fraction.as

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.

//Class:Fraction  Author:Swfdong  Date:2007-7-1
package {
	import AdvancedMath;
	public class Fraction {
		private var FRACTION_NUMERATOR:Number;
		private var FRACTION_DENOMINATOR:Number;
		function Fraction(str:String) {
			var tIndex:Number=str.indexOf("|", 0);
			if (tIndex!= -1&&tIndex!=0) {
				FRACTION_NUMERATOR=parseFloat(str.substring(0,tIndex));
				FRACTION_DENOMINATOR=parseInt(str.substring(tIndex+1,str.length));
			} else {
				FRACTION_NUMERATOR=parseFloat(str);
				FRACTION_DENOMINATOR=1;
			}
			format();
		}
		//约分
		private function reduction() {
			if(parseInt(FRACTION_NUMERATOR)==parseFloat(FRACTION_NUMERATOR)&&FRACTION_NUMERATOR!=0){
			var tNum:Number=AdvancedMath.gcd(FRACTION_NUMERATOR,FRACTION_DENOMINATOR);
			FRACTION_NUMERATOR=AdvancedMath.fix(FRACTION_NUMERATOR/tNum);
			FRACTION_DENOMINATOR=AdvancedMath.fix(FRACTION_DENOMINATOR/tNum);
			}
		}
		//格式化(如果分母含有负数则将负号乘到分子上)
		private function format() {
			if(FRACTION_DENOMINATOR<0){
			FRACTION_NUMERATOR=-FRACTION_NUMERATOR;
			FRACTION_DENOMINATOR=-FRACTION_DENOMINATOR;
			}
		}
		//分母
		public function get denominator():Number {
			return FRACTION_DENOMINATOR;
		}
		//分子
		public function get numerator():Number {
			return FRACTION_NUMERATOR;
		}
		public function set denominator(num:Number) {
			FRACTION_DENOMINATOR=Math.round(num);
		}
		public function set numerator(num:Number) {
			FRACTION_NUMERATOR=num;
			reduction();
			format();
		}
		public function get value():String {
			return FRACTION_NUMERATOR + (FRACTION_DENOMINATOR!=1?"|" + FRACTION_DENOMINATOR:"");
		}
	}
}