diff --git a/dist/expression-builder.js b/dist/expression-builder.js
index d6c2b10..e0c06e0 100644
--- a/dist/expression-builder.js
+++ b/dist/expression-builder.js
@@ -1,4 +1,4 @@
-angular.module('expression-builder', [])
+angular.module('expression-builder', ['ui.bootstrap'])
 
 	.controller('ExpressionBuilderController', function($scope){
 		
@@ -19,6 +19,18 @@ angular.module('expression-builder', [])
 		$scope.removeAt=function(idx){
 			$scope.conditions.splice(idx,1);
 		}
+		
+		$scope.getLeftOperands=function($viewValue){
+			return ($scope.leftOperandProvider)
+				? $scope.leftOperandProvider($viewValue)
+				: [];				
+		}
+		
+		$scope.getRightOperands=function($viewValue){
+			return ($scope.rightOperandProvider)
+				? $scope.rightOperandProvider($viewValue)
+				: [];		
+		}
 	})
 	
 	.directive('expressionBuilder', function($compile){
@@ -30,7 +42,9 @@ angular.module('expression-builder', [])
 			scope: {
 				conditions: '=',
 				booleanOperators: '=?',
-				comparisonOperators: '=?'
+				comparisonOperators: '=?',
+				leftOperandProvider: '&',
+				rightOperandProvider: '&'
 			},
 			compile: function (element) {
 				var contents = element.contents().remove();
@@ -46,12 +60,19 @@ angular.module('expression-builder', [])
 					});
 					
 					if(scope.booleanOperators === undefined)
-						scope.booleanOperators = ['AND', 'OR', 'AND NOT', 'XOR'];
+						scope.booleanOperators = ['AND', 'OR', 'XOR'];
 					
