diff --git a/test/json.nas b/test/json.nas
index 39f5686..5d65e47 100644
--- a/test/json.nas
+++ b/test/json.nas
@@ -1,196 +1,324 @@
 #lib json.nas
 import("lib.nas");
-var json={
-    text:'',
-    line:1,
-    size:0,
-    ptr:0,
-    get:nil,
-    check:nil,
-    next:nil,
-    match:nil,
-    hash_gen:nil,
-    vec_gen:nil,
-    member:nil,
-    parse:nil,
-    token:{content:'',type:''},
-    content:[],
-};
 
-json.get=func(filename)
-{
-    me.line=1;
-    me.ptr=0;
-    me.content=[];
-    me.token={content:'',type:''};
-    me.text=io.fin(filename);
-    if(!size(me.text))
-        die("cannot open "~filename);
-    me.text=split('',me.text);
-    me.size=size(me.text);
-    return;
-}
+var JSON=func(){
 
-json.check=func(ptr)
-{
-    var str=me.text[ptr];
-    return (str=='{' or str=='}' or str=='[' or str==']' or str==',' or str==':' or str=='\"' or ('0'<=str and str<='9'));
-}
+    var (
+        j_eof,
+        j_lbrace,
+        j_rbrace,
+        j_lbracket,
+        j_rbracket,
+        j_comma,
+        j_colon,
+        j_str,
+        j_num,
+        j_id
+    )=(
+        0,
+        1,
+        2,
+        3,
+        4,
+        5,
+        6,
+        7,
+        8,
+        9
+    );
+    var j_content=[
+        "eof",
+        "`{`",
+        "`}`",
+        "`[`",
+        "`]`",
+        "`,`",
+        "`:`",
+        "string",
+        "number",
+        "identifier"
+    ];
 
-json.next=func()
-{
-    while(me.ptr<me.size and !json.check(me.ptr))
-    {
-        if(me.text[me.ptr]=='\n')
-            me.line+=1;
-        me.ptr+=1;
+    var text='';
+    var line=1;
+    var text_size=0;
+    var ptr=0;
+    var token={content:'',type:''};
+    var content={};
+    var init=func(){
+        line=1;
+        text_size=0;
+        ptr=0;
+        content={};
+        token={content:'',type:''};
+        text='';
     }
-    if(me.ptr>=me.size)
+
+    var isnum=func(c){
+        return '0'<=c and c<='9';
+    }
+    var isid=func(c){
+        var tmp=c[0];
+        return ('a'[0]<=tmp and tmp<='z'[0]) or
+        ('A'[0]<=tmp and tmp<='Z'[0]) or
+        c=='_';
+    }
+    var check=func()
     {
-        me.token.content="";
-        me.token.type="eof";
+        var c=text[ptr];
+        return (
+            c=='{' or c=='}' or
+            c=='[' or c==']' or
+            c==',' or c==':' or
+            c=='\"' or c=='\'' or
+            isnum(c) or isid(c)
+        );
+    }
+
+    var get=func(str)
+    {
+        init();
+        if(!size(str))
+            die("empty string");
+        text=split('',str);
+        text_size=size(text);
         return;
     }
-    
-    if(me.text[me.ptr]=='{')
+    var next=func()
     {
-        me.token.content='{';
-        me.token.type="left brace";
-    }
-    elsif(me.text[me.ptr]=='}')
-    {
-        me.token.content='}';
-        me.token.type="right brace";
-    }
-    elsif(me.text[me.ptr]=='[')
-    {
-        me.token.content='[';
-        me.token.type="left bracket";
-    }
-    elsif(me.text[me.ptr]==']')
-    {
-        me.token.content=']';
-        me.token.type="right bracket";
-    }
-    elsif(me.text[me.ptr]==',')
-    {
-        me.token.content=',';
-        me.token.type="comma";
-    }
-    elsif(me.text[me.ptr]==':')
-    {
-        me.token.content=':';
-        me.token.type="colon";
-    }
-    elsif(me.text[me.ptr]=='\"')
-    {
-        var s="";
-        me.ptr+=1;
-        while(me.ptr<me.size and me.text[me.ptr]!='\"')
+        while(ptr<text_size and !check())
         {
-            s~=me.text[me.ptr];
-            me.ptr+=1;
+            if(text[ptr]=='\n')
+                line+=1;
+            ptr+=1;
         }
-        me.token.content=s;
-        me.token.type="string";
-    }
-    elsif('0'<=me.text[me.ptr] and me.text[me.ptr]<='9')
-    {
-        var s=me.text[me.ptr];
-        me.ptr+=1;
-        while(me.ptr<me.size and (('0'<=me.text[me.ptr] and me.text[me.ptr]<='9') or me.text[me.ptr]=='.'))
