org.json4s.MonadicJValue.scala Maven / Gradle / Ivy
package org.json4s
import java.util.Locale.ENGLISH
class MonadicJValue(jv: JValue) {
/**
* XPath-like expression to query JSON fields by name. Matches only fields on
* next level.
*
* Example:
* json \ "name"
*
*/
def \(nameToFind: String): JValue = jv match {
case JArray(xs) => JArray(findDirectByName(xs, nameToFind))
case _ =>
findDirectByName(jv :: Nil, nameToFind) match {
case Nil => JNothing
case x :: Nil => x
case x => JArray(x)
}
}
private[this] def findDirectByName(xs: List[JValue], name: String): List[JValue] = xs.flatMap {
case JObject(l) => l.collect { case (n, v) if n == name => v }
case JArray(l) => findDirectByName(l, name)
case _ => Nil
}
private[this] def findDirect(xs: List[JValue], p: JValue => Boolean): List[JValue] = xs.flatMap {
case JObject(l) => l.collect { case (_, x) if p(x) => x }
case JArray(l) => findDirect(l, p)
case x if p(x) => x :: Nil
case _ => Nil
}
/**
* XPath-like expression to query JSON fields by name. Returns all matching fields.
*
* Example:
* json \\ "name"
*
*/
def \\(nameToFind: String): JValue = {
def find(json: JValue): List[JField] = json match {
case JObject(l) => l.foldLeft(List[JField]()) {
case (a, (name, value)) =>
if (name == nameToFind) a ::: List((name, value)) ::: find(value) else a ::: find(value)
}
case JArray(l) => l.foldLeft(List[JField]())((a, json) => a ::: find(json))
case _ => Nil
}
find(jv) match {
case (_, x) :: Nil => x
case xs => JObject(xs)
}
}
/**
* XPath-like expression to query JSON fields by type. Matches only fields on
* next level.
*
* Example:
* json \ classOf[JInt]
*
*/
def \[A <: JValue](clazz: Class[A]): List[A#Values] =
findDirect(jv.children, typePredicate(clazz) _).asInstanceOf[List[A]] map { _.values }
/**
* XPath-like expression to query JSON fields by type. Returns all matching fields.
*
* Example:
* json \\ classOf[JInt]
*
*/
def \\[A <: JValue](clazz: Class[A]): List[A#Values] =
(jv filter typePredicate(clazz) _).asInstanceOf[List[A]] map { _.values }
private def typePredicate[A <: JValue](clazz: Class[A])(json: JValue) = json match {
case x if x.getClass == clazz => true
case _ => false
}
/**
* Return a combined value by folding over JSON by applying a function f
* for each element. The initial value is z.
*/
def fold[A](z: A)(f: (A, JValue) => A): A = {
def rec(acc: A, v: JValue) = {
val newAcc = f(acc, v)
v match {
case JObject(l) => l.foldLeft(newAcc) { case (a, (_, value)) => value.fold(a)(f) }
case JArray(l) => l.foldLeft(newAcc)((a, e) => e.fold(a)(f))
case _ => newAcc
}
}
rec(z, jv)
}
/**
* Return a combined value by folding over JSON by applying a function f
* for each field. The initial value is z.
*/
def foldField[A](z: A)(f: (A, JField) => A): A = {
def rec(acc: A, v: JValue) = {
v match {
case JObject(l) => l.foldLeft(acc) {
case (a, field @ (_, value)) => value.foldField(f(a, field))(f)
}
case JArray(l) => l.foldLeft(acc)((a, e) => e.foldField(a)(f))
case _ => acc
}
}
rec(z, jv)
}
/**
* Return a new JValue resulting from applying the given function f
* to each value in JSON.
