cstella-stripe commented on a change in pull request #1385: METRON-2071 Add
MAP_PUT and MAP_MERGE to Stellar
URL: https://github.com/apache/metron/pull/1385#discussion_r275782059
##########
File path:
metron-stellar/stellar-common/src/main/java/org/apache/metron/stellar/dsl/functions/MapFunctions.java
##########
@@ -82,4 +83,67 @@ public Object apply(List<Object> objects) {
return ret;
}
}
+
+ @Stellar(name = "PUT",
+ namespace = "MAP",
+ description = "Adds a key/value pair to a map",
+ params = {
+ "key - The key",
+ "value - The value",
+ "map - The map to perform the put on"
+ },
+ returns = "The original map modified with the key/value. If the map
argument is null, a new map will be created and returned that contains the
provided key and value - note: if the 'map' argument is null, only the returned
map will be non-null and contain the key/value."
+ )
+ public static class MapPut extends BaseStellarFunction {
+
+ @Override
+ @SuppressWarnings("unchecked")
+ public Object apply(List<Object> objects) {
+ if (objects.size() < 3) {
+ throw new IllegalArgumentException("Must pass a key, value, and map");
+ } else {
+ Object keyObj = objects.get(0);
+ Object valueObj = objects.get(1);
+ Object mapObj = objects.get(2);
+ if (mapObj == null) {
+ mapObj = new HashMap<>();
+ }
+ Map<Object, Object> map = (Map) mapObj;
+ map.put(keyObj, valueObj);
+ return map;
+ }
+ }
+ }
+
+ @Stellar(name = "MERGE",
+ namespace = "MAP",
+ description = "Merges a list of maps",
+ params = {"maps - A collection of maps to merge"},
+ returns = "A Map. null if the list of maps is empty."
+ )
+ public static class MapMerge extends BaseStellarFunction {
+
+ @Override
+ @SuppressWarnings("unchecked")
+ public Object apply(List<Object> list) {
+ if (list.size() < 1) {
+ return null;
+ }
+ LinkedHashMap<Object, Object> ret = new LinkedHashMap<>();
+ Object o = list.get(0);
+ if (o != null) {
+ if (!(o instanceof Iterable)) {
+ throw new IllegalArgumentException("Expected an Iterable, but " + o
+ " is of type " + o.getClass());
+ }
+ Iterable<? extends Map> maps = (Iterable<? extends Map>) o;
Review comment:
Perhaps `if(Iterables.isEmpty(maps)) { return Iterables.getFirst(maps);)`?
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