+        if(ptr>=text_size)
         {
-            s~=me.text[me.ptr];
-            me.ptr+=1;
+            token.content="eof";
+            token.type=j_eof;
+            return;
         }
-        me.ptr-=1;
-        me.token.content=num(s);
-        me.token.type="number";
-    }
-    me.ptr+=1;
-    return;
-}
-
-json.match=func(type)
-{
-    if(me.token.type!=type)
-        print("line ",me.line,": expect ",type," but get ",me.token.content,".");
-    me.next();
-    return;
-}
-
-json.hash_gen=func()
-{
-    var hash={};
-    me.match("left brace");
-    me.member(hash);
-    while(me.token.type=="comma")
-    {
-        me.match("comma");
-        me.member(hash);
-    }
-    me.match("right brace");
-    return hash;
-}
-
-json.vec_gen=func()
-{
-    var vec=[];
-    me.match("left bracket");
-    if(me.token.type=="left brace")
-        append(vec,me.hash_gen());
-    elsif(me.token.type=="left bracket")
-        append(vec,me.vec_gen());
-    elsif(me.token.type=="string" or me.token.type=="number")
-    {
-        append(vec,me.token.content);
-        me.next();
-    }
-    while(me.token.type=="comma")
-    {
-        me.match("comma");
-        if(me.token.type=="left brace")
-            append(vec,me.hash_gen());
-        elsif(me.token.type=="left bracket")
-            append(vec,me.vec_gen());
-        elsif(me.token.type=="string" or me.token.type=="number")
+        
+        var c=text[ptr];
+        if(c=='{')
         {
-            append(vec,me.token.content);
-            me.next();
+            token.content='{';
+            token.type=j_lbrace;
+        }
+        elsif(c=='}')
+        {
+            token.content='}';
+            token.type=j_rbrace;
+        }
+        elsif(c=='[')
+        {
+            token.content='[';
+            token.type=j_lbracket;
+        }
+        elsif(c==']')
+        {
+            token.content=']';
+            token.type=j_rbracket;
+        }
+        elsif(c==',')
+        {
+            token.content=',';
+            token.type=j_comma;
+        }
+        elsif(c==':')
+        {
+            token.content=':';
+            token.type=j_colon;
+        }
+        elsif(c=='\"' or c=='\'')
+        {
+            var strbegin=c;
+            var s="";
+            ptr+=1;
+            while(ptr<text_size and text[ptr]!=strbegin)
+            {
+                s~=text[ptr];
+                ptr+=1;
+            }
+            token.content=s;
+            token.type=j_str;
+        }
+        elsif(isnum(c))
+        {
+            var s=c;
+            ptr+=1;
+            while(ptr<text_size and ((isnum(text[ptr]) or text[ptr]=='.')))
