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scala.util.matching

UnanchoredRegex

trait UnanchoredRegex extends Regex

A Regex that finds the first match when used in a pattern match.

Source
Regex.scala
See also

Regex#unanchored

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  1. UnanchoredRegex
  2. Regex
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  2. by StringFormat
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  1. def anchored: Regex
    Definition Classes
    Regex
  2. def findAllIn(source: CharSequence): MatchIterator

    Return all non-overlapping matches of this Regex in the given character sequence as a scala.util.matching.Regex.MatchIterator, which is a special scala.collection.Iterator that returns the matched strings but can also be queried for more data about the last match, such as capturing groups and start position.

    Return all non-overlapping matches of this Regex in the given character sequence as a scala.util.matching.Regex.MatchIterator, which is a special scala.collection.Iterator that returns the matched strings but can also be queried for more data about the last match, such as capturing groups and start position.

    A MatchIterator can also be converted into an iterator that returns objects of type scala.util.matching.Regex.Match, such as is normally returned by findAllMatchIn.

    Where potential matches overlap, the first possible match is returned, followed by the next match that follows the input consumed by the first match:

    val hat  = "hat[^a]+".r
    val hathaway = "hathatthattthatttt"
    val hats = hat.findAllIn(hathaway).toList                     // List(hath, hattth)
    val pos  = hat.findAllMatchIn(hathaway).map(_.start).toList   // List(0, 7)

    To return overlapping matches, it is possible to formulate a regular expression with lookahead (?=) that does not consume the overlapping region.

    val madhatter = "(h)(?=(at[^a]+))".r
    val madhats   = madhatter.findAllMatchIn(hathaway).map {
      case madhatter(x,y) => s"$x$y"
    }.toList                                       // List(hath, hatth, hattth, hatttt)

    Attempting to retrieve match information after exhausting the iterator results in java.lang.IllegalStateException. See scala.util.matching.Regex.MatchIterator for details.

    source

    The text to match against.

    returns

    A scala.util.matching.Regex.MatchIterator of matched substrings.

    Definition Classes
    Regex
    Example:
    1. for (words <- """\w+""".r findAllIn "A simple example.") yield words
  3. def findAllMatchIn(source: CharSequence): Iterator[Match]

    Return all non-overlapping matches of this regexp in given character sequence as a scala.collection.Iterator of scala.util.matching.Regex.Match.

    Return all non-overlapping matches of this regexp in given character sequence as a scala.collection.Iterator of scala.util.matching.Regex.Match.

    source

    The text to match against.

    returns

    A scala.collection.Iterator of scala.util.matching.Regex.Match for all matches.

    Definition Classes
    Regex
    Example:
    1. for (words <- """\w+""".r findAllMatchIn "A simple example.") yield words.start
  4. def findFirstIn(source: CharSequence): Option[String]

    Return an optional first matching string of this Regex in the given character sequence, or None if there is no match.

    Return an optional first matching string of this Regex in the given character sequence, or None if there is no match.

    source

    The text to match against.

    returns

    An scala.Option of the first matching string in the text.

    Definition Classes
    Regex
    Example:
    1. """\w+""".r findFirstIn "A simple example." foreach println // prints "A"
  5. def findFirstMatchIn(source: CharSequence): Option[Match]

    Return an optional first match of this Regex in the given character sequence, or None if it does not exist.

    Return an optional first match of this Regex in the given character sequence, or None if it does not exist.

    If the match is successful, the scala.util.matching.Regex.Match can be queried for more data.

    source

    The text to match against.

    returns

    A scala.Option of scala.util.matching.Regex.Match of the first matching string in the text.

    Definition Classes
    Regex
    Example:
    1. ("""[a-z]""".r findFirstMatchIn "A simple example.") map (_.start) // returns Some(2), the index of the first match in the text
  6. def findPrefixMatchOf(source: CharSequence): Option[Match]

    Return an optional match of this Regex at the beginning of the given character sequence, or None if it matches no prefix of the character sequence.

    Return an optional match of this Regex at the beginning of the given character sequence, or None if it matches no prefix of the character sequence.

    Unlike findFirstMatchIn, this method will only return a match at the beginning of the input.

    source

    The text to match against.

    returns

    A scala.Option of the scala.util.matching.Regex.Match of the matched string.

    Definition Classes
    Regex
    Example:
    1. """\w+""".r findPrefixMatchOf "A simple example." map (_.after) // returns Some(" simple example.")
  7. def findPrefixOf(source: CharSequence): Option[String]

    Return an optional match of this Regex at the beginning of the given character sequence, or None if it matches no prefix of the character sequence.

