diff --git a/version0.9/a.txt b/version0.9/a.txt
new file mode 100644
index 0000000..422eeb6
--- /dev/null
+++ b/version0.9/a.txt
@@ -0,0 +1,3 @@
+var e=1;
+var a=2;
+var c=3;
diff --git a/version0.9/lr_pda_demo.cpp b/version0.9/lr_pda_demo.cpp
new file mode 100644
index 0000000..4ee3972
--- /dev/null
+++ b/version0.9/lr_pda_demo.cpp
@@ -0,0 +1,179 @@
+#include <list>
+#include <stack>
+#include <cstring>
+#include <iostream>
+
+enum token_type
+{
+	S=1,a,T,__tri,__comma,__left_curve,__right_curve,sharp
+};
+
+const int max_len=5;
+struct cmp_seq
+{
+	int tokens[max_len];
+	int res;
+};
+cmp_seq par[]=
+{
+	{{a},                            S},
+	{{__tri},                        S},
+	{{__right_curve,T,__left_curve}, S},
+	{{S},                            T},
+	{{T,__comma,T},                  T},
+};
+int num_of_par=sizeof(par)/sizeof(cmp_seq);
+
+void print_token(int type)
+{
+	std::string context="";
+	switch(type)
+	{
+		case sharp:
+			context="#";
+			break;
+		case S:
+			context="S";
+			break;
+		case a:
+			context="a";
+			break;
+		case T:
+			context="T";
+			break;
+		case __tri:
+			context="^";
+			break;
+		case __comma:
+			context=",";
+			break;
+		case __left_curve:
+			context="(";
+			break;
+		case __right_curve:
+			context=")";
+			break;
+	}
+	std::cout<<context;
+	return;
+}
+
+class PDA
+{
+	private:
+		std::stack<int> main_stack;
+		std::stack<int> comp_stack;
+	public:
+		PDA(std::string& text)
+		{
+			main_stack.push(sharp);
+			for(int i=0;i<(int)text.length();++i)
+			{
+				if(text[i]=='(')
+					main_stack.push(__left_curve);
+				else if(text[i]==')')
+					main_stack.push(__right_curve);
+				else if(text[i]=='a')
+					main_stack.push(a);
+				else if(text[i]=='^')
+					main_stack.push(__tri);
+				else if(text[i]==',')
+					main_stack.push(__comma);
+			}
+			comp_stack.push(sharp);
+		}
+		void print_stack(std::stack<int>& temp)
+		{
+			std::stack<int> t;
+			while(!temp.empty())
+			{
+				t.push(temp.top());
+				print_token(t.top());
+				temp.pop();
+			}
+			while(!t.empty())
+			{
+				temp.push(t.top());
+				t.pop();
+			}
+			return;
+		}
+		void print_main_and_comp()
+		{
+			print_stack(main_stack);
+			std::cout<<"		";
+			print_stack(comp_stack);
+			std::cout<<std::endl;
+			return;
+		}
+		bool reducable()
+		{
+			std::stack<int> temp;
+			for(int i=0;i<num_of_par;++i)
+			{
+				for(int j=max_len-1;j>=0;--j)
+				{
+					if(!par[i].tokens[j])
+						continue;
+					// if par[i].tokens[j] is 0 then continue until the tokens[j] is not 0
+					temp.push(comp_stack.top());
+					comp_stack.pop();
+					if((par[i].tokens[j]!=temp.top()) || (comp_stack.empty() && par[i].tokens[j]))
+					{
+						while(!temp.empty())
+						{
+							comp_stack.push(temp.top());
+							temp.pop();
+						}
+						break;
+					}
+					if((par[i].tokens[j]==temp.top()) && (j==0))
+					{
+						comp_stack.push(par[i].res);
+						return true;
+					}
+				}
+			}
+			return false;
+		}
+		void work()
+		{
+			print_main_and_comp();
+			while(main_stack.top()!=sharp)
+			{
+				
+				comp_stack.push(main_stack.top());
+				main_stack.pop();
+				while(1)
+				{
+					if(!reducable())
+						break;
+					print_main_and_comp();
+				}
+			}
+			print_main_and_comp();
+			if(comp_stack.top()==T)
+			{
+				comp_stack.pop();
+				if(comp_stack.top()==sharp)
+					std::cout<<"accept."<<std::endl;
+				else
+					std::cout<<"error."<<std::endl;
+			}
+			else
+				std::cout<<"error."<<std::endl;
+			return;
+		}
+};
+
+int main()
+{
+	std::string text;
+	while(1)
+	{
+		std::cin>>text;
+		PDA m(text);
+		m.work();
+	}
+	return 0;
+}
diff --git a/version0.9/main.cpp b/version0.9/main.cpp
new file mode 100644
index 0000000..bf1d5ca
--- /dev/null
+++ b/version0.9/main.cpp
@@ -0,0 +1,68 @@
+#include "nasal_lexer.h"
+#include "nasal_parser.h"
+#include <iostream>
+#include <cstring>
+
+int main()
+{
+	resource_programme_process prog;
+	nasal_lexer lex;
+	nasal_parser pas;
+	std::string command;
+	std::cout<<">> nasal script interpreter by ValKmjolnir"<<std::endl;
+	std::cout<<">> input \"help\" to find help."<<std::endl;
+	std::cout<<">> Be careful: this interpreter uses strict methods to check if there's an error."<<std::endl;
+	std::cout<<"   Always add \";\" after each statement (except loop and if-else)."<<std::endl;
+	while(1)
+	{
+		std::cout<<">> ";
+		std::getline(std::cin,command);
+		if(command=="help")
+		{
+			std::cout<<">> nasal script interpreter by ValKmjolnir"<<std::endl;
+			std::cout<<">> 1.         |input file name to load the file."<<std::endl;
+			std::cout<<">> 2. \"cls\"   |clear the screen."<<std::endl;
+			std::cout<<">> 3. \"exit\"  |shut down the interpreter."<<std::endl;
+			std::cout<<">> 4. \"lexer\" |run and show the lexer. (-lexer)"<<std::endl;
+			std::cout<<">> 5. \"parser\"|run parser. (-parser)"<<std::endl;
+			std::cout<<">> 6. \"del\"   |delete all elements in stack."<<std::endl;
+			std::cout<<">> 7. \"run\"   |run the programme in stack. (-lexer -parser)"<<std::endl;
+			std::cout<<">> 8. \"rs\"    |check the source program."<<std::endl;
+		}
+		else if(command=="cls")
+		{
+			system("cls");
+			//windows  system("cls);
+			//linux system("clear");
+			//macOS system("clear");
+		}
+		else if(command=="rs")
+			prog.print_file();
+		else if(command=="exit")
+		{
+			break;
+		}
+		else if(command=="lexer")
+		{
+			lex.lexer_process(prog.use_file());
+			lex.print_lexer();
+		}
+		else if(command=="del")
+		{
+			prog.del_file();
+			std::cout<<">>[Delete] Complete."<<std::endl;
+		}
+		else if(command=="parser")
+		{
+			pas.parse_process(lex.return_list(),true);
+		}
+		else if(command=="run")
+		{
+			lex.lexer_process(prog.use_file());
+			pas.parse_process(lex.return_list(),false);
+		}
+		else
+			prog.input_file(command);
+	}
+	return 0;
+}
diff --git a/version0.9/nasal_LR_demo.cpp b/version0.9/nasal_LR_demo.cpp
new file mode 100644
index 0000000..e62841d
--- /dev/null
+++ b/version0.9/nasal_LR_demo.cpp
@@ -0,0 +1,548 @@
+
+#include <cstring>
+#include <iostream>
+#include <list>
+#include <stack>
+
+#include "nasal_lexer.h"
+
+enum token_type
+{
+	__stack_end=1,
+	__equal,// =
+	__cmp_equal,// ==
+	__cmp_not_equal,// !=
+	__cmp_less,__cmp_less_or_equal,// < <=
+	__cmp_more,__cmp_more_or_equal,// > >=
+	__and_operator,__or_operator,__nor_operator,// and or !
