支持分数约分/基本三角函数计算的AS3表达式解析类,可以将字符串中的算式解析为结果值.

表达式计算代码,按优先级计算输入的表达式,支持括号,阶乘号,暂不支持三角函数！--Expression calculating code, it can calculate inputed expression by priority ,and supports parenthesis, factorial sign, and it does not support trigonometrical functions for now!