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/*
* Scala (https://www.scala-lang.org)
*
* Copyright EPFL and Lightbend, Inc.
*
* Licensed under Apache License 2.0
* (http://www.apache.org/licenses/LICENSE-2.0).
*
* See the NOTICE file distributed with this work for
* additional information regarding copyright ownership.
*/
/**
* This package is concerned with regular expression (regex) matching against strings,
* with the main goal of pulling out information from those matches, or replacing
* them with something else.
*
* [[scala.util.matching.Regex]] is the class users instantiate to do regular expression matching.
*
* The companion object to [[scala.util.matching.Regex]] contains supporting members:
* * [[scala.util.matching.Regex.Match]] makes more information about a match available.
* * [[scala.util.matching.Regex.MatchIterator]] is used to iterate over matched strings.
* * [[scala.util.matching.Regex.MatchData]] is just a base trait for the above classes.
* * [[scala.util.matching.Regex.Groups]] extracts group from a [[scala.util.matching.Regex.Match]]
* without recomputing the match.
*/
package scala.util.matching
import scala.collection.AbstractIterator
import java.util.regex.{ Pattern, Matcher }
/** 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.
*
* === Usage ===
* 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 used `Regex`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 method `r`, provided
* implicitly for strings:
*
* {{{
* val date = raw"(\d{4})-(\d{2})-(\d{2})".r
* }}}
*
* 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"""`.
* The same result is achieved with certain interpolators, such as `raw"\d".r` or
* a custom interpolator `r"\d"` that also compiles the `Regex`.
*
* === Extraction ===
* To extract the capturing groups when a `Regex` is matched, use it as
* an extractor in a pattern match:
*
* {{{
* "2004-01-20" match {
* case date(year, month, day) => s"\$year was a good year for PLs."
* }
* }}}
*
* To check only whether the `Regex` matches, ignoring any groups,
* use a sequence wildcard:
*
* {{{
* "2004-01-20" match {
* case date(_*) => "It's a date!"
* }
* }}}
*
* 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:
*
* {{{
* "2004-01-20" match {
* case date(year, _*) => s"\$year was a good year for PLs."
* }
* }}}
*
* In a pattern match, `Regex` normally matches the entire input.
* However, an unanchored `Regex` finds the pattern anywhere
* in the input.
*
* {{{
* val embeddedDate = date.unanchored
* "Date: 2004-01-20 17:25:18 GMT (10 years, 28 weeks, 5 days, 17 hours and 51 minutes ago)" match {
* case embeddedDate("2004", "01", "20") => "A Scala is born."
* }
* }}}
*
* === Find Matches ===
* To find or replace matches of the pattern, use the various find and replace methods.
* For each method, there is a version for working with matched strings and
* another for working with `Match` objects.
*
* For example, pattern matching with an unanchored `Regex`, as in the previous example,
* can also be accomplished using `findFirstMatchIn`. The `findFirst` methods return an `Option`
* which is non-empty if a match is found, or `None` for no match:
*
* {{{
* val dates = "Important dates in history: 2004-01-20, 1958-09-05, 2010-10-06, 2011-07-15"
* val firstDate = date.findFirstIn(dates).getOrElse("No date found.")
* val firstYear = for (m <- date.findFirstMatchIn(dates)) yield m.group(1)
* }}}
*
* To find all matches:
*
* {{{
* val allYears = for (m <- date.findAllMatchIn(dates)) yield m.group(1)
* }}}
*
* To check whether input is matched by the regex:
*
* {{{
* date.matches("2018-03-01") // true
* date.matches("Today is 2018-03-01") // false
* date.unanchored.matches("Today is 2018-03-01") // true
* }}}
*
* To iterate over the matched strings, use `findAllIn`, which returns a special iterator
* that can be queried for the `MatchData` of the last match:
*
* {{{
* val mi = date.findAllIn(dates)
* while (mi.hasNext) {
* val d = mi.next
* if (mi.group(1).toInt < 1960) println(s"\$d: An oldie but goodie.")
* }
* }}}
*
* Although the `MatchIterator` returned by `findAllIn` is used like any `Iterator`,
* with alternating calls to `hasNext` and `next`, `hasNext` has the additional
* side effect of advancing the underlying matcher to the next unconsumed match.
* This effect is visible in the `MatchData` representing the "current match".
