diff --git a/version2.0/nasal_symbol_table.h b/version2.0/nasal_symbol_table.h
deleted file mode 100644
index 3c5647a..0000000
--- a/version2.0/nasal_symbol_table.h
+++ /dev/null
@@ -1,375 +0,0 @@
-#ifndef __NASAL_SYMBOL_TABLE_H__
-#define __NASAL_SYMBOL_TABLE_H__
-
-struct symbol_table_unit
-{
-    std::string symbol_name;
-    int symbol_number;
-    int symbol_line;
-    symbol_table_unit()
-    {
-        symbol_name="";
-        symbol_number=0;
-        symbol_line=-1;
-        return;
-    }
-    symbol_table_unit(const symbol_table_unit& tmp)
-    {
-        symbol_name=tmp.symbol_name;
-        symbol_number=tmp.symbol_number;
-        symbol_line=tmp.symbol_line;
-        return;
-    }
-    symbol_table_unit& operator=(const symbol_table_unit& tmp)
-    {
-        symbol_line=tmp.symbol_line;
-        symbol_name=tmp.symbol_name;
-        symbol_number=tmp.symbol_number;
-        return *this;
-    }
-};
-
-class nasal_symbol_table
-{
-    private:
-        int error;
-        int global_number;
-        int local_number;
-        std::list<symbol_table_unit> global_symbol_dictionary;// used to save symbols appeared in global scope
-        std::list<symbol_table_unit> local_symbol_dictionary; // used to save symbols appeared in local scopes
-        std::list<symbol_table_unit> global_scope;            // global scope
-        std::list<std::list<symbol_table_unit> > local_list;  // local scopes
-        void symbol_table_block_generate(abstract_syntax_tree&);
-        void global_scope_add_symbol(symbol_table_unit);
-        void local_list_add_scope();
-        void local_list_del_scope();
-        void local_scope_add_symbol(symbol_table_unit);
-        int search_symbol_id(symbol_table_unit);
-        bool search_scope(symbol_table_unit);
-    public:
-        nasal_symbol_table();
-        ~nasal_symbol_table();
-        void set_scope_clear();
-        void print_symbol_table();
-        int get_error();
-        void symbol_table_main_generate(abstract_syntax_tree&);
-};
-
-nasal_symbol_table::nasal_symbol_table()
-{
-    error=0;
-    global_number=0;
-    local_number=0;
-    global_symbol_dictionary.clear();
-    global_scope.clear();
-    local_symbol_dictionary.clear();
-    local_list.clear();
-    return;
-}
-
-nasal_symbol_table::~nasal_symbol_table()
-{
-    error=0;
-    global_number=0;
-    local_number=0;
-    global_symbol_dictionary.clear();
-    global_scope.clear();
-    local_symbol_dictionary.clear();
-    local_list.clear();
-    return;
-}
-
-void nasal_symbol_table::set_scope_clear()
-{
-    error=0;
-    global_number=0;
-    local_number=0;
-    global_symbol_dictionary.clear();
-    global_scope.clear();
-    local_symbol_dictionary.clear();
-    local_list.clear();
-    return;
-}
-
-void nasal_symbol_table::print_symbol_table()
-{
-    if(!global_symbol_dictionary.empty())
-    {
-        std::cout<<">> [Symbol] global scope:"<<std::endl;
-        for(std::list<symbol_table_unit>::iterator i=global_symbol_dictionary.begin();i!=global_symbol_dictionary.end();++i)
-            std::cout<<"  line "<<i->symbol_line<<": "<<i->symbol_name<<"|"<<i->symbol_number<<std::endl;
-    }
-    else
-        std::cout<<">> [Symbol] empty global symbol list."<<std::endl;
-    if(!local_symbol_dictionary.empty())
-    {
-        std::cout<<">>[Symbol] local scope:"<<std::endl;
-        for(std::list<symbol_table_unit>::iterator i=local_symbol_dictionary.begin();i!=local_symbol_dictionary.end();++i)
-            std::cout<<"  line "<<i->symbol_line<<": "<<i->symbol_name<<"|"<<i->symbol_number<<std::endl;
-    }
-    else
-        std::cout<<">> [Symbol] empty local symbol list."<<std::endl;
-    return;
-}
-
-void nasal_symbol_table::global_scope_add_symbol(symbol_table_unit tmp)
-{
-    // this conditional expression is used to avoid wrong use of this function
-    // repeat symbol will get the same number
-    for(std::list<symbol_table_unit>::iterator i=global_scope.begin();i!=global_scope.end();++i)
-        if(i->symbol_name==tmp.symbol_name)
-            return;
-    ++global_number;
-    tmp.symbol_number=global_number;
-    global_scope.push_back(tmp);
-    global_symbol_dictionary.push_back(tmp);
-    return;
-}
-
-void nasal_symbol_table::local_list_add_scope()
-{
-    std::list<symbol_table_unit> new_scope;
-    local_list.push_back(new_scope);
-    return;
-}
-
-void nasal_symbol_table::local_list_del_scope()
-{
-    if(local_list.empty())
-    {
-        ++error;
-        std::cout<<">> [Symbol-error] fatal error: empty block_scope_list."<<std::endl;
-    }
-    else
-        local_list.pop_back();
-    
-    if(local_list.empty())
-        local_number=0;
-    return;
-}
-
-void nasal_symbol_table::local_scope_add_symbol(symbol_table_unit tmp)
-{
-    if(!local_list.empty())
-    {
-        // if in the last scope there is a sym which symbol_name is the same as tmp.symbol_name
