org.opencms.json.JSONTokener Maven / Gradle / Ivy
Show all versions of opencms-core Show documentation
/*
* This library is part of OpenCms -
* the Open Source Content Management System
*
* Copyright (c) Alkacon Software GmbH & Co. KG (http://www.alkacon.com)
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* For further information about Alkacon Software GmbH & Co. KG, please see the
* company website: http://www.alkacon.com
*
* For further information about OpenCms, please see the
* project website: http://www.opencms.org
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* This file is based on:
* org.json.JSONTokener
* from the JSON in Java implementation.
*
* Copyright (c) 2002 JSON.org
*
* 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 shall be used for Good, not Evil.
*
* 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 org.opencms.json;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;
/**
* A JSONTokener takes a source string and extracts characters and tokens from
* it.
*
* It is used by the JSONObject and JSONArray constructors to parse
* JSON source strings.
*
*/
public class JSONTokener {
/** The index. */
private int m_index;
/** The last character. */
private char m_lastChar;
/** Flag which controls whether JSONObjects created by this tokener are ordered. */
private boolean m_ordered;
/** The reader. */
private Reader m_reader;
/** Flag indicating if the last character should be used. */
private boolean m_useLastChar;
/**
* Construct a JSONTokener from a string.
*
* @param reader a reader.
*/
public JSONTokener(Reader reader) {
m_reader = reader.markSupported() ? reader : new BufferedReader(reader);
m_useLastChar = false;
m_index = 0;
}
/**
* Construct a JSONTokener from a string.
*
* @param s a source string
*/
public JSONTokener(String s) {
this(new StringReader(s));
}
/**
* Get the hex value of a character (base16).
*
* @param c a character between '0' and '9' or between 'A' and 'F' or
* between 'a' and 'f'
* @return an int between 0 and 15, or -1 if c was not a hex digit
*/
public static int dehexchar(char c) {
if ((c >= '0') && (c <= '9')) {
return c - '0';
}
if ((c >= 'A') && (c <= 'F')) {
return c - ('A' - 10);
}
if ((c >= 'a') && (c <= 'f')) {
return c - ('a' - 10);
}
return -1;
}
/**
* Back up one character.
*
* This provides a sort of lookahead capability,
* so that you can test for a digit or letter before attempting to parse
* the next number or identifier.
*
* @throws JSONException if something goes wrong
*/
public void back() throws JSONException {
if (m_useLastChar || (m_index <= 0)) {
throw new JSONException("Stepping back two steps is not supported");
}
m_index -= 1;
m_useLastChar = true;
}
/**
* Determine if the source string still contains characters that next()
* can consume.
*
* @return true if not yet at the end of the source
* @throws JSONException if something goes wrong
*/
public boolean more() throws JSONException {
char nextChar = next();
if (nextChar == 0) {
return false;
}
back();
return true;
}
/**
* Get the next character in the source string.
*
* @return the next character, or 0 if past the end of the source string
* @throws JSONException if something goes wrong
*/
public char next() throws JSONException {
if (m_useLastChar) {
m_useLastChar = false;
if (m_lastChar != 0) {
m_index += 1;
}
return m_lastChar;
}
int c;
try {
c = m_reader.read();
} catch (IOException exc) {
throw new JSONException(exc);
}
if (c <= 0) { // End of stream
m_lastChar = 0;
return 0;
}
m_index += 1;
m_lastChar = (char)c;
return m_lastChar;
}
/**
* Consume the next character, and check that it matches a specified
* character.
*
* @param c the character to match
* @return the character
* @throws JSONException if the character does not match
*/
public char next(char c) throws JSONException {
char n = next();
if (n != c) {
throw syntaxError("Expected '" + c + "' and instead saw '" + n + "'");
}
return n;
}
/**
* Get the next n characters.
*
* @param n the number of characters to take
* @return a string of n characters
*
* @throws JSONException substring bounds error if there are not n characters remaining in the source string
*/
public String next(int n) throws JSONException {
if (n == 0) {
return "";
}
char[] buffer = new char[n];
int pos = 0;
if (m_useLastChar) {
m_useLastChar = false;
buffer[0] = m_lastChar;
pos = 1;
}
try {
int len = m_reader.read(buffer, pos, n - pos);
while ((pos < n) && (len != -1)) {
pos += len;
len = m_reader.read(buffer, pos, n - pos);
}
} catch (IOException exc) {
throw new JSONException(exc);
}
m_index += pos;
if (pos < n) {
throw syntaxError("Substring bounds error");
}
m_lastChar = buffer[n - 1];
return new String(buffer);
}
/**
* Get the next char in the string, skipping whitespace
* and comments (slashslash, slashstar, and hash).
*
* @return a character, or 0 if there are no more characters
* @throws JSONException if something goes wrong
*/
public char nextClean() throws JSONException {
for (;;) {
char c = next();
if (c == '/') {
switch (next()) {
case '/':
do {
c = next();
} while ((c != '\n') && (c != '\r') && (c != 0));
break;
case '*':
for (;;) {
c = next();
if (c == 0) {
throw syntaxError("Unclosed comment");
}
if (c == '*') {
if (next() == '/') {
break;
}
back();
}
}
break;
default:
back();
return '/';
}
} else if (c == '#') {
do {
c = next();
} while ((c != '\n') && (c != '\r') && (c != 0));
} else if ((c == 0) || (c > ' ')) {
return c;
}
}
}
/**
* Return the characters up to the next close quote character.
*
* Backslash processing is done. The formal JSON format does not
* allow strings in single quotes, but an implementation is allowed to
* accept them.
