/*******************************************************************************
* Copyright (c) 2013, 2015 EclipseSource.
*
* 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 Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
******************************************************************************/
package com.blade.kit.json;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import com.blade.kit.json.JSONObject.Member;
/**
* Represents a JSON object, a set of name/value pairs, where the names are
* strings and the values are JSON values.
* <p>
* Members can be added using the <code>add(String, ...)</code> methods which
* accept instances of {@link JSONValue}, strings, primitive numbers, and
* boolean values. To modify certain values of an object, use the
* <code>set(String, ...)</code> methods. Please note that the <code>add</code>
* methods are faster than <code>set</code> as they do not search for existing
* members. On the other hand, the <code>add</code> methods do not prevent
* adding multiple members with the same name. Duplicate names are discouraged
* but not prohibited by JSON.
* </p>
* <p>
* Members can be accessed by their name using {@link #get(String)}. A list of
* all names can be obtained from the method {@link #names()}. This class also
* supports iterating over the members in document order using an
* {@link #iterator()} or an enhanced for loop:
* </p>
*
* <pre>
* for (Member member : jsonObject) {
* String name = member.getName();
* JsonValue value = member.getValue();
* ...
* }
* </pre>
* <p>
* Even though JSON objects are unordered by definition, instances of this class
* preserve the order of members to allow processing in document order and to
* guarantee a predictable output.
* </p>
* <p>
* Note that this class is <strong>not thread-safe</strong>. If multiple threads
* access a <code>JsonObject</code> instance concurrently, while at least one of
* these threads modifies the contents of this object, access to the instance
* must be synchronized externally. Failure to do so may lead to an inconsistent
* state.
* </p>
* <p>
* This class is <strong>not supposed to be extended</strong> by clients.
* </p>
*/
@SuppressWarnings("serial") // use default serial UID
public class JSONObject extends JSONValue implements Iterable<Member> {
private final List<String> names;
private final List<JSONValue> values;
private transient HashIndexTable table;
/**
* Creates a new empty JsonObject.
*/
public JSONObject() {
names = new ArrayList<String>();
values = new ArrayList<JSONValue>();
table = new HashIndexTable();
}
/**
* Creates a new JsonObject, initialized with the contents of the specified
* JSON object.
*
* @param object
* the JSON object to get the initial contents from, must not be
* <code>null</code>
*/
public JSONObject(JSONObject object) {
this(object, false);
}
private JSONObject(JSONObject object, boolean unmodifiable) {
if (object == null) {
throw new NullPointerException("object is null");
}
if (unmodifiable) {
names = Collections.unmodifiableList(object.names);
values = Collections.unmodifiableList(object.values);
} else {
names = new ArrayList<String>(object.names);
values = new ArrayList<JSONValue>(object.values);
}
table = new HashIndexTable();
updateHashIndex();
}
/**
* Returns an unmodifiable JsonObject for the specified one. This method
* allows to provide read-only access to a JsonObject.
* <p>
* The returned JsonObject is backed by the given object and reflect changes
* that happen to it. Attempts to modify the returned JsonObject result in
* an <code>UnsupportedOperationException</code>.
* </p>
*
* @param object
* the JsonObject for which an unmodifiable JsonObject is to be
* returned
* @return an unmodifiable view of the specified JsonObject
*/
public static JSONObject unmodifiableObject(JSONObject object) {
return new JSONObject(object, true);
}
/**
* Appends a new member to the end of this object, with the specified name
* and the JSON representation of the specified <code>int</code> value.
* <p>
* This method <strong>does not prevent duplicate names</strong>. Calling
* this method with a name that already exists in the object will append
* another member with the same name. In order to replace existing members,
* use the method <code>set(name, value)</code> instead. However, <strong>
* <em>add</em> is much faster than <em>set</em></strong> (because it does
* not need to search for existing members). Therefore <em>add</em> should
* be preferred when constructing new objects.
