cpp
index d712896..4179578 100644
--- a/main.cpp
+++ b/main.cpp
@@ -1,20 +1,18 @@
 #include "nasal.h"
 
-nasal_resource resource;
 nasal_lexer    lexer;
 nasal_parse    parse;
 nasal_import   preprocessor;
 nasal_codegen  code_generator;
-std::string    command;
 std::string    inputfile="null";
 nasal_runtime  runtime;
 
 void help()
 {
 	std::cout<<">> [\"file\"] input a file name.\n";
+	std::cout<<">> [help  ] show help.\n";
 	std::cout<<">> [clear ] clear the screen.\n";
 	std::cout<<">> [del   ] clear the input filename.\n";
-	std::cout<<">> [rs    ] print source code.\n";
 	std::cout<<">> [lex   ] use lexer to turn code into tokens.\n";
 	std::cout<<">> [ast   ] do parsing and check the abstract syntax tree.\n";
 	std::cout<<">> [run   ] run abstract syntax tree.\n";
@@ -37,7 +35,6 @@ void logo()
 
 void del_func()
 {
-	resource.clear();
 	lexer.clear();
 	parse.clear();
 	inputfile="null";
@@ -53,12 +50,8 @@ void die(std::string stage,std::string filename)
 
 void lex_func()
 {
-	if(!resource.input_file(inputfile))
-	{
-		die("resource",inputfile);
-		return;
-	}
-	lexer.scanner(resource.get_file());
+	lexer.openfile(inputfile);
+	lexer.scanner();
 	if(lexer.get_error())
 	{
 		die("lexer",inputfile);
@@ -70,12 +63,8 @@ void lex_func()
 
 void ast_print()
 {
-	if(!resource.input_file(inputfile))
-	{
-		die("resource",inputfile);
-		return;
-	}
-	lexer.scanner(resource.get_file());
+	lexer.openfile(inputfile);
+	lexer.scanner();
 	if(lexer.get_error())
 	{
 		die("lexer",inputfile);
@@ -93,12 +82,8 @@ void ast_print()
 }
 void runtime_start()
 {
-	if(!resource.input_file(inputfile))
-	{
-		die("resource",inputfile);
-		return;
-	}
-	lexer.scanner(resource.get_file());
+	lexer.openfile(inputfile);
+	lexer.scanner();
 	if(lexer.get_error())
 	{
 		die("lexer",inputfile);
@@ -124,12 +109,8 @@ void runtime_start()
 
 void codegen_start()
 {
-	if(!resource.input_file(inputfile))
-	{
-		die("resource",inputfile);
-		return;
-	}
-	lexer.scanner(resource.get_file());
+	lexer.openfile(inputfile);
+	lexer.scanner();
 	if(lexer.get_error())
 	{
 		die("lexer",inputfile);
@@ -173,6 +154,7 @@ void execution_start()
 
 int main()
 {
+	std::string command;
 #ifdef _WIN32
 	// use chcp 65001 to use unicode io
 	system("chcp 65001");
@@ -213,11 +195,6 @@ int main()
 		}
 		else if(command=="del")
 			del_func();
-		else if(command=="rs")
-		{
-			if(resource.input_file(inputfile))
-				resource.print_file();
-		}
 		else if(command=="lex")
 			lex_func();
 		else if(command=="ast")
@@ -233,16 +210,7 @@ int main()
 		else if(command=="exit")
 			break;
 		else
-		{
 			inputfile=command;
-			std::ifstream fin(command);
-			if(fin.fail())
-			{
-				std::cout<<">> [file] cannot open file \""<<command<<"\".\n";
-				inputfile="null";
-			}
-			fin.close();
-		}
 	}
     return 0;
 }
\ No newline at end of file
diff --git a/nasal.h b/nasal.h
index cea2911..df349ee 100644
--- a/nasal.h
+++ b/nasal.h
@@ -11,8 +11,7 @@
 #include <cstdlib>
 #include <ctime>
 #include <cmath>
-/* if thread is used, don't forget to add -std=c++11 or higher standard before executing */
-// #include <thread>
+#include <thread>
 #include <list>
 #include <stack>
 #include <queue>
@@ -21,7 +20,6 @@
 
