public static bool Get <T>(this WrapperContext context, out Type mapped)
{
if (context == null)
{
throw new ArgumentNullException(nameof(context));
}
return(context.Get(typeof(T), out mapped));
}
public static void Set <T, M>(this WrapperContext context)
{
if (context == null)
{
throw new ArgumentNullException(nameof(context));
}
context.Set(typeof(T), typeof(M));
}
public static IQueryable <T> Wrap <T>(this IQueryable <T> queryable, WrapperContext context)
{
if (queryable == null)
{
throw new ArgumentNullException(nameof(queryable));
}
var visitor = new WrapperVisitor(context);
return(queryable.Provider.CreateQuery <T>(visitor.Visit(queryable.Expression)));
}
public static IQueryable <T> Wrap <T, M>(this IQueryable <M> queryable, WrapperContext context = null)
where M : T
{
if (queryable == null)
{
throw new ArgumentNullException(nameof(queryable));
}
if (context == null)
{
context = new WrapperContext();
}
WrappedQueryableProvider <T, M> provider = new WrappedQueryableProvider <T, M>(queryable.Provider, context);
return(provider.CreateQuery <T>(queryable.Expression));
}
public static IQueryable <M> Unwrap <T, M>(this IQueryable <T> queryable, WrapperContext context = null)
where M : T
{
if (queryable == null)
{
throw new ArgumentNullException(nameof(queryable));
}
WrappedQueryable <T, M> wrapped = queryable as WrappedQueryable <T, M>;
if (wrapped == null)
{
throw new NotSupportedException("不支持的类型。");
}
WrappedQueryableProvider <T, M> provider = wrapped.Provider;
var visitor = new WrapperVisitor(context ?? provider.Context);
var expression = visitor.Visit(wrapped.Expression);
return(provider.InnerQueryProvider.CreateQuery <M>(expression));
}
public static void Set <T, M>(this WrapperContext context, string targetMethod, string mappedMethod)
{
if (context == null)
{
throw new ArgumentNullException(nameof(context));
}
var target = typeof(T).GetMethod(targetMethod);
if (target == null)
{
throw new ArgumentException(nameof(targetMethod), "方法不存在。");
}
var mapped = typeof(M).GetMethod(mappedMethod);
if (mapped == null)
{
throw new ArgumentException(nameof(mappedMethod), "方法不存在。");
}
context.Set(target, mapped);
}
public static void Set <T, M, P>(this WrapperContext context, Expression <Func <T, P> > target, Expression <Func <M, P> > mapped)
{
if (context == null)
{
throw new ArgumentNullException(nameof(context));
}
if (target == null)
{
throw new ArgumentNullException(nameof(target));
}
if (mapped == null)
{
throw new ArgumentNullException(nameof(mapped));
}
if (target.Body.NodeType != ExpressionType.MemberAccess || ((MemberExpression)target.Body).Expression.NodeType != ExpressionType.Parameter)
{
throw new ArgumentException("目标只能为类型成员。");
}
if (mapped.Body.NodeType != ExpressionType.MemberAccess || ((MemberExpression)mapped.Body).Expression.NodeType != ExpressionType.Parameter)
{
throw new ArgumentException("映射只能为类型成员。");
}
context.Set(((MemberExpression)target.Body).Member, ((MemberExpression)mapped.Body).Member);
}
public WrapperVisitor(WrapperContext context)
{
Context = context ?? throw new ArgumentNullException(nameof(context));
_Parameters = new Dictionary <ParameterExpression, ParameterExpression>();
}
public WrappedQueryableProvider(IQueryProvider queryProvider, WrapperContext context)
{
Context = context ?? throw new ArgumentNullException(nameof(context));
InnerQueryProvider = queryProvider ?? throw new ArgumentNullException(nameof(queryProvider));
}