+	__add_operator,__sub_operator,__mul_operator,__div_operator,__link_operator,// + - * / ~
+	__add_equal,__sub_equal,__mul_equal,__div_equal,__link_equal,// += -= *= /= ~=
+	__left_brace,__right_brace,// {}
+	__left_bracket,__right_bracket,// []
+	__left_curve,__right_curve,// ()
+	__semi,// ;
+	__comma,// ,
+	__colon,// :
+	__dot,// .
+	__var,
+	__func,
+	__id,
+	__return,
+	__if,__elsif,__else,
+	__continue,__break,__for,__forindex,__foreach,__while,
+	
+	__scalar,
+	__number,__string,__char,
+	__list,
+	__hash,
+	__hash_member,
+	__statement,
+	__function,
+	__call_function,
+	__definition,
+	__assignment,
+	__calculation,
+	__loop,
+	__choose,
+	__program
+};
+
+const int max_len=10;
+struct cmp_seq
+{
+	int tokens[max_len];
+	int res;
+};
+// must put in a reverse way
+cmp_seq par[]=
+{
+	{{__statement,__program},                __program},
+	{{__statement},                          __program},
+	{{__semi,__number,__equal,__id,__var},__definition},
+	{{__definition},                       __statement}
+};
+int num_of_par=sizeof(par)/sizeof(cmp_seq);
+
+void print_token(int type)
+{
+	std::string context="";
+	switch(type)
+	{
+		case __stack_end:
+			context="#";
+			break;
+		case __equal:
+			context="=";
+			break;
+		case __cmp_equal:
+			context="==";
+			break;
+		case __cmp_not_equal:
+			context="!=";
+			break;
+		case __cmp_less:
+			context="<";
+			break;
+		case __cmp_less_or_equal:
+			context="<=";
+			break;
+		case __cmp_more:
+			context=">";
+			break;
+		case __cmp_more_or_equal:
+			context=">=";
+			break;
+		case __and_operator:
+			context="and";
+			break;
+		case __or_operator:
+			context="or";
+			break;
+		case __nor_operator:
+			context="!";
+			break;
+		case __add_operator:
+			context="+";
+			break;
+		case __sub_operator:
+			context="-";
+			break;
+		case __mul_operator:
+			context="*";
+			break;
+		case __div_operator:
+			context="/";
+			break;
+		case __link_operator:
+			context="~";
+			break;
+		case __add_equal:
+			context="+=";
+			break;
+		case __sub_equal:
+			context="-=";
+			break;
+		case __mul_equal:
+			context="*=";
+			break;
+		case __div_equal:
+			context="/=";
+			break;
+		case __link_equal:
+			context="~=";
+			break;
+		case __left_brace:
+			context="{";
+			break;
+		case __right_brace:
+			context="}";
+			break;
+		case __left_bracket:
+			context="[";
+			break;
+		case __right_bracket:
+			context="]";
+			break;
+		case __left_curve:
+			context="(";
+			break;
+		case __right_curve:
+			context=")";
+			break;
+		case __semi:
+			context=";";
+			break;
+		case __comma:
+			context=",";
+			break;
+		case __colon:
+			context=":";
+			break;
+		case __dot:
+			context=".";
+			break;
+		case __var:
+			context="var";
+			break;
+		case __func:
+			context="func";
+			break;
+		case __id:
+			context="id";
+			break;
+		case __number:
+			context="number";
+			break;
+		case __string:
+			context="string";
+			break;
+		case __char:
+			context="char";
+			break;
+		case __continue:
+			context="continue";
+			break;
+		case __break:
+			context="break";
+			break;
+		case __for:
+			context="for";
+			break;
+		case __forindex:
+			context="forindex";
+			break;
+		case __foreach:
+			context="foreach";
+			break;
+		case __while:
+			context="while";
+			break;
+		case __if:
+			context="if";
+			break;
+		case __elsif:
+			context="elsif";
+			break;
+		case __else:
+			context="else";
+			break;
+		case __return:
+			context="return";
+			break;
+		case __scalar:
+			context="scalar";
+			break;
+		case __list:
+			context="list";
+			break;
+		case __hash:
+			context="hash";
+			break;
+		case __hash_member:
+			context="hash_member";
+			break;
+		case __statement:
+			context="statement";
+			break;
+		case __function:
+			context="function";
+			break;
+		case __call_function:
+			context="call_func";
+			break;
+		case __definition:
+			context="definition";
+			break;
+		case __assignment:
+			context="assignment";
+			break;
+		case __calculation:
+			context="calc";
+			break;
+		case __loop:
+			context="loop";
+			break;
+		case __choose:
+			context="choose";
+			break;
+		case __program:
+			context="program";
+			break;
+	}
+	std::cout<<context;
+	return;
+}
+
+struct parse_unit
+{
+	int line;
+	int type;
+};
+class PDA
+{
+	private:
+		std::stack<int> main_stack;
+		std::stack<int> comp_stack;
+	public:
+		void set_stack_empty()
+		{
+			while(!main_stack.empty())
+				main_stack.pop();
+			while(!comp_stack.empty())
+				comp_stack.pop();
+			main_stack.push(__stack_end);
+			comp_stack.push(__stack_end);
+		}
+		void stack_input(std::stack<parse_unit>& temp)
+		{
+			set_stack_empty();
+			while(!temp.empty())
+			{
+				main_stack.push(temp.top().type);
+				temp.pop();
+			}
+			return;
+		}
+		void print_stack(std::stack<int>& temp)
+		{
+			std::stack<int> t;
+			while(!temp.empty())
+			{
+				t.push(temp.top());
+				print_token(t.top());
+				std::cout<<" ";
+				temp.pop();
+			}
+			while(!t.empty())
+			{
+				temp.push(t.top());
+				t.pop();
+			}
+			return;
+		}
+		void print_main_and_comp()
+		{
+			std::cout<<">>[Main stack] ";
+			print_stack(main_stack);
+			std::cout<<std::endl<<">>[Comp stack] ";
