表达式使用的特殊构造

问题描述

使用If-Then-Else Conditionalsa> 在正则表达式中，我想知道尝试将 many 构造操纵成多个匹配的单个表达式的可能结果.

With the construct of using If-Then-Else Conditionals in regular expressions, I would like to know the possible outcome of trying to manipulate many constructs into a single expression for multiple matches.

让我们以下面这个例子为例.

Let's take this example below.

foo(bar)?(?(1)baz|quz)

现在与一个匹配前一个条件的表达式组合，然后我们用以下条件添加到前一个条件..

Now being combined with an expression, which matches the previous conditions and then we add on to the previous with the following conditions..

foo(bar)?(?(1)baz|quz)|(?(?=.*baz)bar|foo)

我主要是问您是否应该以这种方式构建正则表达式，以及您需要以这种方式使用它的目的是什么?

Mainly I am asking should you construct a regular expression in this way, and what would ever be the purpose that you would need to use it in this way?

推荐答案

在这种情况下，并且可能在大多数情况下，我会说不".

In this case, and probably most cases, I would say "no".

我经常发现条件可以重写为环视或在交替中简化.

I often find that conditionals can be rewritten as lookarounds or simplified within alternations.

例如，在我看来，你提供的正则表达式，

For instance, it seems to me that the regex you supplied,

foo(bar)?(?(1)baz|quz)|(?(?=.*baz)bar|foo)

可以替换为更清晰的

bar(?=.*baz)|foo(?:quz|barbaz)?

这给了我们两个简单的匹配路径.

which gives us two simple match paths.

但是您发布问题已经六个月了.在这段时间里，回答了很多关于 SO 的问题，你有没有觉得需要这样的建设?

But it's been six months since you posted the question. During this time, answering a great many questions on SO, have you ever felt the need for that kind of construction?

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