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JSON (JavaScript Object Notation) is a lightweight data-interchange format. It is easy for humans to read and write. It is easy for machines to parse and generate. It is based on a subset of the JavaScript Programming Language, Standard ECMA-262 3rd Edition - December 1999. JSON is a text format that is completely language independent but uses conventions that are familiar to programmers of the C-family of languages, including C, C++, C#, Java, JavaScript, Perl, Python, and many others. These properties make JSON an ideal data-interchange language.

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package net.minidev.json.actions;

import net.minidev.json.JSONArray;
import net.minidev.json.JSONObject;
import net.minidev.json.actions.navigate.CopyPathsAction;
import net.minidev.json.actions.navigate.JSONNavigator;

import java.util.Arrays;
import java.util.Collections;
import java.util.LinkedList;
import java.util.List;

/**
 * Creates a copy of a {@link JSONObject} consisting only of the nodes on the user-specified paths.
 * 
 * Paths that do not exist in the specified object are ignored silently. Specifying an empty list of paths
 * to copy or only non-existent paths will result in an empty object being returned.
 * 

 * 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.
 * 

 *  Sample usage:
 * 

 * To replicate the branch k1.k2 from {k1:{k2:v2}, k3:{k4:v4}} use the {@link PathReplicator} like so:
 * 
 * PathReplicator pr = new {@link PathReplicator}("k1.k2")
 * JSONObject copiedObject = pr.copy(new JSONObject(...))
 * 
 * The resulting object 'copiedObject' would be {k1:{k2:v2}}
 * 
 * see unit tests for more examples
 *
 * @author [email protected]
 * @since 15 March 2016.
 */
public class PathReplicator {
	protected List pathsToCopy;

	public PathReplicator(JSONArray pathsToCopy) {
		if (pathsToCopy == null || pathsToCopy.isEmpty()) {
			this.pathsToCopy = Collections.emptyList();
		} else {
			this.pathsToCopy = new LinkedList();
			for (Object s : pathsToCopy) {
				this.pathsToCopy.add((String) s);
			}
		}
	}

	public PathReplicator(List pathsToCopy) {
		this.pathsToCopy = pathsToCopy == null || pathsToCopy.size() == 0 ? Collections. emptyList() : pathsToCopy;
	}

	public PathReplicator(String... pathsToCopy) {
		this.pathsToCopy = pathsToCopy == null || pathsToCopy.length == 0 ? Collections. emptyList()
				: new LinkedList(Arrays.asList(pathsToCopy));
	}

	public JSONObject replicate(JSONObject sourceObj) throws Exception {
		CopyPathsAction s = new CopyPathsAction();
		JSONNavigator n = new JSONNavigator(s, pathsToCopy);
		n.nav(sourceObj);
		return (JSONObject) s.result();
	}
}