Swift 2 中的正则表达式 matchesInString

Question

此 String 扩展中的 toCamel() 函数应该删除任何 _ 后跟字符串中间的字符，并将这两个字符替换为大写。

public extension String {
    public func rangeFromNSRange(aRange: NSRange) -> Range<String.Index> {
        let s = advance(self.startIndex, aRange.location)
        let e = advance(self.startIndex, aRange.location + aRange.length)
        return s..<e
    }
    public var ns : NSString {return self as NSString}
    public subscript (aRange: NSRange) -> String? {
        get {return self.substringWithRange(self.rangeFromNSRange(aRange))}
    }

    public var cdr: String {return isEmpty ? "" : String(characters.dropFirst())}

    public func toCamel() throws -> String {
        var s = self
        let regex = try NSRegularExpression(pattern: "_.", options: [])
        let matches = regex.matchesInString(s, options:[], range:NSMakeRange(0, s.ns.length)).reverse()
        for match in matches {
            print("match = \(s[match.range]!)")
            let matchRange = s.rangeFromNSRange(match.range)
            let uc = s[match.range]!.uppercaseString.cdr
            s.replaceRange(matchRange, with: uc)
        }
        if s.hasPrefix("_") {s = s.cdr}
        return s
    }
}

问题是 matchesInString 不会 return 那些 _ 已经是上一场比赛的一部分的比赛。因此，它给出了以下结果：

try "hello_world".toCamel()    //"helloWorld"

try "hello__world".toCamel()   //"hello_world"

try "hello___world".toCamel()  //"hello_World"

如何解决这个问题？

Answer 1

尝试NSRegularExpression(pattern: "_+.", options: [])

您还应该阅读 NSRegularExpression Class Reference。

+ 匹配 1 次或多次。尽可能匹配多次。

Answer 2

将您的模式更改为 _+(.)。这匹配一个或多个下划线后跟另一个字符。圆括号将该字符放入 捕获组 。您可以通过 rangeAtIndex

取回捕获的角色

public func toCamel() throws -> String {
    var s = self
    let regex = try NSRegularExpression(pattern: "_+(.)", options: [])
    let matches = regex.matchesInString(s, options:[], range:NSMakeRange(0, s.ns.length)).reverse()
    for match in matches {
        print("match = \(s[match.range]!)")
        let matchRange = s.rangeFromNSRange(match.range) // the whole match range
        let replaceRange = match.rangeAtIndex(1)         // range of the capture group
        let uc = s[replaceRange]!.uppercaseString
        s.replaceRange(matchRange, with: uc)
    }
    if s.hasPrefix("_") {s = s.cdr}
    return s
}

示例：

"hello_world".toCamel()              // helloWorld
"hello___world".toCamel()            // helloWorld
"hello_beautiful____world".toCamel() // helloBeautifulWolrd

更新 Swift 2.1.1

public extension String {

    public func rangeFromNSRange(aRange: NSRange) -> Range<String.Index> {
        let s = self.startIndex.advancedBy(aRange.location)
        let e = self.startIndex.advancedBy(aRange.location + aRange.length)
        return s..<e
    }
    public var ns : NSString {return self as NSString}
    public subscript (aRange: NSRange) -> String? {
        get {return self.substringWithRange(self.rangeFromNSRange(aRange))}
    }

    public var cdr: String {return isEmpty ? "" : String(characters.dropFirst())}

    public func toCamel() throws -> String {
        var s = self
        let regex = try NSRegularExpression(pattern: "_+(.)", options: [])
        let matches = regex.matchesInString(s, options:[], range:NSMakeRange(0, s.ns.length)).reverse()
        for match in matches {
            print("match = \(s[match.range]!)")
            let matchRange = s.rangeFromNSRange(match.range) // the whole match range
            let replaceRange = match.rangeAtIndex(1)         // range of the capture group
            let uc = s[replaceRange]!.uppercaseString
            s.replaceRange(matchRange, with: uc)
        }
        if s.hasPrefix("_") {s = s.cdr}
        return s
    }
}

Answer 3

你的代码有两个问题。

首先符合您要求的正则表达式应该是 _+[^_]{1}.

第二个在你的 cdr 计算属性中，String(characters.dropFirst()) 只排除第一个 _ 字符。您可以使用 String(characters.suffix(1))

编辑代码：

public extension String {
    public func rangeFromNSRange(aRange: NSRange) -> Range<String.Index> {
        let s = advance(self.startIndex, aRange.location)
        let e = advance(self.startIndex, aRange.location + aRange.length)
        return s..<e
    }
    public var ns : NSString {return self as NSString}
    public subscript (aRange: NSRange) -> String? {
        get {return self.substringWithRange(self.rangeFromNSRange(aRange))}
    }

    public var cdr: String {return isEmpty ? "" : String(characters.suffix(1))}

    public func toCamel() throws -> String {
        var s = self
        let regex = try NSRegularExpression(pattern: "_+[^_]{1}", options: [])
        let matches = regex.matchesInString(s, options:[], range:NSMakeRange(0, s.ns.length)).reverse()
        for match in matches {
            print("match = \(s[match.range]!)")
            let matchRange = s.rangeFromNSRange(match.range)
            let uc = s[match.range]!.uppercaseString.cdr
            s.replaceRange(matchRange, with: uc)
        }
        if s.hasPrefix("_") {s = s.cdr}
        return s
    }
}

我在操场上测试了这个。

Swift 2 中的正则表达式 matchesInString

regex matchesInString in Swift 2

regex

swift

nsregularexpression

更新 Swift 2.1.1