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XPath support

Add XPath support.

libraryDependencies += "com.github.geirolz" %% "cats-xml-xpath" % "0.0.18"

With this module you can create NodeCursors instances using XPath.

Using NodeCursor companion object

import cats.xml.cursor.NodeCursor
import cats.xml.xpath.error.*
import cats.xml.xpath.implicits.*

val cursor: Either[XPathError, NodeCursor] = NodeCursor.fromXPath("/root[@id='1']")
// cursor: Either[XPathError, NodeCursor] = Right(
//   value = /root[filter cats.xml.xpath.CursorBuilder$PredicateBuilder$$$Lambda$11249/0x0000000802d53028@7b3fbbaf]
// )

Using string interpolation

import cats.xml.cursor.NodeCursor
import cats.xml.xpath.error.*
import cats.xml.xpath.implicits.*

val cursor: Either[XPathError, NodeCursor] = xpath"/root[@id='1']"
// cursor: Either[XPathError, NodeCursor] = Right(
//   value = /root[filter cats.xml.xpath.CursorBuilder$PredicateBuilder$$$Lambda$11249/0x0000000802d53028@72be9ffd]
// )

Full example

import cats.xml.XmlNode
import cats.xml.cursor.NodeCursor
import cats.xml.xpath.error.*

import cats.implicits.*
import cats.xml.implicits.*
import cats.xml.xpath.implicits.*

val cursor: Either[XPathError, NodeCursor] = xpath"/root[@id='1']"
// cursor: Either[XPathError, NodeCursor] = Right(
//   value = /root[filter cats.xml.xpath.CursorBuilder$PredicateBuilder$$$Lambda$11249/0x0000000802d53028@dac049]
// )

val data = XmlNode("wrapper").withChildren(
  XmlNode("root").withAttrs("id" := 1)
)
// data: XmlNode.Node = <wrapper>
//  <root id="1"/>
// </wrapper>
val result: Either[Throwable, XmlNode] =
  cursor
    .leftMapThrowable
    .flatMap(_.focus(data).leftMap(_.asException))
// result: Either[Throwable, XmlNode] = Right(value = <root id="1"/>)

If you want you can use the xpath expression directly on a XmlNode focusing using that xpath

import cats.xml.XmlNode
import cats.xml.cursor.Cursor

import cats.xml.implicits.*
import cats.xml.xpath.implicits.*

val data = XmlNode("wrapper").withChildren(
  XmlNode("root").withAttrs("id" := 1)
)
// data: XmlNode.Node = <wrapper>
//  <root id="1"/>
// </wrapper>
val result: Cursor.Result[XmlNode] = data.xpath("/root[@id='1']")
// result: Cursor.Result[XmlNode] = Right(value = <root id="1"/>)