*
* {{{
* val r = "(ab+c)".r
* val s = "xxxabcyyyabbczzz"
* r.findAllIn(s).start // 3
* val mi = r.findAllIn(s)
* mi.hasNext // true
* mi.start // 3
* mi.next() // "abc"
* mi.start // 3
* mi.hasNext // true
* mi.start // 9
* mi.next() // "abbc"
* }}}
*
* The example shows that methods on `MatchData` such as `start` will advance to
* the first match, if necessary. It also shows that `hasNext` will advance to
* the next unconsumed match, if `next` has already returned the current match.
*
* The current `MatchData` can be captured using the `matchData` method.
* Alternatively, `findAllMatchIn` returns an `Iterator[Match]`, where there
* is no interaction between the iterator and `Match` objects it has already produced.
*
* Note that `findAllIn` finds matches that don't overlap. (See [[findAllIn]] for more examples.)
*
* {{{
* val num = raw"(\d+)".r
* val all = num.findAllIn("123").toList // List("123"), not List("123", "23", "3")
* }}}
*
* === Replace Text ===
* Text replacement can be performed unconditionally or as a function of the current match:
*
* {{{
* val redacted = date.replaceAllIn(dates, "XXXX-XX-XX")
* val yearsOnly = date.replaceAllIn(dates, m => m.group(1))
* val months = (0 to 11).map { i => val c = Calendar.getInstance; c.set(2014, i, 1); f"\$c%tb" }
* val reformatted = date.replaceAllIn(dates, _ match { case date(y,m,d) => f"\${months(m.toInt - 1)} \$d, \$y" })
* }}}
*
* Pattern matching the `Match` against the `Regex` that created it does not reapply the `Regex`.
* In the expression for `reformatted`, each `date` match is computed once. But it is possible to apply a
* `Regex` to a `Match` resulting from a different pattern:
*
* {{{
* val docSpree = """2011(?:-\d{2}){2}""".r
* val docView = date.replaceAllIn(dates, _ match {
* case docSpree() => "Historic doc spree!"
* case _ => "Something else happened"
* })
* }}}
*
* @see [[java.util.regex.Pattern]]
*
* @param pattern The compiled pattern
* @param groupNames A mapping from names to indices in capture groups
*
* @define replacementString
* 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.
*/
@SerialVersionUID(-2094783597747625537L)
class Regex private[matching](val pattern: Pattern, groupNames: String*) extends Serializable {
outer =>
import Regex._
/** 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"
* }}}
*
* Group names supplied to the constructor are preferred to inline group names
* when retrieving matched groups by name. Not all platforms support inline names.
*
* This constructor does not support options as flags, which must be
* supplied as inline flags in the pattern string: `(?idmsux-idmsux)`.
*
* @param regex The regular expression to compile.
* @param groupNames Names of capturing groups.
*/
def this(regex: String, groupNames: String*) = this(Pattern.compile(regex), groupNames: _*)
/** 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 _ => ""
* }
* }}}
*
* @param s The string to match
* @return The matches
*/
def unapplySeq(s: CharSequence): Option[List[String]] = {
val m = pattern matcher s
if (runMatcher(m)) Some(List.tabulate(m.groupCount) { i => m.group(i + 1) })
else None
}
/** 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
* }}}
*
* @param c The Char to match
* @return The match
*/
def unapplySeq(c: Char): Option[List[Char]] = {
val m = pattern matcher c.toString
if (runMatcher(m)) {
if (m.groupCount > 0) Some((m group 1).toList) else Some(Nil)
} else None
}
/** 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.
*/
def unapplySeq(m: Match): Option[List[String]] =
if (m.matched == null) None
else if (m.matcher.pattern == this.pattern) Regex.extractGroupsFromMatch(m)
else unapplySeq(m.matched)
// @see UnanchoredRegex
protected def runMatcher(m: Matcher): Boolean = m.matches()
/** 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.
*
* @param source The text to match against.
* @return A [[scala.util.matching.Regex.MatchIterator]] of matched substrings.
* @example {{{for (words <- """\w+""".r findAllIn "A simple example.") yield words}}}
*/
def findAllIn(source: CharSequence): MatchIterator = new Regex.MatchIterator(source, this, groupNames)
/** Return all non-overlapping matches of this regexp in given character sequence as a
* [[scala.collection.Iterator]] of [[scala.util.matching.Regex.Match]].
*
* @param source The text to match against.
* @return A [[scala.collection.Iterator]] of [[scala.util.matching.Regex.Match]] for all matches.
* @example {{{for (words <- """\w+""".r findAllMatchIn "A simple example.") yield words.start}}}
*/
def findAllMatchIn(source: CharSequence): Iterator[Match] = {
val matchIterator = findAllIn(source)
new AbstractIterator[Match] {
def hasNext = matchIterator.hasNext
def next(): Match = {
matchIterator.next()
new Match(matchIterator.source, matchIterator.matcher, matchIterator.groupNames).force
}
}
}
/** Return an optional first matching string of this `Regex` in the given character sequence,
* or None if there is no match.
