//p=>p
//p=>p.t
//p=>p.Id
protected override Expression VisitLambda <T>(Expression <T> node)
{
LambdaExpression lambda = node as LambdaExpression;
if (lambda.Body.NodeType == ExpressionType.Parameter)
{
// expression like a=> a
Type type = lambda.Body.Type;
string alias = _aliases.GetTableAlias(lambda);
this.VisitAllMember(type, alias);
return(node);
}
if (lambda.Body.NodeType == ExpressionType.MemberAccess)
{
// expression like t=> t.a
// => SELECT a.ClientId
Type type = lambda.Body.Type;
return(TypeUtils.IsPrimitive(type)
? base.VisitLambda(node)
: this.VisitAllMember(type, _aliases.GetTableAlias(lambda.Body), node));
}
if (_mOnly)
{
_mOnly = false;
}
return(base.VisitLambda(node));
}
//遍历New表达式的参数集
private Expression VisitAllArguments(NewExpression node)
{
for (int i = 0; i < node.Arguments.Count; i++)
{
Expression exp = node.Arguments[i];
Type pType = exp.Type;
if (exp.NodeType == ExpressionType.Parameter)
{
// new Client(a)
Type type = exp.Type;
string alias = _aliases.GetTableAlias(exp);
this.VisitAllMember(type, alias);
continue;
}
if (exp.NodeType == ExpressionType.MemberAccess || exp.NodeType == ExpressionType.Call)
{
if (TypeUtils.IsPrimitive(pType))
{
// new Client(a.ClientId)
this.Visit(exp);
// 选择字段
string newName = ColumnExpressionVisitor.AddColumn(_columns, node.Members != null ? node.Members[i].Name : (exp as MemberExpression).Member.Name);
// 添加字段别名
_builder.AppendAs(newName);
_builder.Append(',');
_builder.AppendNewLine();
}
else
{
this.VisitMember_Navigation(exp as MemberExpression);
}
continue;
}
throw new XfwException("NodeType '{0}' not supported.", exp.NodeType);
}
return(node);
}
//{new App() {Id = p.Id}}
protected override Expression VisitMemberInit(MemberInitExpression node)
{
if (node.NewExpression != null)
{
this.VisitAllArguments(node.NewExpression);
}
if (_navDescriptorKeys.Count == 0)
{
_navDescriptorKeys.Add(node.Type.Name);
}
//todo #对 Bindings 进行排序，保证导航属性的赋值一定要最后面#
// 未实现，在书写表达式时人工保证 ##
for (int i = 0; i < node.Bindings.Count; i++)
{
MemberAssignment binding = node.Bindings[i] as MemberAssignment;
if (binding == null)
{
throw new XfwException("Only 'MemberAssignment' binding supported.");
}
Type pType = (node.Bindings[i].Member as System.Reflection.PropertyInfo).PropertyType;
bool visitNav = !TypeUtils.IsPrimitive(pType);
#region 一般属性
// 非导航属性
if (!visitNav)
{
base.VisitMemberBinding(node.Bindings[i]);
// 选择字段
string newName = ColumnExpressionVisitor.AddColumn(_columns, binding.Member.Name);
// 添加字段别名
_builder.AppendAs(newName);
_builder.Append(',');
_builder.AppendNewLine();
continue;
}
#endregion
#region 导航属性
int n = _navDescriptorKeys.Count;
string keyName = _navDescriptorKeys.Count > 0 ? _navDescriptorKeys[_navDescriptorKeys.Count - 1] : string.Empty;
keyName = !string.IsNullOrEmpty(keyName) ? keyName + "." + binding.Member.Name : binding.Member.Name;
ColumnNavDescriptor descriptor = new ColumnNavDescriptor(keyName, binding.Member);
if (!_navDescriptors.ContainsKey(keyName))
{
descriptor.Start = _columns.Count;
descriptor.Count = CountField(binding.Expression);
_navDescriptors.Add(keyName, descriptor);
_navDescriptorKeys.Add(keyName);
}
if (binding.Expression.NodeType == ExpressionType.MemberAccess)
{
this.VisitMember_Navigation(binding.Expression as MemberExpression);
}
else if (binding.Expression.NodeType == ExpressionType.New)
{
this.VisitAllArguments(binding.Expression as NewExpression);
}
else if (binding.Expression.NodeType == ExpressionType.MemberInit)
{
this.VisitMemberInit(binding.Expression as MemberInitExpression);
}
if (_navDescriptorKeys.Count != n)
{
_navDescriptorKeys.RemoveAt(_navDescriptorKeys.Count - 1);
}
#endregion
}
return(node);
}