* </p>
*
* @param name
* the name of the member to add
* @param value
* the value of the member to add
* @return the object itself, to enable method chaining
*/
public JSONObject put(String name, int value) {
put(name, JSON.value(value));
return this;
}
public JSONObject put(String name, Object value) {
put(name, JSON.value(value));
return this;
}
/**
* Appends a new member to the end of this object, with the specified name
* and the JSON representation of the specified <code>long</code> value.
* <p>
* This method <strong>does not prevent duplicate names</strong>. Calling
* this method with a name that already exists in the object will append
* another member with the same name. In order to replace existing members,
* use the method <code>set(name, value)</code> instead. However, <strong>
* <em>add</em> is much faster than <em>set</em></strong> (because it does
* not need to search for existing members). Therefore <em>add</em> should
* be preferred when constructing new objects.
* </p>
*
* @param name
* the name of the member to add
* @param value
* the value of the member to add
* @return the object itself, to enable method chaining
*/
public JSONObject put(String name, long value) {
put(name, JSON.value(value));
return this;
}
/**
* Appends a new member to the end of this object, with the specified name
* and the JSON representation of the specified <code>float</code> value.
* <p>
* This method <strong>does not prevent duplicate names</strong>. Calling
* this method with a name that already exists in the object will append
* another member with the same name. In order to replace existing members,
* use the method <code>set(name, value)</code> instead. However, <strong>
* <em>add</em> is much faster than <em>set</em></strong> (because it does
* not need to search for existing members). Therefore <em>add</em> should
* be preferred when constructing new objects.
* </p>
*
* @param name
* the name of the member to add
* @param value
* the value of the member to add
* @return the object itself, to enable method chaining
*/
public JSONObject put(String name, float value) {
put(name, JSON.value(value));
return this;
}
/**
* Appends a new member to the end of this object, with the specified name
* and the JSON representation of the specified <code>double</code> value.
* <p>
* This method <strong>does not prevent duplicate names</strong>. Calling
* this method with a name that already exists in the object will append
* another member with the same name. In order to replace existing members,
* use the method <code>set(name, value)</code> instead. However, <strong>
* <em>add</em> is much faster than <em>set</em></strong> (because it does
* not need to search for existing members). Therefore <em>add</em> should
* be preferred when constructing new objects.
* </p>
*
* @param name
* the name of the member to add
* @param value
* the value of the member to add
* @return the object itself, to enable method chaining
*/
public JSONObject put(String name, double value) {
put(name, JSON.value(value));
return this;
}
/**
* Appends a new member to the end of this object, with the specified name
* and the JSON representation of the specified <code>boolean</code> value.
* <p>
* This method <strong>does not prevent duplicate names</strong>. Calling
* this method with a name that already exists in the object will append
* another member with the same name. In order to replace existing members,
* use the method <code>set(name, value)</code> instead. However, <strong>
* <em>add</em> is much faster than <em>set</em></strong> (because it does
* not need to search for existing members). Therefore <em>add</em> should
* be preferred when constructing new objects.
* </p>
*
* @param name
* the name of the member to add
* @param value
* the value of the member to add
* @return the object itself, to enable method chaining
*/
public JSONObject put(String name, boolean value) {
put(name, JSON.value(value));
return this;
}
/**
* Appends a new member to the end of this object, with the specified name
* and the JSON representation of the specified string.
* <p>
* This method <strong>does not prevent duplicate names</strong>. Calling
* this method with a name that already exists in the object will append
* another member with the same name. In order to replace existing members,
* use the method <code>set(name, value)</code> instead. However, <strong>
* <em>add</em> is much faster than <em>set</em></strong> (because it does
* not need to search for existing members). Therefore <em>add</em> should
* be preferred when constructing new objects.
* </p>
*
* @param name
* the name of the member to add
* @param value
* the value of the member to add
* @return the object itself, to enable method chaining
*/
public JSONObject put(String name, String value) {
put(name, JSON.value(value));
return this;
}
/**
* Appends a new member to the end of this object, with the specified name
* and the specified JSON value.
