LINQ的;表达式解析器？ [英] Linq; expression parser?
问题描述
在Linq中，你显然可以获得一个有意义的身体和
表达式'.ToString（）;随机问题 - 有没有人知道linq
还包括一个解析器？它似乎可能是一个方便的方式
为
IBindingListView.Filter写一个安全但简单的实现（即没有编码）（通过编译为Predicate< T> ;）。
有人知道这是否可行吗？
Marc
In Linq, you can apparently get a meaningful body from and
expression''s .ToString(); random question - does anybody know if linq
also includes a parser? It just seemed it might be a handy way to
write a safe but easy implementation (i.e. no codedom) for an
IBindingListView.Filter (by compiling to a Predicate<T>).
Anybody know if this is possible at all?
Marc
推荐答案
Marc Gravell写道：
Marc Gravell wrote:
在Linq中，你显然可以获得一个有意义的身体和
expression'的.ToString（）;随机问题 - 有没有人知道linq
还包括一个解析器？它似乎可能是一个方便的方式
为
IBindingListView.Filter写一个安全但简单的实现（即没有编码）（通过编译为Predicate< T> ;）。
有人知道这是否可行？
In Linq, you can apparently get a meaningful body from and
expression''s .ToString(); random question - does anybody know if linq
also includes a parser? It just seemed it might be a handy way to
write a safe but easy implementation (i.e. no codedom) for an
IBindingListView.Filter (by compiling to a Predicate<T>).
Anybody know if this is possible at all?
为什么要在字符串输出上使用解析器？因为那个解析器
会生成一个解析树，它看起来非常类似于你在上面调用ToString（）的
表达式树。
所以解释表达式树。
FB
-
----- -------------------------------------------------- -----------------
LLBLGen Pro的首席开发人员，.NET的高效O / R映射器
LLBLGen Pro网站： http://www.llblgen.com
我的.NET博客： http://weblogs.asp.net/fbouma
Microsoft MVP（C＃）
-------------------------------- ----------------------------------------
Why would you use a parser on the string output? Because that parser
will produce a parse tree which will look very similar to the
expression tree you called ToString() on :)
So interpret the expression tree instead.
FB
--
------------------------------------------------------------------------
Lead developer of LLBLGen Pro, the productive O/R mapper for .NET
LLBLGen Pro website: http://www.llblgen.com
My .NET blog: http://weblogs.asp.net/fbouma
Microsoft MVP (C#)
------------------------------------------------------------------------
Frans Bouma [C＃MVP]< pe ****************** @ xs4all.nlwrote：
Frans Bouma [C# MVP] <pe******************@xs4all.nlwrote:
Marc Gravell写道：
Marc Gravell wrote:
In Lin q，你显然可以得到一个有意义的身体和
表达式'.ToString（）;随机问题 - 有没有人知道linq
还包括一个解析器？它似乎可能是一个方便的方式
为
IBindingListView.Filter写一个安全但简单的实现（即没有编码）（通过编译为Predicate< T> ;）。
有人知道这是否可行？
In Linq, you can apparently get a meaningful body from and
expression''s .ToString(); random question - does anybody know if linq
also includes a parser? It just seemed it might be a handy way to
write a safe but easy implementation (i.e. no codedom) for an
IBindingListView.Filter (by compiling to a Predicate<T>).
Anybody know if this is possible at all?
为什么要在字符串输出上使用解析器？因为那个解析器
会生成一个解析树，它看起来非常类似于你在上面调用ToString（）的
表达式树。
因此，请解释表达式树。
Why would you use a parser on the string output? Because that parser
will produce a parse tree which will look very similar to the
expression tree you called ToString() on :)
So interpret the expression tree instead.
我认为重点是解析从ToString创建*没有*
的表达式树，但是从我理解了
Marc'的介绍性句子实际上意味着：有一个有用的
格式的LINQ表达式，如ToString方法所示 ;
-
Jon Skeet - < sk *** @ pobox.com>
http://www.pobox.com/~skeet 博客： http://www.msmvps.com/jon.skeet
如果回复该群组，请不要给我发邮件
I think the point would be to parse expression trees which *hadn''t*
been created from ToString, but read in from a file etc. I understood
Marc''s introductory sentence to effectively mean: "there''s a useful
format for LINQ expressions, as shown by the ToString method".
--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
If replying to the group, please do not mail me too
Jon正确地解释了我的烦恼...我的观点是，与原始的.Net 2.0谓词不同，它是b $ b。等），LINQ表达式树非常结构化。显然C＃3系列编译器可以解析源代码来创建表达式，但是我不清楚（至少直到
Reflector支持CLR 3.5 ;-p）如何其中大部分是编译器和
运行时多少。
将字符串解析为表达式的能力非常好
功能强大......虽然如果解析外部实体，显然会有一些限制
条款......但是heck：只需访问
表达式参数和文字会非常强大。
也许我只是关闭一个......
Marc
Jon has correctly interpreted my witterings... my point being, that
unlike raw .Net 2.0 predicates (etc), LINQ expression trees are quite
structured. Obviously the C# 3-series compiler can parse source to
create an expression, but it is unclear to me (at least until
Reflector supports CLR 3.5 ;-p) how much of this is the compiler and
how much is the runtime.
The ability to parse a string to an expression would be very
powerful... although there would obviously be some limitations in
terms if resolving external entities... but heck: just access to the
expression arguments and literals would be pretty powerful.
Maybe I''m just "off on one"...
Marc
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