JSONTokener.java
package org.json;
import java.io.*;
import java.nio.charset.Charset;
/*
Public Domain.
*/
/**
* 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.
* @author JSON.org
* @version 2014-05-03
*/
public class JSONTokener {
/** current read character position on the current line. */
private long character;
/** flag to indicate if the end of the input has been found. */
private boolean eof;
/** current read index of the input. */
private long index;
/** current line of the input. */
private long line;
/** previous character read from the input. */
private char previous;
/** Reader for the input. */
private final Reader reader;
/** flag to indicate that a previous character was requested. */
private boolean usePrevious;
/** the number of characters read in the previous line. */
private long characterPreviousLine;
/**
* Construct a JSONTokener from a Reader. The caller must close the Reader.
*
* @param reader A reader.
*/
public JSONTokener(Reader reader) {
this.reader = reader.markSupported()
? reader
: new BufferedReader(reader);
this.eof = false;
this.usePrevious = false;
this.previous = 0;
this.index = 0;
this.character = 1;
this.characterPreviousLine = 0;
this.line = 1;
}
/**
* Construct a JSONTokener from an InputStream. The caller must close the input stream.
* @param inputStream The source.
*/
public JSONTokener(InputStream inputStream) {
this(new InputStreamReader(inputStream, Charset.forName("UTF-8")));
}
/**
* Construct a JSONTokener from a string.
*
* @param s A source string.
*/
public JSONTokener(String s) {
this(new StringReader(s));
}
/**
* 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 Thrown if trying to step back more than 1 step
* or if already at the start of the string
*/
public void back() throws JSONException {
if (this.usePrevious || this.index <= 0) {
throw new JSONException("Stepping back two steps is not supported");
}
this.decrementIndexes();
this.usePrevious = true;
this.eof = false;
}
/**
* Decrements the indexes for the {@link #back()} method based on the previous character read.
*/
private void decrementIndexes() {
this.index--;
if(this.previous=='\r' || this.previous == '\n') {
this.line--;
this.character=this.characterPreviousLine ;
} else if(this.character > 0){
this.character--;
}
}
/**
* 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;
}
/**
* Checks if the end of the input has been reached.
*
* @return true if at the end of the file and we didn't step back
*/
public boolean end() {
return this.eof && !this.usePrevious;
}
/**
* 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 thrown if there is an error stepping forward
* or backward while checking for more data.
*/
public boolean more() throws JSONException {
if(this.usePrevious) {
return true;
}
try {
this.reader.mark(1);
} catch (IOException e) {
throw new JSONException("Unable to preserve stream position", e);
}
try {
// -1 is EOF, but next() can not consume the null character '\0'
if(this.reader.read() <= 0) {
this.eof = true;
return false;
}
this.reader.reset();
} catch (IOException e) {
throw new JSONException("Unable to read the next character from the stream", e);
}
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 Thrown if there is an error reading the source string.
*/
public char next() throws JSONException {
int c;
if (this.usePrevious) {
this.usePrevious = false;
c = this.previous;
} else {
try {
c = this.reader.read();
} catch (IOException exception) {
throw new JSONException(exception);
}
}
if (c <= 0) { // End of stream
this.eof = true;
return 0;
}
this.incrementIndexes(c);
this.previous = (char) c;
return this.previous;
}
/**
* Get the last character read from the input or '\0' if nothing has been read yet.
* @return the last character read from the input.
*/
protected char getPrevious() { return this.previous;}
/**
* Increments the internal indexes according to the previous character
* read and the character passed as the current character.
* @param c the current character read.
*/
private void incrementIndexes(int c) {
if(c > 0) {
this.index++;
if(c=='\r') {
this.line++;
this.characterPreviousLine = this.character;
this.character=0;
}else if (c=='\n') {
if(this.previous != '\r') {
this.line++;
this.characterPreviousLine = this.character;
}
this.character=0;
} else {
this.character++;
}
}
}
/**
* 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 = this.next();
if (n != c) {
if(n > 0) {
throw this.syntaxError("Expected '" + c + "' and instead saw '" +
n + "'");
}
throw this.syntaxError("Expected '" + c + "' and instead saw ''");
}
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[] chars = new char[n];
int pos = 0;
while (pos < n) {
chars[pos] = this.next();
if (this.end()) {
throw this.syntaxError("Substring bounds error");
}
pos += 1;
}
return new String(chars);
}
/**
* Get the next char in the string, skipping whitespace.
