基於JavaScript的公式解譯器 – 8 【比較操作符的實現】

比較操作符基類

檔案：OperatorCompareBase.js

function OperatorCompareBase() {<br /> this.DeriveFrom(new OperatorBinaryBase());<br /> this.set_ClassName("OperatorCompareBase");<br /> this.set_Sign("OperatorCompareBase");</p><p> this._getTwoNumberOperands = function(operands) {<br /> var right = operands.pop(),<br /> left = operands.pop(),<br /> leftVal,<br /> rightVal;</p><p> if (left.IsString() || right.IsString()) {<br /> leftVal = left.ToString();<br /> rightVal = right.ToString();<br /> }<br /> else {<br /> if (left.get_Type() == right.get_Type()) {<br /> if (left.IsNumber() || left.IsBoolean()) {<br /> leftVal = left.get_Value();<br /> rightVal = right.get_Value();<br /> }<br /> else<br /> throw new Exception(this, "Unsupported type:" + $T(left));<br /> }<br /> else {<br /> leftVal = left.IsNumber() ? left.get_Value() : (new OperandNumber(left)).get_Value();<br /> rightVal = left.IsNumber() ? right.get_Value() : (new OperandNumber(right)).get_Value();<br /> }<br /> }</p><p> return [leftVal, rightVal];<br /> }; // _getTwoNumberOperands<br />};

 

比較操作符

包括：>、>=、<、<=

檔案：OperatorCompare.js

function OperatorLessThan() {<br /> this.DeriveFrom(new OperatorCompareBase());<br /> this.set_ClassName("OperatorLessThan");<br /> this.set_Sign("<");<br />}</p><p>OperatorLessThan.prototype.Evaluate = function(operands) {<br /> var values = this._getTwoNumberOperands(operands);</p><p> return new OperandBoolean(values[0] < values[1]);<br />};</p><p>function OperatorLessEqual() {<br /> this.DeriveFrom(new OperatorCompareBase());<br /> this.set_ClassName("OperatorLessEqual");<br /> this.set_Sign("<=");<br />}</p><p>OperatorLessEqual.prototype.Evaluate = function(operands) {<br /> var values = this._getTwoNumberOperands(operands);</p><p> return new OperandBoolean(values[0] <= values[1]);<br />};</p><p>function OperatorGreaterThan() {<br /> this.DeriveFrom(new OperatorCompareBase());<br /> this.set_ClassName("OperatorGreaterThan");<br /> this.set_Sign(">");<br />};</p><p>OperatorGreaterThan.prototype.Evaluate = function(operands) {<br /> var values = this._getTwoNumberOperands(operands);</p><p> return new OperandBoolean(values[0] > values[1]);<br />};</p><p>function OperatorGreaterEqual() {<br /> this.DeriveFrom(new OperatorCompareBase());<br /> this.set_ClassName("OperatorGreaterEqual");<br /> this.set_Sign(">=");<br />};</p><p>OperatorGreaterEqual.prototype.Evaluate = function(operands) {<br /> var values = this._getTwoNumberOperands(operands);</p><p> return new OperandBoolean(values[0] >= values[1]);<br />};