Provides named capturing groups with the following enhanced features.
- Allows multiple groups with the same name
- Allows defining named groups as
case object - Provides methods to replace groups in a pattern or a matched instance
- Provides a string interpolation to make a pattern
Add dependency in your build.sbt as the following.
libraryDependencies ++= Seq(
"com.github.tarao" %% "namedcap" % "1.0.0"
)The library is available on Maven Central. Currently, supported Scala versions are 2.13.
import com.github.tarao.namedcap.Group
import com.github.tarao.namedcap.Implicits._ // for string interpolation
case object Url extends Group("https?://.*")
case object Sha1 extends Group("[0-9a-f]{40}")
val p = pattern"/object/$Sha1/for/$Url"
val m = p("/object/6c250662d7ac79316ec20b50accd4723d2bf17a7/for/https://github.com/tarao/namedcap-scala/")
m(Sha1.name) // 6c250662d7ac79316ec20b50accd4723d2bf17a7
// or m("Sha1")
m(Url.name) // https://github.com/tarao/namedcap-scala/
// or m("Url")You can define a named capturing group by Group. case object YourGroup extends Group(pattern) defines a group of pattern as an
identifier YourGroup. A matched portion for the group is accessible
by the same name as the case object ("YourGroup" in this case).
val YourGroup = Group.apply("YourGroup", pattern) has the same
effect if you want to avoid using case object.
pattern interpolation allows you to define a pattern containing
named capturing groups. A pattern object returned by the
interpolation has apply() method to make a match against a string
and returns matched portions with capturing group names.
import com.github.tarao.namedcap.{Group, NestedGroup}
import com.github.tarao.namedcap.Implicits._ // for string interpolation
case object Day extends Group("[0-9]{2}")
case object Month extends Group("[0-9]{2}")
case object Year extends Group("[0-9]{4}")
case object FullDate extends NestedGroup(pattern"$Year-$Month-$Day")
val p = pattern"Since $FullDate"
val m = p("Since 2016-02-11")
m("Day") // 11
m("Month") // 02
m("Year") // 2016
m("FullDate") // 2016-02-11If you want to have a named capturing group within another group, use
NestedGroup. NestedGroup takes a pattern (a value returned by
pattern interpolation) so you can embed arbitrary subgroups with
surrounding pattern expressions.
import com.github.tarao.namedcap.{Group, NestedGroup}
import com.github.tarao.namedcap.Implicits._ // for string interpolation
case object Day extends Group("[0-9]{2}")
case object Month extends Group("[0-9]{2}")
case object Year extends Group("[0-9]{4}")
case object FullDate extends NestedGroup(pattern"$Year-$Month-$Day")
val p = pattern"From $FullDate to $FullDate"
val m = p("From 1985-10-26 to 2015-10-21")
m("FullDate") // 1985-10-26
m.getAll("FullDate") // Seq(1985-10-26, 2015-10-21)A pattern can contain multiple groups with the same name (note that
this is not allowed with the standard
java.util.regex.Pattern notation (?<name>X)).
Captured portions can be retrieve by getAll() of the match result.
In this case, apply() or get() on the match result is still
available and returns the first one.
import com.github.tarao.namedcap.Group
import com.github.tarao.namedcap.Implicits._ // for string interpolation
case object Sha1 extends Group("[0-9a-f]{40}")
val p = pattern"commit $Sha1"
p.mapGroupsIn("commit 6c250662d7ac79316ec20b50accd4723d2bf17a7") { (g, s) =>
if (g.name == "Sha1") s"""<a href="https://github.com/tarao/namedcap-scala/commit/$s">$s</a>"""
else s
} // commit <a href="https://github.com/tarao/namedcap-scala/commit/6c250662d7ac79316ec20b50accd4723d2bf17a7">6c250662d7ac79316ec20b50accd4723d2bf17a7</a>mapGroupsIn() method on a pattern replaces captured groups in an
matched instance. This is useful especially when you want to
highlight the captured groups in the instance.
- Copyright (C) INA Lintaro
- MIT License