* <p>
* This method <strong>does not prevent duplicate names</strong>. Calling
* this method with a name that already exists in the object will append
* another member with the same name. In order to replace existing members,
* use the method <code>set(name, value)</code> instead. However, <strong>
* <em>add</em> is much faster than <em>set</em></strong> (because it does
* not need to search for existing members). Therefore <em>add</em> should
* be preferred when constructing new objects.
* </p>
*
* @param name
* the name of the member to add
* @param value
* the value of the member to add, must not be <code>null</code>
* @return the object itself, to enable method chaining
*/
public JSONObject put(String name, JSONValue value) {
if (name == null) {
throw new NullPointerException("name is null");
}
if (value == null) {
throw new NullPointerException("value is null");
}
table.add(name, names.size());
names.add(name);
values.add(value);
return this;
}
/**
* Sets the value of the member with the specified name to the JSON
* representation of the specified <code>int</code> value. If this object
* does not contain a member with this name, a new member is added at the
* end of the object. If this object contains multiple members with this
* name, only the last one is changed.
* <p>
* This method should <strong>only be used to modify existing
* objects</strong>. To fill a new object with members, the method
* <code>add(name, value)</code> should be preferred which is much faster
* (as it does not need to search for existing members).
* </p>
*
* @param name
* the name of the member to replace
* @param value
* the value to set to the member
* @return the object itself, to enable method chaining
*/
public JSONObject set(String name, int value) {
set(name, JSON.value(value));
return this;
}
/**
* Sets the value of the member with the specified name to the JSON
* representation of the specified <code>long</code> value. If this object
* does not contain a member with this name, a new member is added at the
* end of the object. If this object contains multiple members with this
* name, only the last one is changed.
* <p>
* This method should <strong>only be used to modify existing
* objects</strong>. To fill a new object with members, the method
* <code>add(name, value)</code> should be preferred which is much faster
* (as it does not need to search for existing members).
* </p>
*
* @param name
* the name of the member to replace
* @param value
* the value to set to the member
* @return the object itself, to enable method chaining
*/
public JSONObject set(String name, long value) {
set(name, JSON.value(value));
return this;
}
/**
* Sets the value of the member with the specified name to the JSON
* representation of the specified <code>float</code> value. If this object
* does not contain a member with this name, a new member is added at the
* end of the object. If this object contains multiple members with this
* name, only the last one is changed.
* <p>
* This method should <strong>only be used to modify existing
* objects</strong>. To fill a new object with members, the method
* <code>add(name, value)</code> should be preferred which is much faster
* (as it does not need to search for existing members).
* </p>
*
* @param name
* the name of the member to add
* @param value
* the value of the member to add
* @return the object itself, to enable method chaining
*/
public JSONObject set(String name, float value) {
set(name, JSON.value(value));
return this;
}
/**
* Sets the value of the member with the specified name to the JSON
* representation of the specified <code>double</code> value. If this object
* does not contain a member with this name, a new member is added at the
* end of the object. If this object contains multiple members with this
* name, only the last one is changed.
* <p>
* This method should <strong>only be used to modify existing
* objects</strong>. To fill a new object with members, the method
* <code>add(name, value)</code> should be preferred which is much faster
* (as it does not need to search for existing members).
* </p>
*
* @param name
* the name of the member to add
* @param value
* the value of the member to add
* @return the object itself, to enable method chaining
*/
public JSONObject set(String name, double value) {
set(name, JSON.value(value));
return this;
}
/**
* Sets the value of the member with the specified name to the JSON
* representation of the specified <code>boolean</code> value. If this
* object does not contain a member with this name, a new member is added at
* the end of the object. If this object contains multiple members with this
* name, only the last one is changed.
* <p>
* This method should <strong>only be used to modify existing
* objects</strong>. To fill a new object with members, the method
* <code>add(name, value)</code> should be preferred which is much faster
* (as it does not need to search for existing members).
