Compile a regular expression, supplied as a string, into a pattern that can be matched against inputs.
Compile a regular expression, supplied as a string, into a pattern that can be matched against inputs.
If group names are supplied, they can be used this way:
val namedDate = new Regex("""(\d\d\d\d)-(\d\d)-(\d\d)""", "year", "month", "day") val namedYears = for (m <- namedDate findAllMatchIn dates) yield m group "year"
This constructor does not support options as flags, which must be
supplied as inline flags in the pattern string: (?idmsux-idmsux)
.
The regular expression to compile.
Names of capturing groups.
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 before performing the first match or after exhausting the iterator results in java.lang.IllegalStateException. See scala.util.matching.Regex.MatchIterator for details.
The text to match against.
A scala.util.matching.Regex.MatchIterator of matched substrings.
for (words <- """\w+""".r findAllIn "A simple example.") yield words
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.
The text to match against.
A scala.collection.Iterator of scala.util.matching.Regex.Match for all matches.
for (words <- """\w+""".r findAllMatchIn "A simple example.") yield words.start
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.
The text to match against.
An scala.Option of the first matching string in the text.
"""\w+""".r findFirstIn "A simple example." foreach println // prints "A"
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.
The text to match against.
A scala.Option of scala.util.matching.Regex.Match of the first matching string in the text.
("""[a-z]""".r findFirstMatchIn "A simple example.") map (_.start) // returns Some(2), the index of the first match in the text
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.
The text to match against.
A scala.Option of the scala.util.matching.Regex.Match of the matched string.
"""\w+""".r findPrefixMatchOf "A simple example." map (_.after) // returns Some(" simple example.")
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.
The text to match against.
A scala.Option of the matched prefix.
"""\p{Lower}""".r findPrefixOf "A simple example." // returns None, since the text does not begin with a lowercase letter
The compiled pattern
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.
The string to match.
The function which maps a match to another string.
The target string after replacements.
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.
The string to match
The string that will replace each match
The resulting string
"""\d+""".r replaceAllIn ("July 15", "" ) // returns "July"
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.
The string to match
The string that will replace the match
The resulting 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.
The string to match.
The function which optionally maps a match to another string.
The target string after replacements.
Splits the provided character sequence around matches of this regexp.
Splits the provided character sequence around matches of this regexp.
The character sequence to split
The array of strings computed by splitting the input around matches of this regexp
The string defining the regular expression
The string defining the regular expression
Create a new Regex with the same pattern, but no requirement that the entire String matches in extractor patterns.
Create a new Regex with the same pattern, but no requirement that the entire String matches in extractor patterns.
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" }
The new unanchored regex
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.
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
The Char to match
The match
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 _ => "" }
The string to match
The matches
Tries to match target.
Tries to match target.
The string to match
The matches
(Since version 2.11.0) Extracting a match result from anything but a CharSequence or Match is deprecated
A regular expression is used to determine whether a string matches a pattern and, if it does, to extract or transform the parts that match.
This class delegates to the java.util.regex package of the Java Platform. See the documentation for java.util.regex.Pattern for details about the regular expression syntax for pattern strings.
An instance of
Regex
represents a compiled regular expression pattern. Since compilation is expensive, frequently usedRegex
es should be constructed once, outside of loops and perhaps in a companion object.The canonical way to create a
Regex
is by using the methodr
, provided implicitly for strings:Since escapes are not processed in multi-line string literals, using triple quotes avoids having to escape the backslash character, so that
"\\d"
can be written"""\d"""
.To extract the capturing groups when a
Regex
is matched, use it as an extractor in a pattern match:To check only whether the
Regex
matches, ignoring any groups, use a sequence wildcard:That works because a
Regex
extractor produces a sequence of strings. Extracting only the year from a date could also be expressed with a sequence wildcard:In a pattern match,
Regex
normally matches the entire input. However, an unanchoredRegex
finds the pattern anywhere in the input.To find or replace matches of the pattern, use the various find and replace methods. There is a flavor of each method that produces matched strings and another that produces
Match
objects.For example, pattern matching with an unanchored
Regex
, as in the previous example, is the same as usingfindFirstMatchIn
, except that the findFirst methods return anOption
, orNone
for no match:To find all matches:
But
findAllIn
returns a special iterator of strings that can be queried for theMatchData
of the last match:Note that
findAllIn
finds matches that don't overlap. (See findAllIn for more examples.)Text replacement can be performed unconditionally or as a function of the current match:
Pattern matching the
Match
against theRegex
that created it does not reapply theRegex
. In the expression forreformatted
, eachdate
match is computed once. But it is possible to apply aRegex
to aMatch
resulting from a different pattern:1.1, 29/01/2008
java.util.regex.Pattern