Xcode 中的 RegExp:从结果集中排除匹配项? [英] RegExp in Xcode: exclude matches from result set?

问题描述

在 Xcode 的项目查找"中寻找正确的正则表达式语法，以获取所有出现的nslog"而不是//nslog".可以独立进行每个搜索，但不确定如何链接"它们.

解决方案

用正则表达式说不遵循"的正常方式是使用 (?<!...) 结构.所以有可能

<前>(?<!//)nslog

可能工作.这取决于您使用的工具遵循哪种正则表达式，这是我不知道的.但是自从你问起已经一个小时了，没有其他人给你任何答案，所以我认为尝试没有任何伤害.

如果你不能做lookbehind negations，一个保证在任何地方都有效的模式是

[^/][^/]nslog

然而，这并不意味着与之前的模式相同！

不是说一定不能跟在两个斜杠后面，而是意味着前面必须有两个非斜杠.这些实际上是不同的；考虑 nslog 出现在行首的情况.第一个模式会成功，第二个会失败.

最后，如果斜线被用作模式分隔符——意思是，它包围并引用模式——那么你必须执行以下操作之一:

1. 选择一个备用模式分隔符；例如，#(?<!//)nslog#，如果您可以选择八索作为模式周围的引用分隔符.
2. 对内部使用的任何斜线进行反击并诱发 LTS(倾斜牙签综合症)；例如，(?.
3. 使用某种形式的数字转义，例如 \057 表示八进制或 \x2F 表示十六进制；例如，(?.

希望这会有所帮助.

Looking for proper regular expression syntax to use in Xcode’s "Project Find" to get all occurrences of "nslog" but not "//nslog". Can do each search independently but not sure how to "chain" them.

解决方案

The normal way to say "does not follow" with regular expressions is using the (?<!...) construct. So it’s possible that

(?<!//)nslog

may work. It depends on which regex flavor the tool you’re using follows, which is something I don’t know. But it’s been an hour since you asked, and no one else has offered you any answers, so I figure it can’t hurt anything to try.

In case you cannot do lookbehind negations, a pattern that’s guaranteed to work anywhere is

[^/][^/]nslog

However, that does not mean the same thing as the previous pattern!

Instead of saying must not follow two slashes, it instead means there must be two non-slashes previous to that. These are actually different; consider the case of nslog occurring at the start of the line. The first pattern would succeed and the second one would fail.

Finally, if slash is used as a pattern delimiter — meaning, it surrounds and quotes the pattern — then you would have to do one of:

1. Select an alternate pattern delimiter; for example, #(?<!//)nslog# if you are permitted to select an octothorpe as the quoting delimiter around your pattern.
2. Backwhack any slashes used internally and induce LTS (Leaning Toothpick Syndrome); for example, (?<!\/\/)nslog.
3. Use some form of numeric escape, such as \057 for octal or \x2F for hex; for example, (?<!\x2F\x2F)nslog.

Hope this helps.

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