*
* @param source The text to match against.
* @return An [[scala.Option]] of the first matching string in the text.
* @example {{{"""\w+""".r findFirstIn "A simple example." foreach println // prints "A"}}}
*/
def findFirstIn(source: CharSequence): Option[String] = {
val m = pattern.matcher(source)
if (m.find) Some(m.group) else None
}
/** 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.
*
* @param source The text to match against.
* @return A [[scala.Option]] of [[scala.util.matching.Regex.Match]] of the first matching string in the text.
* @example {{{("""[a-z]""".r findFirstMatchIn "A simple example.") map (_.start) // returns Some(2), the index of the first match in the text}}}
*/
def findFirstMatchIn(source: CharSequence): Option[Match] = {
val m = pattern.matcher(source)
if (m.find) Some(new Match(source, m, groupNames)) else None
}
/** 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.
*
* @param source The text to match against.
* @return A [[scala.Option]] of the matched prefix.
* @example {{{"""\p{Lower}""".r findPrefixOf "A simple example." // returns None, since the text does not begin with a lowercase letter}}}
*/
def findPrefixOf(source: CharSequence): Option[String] = {
val m = pattern.matcher(source)
if (m.lookingAt) Some(m.group) else None
}
/** 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.
*
* @param source The text to match against.
* @return A [[scala.Option]] of the [[scala.util.matching.Regex.Match]] of the matched string.
* @example {{{"""\w+""".r findPrefixMatchOf "A simple example." map (_.after) // returns Some(" simple example.")}}}
*/
def findPrefixMatchOf(source: CharSequence): Option[Match] = {
val m = pattern.matcher(source)
if (m.lookingAt) Some(new Match(source, m, groupNames)) else None
}
/** Returns whether this `Regex` matches the given character sequence.
*
* Like the extractor, this method takes anchoring into account.
*
* @param source The text to match against
* @return true if and only if `source` matches this `Regex`.
* @see [[Regex#unanchored]]
* @example {{{"""\d+""".r matches "123" // returns true}}}
*/
def matches(source: CharSequence): Boolean =
runMatcher(pattern.matcher(source))
/** Replaces all matches by a string.
*
* $replacementString
*
* @param target The string to match
* @param replacement The string that will replace each match
* @return The resulting string
* @example {{{"""\d+""".r replaceAllIn ("July 15", "") // returns "July "}}}
*/
def replaceAllIn(target: CharSequence, replacement: String): String = {
val m = pattern.matcher(target)
m.replaceAll(replacement)
}
/**
* 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"}")
* }}}
*
* $replacementString
*
* @param target The string to match.
* @param replacer The function which maps a match to another string.
* @return The target string after replacements.
*/
def replaceAllIn(target: CharSequence, replacer: Match => String): String = {
val it = new Regex.MatchIterator(target, this, groupNames).replacementData
it foreach (md => it replace replacer(md))
it.replaced
}
/**
* 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)
* }}}
*
* $replacementString
*
* @param target The string to match.
* @param replacer The function which optionally maps a match to another string.
* @return The target string after replacements.
*/
def replaceSomeIn(target: CharSequence, replacer: Match => Option[String]): String = {
val it = new Regex.MatchIterator(target, this, groupNames).replacementData
for (matchdata <- it ; replacement <- replacer(matchdata))
it replace replacement
it.replaced
}
/** Replaces the first match by a string.
*
* $replacementString
*
* @param target The string to match
* @param replacement The string that will replace the match
* @return The resulting string
*/
def replaceFirstIn(target: CharSequence, replacement: String): String = {
val m = pattern.matcher(target)
m.replaceFirst(replacement)
}
/** Splits the provided character sequence around matches of this regexp.
*
* @param toSplit The character sequence to split
* @return The array of strings computed by splitting the
* input around matches of this regexp
*/
def split(toSplit: CharSequence): Array[String] =
pattern.split(toSplit)
/** 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"
* }
* }}}
*
* @return The new unanchored regex
*/
def unanchored: UnanchoredRegex = new Regex(pattern, groupNames: _*) with UnanchoredRegex { override def anchored = outer }
def anchored: Regex = this
def regex: String = pattern.pattern
/** The string defining the regular expression */
override def toString: String = regex
}
/** A [[Regex]] that finds the first match when used in a pattern match.
