JSON-java/stream/JSONLimitStreamReader.java at writeable · run2000/JSON-java

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package org.json.stream;
Copyright (c) 2002 JSON.org
Permission is hereby granted, free of charge, to any person obtaining a copy
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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
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import org.json.JSONException;
import org.json.JSONParseException;
import org.json.stream.JSONLexer.Token;
import org.json.util.BufferedAppendable;
import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.nio.charset.Charset;
 * Reads a JSON document as a stream of JSON events, using secure principles
 * derived from XML parsers. Uses an iterator model to produce each event.
 * Similar to a StAX event model in XML processing.
 * The {@code JSONLimitStreamReader} class is similar to the {@code JSONStreamReader}
 * class, but intended to be more robust against untrusted JSON sources.
 * For a more robust solution to building object structures, see
 * {@link JSONLimitBuilder}.
 * A simple example of how to use this class:</p>
 * JSONLimitStreamReader reader = new JSONLimitStreamReader(JSON_TEXT);
 * reader.withLimits(BuilderLimits.secureDefaults());
 * while(reader.hasNext()) {
 *     ParseState state = reader.nextState();
 *     switch(state) {
 *         case KEY:
 *             System.out.println("KEY = " + reader.nextKey() );
 *             break;
 *         case NULL_VALUE:
 *         case BOOLEAN_VALUE:
 *         case NUMBER_VALUE:
 *         case STRING_VALUE:
 *             System.out.println(state + " = " + reader.nextValue());
 *             break;
 *         default:
 *             System.out.println(state);
 * For a streaming equivalent for writing JSON data, see the {@link org.json.JSONWriter}
 * and {@link org.json.JSONStringer} classes.</p>
 * @author JSON.org
 * @version 2016-06-26
public final class JSONLimitStreamReader extends JSONStreamReader {
    private int keyLength = Integer.MAX_VALUE;
    private int stringLength = Integer.MAX_VALUE;
    private int mantissaDigits = Short.MAX_VALUE;
    private int exponentDigits = Byte.MAX_VALUE;
     * Construct a {@code JSONStreamReader} from a {@code Reader}.
     * @param reader     A reader.
    public JSONLimitStreamReader(Reader reader) {
        super(reader);
     * Construct a {@code JSONStreamReader} from an {@code InputStream} and
     * a supplied {@code Charset}.
     * @param inputStream   the input stream containing the JSON data
     * @param charset       the character set with which to interpret the
     *                      input stream
    public JSONLimitStreamReader(InputStream inputStream, Charset charset) {
        super(inputStream, charset);
     * Construct a {@code JSONStreamReader} from a {@code String}.
     * @param s     A source string.
    public JSONLimitStreamReader(String s) {
        super(s);
     * Set keyLength, stringLength, mantissaDigits, and exponentDigits
     * using values from the supplied {@link BuilderLimits} object.
     * See {@link BuilderLimits#secureDefaults()} for some practical limits.</p>
     * @param limits the limits to be set
     * @return this object
    public JSONLimitStreamReader withLimits(BuilderLimits limits) {
        this.keyLength = limits.getKeyLength();
        this.stringLength = limits.getStringLength();
        this.mantissaDigits = limits.getMantissaDigits();
        this.exponentDigits = limits.getExponentDigits();
        return this;
     * The maximum length of any key.
     * @param keyLength the maximum length of any key
    public void setKeyLength(int keyLength) {
        this.keyLength = (keyLength <= 0) ? Integer.MAX_VALUE : keyLength;
     * The maximum length of any string value.
     * @param stringLength the maximum length of any string value
    public void setStringLength(int stringLength) {
        this.stringLength = (stringLength <= 0) ? Integer.MAX_VALUE : stringLength;
     * The maximum number of mantissa digits in a number.
     * @param mantissaDigits the maximum number of mantissa digits of any
     *                       number value
    public void setMantissaDigits(int mantissaDigits) {
        this.mantissaDigits = (mantissaDigits <= 0) ? Short.MAX_VALUE : mantissaDigits;
     * The maximum number of exponent digits in a number. May be 0 to indicate
     * integer-only values.
     * @param exponentDigits the maximum number of exponent digits of any
     *                       number value
    public void setExponentDigits(int exponentDigits) {
        this.exponentDigits = (exponentDigits < 0) ? Byte.MAX_VALUE : exponentDigits;
     * If the {@code ParseState} was {@link JSONStreamReader.ParseState#KEY},
     * return the text of the key name.