* </p>
*
* @param name
* the name of the member to add
* @param value
* the value of the member to add
* @return the object itself, to enable method chaining
*/
public JSONObject set(String name, boolean value) {
set(name, JSON.value(value));
return this;
}
/**
* Sets the value of the member with the specified name to the JSON
* representation of the specified string. If this object does not contain a
* member with this name, a new member is added at the end of the object. If
* this object contains multiple members with this name, only the last one
* is changed.
* <p>
* This method should <strong>only be used to modify existing
* objects</strong>. To fill a new object with members, the method
* <code>add(name, value)</code> should be preferred which is much faster
* (as it does not need to search for existing members).
* </p>
*
* @param name
* the name of the member to add
* @param value
* the value of the member to add
* @return the object itself, to enable method chaining
*/
public JSONObject set(String name, String value) {
set(name, JSON.value(value));
return this;
}
/**
* Sets the value of the member with the specified name to the specified
* JSON value. If this object does not contain a member with this name, a
* new member is added at the end of the object. If this object contains
* multiple members with this name, only the last one is changed.
* <p>
* This method should <strong>only be used to modify existing
* objects</strong>. To fill a new object with members, the method
* <code>add(name, value)</code> should be preferred which is much faster
* (as it does not need to search for existing members).
* </p>
*
* @param name
* the name of the member to add
* @param value
* the value of the member to add, must not be <code>null</code>
* @return the object itself, to enable method chaining
*/
public JSONObject set(String name, JSONValue value) {
if (name == null) {
throw new NullPointerException("name is null");
}
if (value == null) {
throw new NullPointerException("value is null");
}
int index = indexOf(name);
if (index != -1) {
values.set(index, value);
} else {
table.add(name, names.size());
names.add(name);
values.add(value);
}
return this;
}
/**
* Removes a member with the specified name from this object. If this object
* contains multiple members with the given name, only the last one is
* removed. If this object does not contain a member with the specified
* name, the object is not modified.
*
* @param name
* the name of the member to remove
* @return the object itself, to enable method chaining
*/
public JSONObject remove(String name) {
if (name == null) {
throw new NullPointerException("name is null");
}
int index = indexOf(name);
if (index != -1) {
table.remove(index);
names.remove(index);
values.remove(index);
}
return this;
}
/**
* Copies all members of the specified object into this object. When the
* specified object contains members with names that also exist in this
* object, the existing values in this object will be replaced by the
* corresponding values in the specified object.
*
* @param object
* the object to merge
* @return the object itself, to enable method chaining
*/
public JSONObject merge(JSONObject object) {
if (object == null) {
throw new NullPointerException("object is null");
}
for (Member member : object) {
this.set(member.name, member.value);
}
return this;
}
/**
* Returns the value of the member with the specified name in this object.
* If this object contains multiple members with the given name, this method
* will return the last one.
*
* @param name
* the name of the member whose value is to be returned
* @return the value of the last member with the specified name, or
* <code>null</code> if this object does not contain a member with
* that name
*/
public JSONValue get(String name) {
if (name == null) {
throw new NullPointerException("name is null");
}
int index = indexOf(name);
return index != -1 ? values.get(index) : null;
}
public boolean contains(String name) {
if (name == null) {
throw new NullPointerException("name is null");
}
int index = indexOf(name);
return index != -1;
}
/**
* Returns the <code>int</code> value of the member with the specified name
* in this object. If this object does not contain a member with this name,
* the given default value is returned. If this object contains multiple
* members with the given name, the last one will be picked. If this
* member's value does not represent a JSON number or if it cannot be
* interpreted as Java <code>int</code>, an exception is thrown.
*
* @param name
* the name of the member whose value is to be returned
* @param defaultValue
* the value to be returned if the requested member is missing
* @return the value of the last member with the specified name, or the
* given default value if this object does not contain a member with
* that name
*/
public Integer getInt(String name, Integer defaultValue) {
JSONValue value = get(name);
return value != null ? value.asInt() : defaultValue;
}
public Integer getInt(String name) {
return getInt(name, null);
}
/**
* Returns the <code>long</code> value of the member with the specified name
* in this object. If this object does not contain a member with this name,
* the given default value is returned. If this object contains multiple
* members with the given name, the last one will be picked. If this
* member's value does not represent a JSON number or if it cannot be
* interpreted as Java <code>long</code>, an exception is thrown.
