/// <summary>
/// 访问 <see cref="T:System.Linq.Expressions.MemberExpression"/> 的子级。
/// </summary>
/// <returns>
/// 如果修改了该表达式或任何子表达式，则为修改后的表达式；否则返回原始表达式。
/// </returns>
/// <param name="node">要访问的表达式。</param>
protected override Expression VisitMember(MemberExpression node)
{
Check.NotNull(node, nameof(node));
var translatedExpression = _memberTranslator.Translate(node);
if (translatedExpression != null)
{
return(Visit(translatedExpression));
}
var expr = node.Expression;
if (expr.NodeType == ExpressionType.Convert)
{
expr = expr.RemoveConvert();
}
switch (expr.NodeType)
{
case ExpressionType.Parameter:
_builder.Append(Delimter(node.Member, expr.Type));
break;
case ExpressionType.MemberAccess:
case ExpressionType.Constant:
AppendInvoke(node);
break;
}
return(node);
}
protected override Expression VisitMember(MemberExpression expression)
{
Check.NotNull(expression, nameof(expression));
if (!(expression.Expression is QuerySourceReferenceExpression) &&
!(expression.Expression is SubQueryExpression))
{
var newExpression = Visit(expression.Expression);
if (newExpression != null ||
expression.Expression == null)
{
var newMemberExpression
= newExpression != expression.Expression
? Expression.Property(newExpression, expression.Member.Name)
: expression;
var translatedExpression = _memberTranslator.Translate(newMemberExpression);
if (translatedExpression != null)
{
return(translatedExpression);
}
}
}
var aliasExpression
= _queryModelVisitor
.BindMemberExpression(expression, CreateAliasedColumnExpression);
if (aliasExpression == null &&
_bindParentQueries)
{
aliasExpression
= _queryModelVisitor?.ParentQueryModelVisitor
.BindMemberExpression(expression, CreateAliasedColumnExpressionCore);
}
if (aliasExpression == null)
{
var querySourceReferenceExpression
= expression.Expression as QuerySourceReferenceExpression;
if (querySourceReferenceExpression != null)
{
var selectExpression
= _queryModelVisitor.TryGetQuery(querySourceReferenceExpression.ReferencedQuerySource);
if (selectExpression != null)
{
aliasExpression
= selectExpression.Projection
.OfType <AliasExpression>()
.SingleOrDefault(ae => ae.SourceMember == expression.Member);
}
}
}
return(aliasExpression);
}
public MemberInfo TranslateMember(Type targetType, MemberInfo memberInfo)
{
if (memberInfo.DeclaringType.Namespace != FromNamespace)
{
return(memberInfo);
}
IMemberTranslator translator = memberInfo.GetCustomTranslator() ?? MemberTranslator;
translator.Verifier = StructureVerifier;
translator.TargetType = targetType;
return(translator.Translate(memberInfo));
}
