var Class = require('../utils/Class'); 
var ProcessQueue = new Class({ 
initialize: function ProcessQueue(){ 
this._pending = [] ; 
this._active = [] ; 
this._destroy = [] ; 
this._toProcess = 0; 
} 
,
add: function (item){ 
this._pending.push(item); 
this._toProcess++ ; 
return this; 
} 
,
remove: function (item){ 
this._destroy.push(item); 
this._toProcess++ ; 
return this; 
} 
,
update: function (){ 
if (this._toProcess === 0) { 
return this._active; 
} 
var list = this._destroy; 
var active = this._active; 
var i; 
var item; 
for (i = 0; i < (_AN_Read_length('length', list)); i++ ){ 
item = list[i]; 
var idx = active.indexOf(item); 
if (idx !== -1) { 
active.splice(idx, 1); 
} 
} 
list.length = 0; 
list = this._pending; 
for (i = 0; i < (_AN_Read_length('length', list)); i++ ){ 
item = list[i]; 
this._active.push(item); 
} 
list.length = 0; 
this._toProcess = 0; 
return this._active; 
} 
,
getActive: function (){ 
return this._active; 
} 
,
destroy: function (){ 
this._pending = [] ; 
this._active = [] ; 
this._destroy = [] ; 
} 
}
); 
module.exports = ProcessQueue;