+			print_stack(comp_stack);
+			std::cout<<std::endl;
+			return;
+		}
+		bool reducable()
+		{
+			std::stack<int> temp;
+			for(int i=0;i<num_of_par;++i)
+			{
+				for(int j=max_len-1;j>=0;--j)
+				{
+					if(!par[i].tokens[j])
+						continue;
+					// if par[i].tokens[j] is 0 then continue until the tokens[j] is not 0
+					temp.push(comp_stack.top());
+					comp_stack.pop();
+					if((par[i].tokens[j]!=temp.top()) || (comp_stack.empty() && par[i].tokens[j]))
+					{
+						while(!temp.empty())
+						{
+							comp_stack.push(temp.top());
+							temp.pop();
+						}
+						break;
+					}
+					if((par[i].tokens[j]==temp.top()) && (j==0))
+					{
+						comp_stack.push(par[i].res);
+						return true;
+					}
+				}
+			}
+			return false;
+		}
+		void main_comp_progress()
+		{
+			print_main_and_comp();
+			while(main_stack.top()!=__stack_end)
+			{
+				comp_stack.push(main_stack.top());
+				main_stack.pop();
+				print_main_and_comp();
+				while(1)
+				{
+					if(!reducable())
+						break;
+					print_main_and_comp();
+				}
+			}
+			if(comp_stack.top()==__program)
+			{
+				comp_stack.pop();
+				if(comp_stack.top()==__stack_end)
+					std::cout<<">>[Parse] 0 error(s)."<<std::endl;
+				else
+					std::cout<<">>[Parse] Error:"<<std::endl;
+			}
+			else
+				std::cout<<">>[Parse] Error:"<<std::endl;
+			std::cout<<">>[Parse] Complete checking."<<std::endl;
+			//print_error();
+			return;
+		}
+};
+
+class nasal_parser
+{
+	private:
+		std::stack<parse_unit> parser;
+	public:
+		void parse_process(std::list<token>& lexer)
+		{
+			while(!parser.empty())
+				parser.pop();
+			for(std::list<token>::iterator i=lexer.begin();i!=lexer.end();++i)
+			{
+				parse_unit temp_parse;
+				temp_parse.line=(*i).line;
+				if(((*i).content=="var") || ((*i).content=="func") || ((*i).content=="return") || ((*i).content=="nil") || ((*i).content=="continue") || ((*i).content=="break") || ((*i).content=="and") || ((*i).content=="or"))
+				{
+					if((*i).content=="var")
+						temp_parse.type=__var;
+					else if((*i).content=="func")
+						temp_parse.type=__func;
+					else if((*i).content=="return")
+						temp_parse.type=__return;
+					else if((*i).content=="nil")
+						temp_parse.type=__number;
+					else if((*i).content=="continue")
+						temp_parse.type=__continue;
+					else if((*i).content=="break")
+						temp_parse.type=__break;
+					else if((*i).content=="and")
+						temp_parse.type=__and_operator;
+					else if((*i).content=="or")
+						temp_parse.type=__or_operator;
+				}
+				else if((*i).type==IDENTIFIER)
+				{
+					temp_parse.type=__id;
+				}
+				else if(((*i).content=="for") || ((*i).content=="foreach") || ((*i).content=="while") || ((*i).content=="forindex"))
+				{
+					if((*i).content=="for")
+						temp_parse.type=__for;
+					else if((*i).content=="forindex")
+						temp_parse.type=__forindex;
+					else if((*i).content=="foreach")
+						temp_parse.type=__foreach;
+					else if((*i).content=="while")
+						temp_parse.type=__while;
+				}
+				else if(((*i).content=="if") || ((*i).content=="else") || ((*i).content=="elsif"))
+				{
+					if((*i).content=="if")
+						temp_parse.type=__if;
+					else if((*i).content=="else")
+						temp_parse.type=__else;
+					else if((*i).content=="elsif")
+						temp_parse.type=__elsif;
+				}
+				else if(((*i).content=="==") || ((*i).content=="!=") || ((*i).content==">") || ((*i).content==">=") || ((*i).content=="<") || ((*i).content=="<="))
+				{
+					if((*i).content=="==")
+						temp_parse.type=__cmp_equal;
+					else if((*i).content=="!=")
+						temp_parse.type=__cmp_not_equal;
+					else if((*i).content==">")
+						temp_parse.type=__cmp_more;
+					else if((*i).content==">=")
+						temp_parse.type=__cmp_more_or_equal;
+					else if((*i).content=="<")
+						temp_parse.type=__cmp_less;
+					else if((*i).content=="<=")
+						temp_parse.type=__cmp_less_or_equal;
+				}
+				else if(((*i).content==";") || ((*i).content==",") || ((*i).content=="=") || ((*i).content==":") || ((*i).content=="."))
+				{
+					if((*i).content==";")
+						temp_parse.type=__semi;
+					else if((*i).content==",")
+						temp_parse.type=__comma;
+					else if((*i).content=="=")
+						temp_parse.type=__equal;
+					else if((*i).content==":")
+						temp_parse.type=__colon;
+					else if((*i).content==".")
+						temp_parse.type=__dot;
+				}
+				else if(((*i).type==NUMBER) || ((*i).type==STRING) || ((*i).type==CHAR))
+				{
+					if((*i).type==NUMBER)
+						temp_parse.type=__number;
+					else if((*i).type==STRING)
+						temp_parse.type=__string;
+					else if((*i).type==CHAR)
+						temp_parse.type=__char;
+				}
+				else if(((*i).content=="+") || ((*i).content=="-") || ((*i).content=="*") || ((*i).content=="/") || ((*i).content=="~") || ((*i).content=="!"))
+				{
+					if((*i).content=="+")
+						temp_parse.type=__add_operator;
+					else if((*i).content=="-")
+						temp_parse.type=__sub_operator;
+					else if((*i).content=="*")
+						temp_parse.type=__mul_operator;
+					else if((*i).content=="/")
+						temp_parse.type=__div_operator;
+					else if((*i).content=="~")
+						temp_parse.type=__link_operator;
+					else if((*i).content=="!")
