解析算术表达式

/**
* 计算逆波兰表达式的值
*/
function calculate(RPolishArray){
    var result = 0;
    var tempArray = new Array(100);
    var tempNum = -1;
    for(i = 0;i < RPolishArray.length;i++){
        if(RPolishArray[i].match(/\d/)){
            tempNum++;
            tempArray[tempNum] = RPolishArray[i];
        }else{
            switch(RPolishArray[i]){
                case '+':
                    result = (tempArray[tempNum-1] *1) + (tempArray[tempNum] * 1);
                    tempNum--;
                    tempArray[tempNum] = result;
                    break;
                case '-':
                    result = (tempArray[tempNum-1] *1) - (tempArray[tempNum] * 1);
                    tempNum--;
                    tempArray[tempNum] = result;
                    break;
                case '*':
                    result = (tempArray[tempNum-1] *1) * (tempArray[tempNum] * 1);
                    tempNum--;
                    tempArray[tempNum] = result;
                    break;
                case '/':
                    result = (tempArray[tempNum-1] *1) / (tempArray[tempNum] * 1);
                    tempNum--;
                    tempArray[tempNum] = result;
                    break;
            }
        }
    }
    result = tempArray[tempNum];    
    return result;    
}

/**
* 把普通算术表达式转换为逆波兰表达式
*/
function toRPolish(input){
    var regex = /(\(|\)|\+|\-|\*|\/)+/;
    var array = input.split(regex);
    var RPolish = ""
    var isI = false;
    num = 0;
    var SymbolArray = new Array(100);
    var SymbolNum = -1;
    for(j = 0;j < input.length;j++){        
        if(input.charAt(j).match(/\d/)){
            if(isI == false){
                RPolish += ','
                RPolish += array[num];
                num++;
                isI = true;
            }
        }
        else{
            if(SymbolNum == -1){ 
                    SymbolNum++;
                    SymbolArray[SymbolNum] = input.charAt(j);
            }else{
                if(input.charAt(j).match(/\(/)  || SymbolArray[SymbolNum].match(/\(/)){
                        SymbolNum++;
                        SymbolArray[SymbolNum] = input.charAt(j);
                }else if(input.charAt(j).match(/\)/)){
                    while(!SymbolArray[SymbolNum].match(/\(/)){
                        RPolish += ',';                        
                        RPolish += SymbolArray[SymbolNum];
                        SymbolNum--;
                    }
                    SymbolNum--;
                }else if(compare(input.charAt(j),SymbolArray[SymbolNum])){
                        SymbolNum++;
                        SymbolArray[SymbolNum] = input.charAt(j);
                }else if(!compare(input.charAt(j),SymbolArray[SymbolNum])){
                        RPolish += ',';    
                        RPolish += SymbolArray[SymbolNum];
                        SymbolNum--;
                        if(SymbolNum >= 0){
                            if(SymbolArray[SymbolNum].match(/\(/)){
                                SymbolNum++;
                                SymbolArray[SymbolNum] = input.charAt(j);
                            }else if(!compare(input.charAt(j),SymbolArray[SymbolNum])){
                                RPolish += ',';
                                RPolish += SymbolArray[SymbolNum];
                                SymbolArray[SymbolNum] = input.charAt(j);
                            }else{
                                SymbolNum++;
                                SymbolArray[SymbolNum] = input.charAt(j);
                            }
                        }else{
                            SymbolNum++;
                            SymbolArray[SymbolNum] = input.charAt(j);
                        }
                }
            }
            isI = false;
        }
    }            
    while(SymbolNum >=0){
        RPolish += ',';
        RPolish += SymbolArray[SymbolNum];
        SymbolNum--;
    }
    regex =  /,/;
    var RPolishArray = RPolish.split(regex);
    return RPolishArray;
}

function compare(a,b){
    if((a.match(/\*/)||a.match(/\//))&&(b.match(/\+/)||b.match(/\-/))){
        return true;
    }else{
        return false;
    }
}