* @throws JSONException Thrown if there is an error reading the source string.
* @return A character, or 0 if there are no more characters.
*/
public char nextClean() throws JSONException {
for (;;) {
char c = this.next();
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.
* If strictMode is true, this implementation will not accept unbalanced quotes (e.g will not accept <code>"test'</code>).
* @param quote The quoting character, either
* <code>"</code> <small>(double quote)</small> or
* <code>'</code> <small>(single quote)</small>.
* @param strictMode If true, this implementation will not accept unbalanced quotes (e.g will not accept <code>"test'</code>).
* @return A String.
* @throws JSONException Unterminated string or unbalanced quotes if strictMode == true.
*/
public String nextString(char quote, boolean strictMode) throws JSONException {
char c;
StringBuilder sb = new StringBuilder();
for (;;) {
c = this.next();
switch (c) {
case 0:
case '\n':
case '\r':
throw this.syntaxError("Unterminated string. " +
"Character with int code " + (int) c + " is not allowed within a quoted string.");
case '\\':
c = this.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':
String next = this.next(4);
try {
sb.append((char)Integer.parseInt(next, 16));
} catch (NumberFormatException e) {
throw this.syntaxError("Illegal escape. " +
"\\u must be followed by a 4 digit hexadecimal number. \\" + next + " is not valid.", e);
}
break;
case '"':
case '\'':
case '\\':
case '/':
sb.append(c);
break;
default:
throw this.syntaxError("Illegal escape. Escape sequence \\" + c + " is not valid.");
}
break;
default:
if (strictMode && c == '\"' && quote != c) {
throw this.syntaxError(String.format(
"Field contains unbalanced quotes. Starts with %s but ends with double quote.", quote));
}
if (strictMode && c == '\'' && quote != c) {
throw this.syntaxError(String.format(
"Field contains unbalanced quotes. Starts with %s but ends with single quote.", quote));
}
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 delimiter A delimiter character.
* @return A string.
* @throws JSONException Thrown if there is an error while searching
* for the delimiter
*/
public String nextTo(char delimiter) throws JSONException {
StringBuilder sb = new StringBuilder();
for (;;) {
char c = this.next();
if (c == delimiter || c == 0 || c == '\n' || c == '\r') {
if (c != 0) {
this.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 Thrown if there is an error while searching
* for the delimiter
*/
public String nextTo(String delimiters) throws JSONException {
char c;
StringBuilder sb = new StringBuilder();
for (;;) {
c = this.next();
if (delimiters.indexOf(c) >= 0 || c == 0 ||
c == '\n' || c == '\r') {
if (c != 0) {
this.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 syntax error.
*/
public Object nextValue() throws JSONException {
return nextValue(new JSONParserConfiguration());
}
/**
* Get the next value. The value can be a Boolean, Double, Integer, JSONArray, JSONObject, Long, or String, or the
* JSONObject.NULL object. The strictMode parameter controls the behavior of the method when parsing the value.
*
* @param jsonParserConfiguration which carries options such as strictMode, these methods will
* strictly adhere to the JSON syntax, throwing a JSONException for any deviations.
* @return An object.
* @throws JSONException If syntax error.
*/
public Object nextValue(JSONParserConfiguration jsonParserConfiguration) throws JSONException {
char c = this.nextClean();
switch (c) {
case '{':
this.back();
try {
return new JSONObject(this, jsonParserConfiguration);
} catch (StackOverflowError e) {
throw new JSONException("JSON Array or Object depth too large to process.", e);
}
case '[':
this.back();
try {
return new JSONArray(this);
} catch (StackOverflowError e) {
throw new JSONException("JSON Array or Object depth too large to process.", e);
}
default:
return nextSimpleValue(c, jsonParserConfiguration);
}
}
/**
* This method is used to get a JSONObject from the JSONTokener. The strictMode parameter controls the behavior of
* the method when parsing the JSONObject.