*
* @see [[Regex#unanchored]]
*/
trait UnanchoredRegex extends Regex {
override protected def runMatcher(m: Matcher): Boolean = m.find()
override def unanchored: UnanchoredRegex = this
}
/** This object defines inner classes that describe
* regex matches and helper objects.
*/
object Regex {
/** This class provides methods to access
* the details of a match.
*/
trait MatchData {
/** Basically, wraps a platform Matcher. */
protected def matcher: Matcher
/** The source from which the match originated */
val source: CharSequence
/** The names of the groups, or an empty sequence if none defined */
val groupNames: Seq[String]
/** The number of capturing groups in the pattern.
* (For a given successful match, some of those groups may not have matched any input.)
*/
def groupCount: Int
/** The index of the first matched character, or -1 if nothing was matched */
def start: Int
/** The index of the first matched character in group `i`,
* or -1 if nothing was matched for that group.
*/
def start(i: Int): Int
/** The index following the last matched character, or -1 if nothing was matched. */
def end: Int
/** The index following the last matched character in group `i`,
* or -1 if nothing was matched for that group.
*/
def end(i: Int): Int
/** The matched string, or `null` if nothing was matched. */
def matched: String =
if (start >= 0) source.subSequence(start, end).toString
else null
/** The matched string in group `i`,
* or `null` if nothing was matched.
*/
def group(i: Int): String =
if (start(i) >= 0) source.subSequence(start(i), end(i)).toString
else null
/** All capturing groups, i.e., not including group(0). */
def subgroups: List[String] = (1 to groupCount).toList map group
/** The char sequence before first character of match,
* or `null` if nothing was matched.
*/
def before: CharSequence =
if (start >= 0) source.subSequence(0, start)
else null
/** The char sequence before first character of match in group `i`,
* or `null` if nothing was matched for that group.
*/
def before(i: Int): CharSequence =
if (start(i) >= 0) source.subSequence(0, start(i))
else null
/** Returns char sequence after last character of match,
* or `null` if nothing was matched.
*/
def after: CharSequence =
if (end >= 0) source.subSequence(end, source.length)
else null
/** The char sequence after last character of match in group `i`,
* or `null` if nothing was matched for that group.
*/
def after(i: Int): CharSequence =
if (end(i) >= 0) source.subSequence(end(i), source.length)
else null
private[this] lazy val nameToIndex: Map[String, Int] = Map[String, Int]() ++ ("" :: groupNames.toList).zipWithIndex
/** Returns the group with the given name.
*
* Uses explicit group names when supplied; otherwise,
* queries the underlying implementation for inline named groups.
* Not all platforms support inline group names.
*
* @param id The group name
* @return The requested group
* @throws IllegalArgumentException if the requested group name is not defined
*/
def group(id: String): String = (
if (groupNames.isEmpty)
matcher group id
else
nameToIndex.get(id) match {
case Some(index) => group(index)
case None => matcher group id
}
)
/** The matched string; equivalent to `matched.toString`. */
override def toString: String = matched
}
/** Provides information about a successful match. */
class Match(val source: CharSequence,
protected[matching] val matcher: Matcher,
val groupNames: Seq[String]) extends MatchData {
/** The index of the first matched character. */
val start: Int = matcher.start
/** The index following the last matched character. */
val end: Int = matcher.end
/** The number of subgroups. */
def groupCount: Int = matcher.groupCount
private[this] lazy val starts: Array[Int] =
Array.tabulate(groupCount + 1) { matcher.start }
private[this] lazy val ends: Array[Int] =
Array.tabulate(groupCount + 1) { matcher.end }
/** The index of the first matched character in group `i`. */
def start(i: Int): Int = starts(i)
/** The index following the last matched character in group `i`. */
def end(i: Int): Int = ends(i)
/** The match itself with matcher-dependent lazy vals forced,
* so that match is valid even once matcher is advanced.
*/
def force: this.type = { starts; ends; this }
}
/** An extractor object for Matches, yielding the matched string.
*
* This can be used to help writing replacer functions when you
* are not interested in match data. For example:
*
* {{{
* import scala.util.matching.Regex.Match
* """\w+""".r replaceAllIn ("A simple example.", _ match { case Match(s) => s.toUpperCase })
* }}}
*
*/
object Match {
def unapply(m: Match): Some[String] = Some(m.matched)
}
/** An extractor object that yields the groups in the match. Using this extractor
* rather than the original `Regex` ensures that the match is not recomputed.
*
* {{{
* import scala.util.matching.Regex.Groups
*
* val date = """(\d\d\d\d)-(\d\d)-(\d\d)""".r
* val text = "The doc spree happened on 2011-07-15."
