net.minidev.json.actions.PathsRetainer Maven / Gradle / Ivy
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package net.minidev.json.actions;
import net.minidev.json.JSONArray;
import net.minidev.json.JSONObject;
import net.minidev.json.actions.path.DotDelimiter;
import net.minidev.json.actions.path.PathDelimiter;
import net.minidev.json.actions.traverse.JSONTraverseAction;
import net.minidev.json.actions.traverse.JSONTraverser;
import net.minidev.json.actions.traverse.LocatePathsJsonAction;
import net.minidev.json.actions.traverse.RetainPathsJsonAction;
import java.util.Arrays;
import java.util.Collections;
import java.util.LinkedList;
import java.util.List;
/**
* Retains branches of nodes of a {@link JSONObject} matching the list of user-specified paths.
*
* A path to copy must be specified in the n-gram format - a list of keys from the root down separated by dots:
* K0[[[[.K1].K2].K3]...]
*
* A key to the right of a dot is a direct child of a key to the left of a dot. Keys with a dot in their name are
* not supported.
*
* Example:
*
* to retain the field k1.k2 in the {@link JSONObject} {k1:{k2:v1}, k3:{k4:v2}} instantiate the retainer like so:
* new JSONObjectCleaner("k1.k2")
* The resulting object would be {k1:{k2:v1}}
*
* See unit tests in JSONObjectRetainerTest for more examples
*
* @author [email protected]
*/
public class PathsRetainer {
protected List pathsToRetain;
protected PathDelimiter pathDelimiter = new DotDelimiter().withAcceptDelimiterInNodeName(false);
public PathsRetainer(JSONArray pathsToRetain) {
if (pathsToRetain == null || pathsToRetain.isEmpty()) {
this.pathsToRetain = Collections.emptyList();
} else {
this.pathsToRetain = new LinkedList();
for (Object s : pathsToRetain) {
this.pathsToRetain.add((String) s);
}
}
}
public PathsRetainer(List pathsToRetain) {
this.pathsToRetain = pathsToRetain == null || pathsToRetain.size() == 0 ? Collections. emptyList() : pathsToRetain;
}
public PathsRetainer(String... pathsToRetain) {
this.pathsToRetain = pathsToRetain == null || pathsToRetain.length == 0 ? Collections. emptyList()
: new LinkedList(Arrays.asList(pathsToRetain));
}
public PathsRetainer with(PathDelimiter pathDelimiter) {
this.pathDelimiter = pathDelimiter;
return this;
}
@SuppressWarnings("unchecked")
public JSONObject retain(JSONObject object) {
/**
* a path to retain which contains a path in the object, but is not itself a path in the object,
* will cause the sub-path to be retained although it shouldn't:
* object = {k0:v0} retain = {k0.k1}
* so the false path to retain has to be removed from the pathsToRetain list.
*
* The {@link LocatePathsJsonAction} returns only paths which exist in the object.
*/
JSONTraverseAction locateAction = new LocatePathsJsonAction(pathsToRetain, pathDelimiter);
JSONTraverser t1 = new JSONTraverser(locateAction);
t1.traverse(object);
List realPathsToRetain = (List) locateAction.result();
//now reduce the object using only existing paths
JSONTraverseAction retainer = new RetainPathsJsonAction(realPathsToRetain, pathDelimiter);
JSONTraverser t2 = new JSONTraverser(retainer).with(pathDelimiter);
t2.traverse(object);
return (JSONObject) retainer.result();
}
}