com.github.wnameless.json.unflattener.JsonUnflattener Maven / Gradle / Ivy
/*
*
* Copyright 2015 Wei-Ming Wu
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*
*/
package com.github.wnameless.json.unflattener;
import static org.apache.commons.lang3.Validate.notNull;
import java.io.IOException;
import java.io.StringWriter;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import com.eclipsesource.json.Json;
import com.eclipsesource.json.JsonArray;
import com.eclipsesource.json.JsonObject;
import com.eclipsesource.json.JsonValue;
import com.eclipsesource.json.PrettyPrint;
import com.eclipsesource.json.WriterConfig;
import com.github.wnameless.json.flattener.PrintMode;
/**
*
* {@link JsonUnflattener} provides a static {@link #unflatten(String)} method
* to unflatten any flattened JSON string back to nested one.
*
* @author Wei-Ming Wu
*
*/
public final class JsonUnflattener {
private static final String arrayIndex = "\\[\\s*\\d+\\s*\\]";
private static final String objectComplexKey = "\\[\\s*\".*\"\\s*\\]";
private final JsonValue root;
private Character separator = '.';
private PrintMode printMode = PrintMode.MINIMAL;
/**
* Creates a JSON unflattener.
*
* @param json
* the JSON string
*/
public JsonUnflattener(String json) {
root = Json.parse(json);
}
private String objectKey() {
return "[^" + Pattern.quote(separator.toString()) + "\\[\\]]+";
}
private Pattern keyPartPattern() {
return Pattern.compile(arrayIndex + "|" + objectComplexKey + "|"
+ objectKey());
}
/**
* A fluent setter to setup the separator within a key in the flattened JSON.
* The default separator is a dot(.).
*
* @param separator
* any character
* @return this {@link JsonUnflattener}
*/
public JsonUnflattener withSeparator(char separator) {
this.separator = separator;
return this;
}
/**
* A fluent setter to setup a print mode of the {@link JsonUnflattener}. The
* default print mode is minimal.
*
* @param printMode
* a {@link PrintMode}
* @return this {@link JsonUnflattener}
*/
public JsonUnflattener withPrintMode(PrintMode printMode) {
this.printMode = notNull(printMode);
return this;
}
private WriterConfig getWriterConfig() {
switch (printMode) {
case REGULAR:
return PrettyPrint.singleLine();
case PRETTY:
return WriterConfig.PRETTY_PRINT;
default:
return WriterConfig.MINIMAL;
}
}
/**
* Returns a JSON string of nested objects by the given flattened JSON string.
*
* @param json
* a flattened JSON string
* @return a JSON string of nested objects
*/
public static String unflatten(String json) {
return new JsonUnflattener(json).unflatten();
}
/**
* Returns a JSON string of nested objects by the given flattened JSON string.
*
* @return a JSON string of nested objects
*/
public String unflatten() {
StringWriter sw = new StringWriter();
if (root.isArray()) {
try {
unflattenArray(root.asArray()).writeTo(sw, getWriterConfig());
} catch (IOException e) {}
return sw.toString();
}
if (!root.isObject()) {
return root.toString();
}
JsonObject flattened = root.asObject();
JsonValue unflattened = flattened.names().isEmpty() ? Json.object() : null;
for (String key : flattened.names()) {
JsonValue currentVal = unflattened;
String objKey = null;
Integer aryIdx = null;
Matcher matcher = keyPartPattern().matcher(key);
while (matcher.find()) {
String keyPart = matcher.group();
if (objKey != null ^ aryIdx != null) {
if (isJsonArray(keyPart)) {
currentVal = findOrCreateJsonArray(currentVal, objKey, aryIdx);
objKey = null;
aryIdx = extractIndex(keyPart);
} else { // JSON object
if (flattened.get(key).isArray()) { // KEEP_ARRAYS mode