     * This method advances the parser onto the next state.</p>
     * @return the parsed text of the key
     * @throws JSONException there was a problem with the source stream
    @Override
    public String nextKey() throws JSONException {
        if(state != ParseState.KEY) {
            throw new JSONParseException("Invalid state", lexer.parsePosition());
        StringBuilder builder = lexer.nextString(new StringBuilder(), keyLength);
        state = ParseState.KEY_SEPARATOR;
        if(lexer.nextTokenType() != Token.KEY_SEPARATOR) {
            throw new JSONParseException("Expected key separator", lexer.parsePosition());
        return builder.toString();
     * If the {@code ParseState} was {@link JSONStreamReader.ParseState#NULL_VALUE},
     * {@link JSONStreamReader.ParseState#BOOLEAN_VALUE},
     * {@link JSONStreamReader.ParseState#NUMBER_VALUE}, or
     * {@link JSONStreamReader.ParseState#STRING_VALUE}, return the value as
     * an {@code Object}. The values that can be returned here are:
     * <ul>
     *     <li>{@code JSONObject.NULL}</li>
     *     <li>{@code Boolean.TRUE} or {@code Boolean.FALSE}</li>
     *     <li>A {@code Double}, {@code Long}, {@code Integer},
     *     {@code BigInteger}, or {@code BigDecimal}</li>
     *     <li>A {@code String}</li>
     * </ul>
     * This method advances the parser onto the next state.</p>
     * @return an Object of the type described above
    @Override
    public Object nextValue() throws JSONException {
        if (objectStack.isEmpty() || !state.isValue()) {
            throw new JSONParseException("Invalid state", lexer.parsePosition());
        Token token = objectStack.pop();
        switch(token) {
            case NULL_VALUE:
                state = ParseState.VALUE_SEPARATOR;
                return decodeNull();
            case TRUE_VALUE:
                state = ParseState.VALUE_SEPARATOR;
                return Boolean.TRUE;
            case FALSE_VALUE:
                state = ParseState.VALUE_SEPARATOR;
                return Boolean.FALSE;
            case STRING_VALUE:
                state = ParseState.VALUE_SEPARATOR;
                return lexer.nextString(new StringBuilder(), stringLength).toString();
            case NUMBER_VALUE: {
                state = ParseState.VALUE_SEPARATOR;
                StringBuilder sb = new StringBuilder();
                boolean isDbl = lexer.nextNumber(sb, mantissaDigits, exponentDigits);
                return decodeNumber(sb.toString(), isDbl);
            default:
                throw new JSONParseException("Invalid state", lexer.parsePosition());
     * If the {@code ParseState} was {@link JSONStreamReader.ParseState#STRING_VALUE},
     * return the value as a {@code String}.
     * This method advances the parser onto the next state.</p>
     * @return a String value
    @Override
    public String nextStringValue() throws JSONException {
        if ((state != ParseState.STRING_VALUE) || (objectStack.isEmpty())) {
            throw new JSONParseException("Invalid state", lexer.parsePosition());
        Token token = objectStack.pop();
        if (token == Token.STRING_VALUE) {
            state = ParseState.VALUE_SEPARATOR;
            return lexer.nextString(new StringBuilder(), stringLength).toString();
        } else {
            throw new JSONParseException("Invalid state", lexer.parsePosition());
     * If the {@code ParseState} was {@link JSONStreamReader.ParseState#STRING_VALUE},
     * append the decoded value to the given {@code Appendable}.
     * This method is suitable for cases where very long {@code String} data is
     * expected, for instance for base-64 encoded data.</p>
     * This method advances the parser onto the next state.</p>
     * @param <T> the type of Appendable, returned to the caller
     * @param limit the limit of how many decoded characters to append to
     *        the Appendable
     * @param writer the writer to which the String value will be written
     * @return the given Appendable object
    public <T extends Appendable> T appendNextStringValue(T writer, long limit) throws JSONException {
        if ((state != ParseState.STRING_VALUE) || (objectStack.isEmpty())) {
            throw new JSONParseException("Invalid state", lexer.parsePosition());
        if(writer == null) {
            throw new JSONException("writer is null");
        Token token = objectStack.pop();
        if (token == Token.STRING_VALUE) {
            try {
                state = ParseState.VALUE_SEPARATOR;
                BufferedAppendable buff = bufferedAppender.with(writer);
                    lexer.nextString(buff, limit);
                } finally {
                    buff.close();
                return writer;
            } catch (IOException e) {
                throw new JSONParseException("Error parsing string value", e,
                        lexer.parsePosition());
        } else {
            throw new JSONParseException("Invalid state", lexer.parsePosition());
     * If the {@code ParseState} was {@link JSONStreamReader.ParseState#NUMBER_VALUE},
     * return the value as a {@code Number}.