 #include "nasal_enum.h"
 #include "nasal_misc.h"
-#include "nasal_resource.h"
 #include "nasal_lexer.h"
 #include "nasal_ast.h"
 #include "nasal_parse.h"
diff --git a/nasal_import.h b/nasal_import.h
index 2e12b53..efa9aea 100644
--- a/nasal_import.h
+++ b/nasal_import.h
@@ -4,7 +4,6 @@
 class nasal_import
 {
 private:
-    nasal_resource import_src;
     nasal_lexer    import_lex;
     nasal_parse    import_par;
     nasal_ast      import_ast;
@@ -26,7 +25,6 @@ public:
 
 nasal_import::nasal_import()
 {
-    import_src.clear();
     import_lex.clear();
     import_par.clear();
     import_ast.clear();
@@ -43,7 +41,6 @@ void nasal_import::die(std::string filename,std::string error_stage)
 
 void nasal_import::init()
 {
-    import_src.clear();
     import_lex.clear();
     import_par.clear();
     return;
@@ -112,12 +109,8 @@ nasal_ast nasal_import::file_import(nasal_ast& node)
         return tmp;
     
     // start importing...
-    if(!import_src.input_file(filename))
-    {
-        this->die(filename,"resource");
-        return tmp;
-    }
-    import_lex.scanner(import_src.get_file());
+    import_lex.openfile(filename);
+    import_lex.scanner();
     if(import_lex.get_error())
     {
         this->die(filename,"lexer");
diff --git a/nasal_lexer.h b/nasal_lexer.h
index aa9faf9..81a0eaf 100644
--- a/nasal_lexer.h
+++ b/nasal_lexer.h
@@ -81,14 +81,19 @@ class nasal_lexer
 {
 private:
     int error;
+	int res_size;
+	int line;
+	int ptr;
+	std::vector<char> res;
     std::vector<token> token_list;
-	std::string identifier_gen(std::vector<char>&,int&,int&);
+	std::string identifier_gen();
 	void generate_number_error(int,std::string);
-    std::string number_gen(std::vector<char>&,int&,int&);
-    std::string string_gen(std::vector<char>&,int&,int&);
+    std::string number_gen();
+    std::string string_gen();
 public:
     void clear();
-    void scanner(std::vector<char>&);
+	void openfile(std::string);
+    void scanner();
     void print_token();
     int  get_error();
 	std::vector<token>& get_token_list();
@@ -96,13 +101,41 @@ public:
 
 void nasal_lexer::clear()
 {
+	error=0;
+	res_size=0;
+	line=0;
+	ptr=0;
+	res.clear();
     token_list.clear();
     return;
 }
 
-std::string nasal_lexer::identifier_gen(std::vector<char>& res,int& ptr,int& line)
+void nasal_lexer::openfile(std::string filename)
+{
+	error=0;
+	res.clear();
+    std::ifstream fin(filename,std::ios::binary);
+    if(fin.fail())
+    {
+		++error;
+        std::cout<<">> [lexer] cannot open file \""<<filename<<"\".\n";
+        fin.close();
+        return;
+    }
+    while(!fin.eof())
+    {
+        char c=fin.get();
+        if(fin.eof())
+            break;
+        res.push_back(c);
+    }
+    fin.close();
+	res_size=res.size();
+    return;
+}
+
+std::string nasal_lexer::identifier_gen()
 {
-	int res_size=res.size();
 	std::string token_str="";
 	while(ptr<res_size && IS_IDENTIFIER_BODY(res[ptr]))
 		token_str+=res[ptr++];
@@ -116,9 +149,8 @@ void nasal_lexer::generate_number_error(int line,std::string token_str)
 	std::cout<<">> [lexer] line "<<line<<": \""<<token_str<<"\" is not a correct number.\n";
 	return;
 }
-std::string nasal_lexer::number_gen(std::vector<char>& res,int& ptr,int& line)
+std::string nasal_lexer::number_gen()
 {
-	int res_size=res.size();
 	bool scientific_notation=false;// numbers like 1e8 are scientific_notation
 	std::string token_str="";
 	// generate hex number
@@ -203,9 +235,8 @@ std::string nasal_lexer::number_gen(std::vector<char>& res,int& ptr,int& line)
 	return token_str;
 }
 
