Question

如何检查Character是否为单词边界（在Unicode TR#29上定义）？

我有一个使用正则表达式的解决方案，但我认为这很难看。

Answer 1

对于单个字符，您无法确定它是否是单词边界。您只能决定连续两个字符，或者两个连续的字形集群。

这段代码可能对您有用。它为给定的字符串创建一个单词边界数组。它建立在NSString.enumerateSubstrings(in:options:using:)。

之上

您可以在Playground中运行它：

import Foundation

let str = "The quick brown_fox jumps over / the lazy dog. Flag   Emoji    ."

extension String {

    public var wordBoundaries: [String.Index] {

        var boundaries: [String.Index] = []

        let start = startIndex
        let end = endIndex
        boundaries.append(start)

        enumerateSubstrings(in: start ..< end, options: .byWords) {
                    substring, substringRange, enclosingRange, stop in

            let lb = substringRange.lowerBound
            if boundaries.last! != lb {
                boundaries.append(substringRange.lowerBound)
            }
            boundaries.append(substringRange.upperBound)
        }
        if boundaries.last! != end {
            boundaries.append(end)
        }

        return boundaries
    }
}


var prevBoundary: String.Index? = nil
for b in str.wordBoundaries {
    if let lower = prevBoundary {
        let s = str[lower ..< b]
        print(s)
    }
    prevBoundary = b
}

如何检查Character是否是单词边界

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