*
* @param name
* the name of the member whose value is to be returned
* @param defaultValue
* the value to be returned if the requested member is missing
* @return the value of the last member with the specified name, or the
* given default value if this object does not contain a member with
* that name
*/
public Long getLong(String name, Long defaultValue) {
JSONValue value = get(name);
return value != null ? value.asLong() : defaultValue;
}
public Long getLong(String name) {
return getLong(name, null);
}
/**
* Returns the <code>float</code> value of the member with the specified
* name in this object. If this object does not contain a member with this
* name, the given default value is returned. If this object contains
* multiple members with the given name, the last one will be picked. If
* this member's value does not represent a JSON number or if it cannot be
* interpreted as Java <code>float</code>, an exception is thrown.
*
* @param name
* the name of the member whose value is to be returned
* @param defaultValue
* the value to be returned if the requested member is missing
* @return the value of the last member with the specified name, or the
* given default value if this object does not contain a member with
* that name
*/
public Float getFloat(String name, Float defaultValue) {
JSONValue value = get(name);
return value != null ? value.asFloat() : defaultValue;
}
public Float getFloat(String name) {
return getFloat(name, null);
}
/**
* Returns the <code>double</code> value of the member with the specified
* name in this object. If this object does not contain a member with this
* name, the given default value is returned. If this object contains
* multiple members with the given name, the last one will be picked. If
* this member's value does not represent a JSON number or if it cannot be
* interpreted as Java <code>double</code>, an exception is thrown.
*
* @param name
* the name of the member whose value is to be returned
* @param defaultValue
* the value to be returned if the requested member is missing
* @return the value of the last member with the specified name, or the
* given default value if this object does not contain a member with
* that name
*/
public Double getDouble(String name, Double defaultValue) {
JSONValue value = get(name);
return value != null ? value.asDouble() : defaultValue;
}
public Double getDouble(String name) {
return getDouble(name, null);
}
/**
* Returns the <code>boolean</code> value of the member with the specified
* name in this object. If this object does not contain a member with this
* name, the given default value is returned. If this object contains
* multiple members with the given name, the last one will be picked. If
* this member's value does not represent a JSON <code>true</code> or
* <code>false</code> value, an exception is thrown.
*
* @param name
* the name of the member whose value is to be returned
* @param defaultValue
* the value to be returned if the requested member is missing
* @return the value of the last member with the specified name, or the
* given default value if this object does not contain a member with
* that name
*/
public Boolean getBoolean(String name, Boolean defaultValue) {
JSONValue value = get(name);
return value != null ? value.asBoolean() : defaultValue;
}
public boolean getBoolean(String name) {
return getBoolean(name, null);
}
/**
* Returns the <code>String</code> value of the member with the specified
* name in this object. If this object does not contain a member with this
* name, the given default value is returned. If this object contains
* multiple members with the given name, the last one is picked. If this
* member's value does not represent a JSON string, an exception is thrown.
*
* @param name
* the name of the member whose value is to be returned
* @param defaultValue
* the value to be returned if the requested member is missing
* @return the value of the last member with the specified name, or the
* given default value if this object does not contain a member with
* that name
*/
public String getString(String name, String defaultValue) {
JSONValue value = get(name);
return value != null ? value.asString() : defaultValue;
}
public String getString(String name) {
return getString(name, null);
}
/**
* Returns the number of members (name/value pairs) in this object.
*
* @return the number of members in this object
*/
public int size() {
return names.size();
}
/**
* Returns <code>true</code> if this object contains no members.
*
* @return <code>true</code> if this object contains no members
*/
public boolean isEmpty() {
return names.isEmpty();
}
/**
* Returns a list of the names in this object in document order. The
* returned list is backed by this object and will reflect subsequent
* changes. It cannot be used to modify this object. Attempts to modify the
* returned list will result in an exception.
