diff --git a/index.js b/index.js
index d8a328f..e4e9996 100644
--- a/index.js
+++ b/index.js
@@ -78,7 +78,7 @@ yy: {},
 symbols_: {"error":2,"expressions":3,"e":4,"EOF":5,"OR":6,"AND":7,"NOT":8,"term":9,"=":10,"<>":11,"IN":12,"NOT_IN":13,">":14,">=":15,"<":16,"<=":17,"(":18,")":19,"NUMBER":20,"VARIABLE":21,"STRING":22,"ARRAY":23,"DATE":24,"$accept":0,"$end":1},
 terminals_: {2:"error",5:"EOF",6:"OR",7:"AND",8:"NOT",10:"=",11:"<>",12:"IN",13:"NOT_IN",14:">",15:">=",16:"<",17:"<=",18:"(",19:")",20:"NUMBER",21:"VARIABLE",22:"STRING",23:"ARRAY",24:"DATE"},
 productions_: [0,[3,2],[4,3],[4,3],[4,2],[4,3],[4,3],[4,3],[4,3],[4,3],[4,3],[4,3],[4,3],[4,3],[9,1],[9,1],[9,1],[9,1],[9,1]],
-performAction: function anonymous(yytext, yyleng, yylineno, yy, yystate /* action[1] */, $$ /* vstack */, _$ /* lstack */, data, validator) {
+performAction: function anonymous(yytext, yyleng, yylineno, yy, yystate /* action[1] */, $$ /* vstack */, _$ /* lstack */, data, validator, grammar) {
 /* this == yyval */
 
 var $0 = $$.length - 1;
@@ -87,37 +87,37 @@ case 1:
  return $$[$0-1]; 
 break;
 case 2:
-this.$ = $$[$0-2] || $$[$0];
+this.$ = !grammar ? ($$[$0-2] || $$[$0]) : [$$[$0-2], 'or', $$[$0]];
 break;
 case 3:
-this.$ = $$[$0-2] && $$[$0];
+this.$ = !grammar ? ($$[$0-2] && $$[$0]) : [$$[$0-2], 'and', $$[$0]];
 break;
 case 4:
-this.$ = !$$[$0];
+this.$ = !grammar ? !$$[$0] : [$$[$0], 'not', null];
 break;
 case 5:
-this.$ = $$[$0-2] === $$[$0];
+this.$ = !grammar ? ($$[$0-2] === $$[$0]) : [$$[$0-2], 'eq', $$[$0]];
 break;
 case 6:
-this.$ = $$[$0-2] !== $$[$0];
+this.$ = !grammar ? ($$[$0-2] !== $$[$0]) : [$$[$0-2], 'neq', $$[$0]];
 break;
 case 7:
-this.$ = validator ? validator.in($$[$0-2], $$[$0]) : $$[$0].indexOf($$[$0-2]) !== -1
+this.$ = validator ? validator.in($$[$0-2], $$[$0]) : (!grammar ? ($$[$0].indexOf($$[$0-2]) !== -1) : [$$[$0-2], 'in', $$[$0]])
 break;
 case 8:
-this.$ = validator ? validator.not_in($$[$0-2], $$[$0]) : $$[$0].indexOf($$[$0-2]) === -1
+this.$ = validator ? validator.not_in($$[$0-2], $$[$0]) : (!grammar ? ($$[$0].indexOf($$[$0-2]) === -1) : [$$[$0-2], 'nin', $$[$0]])
 break;
 case 9:
-this.$ = $$[$0-2] > $$[$0];
+this.$ = !grammar ? $$[$0-2] > $$[$0] : [$$[$0-2], 'gt', $$[$0]];
 break;
 case 10:
-this.$ = $$[$0-2] >= $$[$0];
+this.$ = !grammar ? $$[$0-2] >= $$[$0] : [$$[$0-2], 'gte', $$[$0]];
 break;
 case 11:
-this.$ = $$[$0-2] < $$[$0];
+this.$ = !grammar ? $$[$0-2] < $$[$0] : [$$[$0-2], 'lt', $$[$0]];
 break;
 case 12:
-this.$ = $$[$0-2] <= $$[$0];
+this.$ = !grammar ? $$[$0-2] <= $$[$0] : [$$[$0-2], 'lte', $$[$0]];
 break;
 case 13:
 this.$ = $$[$0-1];
@@ -126,7 +126,7 @@ case 14:
 this.$ = validator ? validator.number(Number(yytext)) : Number(yytext);
 break;
 case 15:
-this.$ = validator ? validator.variable(yytext, data) : data[yytext];
+this.$ = validator ? validator.variable(yytext, data) : !grammar ? data[yytext]: yytext;
 break;
 case 16:
 this.$ = validator ? validator.string(JSON.parse(yytext)) : JSON.parse(yytext);
@@ -295,7 +295,45 @@ parse: function parse(input) {
 
