RegexBuilder提供了一种方便的方法来构建它。举例来说：

import RegexBuilder

let string = "prefixandthissuffix"

func example(keyword: String) {
    // non-functional concept shorthand
    var regex = Regex {
        "prefix"
        keyword
        "suffix"
    }

    if let match = string.wholeMatch(of: regex) {
        print(match.output)
    } else {
        print("\(keyword): nomatch")
    }
}

example(keyword: "andthis")  // prints match
example(keyword: "andthat")  // nomatch

字符串
请注意，每次需要更改关键字字符串时，都需要重新生成Regex。可以将动态重建封装在函数中。

func quotedRegex(keyword: String) -> Regex<Substring> {
    let regex = Regex {
        /"/
        keyword
        /"/
    }
    return regex
}

let string = "{\"key1\":\"value\"}"
for word in ["key1", "KEY1", "key2"] {
    var regex = quotedRegex(keyword: word)
    regex = regex.ignoresCase() // transformed
    if let match = string.firstMatch(of: regex) {
        print("\(word) matched \(match.output)")
    } else {
        print("\(word) not matched")
    }
}

// print:
//   key1 matched "key1"
//   KEY1 matched "key1"
//   key2 not matched

型