    Return an optional match of this Regex at the beginning of the given character sequence, or None if it matches no prefix of the character sequence.

    Unlike findFirstIn, this method will only return a match at the beginning of the input.

    source

    The text to match against.

    returns

    A scala.Option of the matched prefix.

    Definition Classes
    Regex
    Example:
    1. """\p{Lower}""".r findPrefixOf "A simple example." // returns None, since the text does not begin with a lowercase letter
  8. def matches(source: CharSequence): Boolean

    Returns whether this Regex matches the given character sequence.

    Returns whether this Regex matches the given character sequence.

    Like the extractor, this method takes anchoring into account.

    source

    The text to match against

    returns

    true if and only if source matches this Regex.

    Definition Classes
    Regex
    Example:
    1. """\d+""".r matches "123" // returns true
    See also

    Regex#unanchored

  9. val pattern: Pattern
    Definition Classes
    Regex
  10. def regex: String
    Definition Classes
    Regex
  11. def replaceAllIn(target: CharSequence, replacer: (Match) => String): String

    Replaces all matches using a replacer function.

    Replaces all matches using a replacer function. The replacer function takes a scala.util.matching.Regex.Match so that extra information can be obtained from the match. For example:

    import scala.util.matching.Regex
    val datePattern = new Regex("""(\d\d\d\d)-(\d\d)-(\d\d)""", "year", "month", "day")
    val text = "From 2011-07-15 to 2011-07-17"
    val repl = datePattern replaceAllIn (text, m => s"${m group "month"}/${m group "day"}")

    In the replacement String, a dollar sign ($) followed by a number will be interpreted as a reference to a group in the matched pattern, with numbers 1 through 9 corresponding to the first nine groups, and 0 standing for the whole match. Any other character is an error. The backslash (\) character will be interpreted as an escape character and can be used to escape the dollar sign. Use Regex.quoteReplacement to escape these characters.

    target

    The string to match.

    replacer

    The function which maps a match to another string.

    returns

    The target string after replacements.

    Definition Classes
    Regex
  12. def replaceAllIn(target: CharSequence, replacement: String): String

    Replaces all matches by a string.

    Replaces all matches by a string.

    In the replacement String, a dollar sign ($) followed by a number will be interpreted as a reference to a group in the matched pattern, with numbers 1 through 9 corresponding to the first nine groups, and 0 standing for the whole match. Any other character is an error. The backslash (\) character will be interpreted as an escape character and can be used to escape the dollar sign. Use Regex.quoteReplacement to escape these characters.

    target

    The string to match

    replacement

    The string that will replace each match

    returns

    The resulting string

    Definition Classes
    Regex
    Example:
    1. """\d+""".r replaceAllIn ("July 15", "<NUMBER>") // returns "July <NUMBER>"
  13. def replaceFirstIn(target: CharSequence, replacement: String): String

    Replaces the first match by a string.

    Replaces the first match by a string.

    In the replacement String, a dollar sign ($) followed by a number will be interpreted as a reference to a group in the matched pattern, with numbers 1 through 9 corresponding to the first nine groups, and 0 standing for the whole match. Any other character is an error. The backslash (\) character will be interpreted as an escape character and can be used to escape the dollar sign. Use Regex.quoteReplacement to escape these characters.

    target

    The string to match

    replacement

    The string that will replace the match

    returns

    The resulting string

    Definition Classes
    Regex
  14. def replaceSomeIn(target: CharSequence, replacer: (Match) => Option[String]): String

    Replaces some of the matches using a replacer function that returns an scala.Option.

    Replaces some of the matches using a replacer function that returns an scala.Option. The replacer function takes a scala.util.matching.Regex.Match so that extra information can be obtained from the match. For example:

    import scala.util.matching.Regex._
    
    val vars = Map("x" -> "a var", "y" -> """some $ and \ signs""")
    val text = "A text with variables %x, %y and %z."
    val varPattern = """%(\w+)""".r
    val mapper = (m: Match) => vars get (m group 1) map (quoteReplacement(_))
    val repl = varPattern replaceSomeIn (text, mapper)

    In the replacement String, a dollar sign ($) followed by a number will be interpreted as a reference to a group in the matched pattern, with numbers 1 through 9 corresponding to the first nine groups, and 0 standing for the whole match. Any other character is an error. The backslash (\) character will be interpreted as an escape character and can be used to escape the dollar sign. Use Regex.quoteReplacement to escape these characters.

    target

    The string to match.

    replacer

    The function which optionally maps a match to another string.

    returns

    The target string after replacements.