+						temp_parse.type=__nor_operator;
+				}
+				else if(((*i).content=="+=") || ((*i).content=="-=") || ((*i).content=="*=") || ((*i).content=="/=") || ((*i).content=="~="))
+				{
+					if((*i).content=="+=")
+						temp_parse.type=__add_equal;
+					else if((*i).content=="-=")
+						temp_parse.type=__sub_equal;
+					else if((*i).content=="*=")
+						temp_parse.type=__mul_equal;
+					else if((*i).content=="/=")
+						temp_parse.type=__div_equal;
+					else if((*i).content=="~=")
+						temp_parse.type=__link_equal;
+				}
+				else if(((*i).content=="(") || ((*i).content==")") || ((*i).content=="[") || ((*i).content=="]") || ((*i).content=="{") || ((*i).content=="}"))
+				{
+					char c=(*i).content[0];
+					switch(c)
+					{
+						case '(':
+							temp_parse.type=__left_curve;
+							break;
+						case ')':
+							temp_parse.type=__right_curve;
+							break;
+						case '[':
+							temp_parse.type=__left_bracket;
+							break;
+						case ']':
+							temp_parse.type=__right_bracket;
+							break;
+						case '{':
+							temp_parse.type=__left_brace;
+							break;
+						case '}':
+							temp_parse.type=__right_brace;
+							break;
+					}
+				}
+				parser.push(temp_parse);//push this into stack
+			}
+			std::stack<parse_unit> temp;
+			while(!parser.empty())
+			{
+				temp.push(parser.top());
+				parser.pop();
+			}
+			PDA automata;
+			automata.stack_input(temp);
+			automata.main_comp_progress();
+			return;
+		}
+};
+
+int main()
+{
+	std::string filename;
+	resource_programme_process prog;
+	nasal_lexer lex;
+	nasal_parser pas;
+	while(1)
+	{
+		std::cin>>filename;
+		prog.input_file(filename);
+		lex.lexer_process(prog.use_file());
+		pas.parse_process(lex.return_list());
+	}
+	return 0;
+}
diff --git a/version0.9/nasal_lexer.h b/version0.9/nasal_lexer.h
new file mode 100644
index 0000000..a2df7d3
--- /dev/null
+++ b/version0.9/nasal_lexer.h
@@ -0,0 +1,379 @@
+#ifndef __NASAL_LEXER_H__
+#define __NASAL_LEXER_H__
+
+#include <iostream>
+#include <fstream>
+#include <list>
+#include <cstring>
+
+#define OPERATOR     1 //operator
+#define IDENTIFIER   2 //id
+#define NUMBER       3 //number
+#define RESERVEWORD  4 //reserve word
+#define STRING       5 //string 
+#define CHAR         6 //char
+#define FAIL        -1 //fail
+#define SCANEND     -2 //complete scanning
+#define ERRORFOUND  -3 //error occurred
+
+std::string reserve_word[15]=
+{
+	"for","foreach","forindex","while",
+	"var","func","break","continue","return",
+	"if","else","elsif","nil","and","or"
+};
+
+int isReserveWord(std::string &p)
+{
+	for(int i=0;i<15;++i)
+		if(reserve_word[i]==p)
+			return i+1;
+	return FAIL;
+}
+
+bool isLetter(char t)
+{
+	return (('a'<=t) && (t<='z') || ('A'<=t) && (t<='Z'));
+}
+
+bool isNumber(char t)
+{
+	return (('0'<=t) && (t<='9'));
+}
+
+bool isHex(char t)
+{
+	return ((('0'<=t) && (t<='9')) || (('a'<=t) && (t<='f')));
+}
+
+bool isOct(char t)
+{
+	return (('0'<=t) && (t<='7'));
+}
+
+class resource_programme_process
+{
+	private:
+		char *resource;
+	public:
+		resource_programme_process()
+		{
+			resource=NULL;
+			resource=new char[16777216];
+		}
+		~resource_programme_process()
+		{
+			if(resource)
+				delete []resource;
+		}
+		char* use_file()
+		{
+			return resource;
+		}
+		void input_file(std::string& filename)
+		{
+			std::ifstream fin(filename);
+			if(fin.fail())
+			{
+				std::cout<<">>[Error] Cannot load file: "<<filename<<" ."<<std::endl;
+				fin.close();
+				return;
+			}
+			memset(resource,0,sizeof(char));
+			int i=0;
+			bool findnote=false;// to find the note with # at the head of line.
+			while(!fin.eof())
+			{
+				resource[i]=fin.get();
+				if(resource[i]=='\n')
+					findnote=false;
+				//when meeting '\n' the findnote is set to false then the next statement can be executed.
+				if(resource[i]!='#' && !findnote)
+					++i;
+				else if(resource[i]=='#')
+					findnote=true;
+				if(fin.eof())
+					break;
+			}
+			resource[i]='\0';
+			fin.close();
+			return;
+		}
+		void print_file()
+		{
+			if(!resource[0])
+			{
+				std::cout<<"0	null"<<std::endl;
+				return;
+			}
+			int line=1;
+			std::cout<<line<<"	";
+			for(int i=0;i<16777216;++i)
+			{
+				if(!resource[i])
+					break;
+				std::cout<<resource[i];
+				if(resource[i]=='\n')
+				{
+					++line;
+					std::cout<<line<<"	";
+				}
+			}
+			std::cout<<std::endl;
+			return;
+		}
+		void del_file()
+		{
+			memset(resource,0,sizeof(char));
+			return;
+		}
+};
+
+struct token
+{
+	int line;
+	int type;
+	std::string content;
+};
+
+class nasal_lexer
+{
+	private:
+		std::list<token> lexer;
+	public:
+		void scanner(int &syn,const char* source,std::string &__token,int &ptr,int &line)
+		{
+			char temp;
+			temp=source[ptr];
+			while(temp==' ' || temp=='\n' || temp=='\t' || temp=='\r' || temp<0 || temp>127)
+			{
+				++ptr;
+				if(temp=='\n')
+					++line;
+				temp=source[ptr];
+			}
+			__token="";
+			if(isLetter(temp) || temp=='_')
+			{
+				__token+=temp;
+				++ptr;
+				temp=source[ptr];
+				while(isLetter(temp) || isNumber(temp) || temp=='_')
+				{
+					__token+=temp;
+					++ptr;
+					temp=source[ptr];
+				}
+				syn=isReserveWord(__token);
+				if(syn==FAIL)
+					syn=IDENTIFIER;
+				else