-std::string nasal_lexer::string_gen(std::vector<char>& res,int& ptr,int& line)
+std::string nasal_lexer::string_gen()
 {
-	int res_size=res.size();
 	std::string token_str="";
 	char str_begin=res[ptr++];
 	if(ptr>=res_size) return token_str;
@@ -246,11 +277,12 @@ std::string nasal_lexer::string_gen(std::vector<char>& res,int& ptr,int& line)
 	return token_str;
 }
 
-void nasal_lexer::scanner(std::vector<char>& res)
+void nasal_lexer::scanner()
 {
-    error=0;
     token_list.clear();
-    int line=1,ptr=0,res_size=res.size();
+    line=1;
+	ptr=0;
+
 	std::string token_str;
 	while(ptr<res_size)
 	{
@@ -263,7 +295,7 @@ void nasal_lexer::scanner(std::vector<char>& res)
 		if(ptr>=res_size) break;
 		if(IS_IDENTIFIER_HEAD(res[ptr]))
 		{
-			token_str=identifier_gen(res,ptr,line);
+			token_str=identifier_gen();
 			token new_token;
 			new_token.line=line;
             new_token.str=token_str;
@@ -280,7 +312,7 @@ void nasal_lexer::scanner(std::vector<char>& res)
 		}
 		else if(IS_DIGIT(res[ptr]))
 		{
-			token_str=number_gen(res,ptr,line);
+			token_str=number_gen();
 			token new_token;
 			new_token.line=line;
             new_token.str=token_str;
@@ -289,7 +321,7 @@ void nasal_lexer::scanner(std::vector<char>& res)
 		}
 		else if(IS_STRING_HEAD(res[ptr]))
 		{
-			token_str=string_gen(res,ptr,line);
+			token_str=string_gen();
 			token new_token;
 			new_token.line=line;
 			new_token.type=tok_string;
diff --git a/nasal_resource.h b/nasal_resource.h
deleted file mode 100644
index d65a54d..0000000
--- a/nasal_resource.h
+++ /dev/null
@@ -1,75 +0,0 @@
-#ifndef __NASAL_RESOURCE_H__
-#define __NASAL_RESOURCE_H__
-
-class nasal_resource
-{
-private:
-    std::vector<char> res;
-public:
-    bool input_file(std::string);
-    void clear();
-    void print_file();
-    std::vector<char>& get_file();
-};
-
-bool nasal_resource::input_file(std::string filename)
-{
-    res.clear();
-    std::ifstream fin(filename,std::ios::binary);
-    if(fin.fail())
-    {
-        std::cout<<">> [resource] cannot open file \""<<filename<<"\".\n";
-        fin.close();
-        return false;
-    }
-    while(!fin.eof())
-    {
-        char c=fin.get();
-        if(fin.eof())
-            break;
-        res.push_back(c);
-    }
-    fin.close();
-    return true;
-}
-
-void nasal_resource::clear()
-{
-    res.clear();
-    return;
-}
-
-void nasal_resource::print_file()
-{
-    int size=res.size(),line=1;
-	std::cout<<line<<"\t";
-	std::string unicode_str="";
-	for(int i=0;i<size;++i)
-	{
-		if(res[i]>=0 && unicode_str.length())
-		{
-			std::cout<<unicode_str;
-			unicode_str="";
-		}
-		if(32<=res[i])
-            std::cout<<res[i];
-		else if(res[i]<0)
-            unicode_str+=res[i];
-		else
-            std::cout<<" ";
-		if(res[i]=='\n')
-		{
-			++line;
-			std::cout<<std::endl<<line<<"\t";
-		}
-	}
-	std::cout<<(unicode_str.length()?unicode_str:"")<<'\n';
-	return;
-}
-
-std::vector<char>& nasal_resource::get_file()
-{
-    return res;
-}
-
-#endif
\ No newline at end of file