查询的执行次序和途径并非强制指定的，相反，它可以对表达树进行分析，以发现你所期望的结果，然后再决定如何处理；
Instead, it can analyze the expression tree, discover what you want done, and then decide how to do it.
使用LinQ解决此问题的解决方法是使用表达树，这是一种类似反射的机制，您不仅可以用它反射类的成员，还可以用它反射某个方法的代码。
The LinQ solution for this problem is expression trees, a reflection-like mechanism whereby you can reflect over not only a class's members, but also a method's code.
在希腊神话中，雅典娜女神将橄榄树送给雅典人，雅典人以她的名字命名这座城市以表达他们的感激之情。
In Greek mythology, the goddess Athena gave the olive tree to the people of Athens, who showed their gratitude by naming the city after her.
开发人员必须按照树操作表达自己的问题。
You, the developer, have to express your problem in terms of tree manipulation.
你能用表达式树做些什么呢？
表达式——仅检查返回表达式结果的树内容(元素值)。
Expression — Only examines tree content (element values) returning the result of the expression.
您可以添加消息树的新数据类型或元素，以便在表达式中使用。
You have the ability to add new data types or elements of the message tree for use in the expression.
没有表达式树的话，我们是不可能用描述格式来表示一个表达式的。他们唯一的表示方式是IL(中间语言)，这种语言对于重新表述用户的意图来说太低层次了。
Without expression trees, its impossible to describe expressions in a descriptive format; the only description of them is IL, which is too low level to re-create the user's intent for the expression.
另一种可能是传入一段源代码并返回一颗表达式树，而不是一个编译好的程序集。
One proposed option would be passing in some source code and being returned an expression tree instead of just a compiled assembly.
我们可以从完整的文件创建语法树，也可以从松散的声明或者表达式生成它。
A syntax tree can be created from an entire file or just a loose statement or expression.
抽象语法树是一个表示为对象集合的表达式。
An abstract syntax tree is an expression represented as a collection of objects.
你也能将表达式树中的数据转换到其他的域的数据形式(如xml)。
You can also convert the data in the expression tree into another domain (such as XML).
函数库被保证，一旦这些函数库引用了一个表达式树后，表达式树就不再改变。
Libraries are guaranteed that once they have a reference to an expression tree, that expression tree will never change.
表达式树在任何语言中都是一个强大的功能。
如果一个值绑定表达式引用的模型数据不再可用，或者在组件树被恢复之前发生了更改，那么组件树的一些部分将被撤销。
If model data referenced by a value binding expression is no longer available or has changed prior to the component tree being restored, it can result in portions of the tree being dropped.
评委们觉得这个词表达了现存“战略树”迈出了改进的一步，而且使(战略)概念跨向了一个全新的水准。
The judges felt this represented a step change on the existing strategy tree, and laddered the concept to a whole new level.
这些表达式用于指示输出消息组件中的目标元素，其中获取的元素应该重写现有值(假如树中已经存在元素)。
These are used to indicate a target element in the out going message assembly, where an acquired value should overwrite the existing value (in the case where the element already exists in the tree).
推断表达式树内数据，并对它做自定义处理。
Reason about the data in the expression tree, and do custom processing over it.
IBMJIT编译器使用一个表达式树序列表示方法的操作。
The IBM JIT compiler USES a sequence of expression trees to represent the method's operations.
简单的非递归过程表达式并不能访问所有的元素，尽管许多库都包含有帮助功能，可以用于遍历树。
No simple non-recursive procedural expression accesses all elements, although many libraries include helper functions for walking the tree.
开发人员如果想编辑表达式树，那么不得不通过拷贝现有的一个(表达式树)来手动的创建一个新的。
Developers wishing to edit one have to manually build new expressions by copying existing ones.
如下是一些可能比较有趣的表达式树的用法。
Here are some USES of expression trees that may be interesting.
单个整数表达式的解析树的图片。
他举出了大量的例子告诉你如何巧妙地处理那些表达式树和编译你的带自定义条件的lambda表达式。
He has a great example of how you can manipulate the expression trees and build custom conditions in your lambda expressions.
用.Compile()方法去将一个表达式树转换为一个委托，然后你可以执行它。
Use the .Compile() method to turn the expression tree into a delegate so that you can execute it.
与以前一样，可以使用xsl： copy- of将整个idn树复制到输出，但是也可在路径表达式中使用该变量而不需要转换成节点集。
You can use XSL: copy-of to copy the whole IDN tree to the output, as before, but you can also use the variable in a path expression without a node-set conversion.
图1：单个整数表达式的解析树。
MetaLinq并不是唯一对表达式树进行编辑的方法。
Moq是利用诸如Linq表达式树和Lambda表达式等.NET 3.5的特性，为.NET设计和开发的Mocking库。
Moq is a mocking library for .NET designed and developed to utilize .NET 3.5 features, e.g., Linq expression trees and lambda expressions.
表达式树是lambda表达式的一种数据表示形式，它能使你更方便地读取和推断lambda表达式。
An expression tree is a data representation of the lambda expression in a form that is easy for you to read and reason about the lambda expression in.
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