+					syn=RESERVEWORD;
+			}
+			else if(isNumber(temp))
+			{
+				if((source[ptr]=='0') && (source[ptr+1]=='x'))
+				{
+					__token+=source[ptr];
+					__token+=source[ptr+1];
+					ptr+=2;
+					temp=source[ptr];
+					while(isNumber(temp) || isHex(temp))
+					{
+						__token+=temp;
+						++ptr;
+						temp=source[ptr];
+					}
+				}
+				else if((source[ptr]=='0') && (source[ptr+1]=='o'))
+				{
+					__token+=source[ptr];
+					__token+=source[ptr+1];
+					ptr+=2;
+					temp=source[ptr];
+					while(isNumber(temp) || isOct(temp))
+					{
+						__token+=temp;
+						++ptr;
+						temp=source[ptr];
+					}
+				}
+				else
+				{
+					int PointCnt=0;
+					while(isNumber(temp))
+					{
+						__token+=temp;
+						++ptr;
+						temp=source[ptr];
+						if(temp=='.' && !PointCnt)
+						{
+							++PointCnt;
+							__token+=temp;
+							++ptr;
+							temp=source[ptr];
+						}
+					}
+				}
+				syn=NUMBER;
+			}
+			else if(temp=='(' || temp==')' || temp=='[' || temp==']' || temp=='{' ||
+					temp=='}' || temp==',' || temp==';' || temp=='|' || temp==':' ||
+					temp=='?' || temp=='.' || temp=='`' || temp=='&'||
+					temp=='%' || temp=='$' || temp=='^')
+			{
+				__token+=temp;
+				++ptr;
+				syn=OPERATOR;
+			}
+			else if(temp=='\'')
+			{
+				__token+=temp;
+				++ptr;
+				temp=source[ptr];
+				__token+=temp;
+				++ptr;
+				temp=source[ptr];
+				__token+=temp;
+				++ptr;
+				if(temp!='\'')
+					std::cout<<">>[Lexer] Abnormal char type detected: "<<__token<<" ."<<std::endl;
+				syn=CHAR;
+			}
+			else if(temp=='=' || temp=='+' || temp=='-' || temp=='*' || temp=='!' || temp=='/' || temp=='<' || temp=='>' || temp=='~')
+			{
+				syn=OPERATOR;
+				__token+=temp;
+				++ptr;
+				temp=source[ptr];
+				if(temp=='=')
+				{
+					__token+=temp;
+					++ptr;
+				}
+			}
+			else if(temp=='\\')
+			{
+				syn=OPERATOR;
+				__token+=temp;
+				++ptr;
+				temp=source[ptr];
+				if(temp=='=' || temp=='n' || temp=='t' || temp=='r' || temp=='\\' || temp=='\'' || temp=='\"')
+				{
+					__token+=temp;
+					++ptr;
+				}
+			}
+			else if(temp=='\"')
+			{
+				syn=STRING;
+				__token+=temp;
+				++ptr;
+				temp=source[ptr];
+				while(temp!='\"')
+				{
+					if(temp=='\\')
+					{
+						__token+=temp;
+						
+						++ptr;
+						temp=source[ptr];
+						__token+=temp;
+						
+						++ptr;
+						temp=source[ptr];
+					}
+					else
+					{
+						__token+=temp;
+						++ptr;
+						temp=source[ptr];
+					}
+					if(temp==0 || temp=='\n')
+						break;
+				}
+				//add the last char \"
+				if(temp=='\"')
+				{
+					__token+=temp;
+					++ptr;
+				}
+				else
+					__token+=" __missing_end_of_string";
+			}
+			else if(temp==0)
+			{
+				syn=SCANEND;
+				return;
+			}
+			else
+			{
+				syn=FAIL;
+				std::cout<<">>[Error] Unexpected error occurred: "<<temp<<std::endl;
+				system("pause");
+				++ptr;
+				return;
+			}
+			if(__token=="")
+			{
+				syn=ERRORFOUND;
+				std::cout<<">>[Error] Cannot identify "<<std::endl;
+			}
+			return;
+		}
+		void lexer_process(const char *source)
+		{
+			std::cout<<">>[Lexer] max size: "<<lexer.max_size()<<" ."<<std::endl;
+			lexer.clear();
+			int syn=0;//token type
+			int ptr=0;//pointer to one char in ResourcePrograme
+			int line=1;
+			std::string __token;
+			token temp;
+			while(syn!=SCANEND && syn!=ERRORFOUND)
+			{
+				scanner(syn,source,__token,ptr,line);
+				if(syn>0)//all Syn type is larger than zero
+				{
+					temp.line=line;
+					temp.type=syn;
+					temp.content=__token;
+					lexer.push_back(temp);
+				}
+			}
+			std::cout<<">>[Lexer] Complete scanning."<<std::endl;
+			return;
+		}
+		void print_lexer()
+		{
+			token temp;
+			for(std::list<token>::iterator i=lexer.begin();i!=lexer.end();++i)
+			{
+				temp=*i;
+				std::cout<<"line "<<temp.line<<": ";
+				if(temp.type==OPERATOR)
+					std::cout<<"( Operator     | ";
+				else if(temp.type==IDENTIFIER)
+					std::cout<<"( Identifier   | ";
+				else if(temp.type==NUMBER)
+					std::cout<<"( Number       | ";
+				else if(temp.type==RESERVEWORD)
+					std::cout<<"( ReserveWord  | ";
+				else if(temp.type==STRING)
+					std::cout<<"( String       | ";
+				else if(temp.type==CHAR)
+					std::cout<<"( Char         | ";
+				std::cout<<temp.content<<" )"<<std::endl;
+			}
+			return;
+		}
+		std::list<token>& return_list()
+		{
+			return lexer;
+		}
+};
+		
+
+		
+
+#endif
diff --git a/version0.9/nasal_parser.h b/version0.9/nasal_parser.h
new file mode 100644
index 0000000..9207997
--- /dev/null
+++ b/version0.9/nasal_parser.h
@@ -0,0 +1,534 @@
+#ifndef __NASAL_PARSER_H__
+#define __NASAL_PARSER_H__
+
+#include <stack>
+
+enum token_type
+{
+	__stack_end=1,
+	__equal,// =
+	__cmp_equal,// ==
+	__cmp_not_equal,// !=
+	__cmp_less,__cmp_less_or_equal,// < <=
+	__cmp_more,__cmp_more_or_equal,// > >=
+	__and_operator,__or_operator,__nor_operator,// and or !
+	__add_operator,__sub_operator,__mul_operator,__div_operator,__link_operator,// + - * / ~
+	__add_equal,__sub_equal,__mul_equal,__div_equal,__link_equal,// += -= *= /= ~=
+	__left_brace,__right_brace,// {}
+	__left_bracket,__right_bracket,// []
+	__left_curve,__right_curve,// ()
+	__semi,// ;
+	__comma,// ,
+	__colon,// :
+	__dot,// .
