NSRegularExpression中命名的捕获组 - 获取范围的组名称 [英] Named capture groups in NSRegularExpression - get a range's group's name

问题描述

Apple称NSRegularExpression基于ICU正则表达式库： https://developer.apple.com/library/ios/documentation/Foundation/Reference/NSRegularExpression_Class/

Apple says that NSRegularExpression is based on the ICU Regular Expression library: https://developer.apple.com/library/ios/documentation/Foundation/Reference/NSRegularExpression_Class/

模式目前支持的语法是ICU指定的语法。 ICU正则表达式在 http://userguide.icu-project.org/strings/regexp 。

该页面（在icu-project.org上）声称现在支持命名捕获组，使用相同的语法作为.NET正则表达式：

That page (on icu-project.org) claims that Named Capture Groups are now supported, using the same syntax as .NET Regular Expressions:

（？< name> ...）命名捕获组。 <尖括号> 是字面值 - 它们出现在模式中。

(?<name>...) Named capture group. The <angle brackets> are literal - they appear in the pattern.

我编写了一个程序，它获得了一个看似正确的多个范围的匹配 - 尽管每个范围都返回两次（原因未知） - 但我唯一的信息是范围索引及其文本范围。

I have written a program which gets a single match with multiple ranges which seem correct - though each range is returned twice (for reasons unknown) - but the only information I have is the range's index and its text range.

例如，正则表达式： ^（？< foo> foo）\。（？< bar> bar）\。（？< bar2> ; baz）$ ，测试字符串 foo.bar.baz

For example, the regex: ^(?<foo>foo)\.(?<bar>bar)\.(?<bar2>baz)$ with test string foo.bar.baz

给我这些结果：

Idx    Start    Length     Text
0      0        11         foo.bar.baz
1      0         3         foo
2      4         3         bar
3      8         3         baz

有没有办法知道 baz 来自捕获组 bar2 ？

Is there any way to know that "baz" came from the capture-group bar2?

推荐答案

由于支持iOS11命名的捕获组。 NSTextCheckingResult 具有 open func range（withName name：String） - > NSRange 。

Since iOS11 named capture groups are supported. NSTextCheckingResult has the function open func range(withName name: String) -> NSRange.

使用正则表达式： ^（？< foo> foo）\。 （？< bar> bar）\。（？< bar2> baz）$ ，测试字符串 foo.bar.baz 给出4结果匹配。函数 match.range（withName：bar2）返回字符串的范围 baz

Using the regex: ^(?<foo>foo)\.(?<bar>bar)\.(?<bar2>baz)$ with the test string foo.bar.baz gives 4 result matches. The function match.range(withName: "bar2") returns the range for the String baz

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