*
* @return a list of the names in this object
*/
public List<String> names() {
return Collections.unmodifiableList(names);
}
/**
* Returns an iterator over the members of this object in document order.
* The returned iterator cannot be used to modify this object.
*
* @return an iterator over the members of this object
*/
public Iterator<Member> iterator() {
final Iterator<String> namesIterator = names.iterator();
final Iterator<JSONValue> valuesIterator = values.iterator();
return new Iterator<JSONObject.Member>() {
public boolean hasNext() {
return namesIterator.hasNext();
}
public Member next() {
String name = namesIterator.next();
JSONValue value = valuesIterator.next();
return new Member(name, value);
}
public void remove() {
throw new UnsupportedOperationException();
}
};
}
@Override
void write(JSONWriter writer) throws IOException {
writer.writeObjectOpen();
Iterator<String> namesIterator = names.iterator();
Iterator<JSONValue> valuesIterator = values.iterator();
boolean first = true;
while (namesIterator.hasNext()) {
if (!first) {
writer.writeObjectSeparator();
}
writer.writeMemberName(namesIterator.next());
writer.writeMemberSeparator();
valuesIterator.next().write(writer);
first = false;
}
writer.writeObjectClose();
}
@Override
public boolean isObject() {
return true;
}
@Override
public JSONObject asJSONObject() {
return this;
}
@Override
public int hashCode() {
int result = 1;
result = 31 * result + names.hashCode();
result = 31 * result + values.hashCode();
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj == null) {
return false;
}
if (getClass() != obj.getClass()) {
return false;
}
JSONObject other = (JSONObject) obj;
return names.equals(other.names) && values.equals(other.values);
}
int indexOf(String name) {
int index = table.get(name);
if (index != -1 && name.equals(names.get(index))) {
return index;
}
return names.lastIndexOf(name);
}
private synchronized void readObject(ObjectInputStream inputStream) throws IOException, ClassNotFoundException {
inputStream.defaultReadObject();
table = new HashIndexTable();
updateHashIndex();
}
private void updateHashIndex() {
int size = names.size();
for (int i = 0; i < size; i++) {
table.add(names.get(i), i);
}
}
/**
* Represents a member of a JSON object, a pair of a name and a value.
*/
public static class Member {
private final String name;
private final JSONValue value;
Member(String name, JSONValue value) {
this.name = name;
this.value = value;
}
/**
* Returns the name of this member.
*
* @return the name of this member, never <code>null</code>
*/
public String getName() {
return name;
}
/**
* Returns the value of this member.
*
* @return the value of this member, never <code>null</code>
*/
public JSONValue getValue() {
return value;
}
@Override
public int hashCode() {
int result = 1;
result = 31 * result + name.hashCode();
result = 31 * result + value.hashCode();
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj == null) {
return false;
}
if (getClass() != obj.getClass()) {
return false;
}
Member other = (Member) obj;
return name.equals(other.name) && value.equals(other.value);
}
}
static class HashIndexTable {
private final byte[] hashTable = new byte[32]; // must be a power of two
public HashIndexTable() {
}
public HashIndexTable(HashIndexTable original) {
System.arraycopy(original.hashTable, 0, hashTable, 0, hashTable.length);
}
void add(String name, int index) {
int slot = hashSlotFor(name);
if (index < 0xff) {
// increment by 1, 0 stands for empty
hashTable[slot] = (byte) (index + 1);
} else {
hashTable[slot] = 0;
}
}
void remove(int index) {
for (int i = 0; i < hashTable.length; i++) {
if (hashTable[i] == index + 1) {
hashTable[i] = 0;
} else if (hashTable[i] > index + 1) {
hashTable[i]--;
}
}
}
int get(Object name) {
int slot = hashSlotFor(name);
// subtract 1, 0 stands for empty
return (hashTable[slot] & 0xff) - 1;
}
private int hashSlotFor(Object element) {
return element.hashCode() & hashTable.length - 1;
}
}
}