+	__var,
+	__func,
+	__id,
+	__return,
+	__if,__elsif,__else,
+	__continue,__break,__for,__forindex,__foreach,__while,
+	
+	__scalar,
+	__number,__string,__char,
+	__list,
+	__hash,
+	__hash_member,
+	__statement,
+	__function,
+	__call_function,
+	__definition,
+	__assignment,
+	__calculation,
+	__loop,
+	__choose,
+	__program
+};
+
+const int max_len=10;
+struct cmp_seq
+{
+	int tokens[max_len];
+	int res;
+};
+// must put in a reverse way
+cmp_seq par[]=
+{
+	{{__program,__statement},                __program},
+	{{__semi,__number,__equal,__id,__var},__definition},
+	{{__definition},                       __statement}
+};
+int num_of_par=sizeof(par)/sizeof(cmp_seq);
+
+void print_token(int type)
+{
+	std::string context="";
+	switch(type)
+	{
+		case __stack_end:
+			context="#";
+			break;
+		case __equal:
+			context="=";
+			break;
+		case __cmp_equal:
+			context="==";
+			break;
+		case __cmp_not_equal:
+			context="!=";
+			break;
+		case __cmp_less:
+			context="<";
+			break;
+		case __cmp_less_or_equal:
+			context="<=";
+			break;
+		case __cmp_more:
+			context=">";
+			break;
+		case __cmp_more_or_equal:
+			context=">=";
+			break;
+		case __and_operator:
+			context="and";
+			break;
+		case __or_operator:
+			context="or";
+			break;
+		case __nor_operator:
+			context="!";
+			break;
+		case __add_operator:
+			context="+";
+			break;
+		case __sub_operator:
+			context="-";
+			break;
+		case __mul_operator:
+			context="*";
+			break;
+		case __div_operator:
+			context="/";
+			break;
+		case __link_operator:
+			context="~";
+			break;
+		case __add_equal:
+			context="+=";
+			break;
+		case __sub_equal:
+			context="-=";
+			break;
+		case __mul_equal:
+			context="*=";
+			break;
+		case __div_equal:
+			context="/=";
+			break;
+		case __link_equal:
+			context="~=";
+			break;
+		case __left_brace:
+			context="{";
+			break;
+		case __right_brace:
+			context="}";
+			break;
+		case __left_bracket:
+			context="[";
+			break;
+		case __right_bracket:
+			context="]";
+			break;
+		case __left_curve:
+			context="(";
+			break;
+		case __right_curve:
+			context=")";
+			break;
+		case __semi:
+			context=";";
+			break;
+		case __comma:
+			context=",";
+			break;
+		case __colon:
+			context=":";
+			break;
+		case __dot:
+			context=".";
+			break;
+		case __var:
+			context="var";
+			break;
+		case __func:
+			context="func";
+			break;
+		case __id:
+			context="id";
+			break;
+		case __number:
+			context="number";
+			break;
+		case __string:
+			context="string";
+			break;
+		case __char:
+			context="char";
+			break;
+		case __continue:
+			context="continue";
+			break;
+		case __break:
+			context="break";
+			break;
+		case __for:
+			context="for";
+			break;
+		case __forindex:
+			context="forindex";
+			break;
+		case __foreach:
+			context="foreach";
+			break;
+		case __while:
+			context="while";
+			break;
+		case __if:
+			context="if";
+			break;
+		case __elsif:
+			context="elsif";
+			break;
+		case __else:
+			context="else";
+			break;
+		case __return:
+			context="return";
+			break;
+		case __scalar:
+			context="scalar";
+			break;
+		case __list:
+			context="list";
+			break;
+		case __hash:
+			context="hash";
+			break;
+		case __hash_member:
+			context="hash_member";
+			break;
+		case __statement:
+			context="statement";
+			break;
+		case __function:
+			context="function";
+			break;
+		case __call_function:
+			context="call_func";
+			break;
+		case __definition:
+			context="definition";
+			break;
+		case __assignment:
+			context="assignment";
+			break;
+		case __calculation:
+			context="calc";
+			break;
+		case __loop:
+			context="loop";
+			break;
+		case __choose:
+			context="choose";
+			break;
+		case __program:
+			context="program";
+			break;
+	}
+	std::cout<<context;
+	return;
+}
+
+struct parse_unit
+{
+	int line;
+	int type;
+};
+class PDA
+{
+	private:
+		std::stack<int> main_stack;
+		std::stack<int> comp_stack;
+	public:
+		void set_stack_empty()
+		{
+			while(!main_stack.empty())
+				main_stack.pop();
+			while(!comp_stack.empty())
+				comp_stack.pop();
+			main_stack.push(__stack_end);
+			comp_stack.push(__stack_end);
+			comp_stack.push(__program);
+		}
+		void stack_input(std::stack<parse_unit>& temp)
+		{
+			set_stack_empty();
+			while(!temp.empty())
+			{
+				main_stack.push(temp.top().type);
+				temp.pop();
+			}
+			return;
+		}
+		void print_stack(std::stack<int>& temp)
+		{
+			std::stack<int> t;
+			while(!temp.empty())
+			{
+				t.push(temp.top());
+				print_token(t.top());
+				std::cout<<" ";
+				temp.pop();
+			}
+			while(!t.empty())
+			{
+				temp.push(t.top());
+				t.pop();
+			}
+			return;
+		}
+		void print_main_and_comp()
+		{
+			std::cout<<">>[Main stack] ";
+			print_stack(main_stack);
+			std::cout<<std::endl<<">>[Comp stack] ";
+			print_stack(comp_stack);
+			std::cout<<std::endl;
+			return;
+		}
+		bool reducable()
+		{
+			std::stack<int> temp;
+			for(int i=0;i<num_of_par;++i)
+			{
+				for(int j=max_len-1;j>=0;--j)
+				{
