Predicate, which evaluates to a Boolean value of true or false. (in fact, it is declared as interface Predicate extends Expression.)
其计算为布尔值true或false(事实上，它被声明为interfacePredicateextends Expression)。
ERuby executes it and replaces the whole expression with the value returned by the expression.
eRuby执行该表达式并用其返回的值替换整个表达式。
It's possible to declare conditional breakpoints triggered whenever the value of an expression changes (see Figure 6).
还可以声明条件断点，它在表达式值发生变化时触发(请参见图6)。
Given that JSF does not care to reduce the number of times it resolves a value binding expression, Seam's factory feature often comes in handy.
在JSF不负责减少它解析一个值绑定表达式的次数的情况下，Seam的工厂特性常常变得非常方便。
You might assume that you can stick the logic inside the getter method of the backing bean that maps to the value binding expression in the view.
您可能会认为，可以将逻辑放在映射到视图中值绑定表达式的backingbean的getter方法中。
Each expression returns a value that depends only on the operands of the expression, and no expression has any side effects.
每个表达式仅根据其操作数来返回值，并且都不会产生副作用。
The value returned by the outermost expression in a query is the result of the query.
查询中最外面的表达式所返回的值就是整个查询的结果。
The set.tag file (see Listing 4) can be used in a scriptless JSP page to set the value of a #{...} expression.
可以在没有脚本的JSP页面中使用set.tag文件（参见清单4）来设置 #{...} 表达式的值。
The default expression calculates a value to assign to the global variable the first time it is referenced.
在第一次引用时，默认表达式将为全局变量计算一个值。
The result of that subquery then becomes a value in the WHERE clause expression
它的结果会成为where语句表达式中的一个值。
In general, a lambda function is a function that takes any number of arguments and returns the value of a single expression.
一般来说，lambda函数接收任何数目的参数，并返回单个表达式的值。
In general, each value in the enumeration can be an arbitrary scalar SQL expression.
一般情况下，枚举中的每一个值都可以成为任意标量SQL表达式。
The regular expression captures the value of each attribute and places these in the same hash you used to hold the fields from the TMC2 message earlier.
正则表达式捕获每个属性的值并将其放置到此前用于存放来自TMC2消息的字段的哈希中。
The tag USES an XPath expression to specify the value that you want to copy into the variable.
标记使用一个XPath表达式来指定要拷贝到变量中的值。
A third value, UNKNOWN, is the result of an incorrect expression and has the same behavior as FALSE.
第三个值UNKNOWN是一个错误表达式的结果，处理方法与FALSE相同。
Computed using an arithmetic expression on the original text or attribute value.
使用算术表达式基于初始文本或属性值进行计算。
You can use a scalar subquery to select a specific value that will be used in the expression of the WHERE clause.
可以使用标量子查询选择将用于where子句的表达式中的特定值。
Copy: the copy clause of the transform expression binds the source XML value to a variable.
copy：transform表达式的copy子句将源xml值绑定到一个变量。
It works correctly with undefined values as well, whereas with warnings turned on, a regular expression match on an undefined value will print a warning.
该函数也会正确地处理未定义的值，尽管在警告打开时，常规表达式在匹配未定义的值时会输出警告信息。
The rest of the expression is used to see if the value (without leading or trailing blanks) is an empty string.
表达式的其余部分用来检查值(去掉头尾的空格之后)是否是空字符串。
If an exception was raised, then assignment to the scoped variable will occur: as the EL expression in Listing 18 suggests, its value will not be empty.
如果产生了异常，那么就会对那个限定了作用域的变量进行赋值：如清单18中的EL表达式所显示的那样，该变量的值将不会为空。
In this example, two types of user property are shown: a static string, and an XPath expression that takes its value from the inbound message.
此例中显示了两种类型的用户属性：静态字符串，以及从入站消息中取得其值的XPath表达式。
This pattern is a regular expression that means the acceptable value of store ID should begin with ID followed by six digits.
该模式是一个正则表达式，它表示可接受的storeID的值应该以ID开头，后面紧跟着六位数字。
Up to this point, you've seen how the if statement can be used to execute one of two blocks of program statements, depending on the value of a particular Boolean expression.
至此，已经看到了if语句可以如何用于根据一个特定布尔表达式的值，来执行两个程序语句块中的其中一个。
A filter expression is created in the warehouse target model which will use the default value (if provided).
在仓库目标模型中创建一个过滤器表达式，这将用到默认值(如有提供)。
The equ directive is used to set the value of the variable STR_SIZE to the expression following it. A similar idiom in GAS looks like this.
equ用来将变量str_size的值设置为后面的表达式。
The value of the includes attribute is an XPath expression (possibly chosen from a very restricted subset of XPath) that identifies the element whose text is included.
includes属性的值是一个XPath表达式(可能从非常有限的xpath子集中选择)，它确定了将包含其文本的元素。
The dot (.) is now known as the context item expression, and might be a node or an atomic value, depending on the current item in the sequence being processed.
点号(.)在这里称为上下文项表达式，可以是节点或者原子值，视处理的序列中的当前项而定。
Since you can set any arbitrary attribute value (and yes, that includes values that you define) to a constraint expression or use it in a constraint, there are a lot of possibilities.
由于可以为约束表达式设置任何任意的属性值(包括您自己定义的值)，或者在约束中使用它，因此存在很多可能。
Since you can set any arbitrary attribute value (and yes, that includes values that you define) to a constraint expression or use it in a constraint, there are a lot of possibilities.
由于可以为约束表达式设置任何任意的属性值(包括您自己定义的值)，或者在约束中使用它，因此存在很多可能。
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