// JSON.java
/**
* Copyright (C) 2008 10gen Inc.
*
* 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.mongodb.util;
import org.bson.BSONCallback;
import com.mongodb.DBObject;
/**
* Helper methods for JSON serialization and de-serialization
*/
public class JSON {
/**
* Serializes an object into it's JSON form
*
* @param o object to serialize
* @return String containing JSON form of the object
*/
public static String serialize( Object o ){
StringBuilder buf = new StringBuilder();
serialize( o , buf );
return buf.toString();
}
static void string( StringBuilder a , String s ){
a.append("\"");
for(int i = 0; i < s.length(); ++i){
char c = s.charAt(i);
if (c == '\\')
a.append("\\\\");
else if(c == '"')
a.append("\\\"");
else if(c == '\n')
a.append("\\n");
else if(c == '\r')
a.append("\\r");
else if(c == '\t')
a.append("\\t");
else if(c == '\b')
a.append("\\b");
else if ( c < 32 )
continue;
else
a.append(c);
}
a.append("\"");
}
/**
* Serializes an object into it's JSON form
*
* @param o object to serialize
* @param buf StringBuilder containing the JSON representation under construction
* @return String containing JSON form of the object
*/
public static String serialize( Object o, StringBuilder buf){
BSONObjectSerializer serializer = BSONSerializerFactory.buildLegacyBSONSerializer();
serialize(o, serializer, buf);
return buf.toString();
}
/**
* Serializes an object into it's JSON form
*
* @param o object to serialize
* @param serializer contains instance specific serialization methods
* @param buf StringBuilder containing the JSON representation under construction
* @return String containing JSON form of the object
*/
public static String serialize( Object o, BSONObjectSerializer serializer, StringBuilder buf){
serializer.serialize(o, buf);
return buf.toString();
}
/**
* Serializes an object into it's JSON form
*
* @param o object to serialize
* @param serializer contains instance specific serialization methods
* @return String containing JSON form of the object
*/
public static String serialize( Object o, BSONObjectSerializer serializer){
return serialize(o, serializer, new StringBuilder());
}
/**
* Parses a JSON string representing a JSON value
*
* @param s the string to parse
* @return the object
*/
public static Object parse( String s ){
return parse( s, null );
}
/**
* Parses a JSON string representing a JSON value
*
* @param s the string to parse
* @return the object
*/
public static Object parse( String s, BSONCallback c ){
if (s == null || (s=s.trim()).equals("")) {
return (DBObject)null;
}
JSONParser p = new JSONParser(s, c);
return p.parse();
}
}
/**
* Parser for JSON objects.
*
* Supports all types described at www.json.org, except for
* numbers with "e" or "E" in them.
*/
class JSONParser {
String s;
int pos = 0;
BSONCallback _callback;
/**
* Create a new parser.
*/
public JSONParser(String s) {
this(s, null);
}
/**
* Create a new parser.
*/
public JSONParser(String s, BSONCallback callback) {
this.s = s;
_callback = (callback == null) ? new JSONCallback() : callback;
}
/**
* Parse an unknown type.
*
* @return Object the next item
* @throws JSONParseException if invalid JSON is found
*/
public Object parse() {
return parse(null);
}
/**
* Parse an unknown type.
*
* @return Object the next item
* @throws JSONParseException if invalid JSON is found
*/
protected Object parse(String name) {
Object value = null;
char current = get();
switch(current) {
// null
case 'n':
read('n'); read('u'); read('l'); read('l');
value = null;
break;
// NaN
case 'N':
read('N'); read('a'); read('N');
value = Double.NaN;
break;
// true
case 't':
read('t'); read('r'); read('u'); read('e');
value = true;
break;
// false
case 'f':
read('f'); read('a'); read('l'); read('s'); read('e');
value = false;
break;
// string
case '\'':
case '\"':
value = parseString(true);
break;
// number
case '0': case '1': case '2': case '3': case '4': case '5':
case '6': case '7': case '8': case '9': case '+': case '-':
value = parseNumber();
break;
// array
case '[':
value = parseArray(name);
break;
// object
case '{':
value = parseObject(name);
break;
default:
throw new JSONParseException(s, pos);
}
return value;
}
/**
* Parses an object for the form <i>{}</i> and <i>{ members }</i>.
*
* @return DBObject the next object
* @throws JSONParseException if invalid JSON is found
*/
public Object parseObject() {
return parseObject(null);
}
/**
* Parses an object for the form <i>{}</i> and <i>{ members }</i>.
*
* @return DBObject the next object
* @throws JSONParseException if invalid JSON is found
*/
protected Object parseObject(String name){
if (name != null) {
_callback.objectStart(name);
} else {
_callback.objectStart();
}
read('{');
char current = get();
while(get() != '}') {
String key = parseString(false);
read(':');
Object value = parse(key);
doCallback(key, value);
if((current = get()) == ',') {
read(',');
}
else {
break;
}
}
read('}');
return _callback.objectDone();
}
protected void doCallback(String name, Object value) {
if (value == null) {
_callback.gotNull(name);
} else if (value instanceof String) {
_callback.gotString(name, (String)value);
} else if (value instanceof Boolean) {
_callback.gotBoolean(name, (Boolean)value);
} else if (value instanceof Integer) {
_callback.gotInt(name, (Integer)value);
} else if (value instanceof Long) {
_callback.gotLong(name, (Long)value);
} else if (value instanceof Double) {
_callback.gotDouble(name, (Double)value);
}
}
/**
* Read the current character, making sure that it is the expected character.