* val day = date replaceAllIn(text, _ match { case Groups(_, month, day) => s"\$month/\$day" })
* }}}
*/
object Groups {
def unapplySeq(m: Match): Option[Seq[String]] = {
if (m.groupCount > 0) extractGroupsFromMatch(m) else None
}
}
@inline private def extractGroupsFromMatch(m: Match): Option[List[String]] =
Some(List.tabulate(m.groupCount) { i => m.group(i + 1) })
/** A class to step through a sequence of regex matches.
*
* This is an iterator that returns the matched strings.
*
* Queries about match data pertain to the current state of the underlying
* matcher, which is advanced by calling `hasNext` or `next`.
*
* When matches are exhausted, queries about match data will throw
* [[java.lang.IllegalStateException]].
*
* @see [[java.util.regex.Matcher]]
*/
class MatchIterator(val source: CharSequence, val regex: Regex, val groupNames: Seq[String])
extends AbstractIterator[String] with Iterator[String] with MatchData { self =>
protected[Regex] val matcher = regex.pattern.matcher(source)
// 0 = not yet matched, 1 = matched, 2 = advanced to match, 3 = no more matches
private[this] var nextSeen = 0
/** Return true if `next` will find a match.
* As a side effect, advance the underlying matcher if necessary;
* queries about the current match data pertain to the underlying matcher.
*/
def hasNext: Boolean = {
nextSeen match {
case 0 => nextSeen = if (matcher.find()) 1 else 3
case 1 => ()
case 2 => nextSeen = 0 ; hasNext
case 3 => ()
}
nextSeen == 1 // otherwise, 3
}
/** The next matched substring of `source`.
* As a side effect, advance the underlying matcher if necessary.
*/
def next(): String = {
nextSeen match {
case 0 => if (!hasNext) throw new NoSuchElementException ; next()
case 1 => nextSeen = 2
case 2 => nextSeen = 0 ; next()
case 3 => throw new NoSuchElementException
}
matcher.group
}
/** Report emptiness. */
override def toString: String = super[AbstractIterator].toString
// ensure we're at a match
private[this] def ensure(): Unit = nextSeen match {
case 0 => if (!hasNext) throw new IllegalStateException
case 1 => ()
case 2 => ()
case 3 => throw new IllegalStateException
}
/** The index of the first matched character. */
def start: Int = { ensure() ; matcher.start }
/** The index of the first matched character in group `i`. */
def start(i: Int): Int = { ensure() ; matcher.start(i) }
/** The index of the last matched character. */
def end: Int = { ensure() ; matcher.end }
/** The index following the last matched character in group `i`. */
def end(i: Int): Int = { ensure() ; matcher.end(i) }
/** The number of subgroups. */
def groupCount: Int = { ensure() ; matcher.groupCount }
/** Convert to an iterator that yields MatchData elements instead of Strings. */
def matchData: Iterator[Match] = new AbstractIterator[Match] {
def hasNext = self.hasNext
def next() = { self.next(); new Match(source, matcher, groupNames).force }
}
/** Convert to an iterator that yields MatchData elements instead of Strings and has replacement support. */
private[matching] def replacementData = new AbstractIterator[Match] with Replacement {
def matcher = self.matcher
def hasNext = self.hasNext
def next() = { self.next(); new Match(source, matcher, groupNames).force }
}
}
/**
* A trait able to build a string with replacements assuming it has a matcher.
* Meant to be mixed in with iterators.
*/
private[matching] trait Replacement {
protected def matcher: Matcher
private[this] val sb = new java.lang.StringBuffer
def replaced = {
val newsb = new java.lang.StringBuffer(sb)
matcher.appendTail(newsb)
newsb.toString
}
def replace(rs: String) = matcher.appendReplacement(sb, rs)
}
/** Quotes strings to be used literally in regex patterns.
*
* All regex metacharacters in the input match themselves literally in the output.
*
* @example {{{List("US\$", "CAN\$").map(Regex.quote).mkString("|").r}}}
*/
def quote(text: String): String = Pattern quote text
/** Quotes replacement strings to be used in replacement methods.
*
* Replacement methods give special meaning to backslashes (`\`) and
* dollar signs (`\$`) in replacement strings, so they are not treated
* as literals. This method escapes these characters so the resulting
* string can be used as a literal replacement representing the input
* string.
*
* @param text The string one wishes to use as literal replacement.
* @return A string that can be used to replace matches with `text`.
* @example {{{"CURRENCY".r.replaceAllIn(input, Regex quoteReplacement "US\$")}}}
*/
def quoteReplacement(text: String): String = Matcher quoteReplacement text
}
