Use "with" instead of regex after lemonzi's recommendation

lib/pjs.js

@@ -23,13 +23,14 @@ var _nullObject   = utils._nullObject;
  * returns {Transform} A transform stream in objectMode
  */
 exports.filter = function(expression, outputString, explicit) {
-  var exp, i, include, filterStream;
+  var i, include, filterStream;
 
-  exp = (explicit) ? expression : utils.getBoundExpression(expression, '$');
   i = 0;
 
   include = function($, i) {
-    return eval(exp);
+    with ($) {
+      return eval(expression);
+    }
   };
 
   filterStream = new stream.Transform({objectMode: true});
@@ -58,19 +59,22 @@ exports.filter = function(expression, outputString, explicit) {
  * returns {Transform} A transform stream in objectMode
  */
 exports.map = function(expression, outputString, explicit) {
-  var exp, i, update, mapStream;
+  var i, update, mapStream;
 
-  exp = (explicit) ? expression : utils.getBoundExpression(expression, '$');
   i = 0;
 
   update = function($, i) {
-    var _result = eval('(' + exp + ')');
-    return (_result === null) ? _nullObject : _result;
+    with ($) {
+      var _result = eval('(' + expression + ')');
+      return (_result === null) ? _nullObject : _result;
+    }
   };
 
   if (outputString) {
     update = function($, i) {
-      return String(eval('(' + exp + ')')) + "\n";
+      with ($) {
+        return String(eval('(' + expression + ')')) + "\n";
+      }
     };
   }
 

lib/utils.js

@@ -123,22 +123,3 @@ utils.concat = function(array) {
     return String(curr) + String(prev);
   });
 };
-
-/**
- * Given a string expression to be evaluated, binds any String properties and
- * methods to the provided variable. Returns the resulting string.
- *
- * @param {string} expression The expression to bind
- * @param {string} varName    Variable to which to bind
- */
-utils.getBoundExpression = function(expression, varName) {
-  Object.getOwnPropertyNames(String.prototype).forEach(function(key) {
-    var regexStr, pattern;
-
-    regexStr = '([^\\w\\.\\{]\\s*|^\\s*)(' + key + ')([^\\w\\.]|$)';
-    pattern = new RegExp(regexStr, 'g');
-    expression = expression.replace(pattern, "$1" + varName + ".$2$3");
-  });
-
-  return expression;
-};

spec/utilsSpec.js

@@ -84,30 +84,4 @@ describe('utils', function() {
       expect(result).to.be('foobarnull');
     });
   });
-
-  describe('getBoundExpression', function() {
-    it('prepends identifiers that are keys in String.prototype by the var', function() {
-      var result = utils.getBoundExpression('trim()', '$');
-      expect(result).to.be('$.trim()');
-    });
-
-    it('correctly attributes identifiers given leading whitespace', function() {
-      var result = utils.getBoundExpression('  trim()', '$');
-      expect(result).to.be('  $.trim()');
-    });
-
-    it('does not modify keys in object literals', function() {
-      var result = utils.getBoundExpression('{length: length}', '$');
-      expect(result).to.be('{length: $.length}');
-    });
-
-    it('ignores identifiers in which a prototype key is a substring', function() {
-      var identifiers = ['asubstr', 'substra', 'asubstra', '_substr',
-        'substr_', '_substr_', 'substr123', 'x.substr'];
-
-      identifiers.forEach(function(str) {
-        expect(utils.getBoundExpression(str, '$')).to.be(str);
-      });
-    });
-  });
 });