*
* Example:
* JArray(JInt(1) :: JInt(2) :: Nil) map {
* case JInt(x) => JInt(x+1)
* case x => x
* }
*
*/
def map(f: JValue => JValue): JValue = {
def rec(v: JValue): JValue = v match {
case JObject(l) => f(JObject(l.map { case (n, va) => (n, rec(va)) }))
case JArray(l) => f(JArray(l.map(rec)))
case x => f(x)
}
rec(jv)
}
/**
* Return a new JValue resulting from applying the given function f
* to each field in JSON.
*
* Example:
* JObject(("age", JInt(10)) :: Nil) mapField {
* case ("age", JInt(x)) => ("age", JInt(x+1))
* case x => x
* }
*
*/
def mapField(f: JField => JField): JValue = {
def rec(v: JValue): JValue = v match {
case JObject(l) => JObject(l.map { case (n, va) => f(n -> rec(va)) })
case JArray(l) => JArray(l.map(rec))
case x => x
}
rec(jv)
}
/**
* Return a new JValue resulting from applying the given partial function f
* to each field in JSON.
*
* Example:
* JObject(("age", JInt(10)) :: Nil) transformField {
* case ("age", JInt(x)) => ("age", JInt(x+1))
* }
*
*/
def transformField(f: PartialFunction[JField, JField]): JValue = mapField { x =>
if (f.isDefinedAt(x)) f(x) else x
}
/**
* Return a new JValue resulting from applying the given partial function f
* to each value in JSON.
*
* Example:
* JArray(JInt(1) :: JInt(2) :: Nil) transform { case JInt(x) => JInt(x+1) }
*
*/
def transform(f: PartialFunction[JValue, JValue]): JValue = map { x =>
if (f.isDefinedAt(x)) f(x) else x
}
/**
* Return a new JValue resulting from replacing the value at the specified field
* path with the replacement value provided. This has no effect if the path is empty
* or if the value is not a JObject instance.
*
* Example:
* JObject(List(JField("foo", JObject(List(JField("bar", JInt(1))))))).replace("foo" :: "bar" :: Nil, JString("baz"))
* // returns JObject(List(JField("foo", JObject(List(JField("bar", JString("baz")))))))
*
*/
def replace(l: List[String], replacement: JValue): JValue = {
def rep(l: List[String], in: JValue): JValue = {
l match {
case x :: xs => in match {
case JObject(fields) => JObject(
fields.map {
case JField(`x`, value) => JField(x, if (xs == Nil) replacement else rep(xs, value))
case field => field
})
case other => other
}
case Nil => in
}
}
rep(l, jv)
}
/**
* Return the first field from JSON which matches the given predicate.
*
* Example:
* JObject(("age", JInt(2))) findField { case (n, v) => n == "age" }
*
*/
def findField(p: JField => Boolean): Option[JField] = {
def find(json: JValue): Option[JField] = json match {
case JObject(fs) => fs.find(p).orElse(fs.flatMap { case (_, v) => find(v) }.headOption)
case JArray(l) => l.flatMap(find _).headOption
case _ => None
}
find(jv)
}
/**
* Return the first element from JSON which matches the given predicate.
*
* Example:
* JArray(JInt(1) :: JInt(2) :: Nil) find { _ == JInt(2) } == Some(JInt(2))
*
*/
def find(p: JValue => Boolean): Option[JValue] = {
def find(json: JValue): Option[JValue] = {
if (p(json)) return Some(json)
json match {
case JObject(fs) => fs.flatMap { case (_, v) => find(v) }.headOption
case JArray(l) => l.flatMap(find _).headOption
case _ => None
}
}
find(jv)
}
/**
* Return a List of all fields which matches the given predicate.
*
* Example:
* JObject(("age", JInt(10)) :: Nil) filterField {
* case ("age", JInt(x)) if x > 18 => true
* case _ => false
* }
*
*/
def filterField(p: JField => Boolean): List[JField] =
foldField(List[JField]())((acc, e) => if (p(e)) e :: acc else acc).reverse
/**
* Return a List of all values which matches the given predicate.
