asp.net(三)

[sdfgrtyu]

public static object Eval(object container, string expression)
{
if (expression == null)
{
throw new ArgumentNullException("expression");
}
expression = expression.Trim();
if (expression.Length == 0)
{
throw new ArgumentNullException("expression");
}
if (container == null)
{
return null;
}
string[] expressionParts = expression.Split(expressionPartSeparator);
return Eval(container, expressionParts);
}

private static object Eval(object container, string[] expressionParts)
{
object propertyValue = container;
for (int i = 0; (i < expressionParts.Length) && (propertyValue != null); i++)
{
string propName = expressionParts[i];
if (propName.IndexOfAny(indexExprStartChars) < 0)
{
propertyValue = GetPropertyValue(propertyValue, propName);
}
else
{
propertyValue = GetIndexedPropertyValue(propertyValue, propName);
}
}
return propertyValue;
}

public static string Eval(object container, string expression, string format)
{
object obj2 = Eval(container, expression);
if ((obj2 == null) || (obj2 == DBNull.Value))
{
return string.Empty;
}
if (string.IsNullOrEmpty(format))
{
return obj2.ToString();
}
return string.Format(format, obj2);
}

public static object GetDataItem(object container)
{
bool flag;
return GetDataItem(container, out flag);
}


public virtual void DataBind()
{
this.DataBind(true);
}
protected virtual void DataBind(bool raiseOnDataBinding)
{
bool flag = false;
if (this.IsBindingContainer)
{
bool flag2;
object dataItem = DataBinder.GetDataItem(this, out flag2);
if (flag2 && (this.Page != null))
{
this.Page.PushDataBindingContext(dataItem);）
flag = true;
}
}
try
{
if (raiseOnDataBinding)
{
this.OnDataBinding(EventArgs.Empty);
}
this.DataBindChildren();
}
finally
{
if (flag)
{
this.Page.PopDataBindingContext();
}
}
}

谁能给我详细解释一下上面代码的意思