/*
* $Id$
*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.struts2.json;
import java.text.CharacterIterator;
import java.text.StringCharacterIterator;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* <p>
* Deserializes and object from a JSON string
* </p>
*/
public class JSONReader {
private static final Object OBJECT_END = new Object();
private static final Object ARRAY_END = new Object();
private static final Object COLON = new Object();
private static final Object COMMA = new Object();
private static Map<Character, Character> escapes = new HashMap<Character, Character>();
static {
escapes.put('"', '"');
escapes.put('\\', '\\');
escapes.put('/', '/');
escapes.put('b', '\b');
escapes.put('f', '\f');
escapes.put('n', '\n');
escapes.put('r', '\r');
escapes.put('t', '\t');
}
private CharacterIterator it;
private char c;
private Object token;
private StringBuilder buf = new StringBuilder();
protected char next() {
this.c = this.it.next();
return this.c;
}
protected void skipWhiteSpace() {
while (Character.isWhitespace(this.c)) {
this.next();
}
}
public Object read(String string) throws JSONException {
this.it = new StringCharacterIterator(string);
this.c = this.it.first();
return this.read();
}
protected Object read() throws JSONException {
Object ret;
this.skipWhiteSpace();
if (this.c == '"') {
this.next();
ret = this.string('"');
} else if (this.c == '\'') {
this.next();
ret = this.string('\'');
} else if (this.c == '[') {
this.next();
ret = this.array();
} else if (this.c == ']') {
ret = ARRAY_END;
this.next();
} else if (this.c == ',') {
ret = COMMA;
this.next();
} else if (this.c == '{') {
this.next();
ret = this.object();
} else if (this.c == '}') {
ret = OBJECT_END;
this.next();
} else if (this.c == ':') {
ret = COLON;
this.next();
} else if ((this.c == 't') && (this.next() == 'r') && (this.next() == 'u') && (this.next() == 'e')) {
ret = Boolean.TRUE;
this.next();
} else if ((this.c == 'f') && (this.next() == 'a') && (this.next() == 'l') && (this.next() == 's')
&& (this.next() == 'e')) {
ret = Boolean.FALSE;
this.next();
} else if ((this.c == 'n') && (this.next() == 'u') && (this.next() == 'l') && (this.next() == 'l')) {
ret = null;
this.next();
} else if (Character.isDigit(this.c) || (this.c == '-')) {
ret = this.number();
} else {
throw buildInvalidInputException();
}
this.token = ret;
return ret;
}
@SuppressWarnings("unchecked")
protected Map object() throws JSONException {
Map ret = new HashMap();
Object next = this.read();
if (next != OBJECT_END) {
String key = (String) next;
while (this.token != OBJECT_END) {
this.read(); // should be a colon
if (this.token != OBJECT_END) {
ret.put(key, this.read());
if (this.read() == COMMA) {
Object name = this.read();
if (name instanceof String) {
key = (String) name;
} else
throw buildInvalidInputException();
}
}
}
}
return ret;
}
protected JSONException buildInvalidInputException() {
return new JSONException("Input string is not well formed JSON (invalid char " + this.c + ")");
}
@SuppressWarnings("unchecked")
protected List array() throws JSONException {
List ret = new ArrayList();
Object value = this.read();
while (this.token != ARRAY_END) {
ret.add(value);
Object read = this.read();
if (read == COMMA) {
value = this.read();
} else if (read != ARRAY_END) {
throw buildInvalidInputException();
}
}
return ret;
}
protected Object number() {
this.buf.setLength(0);
boolean toDouble = false;
if (this.c == '-') {
this.add();
}
this.addDigits();
if (this.c == '.') {
toDouble = true;
this.add();
this.addDigits();
}
if ((this.c == 'e') || (this.c == 'E')) {
toDouble = true;
this.add();
if ((this.c == '+') || (this.c == '-')) {
this.add();
}
this.addDigits();
}
if (toDouble) {
return Double.parseDouble(this.buf.toString());
} else {
return Long.parseLong(this.buf.toString());
}
}
protected Object string(char quote) {
this.buf.setLength(0);
while ((this.c != quote) && (this.c != CharacterIterator.DONE)) {
if (this.c == '\\') {
this.next();
if (this.c == 'u') {
this.add(this.unicode());
} else {
Object value = escapes.get(this.c);
if (value != null) {
this.add((Character) value);
}
}
} else {
this.add();
}
}
this.next();
return this.buf.toString();
}
protected void add(char cc) {
this.buf.append(cc);
this.next();
}
protected void add() {
this.add(this.c);
}
protected void addDigits() {
while (Character.isDigit(this.c)) {
this.add();
}
}
protected char unicode() {
int value = 0;
for (int i = 0; i < 4; ++i) {
switch (this.next()) {
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
value = (value << 4) + (this.c - '0');
break;
case 'a':
case 'b':
case 'c':
case 'd':
case 'e':
case 'f':
value = (value << 4) + (this.c - 'W');
break;
case 'A':
case 'B':
case 'C':
case 'D':
case 'E':
case 'F':
value = (value << 4) + (this.c - '7');
break;
}
}
return (char) value;
}
}