+					if(!par[i].tokens[j])
+						continue;
+					// if par[i].tokens[j] is 0 then continue until the tokens[j] is not 0
+					temp.push(comp_stack.top());
+					comp_stack.pop();
+					if((par[i].tokens[j]!=temp.top()) || (comp_stack.empty() && par[i].tokens[j]))
+					{
+						while(!temp.empty())
+						{
+							comp_stack.push(temp.top());
+							temp.pop();
+						}
+						break;
+					}
+					if((par[i].tokens[j]==temp.top()) && (j==0))
+					{
+						comp_stack.push(par[i].res);
+						return true;
+					}
+				}
+			}
+			return false;
+		}
+		void main_comp_progress(bool show)
+		{
+			if(show)
+				print_main_and_comp();
+			while(main_stack.top()!=__stack_end)
+			{
+				comp_stack.push(main_stack.top());
+				main_stack.pop();
+				if(show)
+					print_main_and_comp();
+				while(1)
+				{
+					if(!reducable())
+						break;
+					if(show)
+						print_main_and_comp();
+				}
+			}
+			if(comp_stack.top()==__program)
+			{
+				comp_stack.pop();
+				if(comp_stack.top()==__stack_end)
+					std::cout<<">>[Parse] 0 error(s)."<<std::endl;
+				else
+					std::cout<<">>[Parse] Error:"<<std::endl;
+			}
+			else
+				std::cout<<">>[Parse] Error:"<<std::endl;
+			std::cout<<">>[Parse] Complete checking."<<std::endl;
+			//print_error();
+			return;
+		}
+};
+
+class nasal_parser
+{
+	private:
+		std::stack<parse_unit> parser;
+	public:
+		void parse_process(std::list<token>& lexer,bool show)
+		{
+			while(!parser.empty())
+				parser.pop();
+			for(std::list<token>::iterator i=lexer.begin();i!=lexer.end();++i)
+			{
+				parse_unit temp_parse;
+				temp_parse.line=(*i).line;
+				if(((*i).content=="var") || ((*i).content=="func") || ((*i).content=="return") || ((*i).content=="nil") || ((*i).content=="continue") || ((*i).content=="break") || ((*i).content=="and") || ((*i).content=="or"))
+				{
+					if((*i).content=="var")
+						temp_parse.type=__var;
+					else if((*i).content=="func")
+						temp_parse.type=__func;
+					else if((*i).content=="return")
+						temp_parse.type=__return;
+					else if((*i).content=="nil")
+						temp_parse.type=__number;
+					else if((*i).content=="continue")
+						temp_parse.type=__continue;
+					else if((*i).content=="break")
+						temp_parse.type=__break;
+					else if((*i).content=="and")
+						temp_parse.type=__and_operator;
+					else if((*i).content=="or")
+						temp_parse.type=__or_operator;
+				}
+				else if((*i).type==IDENTIFIER)
+				{
+					temp_parse.type=__id;
+				}
+				else if(((*i).content=="for") || ((*i).content=="foreach") || ((*i).content=="while") || ((*i).content=="forindex"))
+				{
+					if((*i).content=="for")
+						temp_parse.type=__for;
+					else if((*i).content=="forindex")
+						temp_parse.type=__forindex;
+					else if((*i).content=="foreach")
+						temp_parse.type=__foreach;
+					else if((*i).content=="while")
+						temp_parse.type=__while;
+				}
+				else if(((*i).content=="if") || ((*i).content=="else") || ((*i).content=="elsif"))
+				{
+					if((*i).content=="if")
+						temp_parse.type=__if;
+					else if((*i).content=="else")
+						temp_parse.type=__else;
+					else if((*i).content=="elsif")
+						temp_parse.type=__elsif;
+				}
+				else if(((*i).content=="==") || ((*i).content=="!=") || ((*i).content==">") || ((*i).content==">=") || ((*i).content=="<") || ((*i).content=="<="))
+				{
+					if((*i).content=="==")
+						temp_parse.type=__cmp_equal;
+					else if((*i).content=="!=")
+						temp_parse.type=__cmp_not_equal;
+					else if((*i).content==">")
+						temp_parse.type=__cmp_more;
+					else if((*i).content==">=")
+						temp_parse.type=__cmp_more_or_equal;
+					else if((*i).content=="<")
+						temp_parse.type=__cmp_less;
+					else if((*i).content=="<=")
+						temp_parse.type=__cmp_less_or_equal;
+				}
+				else if(((*i).content==";") || ((*i).content==",") || ((*i).content=="=") || ((*i).content==":") || ((*i).content=="."))
+				{
+					if((*i).content==";")
+						temp_parse.type=__semi;
+					else if((*i).content==",")
+						temp_parse.type=__comma;
+					else if((*i).content=="=")
+						temp_parse.type=__equal;
+					else if((*i).content==":")
+						temp_parse.type=__colon;
+					else if((*i).content==".")
+						temp_parse.type=__dot;
+				}
+				else if(((*i).type==NUMBER) || ((*i).type==STRING) || ((*i).type==CHAR))
+				{
+					if((*i).type==NUMBER)
+						temp_parse.type=__number;
+					else if((*i).type==STRING)
+						temp_parse.type=__string;
+					else if((*i).type==CHAR)
+						temp_parse.type=__char;
+				}
+				else if(((*i).content=="+") || ((*i).content=="-") || ((*i).content=="*") || ((*i).content=="/") || ((*i).content=="~") || ((*i).content=="!"))
+				{
+					if((*i).content=="+")
+						temp_parse.type=__add_operator;
+					else if((*i).content=="-")
+						temp_parse.type=__sub_operator;
+					else if((*i).content=="*")
+						temp_parse.type=__mul_operator;
+					else if((*i).content=="/")
+						temp_parse.type=__div_operator;
+					else if((*i).content=="~")
+						temp_parse.type=__link_operator;
+					else if((*i).content=="!")