 function splitArray(input){
   return input.replace(/\[|\]+/g,'').split(',').map(function(item){return item ? JSON.parse(item.trim()): ''});
-}/* generated by jison-lex 0.3.4 */
+}
+
+function _g() { return typeof grammar === 'undefined'; }
+function _v() { return typeof validator !== 'undefined'; }
+
+function isExpr(input) {
+  return Array.isArray(input) && input.length === 3;
+}
+
+function toValue(input) {
+  if (input instanceof Date) return (input.getMonth() + 1) + '/' + input.getDate() + '/' + input.getFullYear();
+  return JSON.stringify(input);
+}
+
+function generate(input) {
+  var lhs = isExpr(input[0]) ? generate(input[0]) : input[0];
+  var op = input[1];
+  var rhs = isExpr(input[2]) ? generate(input[2]) : toValue(input[2]);
+
+  var _s = function(str) { return str; };
+  switch (op) {
+    case 'not'  : return _s('!(' + lhs + ')');
+    case 'eq'   : return _s(lhs + ' = ' + rhs);
+    case 'neq'  : return _s(lhs + ' <> ' + rhs);
+    case 'in'   : return _s(lhs + ' in ' + rhs);
+    case 'nin'  : return _s(lhs + ' not in ' + rhs);
+    case 'gt'   : return _s(lhs + ' > ' + rhs);
+    case 'gte'  : return _s(lhs + ' >= ' + rhs);
+    case 'lt'   : return _s(lhs + ' < ' + rhs);
+    case 'lte'  : return _s(lhs + ' <= ' + rhs);
+    case 'and'  : return _s('(' + lhs + ' and ' + rhs + ')');
+    case 'or'   : return _s('(' + lhs + ' or ' + rhs + ')');
+    default:
+      throw new Error('do not recognize:' + lhs + ', ' + op + ', ' + rhs);
+  }
+}
+
+exports.generate = generate;
+/* generated by jison-lex 0.3.4 */
 var lexer = (function(){
 var lexer = ({
 
diff --git a/rule.jison b/rule.jison
index 939d4de..a918ff8 100644
--- a/rule.jison
+++ b/rule.jison
@@ -60,6 +60,7 @@
 %start expressions
 %parse-param data
 %parse-param validator
+%parse-param grammar
 
