public override void Evaluate()
{
ExpressionEvaluator e = new ExpressionEvaluator();
e.GetEvidence += new EvidenceLookupHandler(RaiseEvidenceLookup);
e.Postfix = this.postfixExpression;
ExpressionEvaluator.Symbol o = e.Evaluate(); //PERFORMANCE: this method is slow.
base.EvidenceValue.Reset(); //clear previous values
//result must be of this type or the expression is invalid, throw exception
IEvidenceValue result = o.value as IEvidenceValue;
//exit if null returned
if (o.type == ExpressionEvaluator.Type.Invalid)
{
return;
}
//see if its value has changed, if so then set the value and call the events
if (base.Value.Equals(result.Value))
{
return; //no change in value, dont raise an event
}
base.Value = result.Value;
RaiseChanged(this, new ChangedArgs());
}
/// <summary>
/// 核心计算
/// </summary>
public override void Evaluate()
{
ExpressionEvaluator e = new ExpressionEvaluator();
e.GetEvidence += new EvidenceLookupHandler(RaiseEvidenceLookup);
e.Postfix = this.postfixExpression;
ExpressionEvaluator.Symbol o = e.Evaluate(); //PERFORMANCE: this method is slow.
base.EvidenceValue.Reset(); //清空之前数据
//result must be of this type or the expression is invalid, throw exception
// 结果是IEvidenceValue类型，或者表达式为无效的，则抛出异常
IEvidenceValue result = o.value as IEvidenceValue;
//exit if null returned
if (o.type == ExpressionEvaluator.Type.Invalid)
{
return;
}
// 值被改变了则调用事件
if (base.Value.Equals(result.Value))
{
return; //no change in value, dont raise an event
}
base.Value = result.Value; // 此方法，引发false时规则条件表达式中的引用为0
RaiseChanged(this, new ChangedArgs());
}