*
* @param quote The quoting character, either
* " (double quote) or
* ' (single quote)
* @return a String
* @throws JSONException in case of an unterminated string
*/
public String nextString(char quote) throws JSONException {
char c;
StringBuffer sb = new StringBuffer();
for (;;) {
c = next();
switch (c) {
case 0:
case '\n':
case '\r':
throw syntaxError("Unterminated string");
case '\\':
c = next();
switch (c) {
case 'b':
sb.append('\b');
break;
case 't':
sb.append('\t');
break;
case 'n':
sb.append('\n');
break;
case 'f':
sb.append('\f');
break;
case 'r':
sb.append('\r');
break;
case 'u':
sb.append((char)Integer.parseInt(next(4), 16));
break;
case 'x':
sb.append((char)Integer.parseInt(next(2), 16));
break;
default:
sb.append(c);
}
break;
default:
if (c == quote) {
return sb.toString();
}
sb.append(c);
}
}
}
/**
* Get the text up but not including the specified character or the
* end of line, whichever comes first.
*
* @param d a delimiter character
* @return a string
* @throws JSONException if something goes wrong
*/
public String nextTo(char d) throws JSONException {
StringBuffer sb = new StringBuffer();
for (;;) {
char c = next();
if ((c == d) || (c == 0) || (c == '\n') || (c == '\r')) {
if (c != 0) {
back();
}
return sb.toString().trim();
}
sb.append(c);
}
}
/**
* Get the text up but not including one of the specified delimiter
* characters or the end of line, whichever comes first.
*
* @param delimiters a set of delimiter characters
* @return a string, trimmed
* @throws JSONException if something goes wrong
*/
public String nextTo(String delimiters) throws JSONException {
char c;
StringBuffer sb = new StringBuffer();
for (;;) {
c = next();
if ((delimiters.indexOf(c) >= 0) || (c == 0) || (c == '\n') || (c == '\r')) {
if (c != 0) {
back();
}
return sb.toString().trim();
}
sb.append(c);
}
}
/**
* Get the next value. The value can be a Boolean, Double, Integer,
* JSONArray, JSONObject, Long, or String, or the JSONObject.NULL object.
*
* @return an object
* @throws JSONException if something goes wrong
*/
public Object nextValue() throws JSONException {
char c = nextClean();
String s;
switch (c) {
case '"':
case '\'':
return nextString(c);
case '{':
back();
return new JSONObject(this, m_ordered);
case '[':
case '(':
back();
return new JSONArray(this);
default:
}
/*
* Handle unquoted text. This could be the values true, false, or
* null, or it can be a number. An implementation (such as this one)
* is allowed to also accept non-standard forms.
*
* Accumulate characters until we reach the end of the text or a
* formatting character.
*/
StringBuffer sb = new StringBuffer();
char b = c;
while ((c >= ' ') && (",:]}/\\\"[{;=#".indexOf(c) < 0)) {
sb.append(c);
c = next();
}
back();
/*
* If it is true, false, or null, return the proper value.
*/
s = sb.toString().trim();
if (s.equals("")) {
throw syntaxError("Missing value");
}
if (s.equalsIgnoreCase("true")) {
return Boolean.TRUE;
}
if (s.equalsIgnoreCase("false")) {
return Boolean.FALSE;
}
if (s.equalsIgnoreCase("null")) {
return JSONObject.NULL;
}
/*
* If it might be a number, try converting it. We support the 0- and 0x-
* conventions. If a number cannot be produced, then the value will just
* be a string. Note that the 0-, 0x-, plus, and implied string
* conventions are non-standard. A JSON parser is free to accept
* non-JSON forms as long as it accepts all correct JSON forms.
*/
if (((b >= '0') && (b <= '9')) || (b == '.') || (b == '-') || (b == '+')) {
if (b == '0') {
if ((s.length() > 2) && ((s.charAt(1) == 'x') || (s.charAt(1) == 'X'))) {
try {
return new Integer(Integer.parseInt(s.substring(2), 16));
} catch (Exception e) {
/* Ignore the error */
}
} else {
try {
return new Integer(Integer.parseInt(s, 8));
} catch (Exception e) {
/* Ignore the error */
}
}
}
try {
return new Integer(s);
} catch (Exception e) {
try {
return new Long(s);
} catch (Exception f) {
try {
return new Double(s);
} catch (Exception g) {
return s;
}
}
}
}
return s;
}
/**
* Sets a flag which makes JSONObjects created by this tokener ordered.
*
* @param ordered true if JSONObjects created by this should be ordered
*/
public void setOrdered(boolean ordered) {
m_ordered = ordered;
}
/**
* Skip characters until the next character is the requested character.
* If the requested character is not found, no characters are skipped.
*
* @param to a character to skip to
* @return the requested character, or zero if the requested character
* is not found
* @throws JSONException if something goes wrong
*/
public char skipTo(char to) throws JSONException {
char c;
try {
int startIndex = m_index;
m_reader.mark(Integer.MAX_VALUE);
do {
c = next();
if (c == 0) {
m_reader.reset();
m_index = startIndex;
return c;
}
} while (c != to);
} catch (IOException exc) {
throw new JSONException(exc);
}
back();
return c;
}
/**
* Make a JSONException to signal a syntax error.
*
* @param message the error message
* @return a JSONException object, suitable for throwing
*/
public JSONException syntaxError(String message) {
return new JSONException(message + toString());
}
/**
* Make a printable string of this JSONTokener.
*
* @return " at character [this.index]"
*/
@Override
public String toString() {
return " at character " + m_index;
}
}