public override Expression DeductInternal(object context)
{
var map = (context as SearchParserContext).Properties;
var lhs = LeftChild.DeductInternal(context);
var rhs = RightChild.DeductInternal(context);
PropertyMap prs = null;
if (LeftChild.Value == null)
{
prs = map["Root"];
var prop = prs.BestMatch(RightChild.Value.ToString());
if (prop != null)
{
DeductedType = prop.TargetType;
return(Expression.Parameter(prop.TargetType, "t"));
}
}
else
{
prs = map[LeftChild.DeductedType.Name];
}
//存在对应的属性列表
if (prs != null)
{
var prop = prs.BestMatch(RightChild.Value.ToString());
if (prop != null)
{
DeductedType = prop.TargetType;
return(Expression.Property(lhs, RightChild.Value.ToString()));
}
}
//只有当前的域没有高级限定符时，才进行模糊查找
if (LeftChild == null)
{
// 如果不存在，应从最近的有左子树的父结点开始，找他的最左子树的是PropertyAstNode结点，
// 判断其DeductedType只否有属性列表
var pNode = this.Parent;
AstNodeBase last = this;
while (pNode != null)
{
//last是右子树说明pNode有已经推断的左孩子可能是Property属性
// 如果 是左子树，则其右子树尚未推断，不符合我们的语法要求,不去访问
if (last == pNode.RightChild)
{
var lch = pNode.LeftChild;
//一直判断其左孩子如果不为空（非叶子结点），并且其类型是PropertyAstNode
//那么尝试获取其属性列表，一旦不为空，匹配是否有合适的属性，若有返回
while (lch.LeftChild != null)
{
if (lch is PropertyAstNode)
{
prs = map[lch.DeductedType.Name];
if (prs != null)
{
var prop = prs.BestMatch(RightChild.Value.ToString());
if (prop != null)
{
DeductedType = prop.TargetType;
return(Expression.Property(lhs, RightChild.Value.ToString()));
}
//未找到 可能是更高层级的域
}
}
lch = lch.LeftChild;
}
}
last = pNode;
pNode = pNode.Parent;
}
}
//遍历所有的结点均未找到合适的属性返回空
Value = null;
return(Expression.Constant(null));
}