*
* @param jsonParserConfiguration which carries options such as strictMode, these methods will
* strictly adhere to the JSON syntax, throwing a JSONException for any deviations.
* deviations.
* @return A JSONObject which is the next value in the JSONTokener.
* @throws JSONException If the JSONObject or JSONArray depth is too large to process.
*/
private JSONObject getJsonObject(JSONParserConfiguration jsonParserConfiguration) {
try {
return new JSONObject(this, jsonParserConfiguration);
} catch (StackOverflowError e) {
throw new JSONException("JSON Array or Object depth too large to process.", e);
}
}
/**
* This method is used to get a JSONArray from the JSONTokener.
*
* @return A JSONArray which is the next value in the JSONTokener.
* @throws JSONException If the JSONArray depth is too large to process.
*/
private JSONArray getJsonArray() {
try {
return new JSONArray(this);
} catch (StackOverflowError e) {
throw new JSONException("JSON Array or Object depth too large to process.", e);
}
}
Object nextSimpleValue(char c, JSONParserConfiguration jsonParserConfiguration) {
boolean strictMode = jsonParserConfiguration.isStrictMode();
if(strictMode && c == '\''){
throw this.syntaxError("Single quote wrap not allowed in strict mode");
}
if (c == '"' || c == '\'') {
return this.nextString(c, strictMode);
}
return parsedUnquotedText(c, strictMode);
}
/**
* Parses unquoted text from the JSON input. This could be the values true, false, or null, or it can be a number.
* Non-standard forms are also accepted. Characters are accumulated until the end of the text or a formatting
* character is reached.
*
* @param c The starting character.
* @return The parsed object.
* @throws JSONException If the parsed string is empty.
*/
private Object parsedUnquotedText(char c, boolean strictMode) {
StringBuilder sb = new StringBuilder();
while (c >= ' ' && ",:]}/\\\"[{;=#".indexOf(c) < 0) {
sb.append(c);
c = this.next();
}
if (!this.eof) {
this.back();
}
String string = sb.toString().trim();
if (strictMode) {
boolean isBooleanOrNumeric = checkIfValueIsBooleanOrNumeric(string);
if (isBooleanOrNumeric) {
return string;
}
throw new JSONException(String.format("Value is not surrounded by quotes: %s", string));
}
if (string.isEmpty()) {
throw this.syntaxError("Missing value");
}
return JSONObject.stringToValue(string);
}
private boolean checkIfValueIsBooleanOrNumeric(Object valueToValidate) {
String stringToValidate = valueToValidate.toString();
if (stringToValidate.equals("true") || stringToValidate.equals("false")) {
return true;
}
try {
Double.parseDouble(stringToValidate);
return true;
} catch (NumberFormatException e) {
return false;
}
}
/**
* 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 Thrown if there is an error while searching
* for the to character
*/
public char skipTo(char to) throws JSONException {
char c;
try {
long startIndex = this.index;
long startCharacter = this.character;
long startLine = this.line;
this.reader.mark(1000000);
do {
c = this.next();
if (c == 0) {
// in some readers, reset() may throw an exception if
// the remaining portion of the input is greater than
// the mark size (1,000,000 above).
this.reader.reset();
this.index = startIndex;
this.character = startCharacter;
this.line = startLine;
return 0;
}
} while (c != to);
this.reader.mark(1);
} catch (IOException exception) {
throw new JSONException(exception);
}
this.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 + this.toString());
}
/**
* Make a JSONException to signal a syntax error.
*
* @param message The error message.
* @param causedBy The throwable that caused the error.
* @return A JSONException object, suitable for throwing
*/
public JSONException syntaxError(String message, Throwable causedBy) {
return new JSONException(message + this.toString(), causedBy);
}
/**
* Make a printable string of this JSONTokener.
*
* @return " at {index} [character {character} line {line}]"
*/
@Override
public String toString() {
return " at " + this.index + " [character " + this.character + " line " +
this.line + "]";
}
/**
* Closes the underlying reader, releasing any resources associated with it.
*
* @throws IOException If an I/O error occurs while closing the reader.
*/
public void close() throws IOException {
if(reader!=null){
reader.close();
}
}
}