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36 package gr.grnet.aquarium.util
38 import java.util.{Map => JMap,
41 ArrayList => JArrayList}
44 * Utility functions for Collections, including recursive conversion to Java
47 * @author Georgios Gousios <gousiosg@gmail.com>
49 trait CollectionUtils {
51 /**Merge input maps on a field by field basis. In case of duplicate keys
52 * values from the first map are prefered.
54 private def mergeMaps[A, B](a: Map[A, B], b: Map[A, B]): Map[A, B] = {
56 case (k, v) => k -> (a.getOrElse(k, v))
60 /**Merge input maps on a field by field basis. In case of duplicate keys,
61 * the provided function is used to determine which value to keep in the
64 private def mergeMaps[A, B](ms: List[Map[A, B]])(f: (B, B) => B): Map[A, B] =
65 (Map[A, B]() /: (for (m <- ms; kv <- m) yield kv)) {
67 a + (if (a.contains(kv._1))
68 kv._1 -> f(a(kv._1), kv._2)
74 * Recursively convert a Scala[String, Any] map to a Java equivalent.
75 * It will also convert values that are Scala Maps or Lists or Seqs
76 * to Java equivalents.
78 def mapToJavaMap(map: Map[String, Any]): JMap[String, Object] = {
79 val result = new JHashMap[String, Object]
81 map.foreach(kv => result.put(kv._1, transformValue(kv._2)))
86 * Recursively convert a Scala List[Any] map to a Java equivalent
87 * List[Object]. If the list's items are of type List[_]
88 * and/or Map[String, Any] those will also be converted to
91 def listToJavaList(seq: List[Any]): JList[Object] = {
92 val list = new JArrayList[Object]
93 seq.foreach(a => list.add(transformValue(a)))
97 private def transformValue(v: Any) = {
99 case l: List[_] => listToJavaList(l)
100 case s: Seq[_] => listToJavaList(s.toList)
101 case i: Iterator[_] => listToJavaList(i.toList)
102 case m: Map[String, Any] => mapToJavaMap(m)
106 v2.asInstanceOf[Object]