+						temp_parse.type=__nor_operator;
+				}
+				else if(((*i).content=="+=") || ((*i).content=="-=") || ((*i).content=="*=") || ((*i).content=="/=") || ((*i).content=="~="))
+				{
+					if((*i).content=="+=")
+						temp_parse.type=__add_equal;
+					else if((*i).content=="-=")
+						temp_parse.type=__sub_equal;
+					else if((*i).content=="*=")
+						temp_parse.type=__mul_equal;
+					else if((*i).content=="/=")
+						temp_parse.type=__div_equal;
+					else if((*i).content=="~=")
+						temp_parse.type=__link_equal;
+				}
+				else if(((*i).content=="(") || ((*i).content==")") || ((*i).content=="[") || ((*i).content=="]") || ((*i).content=="{") || ((*i).content=="}"))
+				{
+					char c=(*i).content[0];
+					switch(c)
+					{
+						case '(':
+							temp_parse.type=__left_curve;
+							break;
+						case ')':
+							temp_parse.type=__right_curve;
+							break;
+						case '[':
+							temp_parse.type=__left_bracket;
+							break;
+						case ']':
+							temp_parse.type=__right_bracket;
+							break;
+						case '{':
+							temp_parse.type=__left_brace;
+							break;
+						case '}':
+							temp_parse.type=__right_brace;
+							break;
+					}
+				}
+				parser.push(temp_parse);//push this into stack
+			}
+			std::stack<parse_unit> temp;
+			while(!parser.empty())
+			{
+				temp.push(parser.top());
+				parser.pop();
+			}
+			PDA automata;
+			automata.stack_input(temp);
+			automata.main_comp_progress(show);
+			return;
+		}
+};
+
+#endif
diff --git a/version0.9/pda_demo.cpp b/version0.9/pda_demo.cpp
new file mode 100644
index 0000000..be371a9
--- /dev/null
+++ b/version0.9/pda_demo.cpp
@@ -0,0 +1,262 @@
+#include <list>
+#include <stack>
+#include <cstring>
+#include <iostream>
+
+enum token_type
+{
+	e=1,E,_E,T,_T,F,I,__add,__sub,__mul,__div,__link,__left_curve,__right_curve,sharp
+};
+
+const int max_len=5;
+struct cmp_seq
+{
+	int tokens[max_len];
+	int res;
+};
+cmp_seq par[]=
+{
+	{{T,_E},                        E},
+	{{__add,T,_E},                 _E},
+	{{__sub,T,_E},                 _E},
+	{{__link,T,_E},                _E},
+	{{e},                          _E},
+	{{F,_T},                        T},
+	{{__mul,F,_T},                 _T},
+	{{__div,F,_T},                 _T},
+	{{e},                          _T},
+	{{__left_curve,E,__right_curve},F},
+	{{I},                           F}
+};
+int num_of_par=sizeof(par)/sizeof(cmp_seq);
+
+cmp_seq first_set[]=
+{
+	{{__left_curve,I},E},
+	{{__left_curve,I},T},
+	{{__left_curve,I},F},
+	{{__add,__sub,__link,e},_E},
+	{{__mul,__div,e},_T},
+};
+int num_of_set=sizeof(first_set)/sizeof(cmp_seq);
+
+bool isEnd(int type)
+{
+	return ((type==__left_curve) || (type==__right_curve) || (type==I) || (type==__add) || (type==__sub) || (type==__mul) || (type==__div) || (type==__link) || (type==e) || (type==sharp));
+}
+bool isHead(int head,int type)
+{
+	for(int i=0;i<num_of_set;++i)
+	{
+		if(type==first_set[i].res)
+		{
+			for(int j=0;j<max_len;++j)
+				if(head==first_set[i].tokens[j])
+					return true;
+		}
+	}
+	return false;
+}
+int correct_token_seq(int head,int type)
+{
+	for(int i=0;i<num_of_par;++i)
+	{
+		if((type==par[i].res) && (isHead(head,par[i].tokens[0]) || (head==par[i].tokens[0])))
+			return i;
+	}
+	for(int i=0;i<num_of_par;++i)
+	{
+		if((type==par[i].res) && (par[i].tokens[0]==e))
+			return i;
+	}
+	return -1;
+}
+int place_operator_end(int type)
+{
+	for(int i=0;i<num_of_par;++i)
+	{
+		if((type==par[i].res) && (par[i].tokens[0]==e))
+			return i;
+	}
+	return -1;
+}
+
+
+
+void print_token(int type)
+{
+	std::string str="";
+	switch(type)
+	{
+		case e:
+			str="e";
+			break;
+		case E:
+			str="E";
+			break;
+		case _E:
+			str="E\'";
+			break;
+		case T:
+			str="T";
+			break;
+		case _T:
+			str="T\'";
+			break;
+		case F:
+			str="F";
+			break;
+		case I:
+			str="i";
+			break;
+		case __add:
+			str="+";
+			break;
+		case __sub:
+			str="-";
+			break;
+		case __mul:
+			str="*";
+			break;
+		case __div:
+			str="/";
+			break;
+		case __link:
+			str="~";
+			break;
+		case __left_curve:
+			str="(";
+			break;
+		case __right_curve:
+			str=")";
+			break;
+		case sharp:
+			str="#";
+			break;
+	}
+	std::cout<<str;
+	return;
+}
+
+class PDA
+{
+	private:
+		std::stack<int> main_stack;
+		std::stack<int> comp_stack;
+	public:
+		PDA(std::string& text)
+		{
+			main_stack.push(sharp);
+			for(int i=(int)text.length()-1;i>=0;--i)
+			{
+				if(text[i]=='(')
+					main_stack.push(__left_curve);
+				else if(text[i]==')')
+					main_stack.push(__right_curve);
+				else if(text[i]=='i')
+					main_stack.push(I);
+				else if(text[i]=='+')
+					main_stack.push(__add);
+				else if(text[i]=='-')
+					main_stack.push(__sub);
+				else if(text[i]=='*')
+					main_stack.push(__mul);
+				else if(text[i]=='/')
+					main_stack.push(__div);
+				else if(text[i]=='~')
+					main_stack.push(__link);
+			}
+			comp_stack.push(sharp);
+			comp_stack.push(E);
+		}
+		void print_stack(std::stack<int>& temp)
+		{
+			std::stack<int> t;
+			while(!temp.empty())
+			{
+				t.push(temp.top());
+				print_token(t.top());
+				temp.pop();
+			}
+			while(!t.empty())
+			{
+				temp.push(t.top());
+				t.pop();
+			}
+			return;
+		}
+		void print_main_and_comp()
+		{
+			print_stack(main_stack);
+			std::cout<<"		";
+			print_stack(comp_stack);
+			std::cout<<std::endl;
+			return;
+		}
+		void work()
+		{
+			print_main_and_comp();
+			while((main_stack.top()!=sharp) || (comp_stack.top()!=sharp))
+			{
+				if(!isEnd(comp_stack.top()))
+				{
+					if(isHead(main_stack.top(),comp_stack.top()))
+					{
+						int i=correct_token_seq(main_stack.top(),comp_stack.top());
+						comp_stack.pop();
+						for(int j=max_len-1;j>=0;--j)
+							if(par[i].tokens[j])
+								comp_stack.push(par[i].tokens[j]);
+					}
+					else if(!isHead(main_stack.top(),comp_stack.top()))
+					{
+						//to check if this can be extended as 'e'
+						int i=place_operator_end(comp_stack.top());
+						if(i!=-1)
+							comp_stack.pop();
+						else
+						{
+							std::cout<<"error."<<std::endl;
+							return;
+						}
+					}
+					else
+					{
+						std::cout<<"error."<<std::endl;
+						return;
+					}
+					print_main_and_comp();
+				}
+				else
+				{
+					if(main_stack.top()==comp_stack.top())
+					{
+						main_stack.pop();
+						comp_stack.pop();
+					}
+					else if(comp_stack.top()==e)
+						comp_stack.pop();
+					else
+					{
+						std::cout<<"error."<<std::endl;
+						return;
+					}
+					print_main_and_comp();
+				}
+			}
+			std::cout<<"accept."<<std::endl;
+			return;
+		}
+};
+
+int main()
+{
+	std::string text;
+	while(1)
+	{
+		std::cin>>text;
+		PDA m(text);
+		m.work();
+	}
+	return 0;
+}