flattened.set(key, unflattenArray(flattened.get(key).asArray()));
}
currentVal = findOrCreateJsonObject(currentVal, objKey, aryIdx);
objKey = extractKey(keyPart);
aryIdx = null;
}
}
if (objKey == null && aryIdx == null) {
if (isJsonArray(keyPart)) {
aryIdx = extractIndex(keyPart);
if (currentVal == null) currentVal = Json.array();
} else { // JSON object
objKey = extractKey(keyPart);
if (currentVal == null) currentVal = Json.object();
}
}
if (unflattened == null) unflattened = currentVal;
}
setUnflattenedValue(flattened, key, currentVal, objKey, aryIdx);
}
try {
unflattened.writeTo(sw, getWriterConfig());
} catch (IOException e) {}
return sw.toString();
}
private JsonArray unflattenArray(JsonArray array) {
JsonArray unflattenArray = Json.array().asArray();
for (JsonValue value : array) {
if (value.isArray()) {
unflattenArray.add(unflattenArray(value.asArray()));
} else if (value.isObject()) {
unflattenArray.add(Json.parse(new JsonUnflattener(value.toString())
.withSeparator(separator).unflatten()));
} else {
unflattenArray.add(value);
}
}
return unflattenArray;
}
private String extractKey(String keyPart) {
if (keyPart.matches(objectComplexKey))
return keyPart.replaceAll("^\\[\\s*\"", "").replaceAll("\"\\s*\\]$", "");
else
return keyPart;
}
private static Integer extractIndex(String keyPart) {
return Integer.valueOf(keyPart.replaceAll("[\\[\\]\\s]", ""));
}
private static boolean isJsonArray(String keyPart) {
return keyPart.matches(arrayIndex);
}
private JsonValue findOrCreateJsonArray(JsonValue currentVal, String objKey,
Integer aryIdx) {
if (objKey != null) {
JsonObject jsonObj = currentVal.asObject();
if (jsonObj.get(objKey) == null) {
JsonValue ary = Json.array();
jsonObj.add(objKey, ary);
return ary;
}
return jsonObj.get(objKey);
} else { // aryIdx != null
JsonArray jsonAry = currentVal.asArray();
if (jsonAry.size() <= aryIdx || jsonAry.get(aryIdx).equals(Json.NULL)) {
JsonValue ary = Json.array();
assureJsonArraySize(jsonAry, aryIdx);
jsonAry.set(aryIdx, ary);
return ary;
}
return jsonAry.get(aryIdx);
}
}
private JsonValue findOrCreateJsonObject(JsonValue currentVal, String objKey,
Integer aryIdx) {
if (objKey != null) {
JsonObject jsonObj = currentVal.asObject();
if (jsonObj.get(objKey) == null) {
JsonValue obj = Json.object();
jsonObj.add(objKey, obj);
return obj;
}
return jsonObj.get(objKey);
} else { // aryIdx != null
JsonArray jsonAry = currentVal.asArray();
if (jsonAry.size() <= aryIdx || jsonAry.get(aryIdx).equals(Json.NULL)) {
JsonValue obj = Json.object();
assureJsonArraySize(jsonAry, aryIdx);
jsonAry.set(aryIdx, obj);
return obj;
}
return jsonAry.get(aryIdx);
}
}
private void setUnflattenedValue(JsonObject flattened, String key,
JsonValue currentVal, String objKey, Integer aryIdx) {
if (objKey != null) {
currentVal.asObject().add(objKey, flattened.get(key));
} else { // aryIdx != null
assureJsonArraySize(currentVal.asArray(), aryIdx);
currentVal.asArray().set(aryIdx, flattened.get(key));
}
}
private void assureJsonArraySize(JsonArray jsonArray, Integer index) {
while (index >= jsonArray.size()) {
jsonArray.add(Json.NULL);
}
}
@Override
public int hashCode() {
int result = 27;
result = 31 * result + root.hashCode();
return result;
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (!(o instanceof JsonUnflattener)) return false;
return root.equals(((JsonUnflattener) o).root);
}
@Override
public String toString() {
return "JsonUnflattener{root=" + root + "}";
}
}
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