Android Open Source - sodf Sodf Parser

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License

The source code is released under:

Copyright (c) 2013 Lorenz Lehmann Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Sof...

Java Source Code

package lal.sodf.framework.parser;
//from  w ww .ja  v  a  2  s. c  o  m
import java.util.Iterator;
import java.util.LinkedList;

import lal.sodf.framework.ontology.FunctionsNode;
import lal.sodf.framework.ontology.KeyNode;
import lal.sodf.framework.ontology.KeyValueNode;
import lal.sodf.framework.ontology.MetadataNode;
import lal.sodf.framework.ontology.PropertiesNode;
import lal.sodf.framework.ontology.SodfTree;
import lal.sodf.framework.ontology.SodfVocabulary;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

/**
 * A parser, which creates a SODF tree from the serialized version or serializes a SODF tree
 * @author Lorenz Lehmann
 *
 */
public class SodfParser {
  
  /**
   * Create a SodfTree from its JSON representation
   * @param serialization The JSON representation of the SodfTree
   * @return The deserialized SodfTree
   */
  public static SodfTree deserializeTree(String serialization){
    SodfTree st = new SodfTree();
    KeyNode keyNode = SodfParser.deserializeNode(serialization);
    if (keyNode == null) return st;
    st.setRoot(keyNode);
    return st;
  }
  
  /**
   * Serialize a SodfTree. This function will create a valid JSON object with the data of the SodfTree
   * @param node The SodfTree to be serialized
   * @return The JSON representation as String
   */
  public static String serializeTree(SodfTree tree){
    //simply serialize the root
    return SodfParser.serializeNode(tree.getRoot());
  }
  
  /**
   * Create a Node from its JSON representation
   * @param serialization The JSON representation of the Node
   * @return The deserialized Node
   */
  public static KeyNode deserializeNode(String serialization){
    try {
      JSONObject json = new JSONObject(serialization);
      //create an empty KeyNode as root
      KeyNode root = new KeyNode("");
      SodfParser.deserializeNode(root, json);
      //return the final tree
      return root;
      } catch(JSONException e){
        e.printStackTrace();
        return null;      
      }    
  }
  
  /** Deserialize a node. Used by {@link deserializeNode()} for recursive calls*/
  private static void deserializeNode(KeyNode root, JSONObject json) throws JSONException{
    Iterator<?> it = json.keys();
    String key;
    //iterate over all the elements of the JSON object
    while (it.hasNext()){
      key = (String) it.next();
      //if the key leads to an object it most likely belongs to a KeyNode  
      if (json.get(key) instanceof JSONObject) {
        KeyNode kn;
        //check if a special node should be created for this key
        if (key.equals(SodfVocabulary.SODF_PROPERTIES))  kn = new PropertiesNode();
        else if (key.equals(SodfVocabulary.SODF_FUNCTIONS)) kn = new FunctionsNode();
        else if (key.equals(SodfVocabulary.SODF_METADATA)) kn = new MetadataNode();
        else kn = new KeyNode(key);
        //the prefixes subtree has to be added in a special way, all other children are added directly
        if (key.equals(SodfVocabulary.SODF_PREFIXES)) ((MetadataNode) root).setPrefixesSubtree(kn); 
        else root.addChild(kn);
        //continue traversing the tree
        SodfParser.deserializeNode(kn, (JSONObject) json.get(key));
      }
      //arrays are only allowed in KeyValueNodes so it has to be a KeyValueNode
      else if (json.get(key) instanceof JSONArray) {
        JSONArray arr = (JSONArray) json.get(key);
        LinkedList<String> values = new LinkedList<String>();
        for (int i = 0; i < arr.length(); i++){
          values.add(arr.get(i).toString());            
        }
        root.addChild(new KeyValueNode(key, values.toArray(new String[values.size()])));
      }
      else {//the attached child is a value
        root.addChild(new KeyValueNode(key, json.get(key).toString()));                    
      }
    }    
  }
  
  /**
   * Serialize a KeyNode. This function will create a valid JSON object with the data of the node.
   * If you want to serialize a KeyValueNode use a KeyNode with an empty key as root.
   * @param node The node to be serialized
   * @return The JSON representation as String or null if an error occured when parsing the object
   */
  public static String serializeNode(KeyNode node){
    if (node == null) return null;
    
    try {
      //if the root is empty ignore it
      if (node.getKey().equals("")) return node.toJSON().toString();
      else {
        //otherwise use its key to for all of its contents
        JSONObject root = new JSONObject();        
        root.put(node.getKey(), node.toJSON());
        return root.toString();        
      }
    } catch (JSONException e) {
      e.printStackTrace();
      return null;
    }
  }

}

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