-        // then the symbol will get the same number
-        std::list<std::list<symbol_table_unit> >::iterator last_scope=local_list.end();--last_scope;
-        for(std::list<std::list<symbol_table_unit> >::iterator i=local_list.begin();i!=local_list.end();++i)
-                for(std::list<symbol_table_unit>::iterator j=i->begin();j!=i->end();++j)
-                    if((i==last_scope) && (j->symbol_name==tmp.symbol_name))
-                        return;
-        ++local_number;
-        tmp.symbol_number=local_number;
-        local_list.back().push_back(tmp);
-        local_symbol_dictionary.push_back(tmp);
-    }
-    else
-    {
-        ++error;
-        std::cout<<">> [Symbol-error] fatal error: empty block_scope_list."<<std::endl;
-    }
-    return;
-}
-
-int nasal_symbol_table::search_symbol_id(symbol_table_unit tmp)
-{
-    // local scope
-    for(std::list<std::list<symbol_table_unit> >::iterator i=local_list.begin();i!=local_list.end();++i)
-        for(std::list<symbol_table_unit>::iterator j=i->begin();j!=i->end();++j)
-            if(j->symbol_name==tmp.symbol_name)
-                return j->symbol_number;
-    // global scope
-    for(std::list<symbol_table_unit>::iterator i=global_scope.begin();i!=global_scope.end();++i)
-        if(i->symbol_name==tmp.symbol_name)
-            return i->symbol_number;
-    // error
-    ++error;
-    std::cout<<">> [Symbol-error] line "<<tmp.symbol_line<<": cannot find var named \'"<<tmp.symbol_name<<"\' ."<<std::endl;
-    return -1;
-}
-
-bool nasal_symbol_table::search_scope(symbol_table_unit tmp)
-{
-	// this function must be used when search_symbol_id()!=-1
-	// because if seach_symbol_id()==-1 it means it haven't found this symbol
-	// true means global scope
-	// false means local scope
-    for(std::list<std::list<symbol_table_unit> >::iterator i=local_list.begin();i!=local_list.end();++i)
-        for(std::list<symbol_table_unit>::iterator j=i->begin();j!=i->end();++j)
-            if(j->symbol_name==tmp.symbol_name)
-                return false;
-    for(std::list<symbol_table_unit>::iterator i=global_scope.begin();i!=global_scope.end();++i)
-        if(i->symbol_name==tmp.symbol_name)
-            return true;
-    return true;
-}
-
-int nasal_symbol_table::get_error()
-{
-    // god knows why i wrote this sh*t.
-    return error;
-}
-
-void nasal_symbol_table::symbol_table_main_generate(abstract_syntax_tree& root)
-{
-    this->set_scope_clear();
-    for(std::list<abstract_syntax_tree>::iterator i=root.get_children().begin();i!=root.get_children().end();++i)
-    {
-        // only definition will call this->global_scope_add_symbol(symbol_table_unit)
-        if(i->get_node_type()==__definition)
-        {
-            symbol_table_unit tmp;
-            tmp.symbol_line=i->get_children().front().get_node_line();
-            tmp.symbol_name=i->get_children().front().get_var_name();
-            this->global_scope_add_symbol(tmp);
-            i->get_children().front().set_symbol_number(this->search_symbol_id(tmp));
-            i->get_children().front().set_var_scope(this->search_scope(tmp));
-            this->symbol_table_block_generate(i->get_children().back());
-        }
-        // when in main_generate loop,local scope is totally empty
-        else
-            this->symbol_table_block_generate(*i);
-    }
-    std::cout<<">> [Symbol] symbol table generating complete. "<<error<<" error(s)."<<std::endl;
-    return;
-}
-
-void nasal_symbol_table::symbol_table_block_generate(abstract_syntax_tree& node)
-{
-    int node_type=node.get_node_type();
-    if(node_type==__function)
-    {
-        this->local_list_add_scope();
-        if(node.get_children().front().get_node_type()==__parameters)
-            for(std::list<abstract_syntax_tree>::iterator i=node.get_children().front().get_children().begin();i!=node.get_children().front().get_children().end();++i)
-            {
-                if(i->get_node_type()==__id || i->get_node_type()==__dynamic_id)
-                {
-                    symbol_table_unit tmp;
-                    tmp.symbol_line=i->get_node_line();
-                    tmp.symbol_name=i->get_var_name();
-                    this->local_scope_add_symbol(tmp);
-                    i->set_symbol_number(this->search_symbol_id(tmp));
-                    i->set_var_scope(this->search_scope(tmp));
-                }
-                else
-                {
-                    symbol_table_unit tmp;
-                    tmp.symbol_line=i->get_children().front().get_node_line();
-                    tmp.symbol_name=i->get_children().front().get_var_name();
-                    this->local_scope_add_symbol(tmp);
-                    i->get_children().front().set_symbol_number(this->search_symbol_id(tmp));
-                    i->get_children().front().set_var_scope(this->search_scope(tmp));
-                    this->symbol_table_block_generate(i->get_children().back());