* Advances the pointer to the next character.
*
* @param ch the character expected
*
* @throws JSONParseException if the current character does not match the given character
*/
public void read(char ch) {
if(!check(ch)) {
throw new JSONParseException(s, pos);
}
pos++;
}
public char read(){
if ( pos >= s.length() )
throw new IllegalStateException( "string done" );
return s.charAt( pos++ );
}
/**
* Read the current character, making sure that it is a hexidecimal character.
*
* @throws JSONParseException if the current character is not a hexidecimal character
*/
public void readHex() {
if (pos < s.length() &&
((s.charAt(pos) >= '0' && s.charAt(pos) <= '9') ||
(s.charAt(pos) >= 'A' && s.charAt(pos) <= 'F') ||
(s.charAt(pos) >= 'a' && s.charAt(pos) <= 'f'))) {
pos++;
}
else {
throw new JSONParseException(s, pos);
}
}
/**
* Checks the current character, making sure that it is the expected character.
*
* @param ch the character expected
*
* @throws JSONParseException if the current character does not match the given character
*/
public boolean check(char ch) {
return get() == ch;
}
/**
* Advances the position in the string past any whitespace.
*/
public void skipWS() {
while(pos < s.length() && Character.isWhitespace(s.charAt(pos))) {
pos++;
}
}
/**
* Returns the current character.
* Returns -1 if there are no more characters.
*
* @return the next character
*/
public char get() {
skipWS();
if(pos < s.length())
return s.charAt(pos);
return (char)-1;
}
/**
* Parses a string.
*
* @return the next string.
* @throws JSONParseException if invalid JSON is found
*/
public String parseString(boolean needQuote) {
char quot = 0;
if(check('\''))
quot = '\'';
else if(check('\"'))
quot = '\"';
else if (needQuote)
throw new JSONParseException(s, pos);
char current;
if (quot > 0)
read(quot);
StringBuilder buf = new StringBuilder();
int start = pos;
while(pos < s.length()) {
current = s.charAt(pos);
if (quot > 0) {
if (current == quot)
break;
} else {
if (current == ':' || current == ' ')
break;
}
if(current == '\\') {
pos++;
char x = get();
char special = 0;
switch ( x ){
case 'u':
{ // decode unicode
buf.append(s.substring(start, pos-1));
pos++;
int tempPos = pos;
readHex();
readHex();
readHex();
readHex();
int codePoint = Integer.parseInt(s.substring(tempPos, tempPos+4), 16);
buf.append((char)codePoint);
start = pos;
continue;
}
case 'n': special = '\n'; break;
case 'r': special = '\r'; break;
case 't': special = '\t'; break;
case 'b': special = '\b'; break;
case '"': special = '\"'; break;
case '\\': special = '\\'; break;
}
buf.append(s.substring(start, pos-1));
if ( special != 0 ){
pos++;
buf.append( special );
}
start = pos;
continue;
}
pos++;
}
buf.append(s.substring(start, pos));
if (quot > 0)
read(quot);
return buf.toString();
}
/**
* Parses a number.
*
* @return the next number (int or double).
* @throws JSONParseException if invalid JSON is found
*/
public Number parseNumber() {
char current = get();
int start = this.pos;
boolean isDouble = false;
if(check('-') || check('+')) {
pos++;
}
outer:
while(pos < s.length()) {
switch(s.charAt(pos)) {
case '0': case '1': case '2': case '3': case '4':
case '5': case '6': case '7': case '8': case '9':
pos++;
break;
case '.':
isDouble = true;
parseFraction();
break;
case 'e': case 'E':
isDouble = true;
parseExponent();
break;
default:
break outer;
}
}
try{
if (isDouble)
return Double.valueOf(s.substring(start, pos));
Long val = Long.valueOf(s.substring(start, pos));
if (val <= Integer.MAX_VALUE && val >= Integer.MIN_VALUE)
return val.intValue();
return val;
}catch(NumberFormatException e){
throw new JSONParseException(s, start, e);
}
}
/**
* Advances the pointed through <i>.digits</i>.
*/
public void parseFraction() {
// get past .
pos++;
outer:
while(pos < s.length()) {
switch(s.charAt(pos)) {
case '0': case '1': case '2': case '3': case '4':
case '5': case '6': case '7': case '8': case '9':
pos++;
break;
case 'e': case 'E':
parseExponent();
break;
default:
break outer;
}
}
}
/**
* Advances the pointer through the exponent.
*/
public void parseExponent() {
// get past E
pos++;
if(check('-') || check('+')) {
pos++;
}
outer:
while(pos < s.length()) {
switch(s.charAt(pos)) {
case '0': case '1': case '2': case '3': case '4':
case '5': case '6': case '7': case '8': case '9':
pos++;
break;
default:
break outer;
}
}
}
/**
* Parses the next array.
*
* @return the array
* @throws JSONParseException if invalid JSON is found
*/
public Object parseArray() {
return parseArray(null);
}
/**
* Parses the next array.
*
* @return the array
* @throws JSONParseException if invalid JSON is found
*/
protected Object parseArray(String name) {
if (name != null) {
_callback.arrayStart(name);
} else {
_callback.arrayStart();
}
read('[');
int i = 0;
char current = get();
while( current != ']' ) {
String elemName = String.valueOf(i++);
Object elem = parse(elemName);
doCallback(elemName, elem);
if((current = get()) == ',') {
read(',');
}
else if(current == ']') {
break;
}
else {
throw new JSONParseException(s, pos);
}
}
read(']');
return _callback.arrayDone();
}
}