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StringInstances.scala
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StringInstances.scala
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/*
* Copyright (c) 2015 Typelevel
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of
* this software and associated documentation files (the "Software"), to deal in
* the Software without restriction, including without limitation the rights to
* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
* the Software, and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
package cats.kernel
package instances
import compat.scalaVersionSpecific._
@suppressUnusedImportWarningForScalaVersionSpecific
trait StringInstances {
implicit val catsKernelStdOrderForString: Order[String] with Hash[String] with LowerBounded[String] = new StringOrder
implicit val catsKernelStdMonoidForString: Monoid[String] = new StringMonoid
}
trait StringLowerBounded extends LowerBounded[String] {
override def minBound: String = ""
}
class StringOrder extends Order[String] with Hash[String] with StringLowerBounded { self =>
def hash(x: String): Int = x.hashCode()
override def eqv(x: String, y: String): Boolean =
x == y
def compare(x: String, y: String): Int =
if (x eq y) 0 else x.compareTo(y)
override val partialOrder: PartialOrder[String] = self
}
class StringMonoid extends Monoid[String] { self =>
def empty: String = ""
def combine(x: String, y: String): String = x + y
override def combineAll(xs: IterableOnce[String]): String = {
val sb = new StringBuilder
xs.iterator.foreach(sb.append)
sb.toString
}
override def reverse: Monoid[String] =
new Monoid[String] {
def empty = self.empty
def combine(x: String, y: String) = y + x
override def combineAll(xs: IterableOnce[String]): String = {
val revStrings = xs.iterator.foldLeft(List.empty[String]) { (acc, s) =>
s :: acc
}
self.combineAll(revStrings)
}
override def reverse = self
}
}