SyntaxAnalyse/TokenRecord/Method/TokenIf.cs

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//xxxxxxxxxxx
using System;
using System.Collections.Generic;
using System.Text;

namespace ConExpress.Calculator
{
    /// <summary>
    /// If记号类，对应关键字if，不区分大小写
    /// </summary>
    /// <example>用法：if(Condition, TrueValue, FalseValue)，如果Condition为true，则返回TrueValue，否则返回FalseValue</example>
    public class TokenIf : TokenMethod
    {
        public TokenIf(int Index, int Length)
            : base(Index, Length)
        {
        }

        protected override void SetChildCount()
        {
            this.m_ChildCount = 3;
        }

        public override void Execute()
        {
            this.CheckChildCount("if语句运算元素数量不合法");

            TokenRecord TokenCondition = this.ChildList[0];
            TokenRecord TokenTrue = this.ChildList[1];
            TokenRecord TokenFalse = this.ChildList[2];

            //execute child token
            TokenCondition.Execute();
            //TODO:优化，根据条件判断执行
            TokenTrue.Execute();
            TokenFalse.Execute();

            //if TokenTrue's type is not equal TokenFalse's type, convert them to string
            if (TokenTrue.TokenValueType != TokenFalse.TokenValueType)
            {
                //Error or set token type as string
                TokenTrue.ChangeTokenToString();
                TokenFalse.ChangeTokenToString();
            }

            this.TokenValueType = TokenTrue.TokenValueType;
            this.TokenValue = TokenCondition.ChangeTokenToBoolean() ? TokenTrue.TokenValue : TokenFalse.TokenValue;
        }
    }
}