    Definition Classes
    Regex
  15. def split(toSplit: CharSequence): Array[String]

    Splits the provided character sequence around matches of this regexp.

    Splits the provided character sequence around matches of this regexp.

    toSplit

    The character sequence to split

    returns

    The array of strings computed by splitting the input around matches of this regexp

    Definition Classes
    Regex
  16. def toString(): String

    The string defining the regular expression

    The string defining the regular expression

    returns

    a String representation of the object.

    Definition Classes
    Regex → AnyRef → Any
  17. def unanchored: UnanchoredRegex

    Create a new Regex with the same pattern, but no requirement that the entire String matches in extractor patterns and Regex#matches.

    Create a new Regex with the same pattern, but no requirement that the entire String matches in extractor patterns and Regex#matches.

    Normally, matching on date behaves as though the pattern were enclosed in anchors, "^pattern$".

    The unanchored Regex behaves as though those anchors were removed.

    Note that this method does not actually strip any matchers from the pattern.

    Calling anchored returns the original Regex.

    val date = """(\d\d\d\d)-(\d\d)-(\d\d)""".r.unanchored
    
    val date(year, month, day) = "Date 2011-07-15"                       // OK
    
    val copyright: String = "Date of this document: 2011-07-15" match {
      case date(year, month, day) => s"Copyright $year"                  // OK
      case _                      => "No copyright"
    }
    returns

    The new unanchored regex

    Definition Classes
    UnanchoredRegexRegex
  18. def unapplySeq(m: Match): Option[List[String]]

    Tries to match on a scala.util.matching.Regex.Match.

    Tries to match on a scala.util.matching.Regex.Match.

    A previously failed match results in None.

    If a successful match was made against the current pattern, then that result is used.

    Otherwise, this Regex is applied to the previously matched input, and the result of that match is used.

    Definition Classes
    Regex
  19. def unapplySeq(c: Char): Option[List[Char]]

    Tries to match the String representation of a scala.Char.

    Tries to match the String representation of a scala.Char.

    If the match succeeds, the result is the first matching group if any groups are defined, or an empty Sequence otherwise.

    For example:

    val cat = "cat"
    // the case must consume the group to match
    val r = """(\p{Lower})""".r
    cat(0) match { case r(x) => true }
    cat(0) match { case r(_) => true }
    cat(0) match { case r(_*) => true }
    cat(0) match { case r() => true }     // no match
    
    // there is no group to extract
    val r = """\p{Lower}""".r
    cat(0) match { case r(x) => true }    // no match
    cat(0) match { case r(_) => true }    // no match
    cat(0) match { case r(_*) => true }   // matches
    cat(0) match { case r() => true }     // matches
    
    // even if there are multiple groups, only one is returned
    val r = """((.))""".r
    cat(0) match { case r(_) => true }    // matches
    cat(0) match { case r(_,_) => true }  // no match
    c

    The Char to match

    returns

    The match

    Definition Classes
    Regex
  20. def unapplySeq(s: CharSequence): Option[List[String]]

    Tries to match a java.lang.CharSequence.

    Tries to match a java.lang.CharSequence.

    If the match succeeds, the result is a list of the matching groups (or a null element if a group did not match any input). If the pattern specifies no groups, then the result will be an empty list on a successful match.

    This method attempts to match the entire input by default; to find the next matching subsequence, use an unanchored Regex.

    For example:

    val p1 = "ab*c".r
    val p1Matches = "abbbc" match {
      case p1() => true               // no groups
      case _    => false
    }
    val p2 = "a(b*)c".r
    val p2Matches = "abbbc" match {
      case p2(_*) => true             // any groups
      case _      => false
    }
    val numberOfB = "abbbc" match {
      case p2(b) => Some(b.length)    // one group
      case _     => None
    }
    val p3 = "b*".r.unanchored
    val p3Matches = "abbbc" match {
      case p3() => true               // find the b's
      case _    => false
    }
    val p4 = "a(b*)(c+)".r
    val p4Matches = "abbbcc" match {
      case p4(_*) => true             // multiple groups
      case _      => false
    }
    val allGroups = "abbbcc" match {
      case p4(all @ _*) => all mkString "/" // "bbb/cc"
      case _            => ""
    }
    val cGroup = "abbbcc" match {
      case p4(_, c) => c
      case _        => ""
    }
    s

    The string to match

    returns

    The matches

    Definition Classes
    Regex