斯卡拉三重引號的字符串和評論

Question

當寫的正則表達式我找到"""語法階的非常方便，因爲我可以在一個新的行寫我的正則表達式一步一步

例如：

val foo = 
""" 
    (
    |(
    |\d{3} 
    || 
    |\(\d{3}\) 
    |)? 
    |(
    |\s|-|\. 
    |)? 
    |\d{3} 
    |(\s|-|\.) 
    |\d{4} 
    |(
    |\s* 
    |(
    |ext|x|extn|extn. 
    |) 
    |\s* 
    |\d{2,6} 
    |)? 
    |)""".stripMargin.replace("\n", "").r 

但是我希望我可以寫評論來解釋我在每條線上做什麼，如

val foo = 
    """(      // start group to capture the phone number 
     |(      // start of optional area code choices 
     |\d{3}     // bare three digits 
     ||      // or 
     |\(\d{3}\)    // three digits enclosed in parentheses 
     |)?      // end of optional area code choices 
     |(      // start of optional separator 
     |\s|-|\.     // start of optional separator 
     |)?      // separator can be whitespace, dash or period 
     |\d{3}     // exchange number (required) 
     |(\s|-|\.)    // same separator but required this time 
     |\d{4}     // final digits (required) 
     |(      // start of optional extension 
     |\s*      // zero or more characters of white space 
     |(      // start of extention indicator 
     |ext.|x.|ext.|extn.  // extention can be indicated by "ext", "x", or extn followed by any character 
     |)      // end of extension indicator 
     |\s*      // zero or more characters of white space 
     |\d{2,6}     // two to five digits of extension number 
     |)?      // end of optional estension 
     |)""".stripMargin.replace("\n", "").trim 
    println(foo) 
    val regex = foo.r 
    val input = "(888)-456-7890 extn: 12345" 
    regex.findAllIn(input).foreach(println) 

但是scala使得註釋成爲字符串本身的一部分。所以，我怎麼能寫註釋和多行字符串喜歡這裏的蟒蛇

verboseRegex = re.compile(r''' 
    (   # start group to capture the phone number 
    (   # start of optional area code choices 
    \d{3}   # bare three digits 
    |    # or 
    \(\d{3}\)  # three digits enclosed in parentheses 
    )?   # end of optional area code choices 
    (   # start of optional separator 
    \s|-|\.  # separator can be whitespace, dash or period 
    )?   # end of optional separator 
    \d{3}   # exchange number (required) 
    (\s|-|\.)  # same separator but required this time 
    \d{4}   # final digits (required) 
    (   # start of optional extension 
    \s*   # zero or more characters of white space 
    (   # start of extention indicator 
    ext|x|ext. # extention can be indicated by "ext", "x", or 
        #  "ext" followed by any character 
    )    # end of extension indicator 
    \s*   # zero or more characters of white space 
    \d{2,5}  # two to five digits of extension number 
    )?   # end of optional estension 
    )    # end phone number capture group 
    ''', re.VERBOSE) 

所以在Python代碼上面我們用的好像我們的斯卡拉"""的'''，但我們也能寫評論。

Answer 1

顯然，(?x)支持忽略空格和註釋：

scala> val r = """(?x)abc 
    | # works ok 
    | def""".r 
r: scala.util.matching.Regex = 
(?x)abc 
# works ok 
def 

scala> "abcdef" match { case r(_*) => } 

scala> val r = s"""(?x)abc\n |def #works, I hope\n |123""".stripMargin.r 
r: scala.util.matching.Regex = 
(?x)abc 
def #works, I hope 
123 

scala> "abcdef123" match { case r(_*) => } 

另一個想法：

scala> val r = s"abc${ "" // comment this 
    | }def${ "" // not pretty 
    | }".r 
r: scala.util.matching.Regex = abcdef 

scala> "abcdef" match { case r(_*) => } 

這可能是很方便的有comment"interpolator"返回在那些洞空字符串。

scala> val r = s"abc${ comment"empty words here" }".r 

如果忽略捕獲組，然後將多餘的括號不是一個麻煩：

scala> val r = s"abc${ // comment 
    | }".r 
r: scala.util.matching.Regex = abc() 

scala> "abc" match { case r(_*) => } 

這太糟糕了它插入，而不是空字符串單元。