 					if(scope.comparisonOperators === undefined)
 						scope.comparisonOperators = ['=', '<>', '<', '<=', '>', '>='];
+					
+					if(scope.leftOperandProvider)
+						scope.leftOperandProvider = scope.leftOperandProvider()
+					
+					if(scope.rightOperandProvider)
+						scope.rightOperandProvider = scope.rightOperandProvider()
 				};
 			}
 		};
 	})
-angular.module("expression-builder").run(["$templateCache", function($templateCache) {$templateCache.put("templates/expressionbuilder.html","<div class=condition-builder><div ng-repeat=\"c in conditions\"><div ng-if=\"$index != 0\" class=\"form-inline bool-op\"><select class=\"form-control input-sm\" ng-options=\"o as o for o in booleanOperators\" ng-model=c.bool></select></div><div ng-if=c.conditions class=condition-group><div class=pull-right><button class=\"btn btn-danger btn-sm\" ng-click=removeAt($index)>&times;</button></div><expression-builder conditions=c.conditions boolean-operators=booleanOperators comparison-operators=comparisonOperators></expression-builder></div><div ng-if=!c.conditions class=form-inline><div class=form-group-sm><input class=form-control ng-model=c.field placeholder=Field><select class=form-control ng-model=c.comparison ng-options=\"o as o for o in comparisonOperators\"></select><input class=form-control ng-model=c.value placeholder=value> <button class=\"btn btn-danger btn-sm\" ng-click=removeAt($index)>&times;</button></div></div></div><div class=condition-group-button-row><button class=\"btn btn-success btn-sm\" ng-click=addCondition()>Add Condition</button> <button class=\"btn btn-success btn-sm\" ng-click=addGroup()>Add Group</button></div></div>");}]);
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+	
+angular.module("expression-builder").run(["$templateCache", function($templateCache) {$templateCache.put("templates/expressionbuilder.html","<div class=condition-builder><div ng-repeat=\"c in conditions\"><div ng-if=\"$index != 0\" class=\"form-inline bool-op\"><select class=\"form-control input-sm\" ng-options=\"o as o for o in booleanOperators\" ng-model=c.bool></select></div><div ng-if=c.conditions class=condition-group><div class=pull-right><button class=\"btn btn-danger btn-sm\" ng-click=removeAt($index)>&times;</button></div><expression-builder conditions=c.conditions boolean-operators=booleanOperators comparison-operators=comparisonOperators left-operand-provider=leftOperandProvider right-operand-provider=rightOperandProvider></expression-builder></div><div ng-if=!c.conditions class=form-inline><div class=form-group-sm><input class=form-control ng-model=c.leftOperand placeholder=\"Left Operand\" typeahead=\"operand for operand in getLeftOperands($viewValue)\"><select class=form-control ng-model=c.comparison ng-options=\"o as o for o in comparisonOperators\"></select><input class=form-control ng-model=c.rightOperand placeholder=\"Right Operand\" typeahead=\"operand for operand in getRightOperands($viewValue)\"> <button class=\"btn btn-danger btn-sm\" ng-click=removeAt($index)>&times;</button></div></div></div><div class=condition-group-button-row><button class=\"btn btn-success btn-sm\" ng-click=addCondition()>Add Condition</button> <button class=\"btn btn-success btn-sm\" ng-click=addGroup()>Add Group</button></div></div>");}]);
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diff --git a/dist/expression-builder.min.js b/dist/expression-builder.min.js
index cf1dd10..4fc3176 100644
--- a/dist/expression-builder.min.js
+++ b/dist/expression-builder.min.js
@@ -1 +1 @@
-angular.module("expression-builder",[]).controller("ExpressionBuilderController",["$scope",function(o){o.addCondition=function(){o.conditions.push({})},o.addGroup=function(){o.conditions.push({conditions:[]})},o.remove=function(n){var i=o.conditions.indexOf(n);o.removeAt(i)},o.removeAt=function(n){o.conditions.splice(n,1)}}]).directive("expressionBuilder",["$compile",function(o){return{restrict:"EA",controller:"ExpressionBuilderController",templateUrl:"templates/expressionbuilder.html",scope:{conditions:"=",booleanOperators:"=?",comparisonOperators:"=?"},compile:function(n){var i,e=n.contents().remove();return function(n,t){angular.isUndefined(i)&&(i=o(e)),i(n,function(o){t.append(o)}),void 0===n.booleanOperators&&(n.booleanOperators=["AND","OR","AND NOT","XOR"]),void 0===n.comparisonOperators&&(n.comparisonOperators=["=","<>","<","<=",">",">="])}}}}]),angular.module("expression-builder").run(["$templateCache",function(o){o.put("templates/expressionbuilder.html",'<div class=condition-builder><div ng-repeat="c in conditions"><div ng-if="$index != 0" class="form-inline bool-op"><select class="form-control input-sm" ng-options="o as o for o in booleanOperators" ng-model=c.bool></select></div><div ng-if=c.conditions class=condition-group><div class=pull-right><button class="btn btn-danger btn-sm" ng-click=removeAt($index)>&times;</button></div><expression-builder conditions=c.conditions boolean-operators=booleanOperators comparison-operators=comparisonOperators></expression-builder></div><div ng-if=!c.conditions class=form-inline><div class=form-group-sm><input class=form-control ng-model=c.field placeholder=Field><select class=form-control ng-model=c.comparison ng-options="o as o for o in comparisonOperators"></select><input class=form-control ng-model=c.value placeholder=value> <button class="btn btn-danger btn-sm" ng-click=removeAt($index)>&times;</button></div></div></div><div class=condition-group-button-row><button class="btn btn-success btn-sm" ng-click=addCondition()>Add Condition</button> <button class="btn btn-success btn-sm" ng-click=addGroup()>Add Group</button></div></div>')}]);
\ No newline at end of file
+angular.module("expression-builder",["ui.bootstrap"]).controller("ExpressionBuilderController",["$scope",function(o){o.addCondition=function(){o.conditions.push({})},o.addGroup=function(){o.conditions.push({conditions:[]})},o.remove=function(e){var n=o.conditions.indexOf(e);o.removeAt(n)},o.removeAt=function(e){o.conditions.splice(e,1)},o.getLeftOperands=function(e){return o.leftOperandProvider?o.leftOperandProvider(e):[]},o.getRightOperands=function(e){return o.rightOperandProvider?o.rightOperandProvider(e):[]}}]).directive("expressionBuilder",["$compile",function(o){return{restrict:"EA",controller:"ExpressionBuilderController",templateUrl:"templates/expressionbuilder.html",scope:{conditions:"=",booleanOperators:"=?",comparisonOperators:"=?",leftOperandProvider:"&",rightOperandProvider:"&"},compile:function(e){var n,r=e.contents().remove();return function(e,i){angular.isUndefined(n)&&(n=o(r)),n(e,function(o){i.append(o)}),void 0===e.booleanOperators&&(e.booleanOperators=["AND","OR","XOR"]),void 0===e.comparisonOperators&&(e.comparisonOperators=["=","<>","<","<=",">",">="]),e.leftOperandProvider&&(e.leftOperandProvider=e.leftOperandProvider()),e.rightOperandProvider&&(e.rightOperandProvider=e.rightOperandProvider())}}}}]),angular.module("expression-builder").run(["$templateCache",function(o){o.put("templates/expressionbuilder.html",'<div class=condition-builder><div ng-repeat="c in conditions"><div ng-if="$index != 0" class="form-inline bool-op"><select class="form-control input-sm" ng-options="o as o for o in booleanOperators" ng-model=c.bool></select></div><div ng-if=c.conditions class=condition-group><div class=pull-right><button class="btn btn-danger btn-sm" ng-click=removeAt($index)>&times;</button></div><expression-builder conditions=c.conditions boolean-operators=booleanOperators comparison-operators=comparisonOperators left-operand-provider=leftOperandProvider right-operand-provider=rightOperandProvider></expression-builder></div><div ng-if=!c.conditions class=form-inline><div class=form-group-sm><input class=form-control ng-model=c.leftOperand placeholder="Left Operand" typeahead="operand for operand in getLeftOperands($viewValue)"><select class=form-control ng-model=c.comparison ng-options="o as o for o in comparisonOperators"></select><input class=form-control ng-model=c.rightOperand placeholder="Right Operand" typeahead="operand for operand in getRightOperands($viewValue)"> <button class="btn btn-danger btn-sm" ng-click=removeAt($index)>&times;</button></div></div></div><div class=condition-group-button-row><button class="btn btn-success btn-sm" ng-click=addCondition()>Add Condition</button> <button class="btn btn-success btn-sm" ng-click=addGroup()>Add Group</button></div></div>')}]);
\ No newline at end of file