+            {
+                s~=text[ptr];
+                ptr+=1;
+            }
+            ptr-=1;
+            token.content=num(s);
+            token.type=j_num;
+        }
+        elsif(isid(c))
+        {
+            var s=c;
+            ptr+=1;
+            while(ptr<text_size and (isid(text[ptr]) or isnum(text[ptr])))
+            {
+                s~=text[ptr];
+                ptr+=1;
+            }
+            ptr-=1;
+            token.content=s;
+            token.type=j_id;
+        }
+        ptr+=1;
+        return;
+    }
+
+    var match=func(type)
+    {
+        if(token.type!=type)
+            print("line ",line,": expect ",j_content[type]," but get `",token.content,"`.\n");
+        next();
+        return;
+    }
+
+    var hash_gen=func()
+    {
+        var hash={};
+        match(j_lbrace);
+        member(hash);
+        while(token.type==j_comma)
+        {
+            match(j_comma);
+            member(hash);
+        }
+        match(j_rbrace);
+        return hash;
+    }
+
+    var vec_gen=func()
+    {
+        var vec=[];
+        match(j_lbracket);
+        if(token.type==j_lbrace)
+            append(vec,hash_gen());
+        elsif(token.type==j_lbracket)
+            append(vec,vec_gen());
+        elsif(token.type==j_str or token.type==j_num)
+        {
+            append(vec,token.content);
+            next();
+        }
+        while(token.type==j_comma)
+        {
+            match(j_comma);
+            if(token.type==j_lbrace)
+                append(vec,me.hash_gen());
+            elsif(token.type==j_lbracket)
+                append(vec,vec_gen());
+            elsif(token.type==j_str or token.type==j_num)
+            {
+                append(vec,token.content);
+                next();
+            }
+        }
+        match(j_rbracket);
+        return vec;
+    }
+
+    var member=func(hash)
+    {
+        var name=token.content;
+        match(j_id);
+        match(j_colon);
+        if(token.type==j_lbrace)
+            hash[name]=hash_gen();
+        elsif(token.type==j_lbracket)
+            hash[name]=vec_gen();
+        elsif(token.type==j_str or token.type==j_num)
+        {
+            hash[name]=token.content;
+            next();
+        }
+        return;
+    }
+    return {
+        parse:func(str)
+        {
+            get(str);
+            next();
+
+            match(j_lbrace);
+            member(content);
+            while(token.type==j_comma)
+            {
+                match(j_comma);
+                member(content);
+            }
+            match(j_rbrace);
+
+            var res=content;
+            init();
+            return res;
+        },
+        stringify:func(hash){
+            var s="";
+            var gen=func(elem){
+                var t=typeof(elem);
+                if(t=="num")
+                    s~=elem;
+                elsif(t=="str")
+                    s~='"'~elem~'"';
+                elsif(t=="vec")
+                    vgen(elem);
+                elsif(t=="hash")
+                    hgen(elem);
+                else
+                    s~='"undefined"';
+            }
+            var vgen=func(v){
+                s~="[";
+                var vsize=size(v);
+                for(var i=0;i<vsize;i+=1){
+                    gen(v[i]);
+                    if(i!=vsize-1)
+                        s~=",";
+                }
+                s~="]";
+            }
+            var hgen=func(h){
+                s~="{";
+                var k=keys(h);
+                var vsize=size(k);
+                for(var i=0;i<vsize;i+=1){
+                    s~=k[i]~":";
+                    gen(h[k[i]]);
+                    if(i!=vsize-1)
+                        s~=",";
+                }
+                s~="}";
+            }
+            hgen(hash);
+            return s;
+        }
+    };
+}();
+
+var ss=JSON.stringify({
+    vec:[
+        0,
+        1,
+        2
+    ],
+    hash:{
+        m1:0,
+        m2:"str",
+        m3:[114514],
+        m4:{
+            year:1919,
+            month:8,
+            date:10
         }
     }
-    me.match("right bracket");
-    return vec;
-}
-
-json.member=func(hash)
-{
-    var name=me.token.content;
-    me.match("string");
-    me.match("colon");
-    if(me.token.type=="left brace")
-        hash[name]=me.hash_gen();
-    elsif(me.token.type=="left bracket")
-        hash[name]=me.vec_gen();
-    elsif(me.token.type=="string" or me.token.type=="number")
-    {
-        hash[name]=me.token.content;
-        me.next();
-    }
-    return;
-}
-
-json.parse=func()
-{
-    me.content={};
-    me.next();
-    me.match("left brace");
-    me.member(me.content);
-    while(me.token.type=="comma")
-    {
-        me.match("comma");
-        me.member(me.content);
-    }
-    me.match("right brace");
-    return;
-}
\ No newline at end of file
+});
+println(ss);
+println(JSON.parse(ss));
\ No newline at end of file