 %% /* language grammar */
 
@@ -70,27 +71,27 @@ expressions
 
 e
     : e OR e
-        {$$ = $1 || $3;}
+        {$$ = !grammar ? ($1 || $3) : [$1, 'or', $3];}
     | e AND e
-        {$$ = $1 && $3;}
+        {$$ = !grammar ? ($1 && $3) : [$1, 'and', $3];}
     | NOT e
-        {$$ = !$2;}
+        {$$ = !grammar ? !$2 : [$2, 'not', null];}
     | term '=' term
-        {$$ = $1 === $3;}
+        {$$ = !grammar ? ($1 === $3) : [$1, 'eq', $3];}
     | term '<>' term
-        {$$ = $1 !== $3;}
+        {$$ = !grammar ? ($1 !== $3) : [$1, 'neq', $3];}
     | term IN term
-        {$$ = validator ? validator.in($1, $3) : $3.indexOf($1) !== -1}
+        {$$ = validator ? validator.in($1, $3) : (!grammar ? ($3.indexOf($1) !== -1) : [$1, 'in', $3])}
     | term NOT_IN term
-        {$$ = validator ? validator.not_in($1, $3) : $3.indexOf($1) === -1}
+        {$$ = validator ? validator.not_in($1, $3) : (!grammar ? ($3.indexOf($1) === -1) : [$1, 'nin', $3])}
     | term '>' term
-        {$$ = $1 > $3;}
+        {$$ = !grammar ? $1 > $3 : [$1, 'gt', $3];}
     | term '>=' term
-        {$$ = $1 >= $3;}
+        {$$ = !grammar ? $1 >= $3 : [$1, 'gte', $3];}
     | term '<' term
-        {$$ = $1 < $3;}
+        {$$ = !grammar ? $1 < $3 : [$1, 'lt', $3];}
     | term '<=' term
-        {$$ = $1 <= $3;}
+        {$$ = !grammar ? $1 <= $3 : [$1, 'lte', $3];}
     | '(' e ')'
         {$$ = $2;}
     ;
@@ -99,7 +100,7 @@ term
     : NUMBER
         {$$ = validator ? validator.number(Number(yytext)) : Number(yytext);}
     | VARIABLE
-        {$$ = validator ? validator.variable(yytext, data) : data[yytext];}
+        {$$ = validator ? validator.variable(yytext, data) : !grammar ? data[yytext]: yytext;}
     | STRING
         {$$ = validator ? validator.string(JSON.parse(yytext)) : JSON.parse(yytext);}
     | ARRAY
@@ -112,4 +113,41 @@ term
 
 function splitArray(input){
   return input.replace(/\[|\]+/g,'').split(',').map(function(item){return item ? JSON.parse(item.trim()): ''});
-}
\ No newline at end of file
+}
+
+function _g() { return typeof grammar === 'undefined'; }
+function _v() { return typeof validator !== 'undefined'; }
+
+function isExpr(input) {
+  return Array.isArray(input) && input.length === 3;
+}
+
+function toValue(input) {
+  if (input instanceof Date) return (input.getMonth() + 1) + '/' + input.getDate() + '/' + input.getFullYear();
+  return JSON.stringify(input);
+}
+
+function generate(input) {
+  var lhs = isExpr(input[0]) ? generate(input[0]) : input[0];
+  var op = input[1];
+  var rhs = isExpr(input[2]) ? generate(input[2]) : toValue(input[2]);
+
+  var _s = function(str) { return str; };
+  switch (op) {
+    case 'not'  : return _s('!(' + lhs + ')');
+    case 'eq'   : return _s(lhs + ' = ' + rhs);
+    case 'neq'  : return _s(lhs + ' <> ' + rhs);
+    case 'in'   : return _s(lhs + ' in ' + rhs);
+    case 'nin'  : return _s(lhs + ' not in ' + rhs);
+    case 'gt'   : return _s(lhs + ' > ' + rhs);
+    case 'gte'  : return _s(lhs + ' >= ' + rhs);
+    case 'lt'   : return _s(lhs + ' < ' + rhs);
+    case 'lte'  : return _s(lhs + ' <= ' + rhs);
+    case 'and'  : return _s('(' + lhs + ' and ' + rhs + ')');
+    case 'or'   : return _s('(' + lhs + ' or ' + rhs + ')');
+    default:
+      throw new Error('do not recognize:' + lhs + ', ' + op + ', ' + rhs);
+  }
+}
+
+exports.generate = generate;