Created
January 10, 2014 08:55
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CircleBuffer
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// http://jsperf.com/circle-buffer-vc-array | |
var CircleBuffer = function (size) { | |
this._size = size; // max count of data | |
this._list = []; | |
this._cursorIndex = 0; | |
this._startIndex = 0; | |
this.length = 0; // actual data length | |
}; | |
CircleBuffer.prototype = { | |
constructor: CircleBuffer, | |
push: function (data) { | |
this.length++; | |
if (this.length > this._size) { | |
this.length = this._size; | |
this._startIndex++; | |
this._startIndex = this._startIndex % this._size; | |
} | |
this._list[this._cursorIndex++] = data; | |
this._cursorIndex = this._cursorIndex % this._size; | |
}, | |
shift: function () { | |
if (this.length > 0) { | |
var _i = this._startIndex % this._size; | |
var _v = this._list[_i]; | |
delete this._list[_i]; | |
this._startIndex += 1; | |
this.length -= 1; | |
return _v; | |
} | |
}, | |
get: function (index) { | |
if (index > -1 && index < this.length) { | |
return this._list[(this._startIndex + index) % this._size]; | |
} | |
}, | |
removeAtBegin: function (count) { | |
if (count >= this.length) { | |
this.clear(); | |
return; | |
} | |
if (count > 0) { | |
for (var i = 0; i < count; i++) { | |
delete this._list[(this._startIndex + i) % this._size]; | |
} | |
this._startIndex += count; | |
this.length -= count; | |
} | |
}, | |
first: function () { | |
if (this.length > 0) { | |
return this._list[this._startIndex % this._size]; | |
} | |
}, | |
last: function () { | |
if (this.length > 0) { | |
return this._list[(this._startIndex + this.length - 1) % this._size]; | |
} | |
}, | |
clear: function () { | |
if (this.length > 0) { | |
this._list.length = 0; | |
this._cursorIndex = 0; | |
this._startIndex = 0; | |
this.length = 0; | |
} | |
} | |
}; |
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