-                }
-            }
-        this->symbol_table_block_generate(node.get_children().back());
-        this->local_list_del_scope();
-    }
-    else if(node_type==__conditional)
-    {
-        for(std::list<abstract_syntax_tree>::iterator i=node.get_children().begin();i!=node.get_children().end();++i)
-        {
-            this->local_list_add_scope();
-            if(i->get_node_type()==__if || i->get_node_type()==__elsif)
-                this->symbol_table_block_generate(i->get_children().front());
-            this->symbol_table_block_generate(i->get_children().back());
-            this->local_list_del_scope();
-        }
-    }
-    else if(node_type==__while)
-    {
-        for(std::list<abstract_syntax_tree>::iterator i=node.get_children().begin();i!=node.get_children().end();++i)
-            this->symbol_table_block_generate(*i);
-    }
-    else if(node_type==__for || node_type==__foreach || node_type==__forindex)
-    {
-        this->local_list_add_scope();
-        for(std::list<abstract_syntax_tree>::iterator i=node.get_children().begin();i!=node.get_children().end();++i)
-        {
-            if(i->get_node_type()==__definition)
-            {
-                symbol_table_unit tmp;
-                tmp.symbol_line=i->get_children().front().get_node_line();
-                tmp.symbol_name=i->get_children().front().get_var_name();
-                this->local_scope_add_symbol(tmp);
-                i->get_children().front().set_symbol_number(this->search_symbol_id(tmp));
-                i->get_children().front().set_var_scope(this->search_scope(tmp));
-                this->symbol_table_block_generate(i->get_children().back());
-            }
-            else
-                this->symbol_table_block_generate(*i);
-        }
-        this->local_list_del_scope();
-    }
-    else if(node_type==__normal_statement_block)
-    {
-        for(std::list<abstract_syntax_tree>::iterator i=node.get_children().begin();i!=node.get_children().end();++i)
-        {
-            if(i->get_node_type()==__definition)
-            {
-                symbol_table_unit tmp;
-                tmp.symbol_line=i->get_children().front().get_node_line();
-                tmp.symbol_name=i->get_children().front().get_var_name();
-                this->local_scope_add_symbol(tmp);
-                i->get_children().front().set_symbol_number(this->search_symbol_id(tmp));
-                i->get_children().front().set_var_scope(this->search_scope(tmp));
-                this->symbol_table_block_generate(i->get_children().back());
-            }
-            else
-                this->symbol_table_block_generate(*i);
-        }
-    }
-    else if((node_type==__id) || (node_type==__call_hash))
-    {
-        symbol_table_unit tmp;
-        tmp.symbol_line=node.get_node_line();
-        tmp.symbol_name=node.get_var_name();
-        int id_symbol_number=this->search_symbol_id(tmp);
-        node.set_symbol_number(id_symbol_number);
-        // if this id does not exist in scopes
-        // then search_scope will not be called
-        if(id_symbol_number>0)
-        	node.set_var_scope(this->search_scope(tmp));
-        if(!node.get_children().empty())
-            for(std::list<abstract_syntax_tree>::iterator i=node.get_children().begin();i!=node.get_children().end();++i)
-                this->symbol_table_block_generate(*i);
-    }
-    else if(node_type==__hash)
-    {
-        this->local_list_add_scope();
-        symbol_table_unit me;
-        me.symbol_line=node.get_node_line();
-        me.symbol_name="me";
-        this->local_scope_add_symbol(me);
-        for(std::list<abstract_syntax_tree>::iterator i=node.get_children().begin();i!=node.get_children().end();++i)
-        {
-        	if(i->get_node_type()==__hash_member)
-        	{
-        		symbol_table_unit tmp;
-	            tmp.symbol_line=i->get_children().front().get_node_line();
-	            if(i->get_children().front().get_node_type()==__id)
-	                tmp.symbol_name=i->get_children().front().get_var_name();
-	            else if(i->get_children().front().get_node_type()==__string)
-	                tmp.symbol_name=i->get_children().front().get_var_string();
-	            this->local_scope_add_symbol(tmp);
-	            i->get_children().front().set_symbol_number(this->search_symbol_id(tmp));
-	            i->get_children().front().set_var_scope(this->search_scope(tmp));
-	            this->symbol_table_block_generate(i->get_children().back());
-			}
-			else
-				this->symbol_table_block_generate(*i);
-        }
-        this->local_list_del_scope();
-    }
-    else
-    {
-        if(!node.get_children().empty())
-            for(std::list<abstract_syntax_tree>::iterator i=node.get_children().begin();i!=node.get_children().end();++i)
-                this->symbol_table_block_generate(*i);
-    }
-    return;
-}
-
-#endif