*
* Example:
* JArray(JInt(1) :: JInt(2) :: Nil) filter { case JInt(x) => x > 1; case _ => false }
*
*/
def filter(p: JValue => Boolean): List[JValue] =
fold(List[JValue]())((acc, e) => if (p(e)) e :: acc else acc).reverse
def withFilter(p: JValue => Boolean) = new JValueWithFilter(jv, p)
class JValueWithFilter(self: JValue, p: JValue => Boolean) {
def map[T](f: JValue => T): List[T] =
self.filter(p).map(f)
def flatMap[T](f: JValue => List[T]): List[T] =
self.filter(p).flatMap(f)
def foreach(f: JValue => Unit): Unit =
self.filter(p).foreach(f)
def withFilter(q: JValue => Boolean): JValueWithFilter =
new JValueWithFilter(self, x => p(x) && q(x))
}
/**
* Return a JSON where all fields matching the given predicate are removed.
*
* Example:
* JObject(("age", JInt(10)) :: Nil) removeField {
* case ("age", _) => true
* case _ => false
* }
*
*/
def removeField(p: JField => Boolean): JValue = jv transform {
case JObject(l) => JObject(l.filterNot(p))
}
/**
* Return a JSON where all values matching the given predicate are removed.
*
* Example:
* JArray(JInt(1) :: JInt(2) :: JNull :: Nil) remove { _ == JNull }
*
*/
def remove(p: JValue => Boolean): JValue = {
if(p(jv)) JNothing
else jv transform {
case JObject(l) => JObject(l.filterNot(f => p(f._2)))
case JArray(l) => JArray(l.filterNot(p))
}
}
private[this] def camelize(word: String): String = {
if (word.nonEmpty) {
val w = pascalize(word)
w.substring(0, 1).toLowerCase(ENGLISH) + w.substring(1)
} else {
word
}
}
private[this] def pascalize(word: String): String = {
val lst = word.split("_").filterNot(_.isEmpty).toList
(lst.headOption.map(s => s.substring(0, 1).toUpperCase(ENGLISH) + s.substring(1)).get ::
lst.tail.map(s => s.substring(0, 1).toUpperCase + s.substring(1))).mkString("")
}
private[this] def underscoreCamelCasesOnly(word: String): String = {
val firstPattern = "([A-Z]+)([A-Z][a-z])".r
val secondPattern = "([a-z\\d])([A-Z])".r
val replacementPattern = "$1_$2"
secondPattern
.replaceAllIn(
firstPattern.replaceAllIn(word, replacementPattern),
replacementPattern
).toLowerCase
}
private[this] def underscore(word: String): String = {
val spacesPattern = "[-\\s]".r
spacesPattern.replaceAllIn(underscoreCamelCasesOnly(word), "_")
}
/**
* Camelize all the keys in this org.json4s.JsonAST.JValue
*/
def camelizeKeys: JValue = rewriteJsonAST(this.camelize)
/**
* Pascalize all the keys in this org.json4s.JsonAST.JValue
*/
def pascalizeKeys: JValue = rewriteJsonAST(this.pascalize)
/**
* Underscore all the keys in this org.json4s.JsonAST.JValue
*/
def snakizeKeys: JValue = rewriteJsonAST(this.underscore)
/**
* Underscore the camel cased only keys in this [[org.json4s.JsonAST.JValue]]
*/
def underscoreCamelCaseKeysOnly = rewriteJsonAST(underscoreCamelCasesOnly)
/**
* Underscore all the keys in this org.json4s.JsonAST.JValue
*/
def underscoreKeys: JValue = snakizeKeys
private[this] def rewriteJsonAST(keyCaseTransform: String => String): JValue =
transformField {
case JField(nm, x) if !nm.startsWith("_") => JField(keyCaseTransform(nm), x)
}
/**
* Remove the org.json4s.JsonAST.JNothing and org.json4s.JsonAST.JNull from
* a org.json4s.JsonAST.JArray or org.json4s.JsonAST.JObject
*/
def noNulls = remove {
case JNull | JNothing => true
case _ => false
}
}
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