     * The number type returned is one of:</p>
     * <ul>
     *     <li>A {@code Double}</li>
     *     <li>A {@code Long}</li>
     *     <li>An {@code Integer}</li>
     *     <li>A {@code BigDecimal}</li>
     *     <li>A {@code BigInteger}</li>
     * </ul>
     * This method advances the parser onto the next state.</p>
     * @return a value that is a subclass of the {@code Number} class
    @Override
    public Number nextNumberValue() throws JSONException {
        if ((state != ParseState.NUMBER_VALUE) || (objectStack.isEmpty())) {
            throw new JSONParseException("Invalid state", lexer.parsePosition());
        Token token = objectStack.pop();
        if (token == Token.NUMBER_VALUE) {
            state = ParseState.VALUE_SEPARATOR;
            StringBuilder sb = new StringBuilder();
            boolean isDbl = lexer.nextNumber(sb, mantissaDigits, exponentDigits);
            return decodeNumber(sb.toString(), isDbl);
        } else {
            throw new JSONParseException("Invalid state", lexer.parsePosition());
     * If the {@code ParseState} was {@link JSONStreamReader.ParseState#NUMBER_VALUE},
     * append the number sequence to the given {@code Appendable}.
     * This method is suitable for cases where the caller wishes to perform
     * their own conversion of number values into a corresponding Object type.
     * </p>
     * This method advances the parser onto the next state.</p>
     * @param <T> the type of Appendable, returned to the caller
     * @param writer the writer to which the number sequence will be written
     * @return the given Appendable object
    @Override
    public <T extends Appendable> T appendNextNumberValue(T writer) throws JSONException {
        if ((state != ParseState.NUMBER_VALUE) || (objectStack.isEmpty())) {
            throw new JSONParseException("Invalid state", lexer.parsePosition());
        Token token = objectStack.pop();
        if (token == Token.NUMBER_VALUE) {
            state = ParseState.VALUE_SEPARATOR;
            lexer.nextNumber(writer, mantissaDigits, exponentDigits);
            return writer;
        } else {
            throw new JSONParseException("Invalid state", lexer.parsePosition());
     * If the {@code ParseState} was {@link JSONStreamReader.ParseState#NUMBER_VALUE},
     * return the value as a {@code BigDecimal}.
     * This method advances the parser onto the next state.</p>
     * @return a number value as a {@code BigDecimal} class
    @Override
    public BigDecimal nextBigDecimalValue() throws JSONException {
        if ((state != ParseState.NUMBER_VALUE) || (objectStack.isEmpty())) {
            throw new JSONParseException("Invalid state", lexer.parsePosition());
        Token token = objectStack.pop();
        if (token == Token.NUMBER_VALUE) {
            state = ParseState.VALUE_SEPARATOR;
            StringBuilder sb = new StringBuilder();
            lexer.nextNumber(sb, mantissaDigits, exponentDigits);
            return decodeBigDecimal(sb.toString());
        } else {
            throw new JSONParseException("Invalid state", lexer.parsePosition());
     * If the {@code ParseState} was {@link JSONStreamReader.ParseState#NUMBER_VALUE},
     * return the value as a {@code BigInteger}.
     * If the JSON value is not parseable as a big integer, as defined by the
     * JSON grammar, a {@code JSONException} will be thrown.</p>
     * This method advances the parser onto the next state.</p>
     * @return a number value as a {@code BigInteger} class
    @Override
    public BigInteger nextBigIntegerValue() throws JSONException {
        if ((state != ParseState.NUMBER_VALUE) || (objectStack.isEmpty())) {
            throw new JSONParseException("Invalid state", lexer.parsePosition());
        Token token = objectStack.pop();
        if (token == Token.NUMBER_VALUE) {
            state = ParseState.VALUE_SEPARATOR;
            StringBuilder sb = new StringBuilder();
            boolean isDbl = lexer.nextNumber(sb, mantissaDigits, exponentDigits);
            return decodeBigInteger(sb.toString(), isDbl);
        } else {
            throw new JSONParseException("Invalid state", lexer.parsePosition());
     * If the {@code ParseState} was {@link JSONStreamReader.ParseState#NUMBER_VALUE},
     * return the value as a double.
     * This method advances the parser onto the next state.</p>
     * @return a double value
    @Override
    public double nextDoubleValue() throws JSONException {
        if ((state != ParseState.NUMBER_VALUE) || (objectStack.isEmpty())) {
            throw new JSONParseException("Invalid state", lexer.parsePosition());
        Token token = objectStack.pop();
        if (token == Token.NUMBER_VALUE) {
            state = ParseState.VALUE_SEPARATOR;
            StringBuilder sb = new StringBuilder();
            boolean isDbl = lexer.nextNumber(sb, mantissaDigits, exponentDigits);
            return decodeDouble(sb.toString(), isDbl);
        } else {
            throw new JSONParseException("Invalid state", lexer.parsePosition());
     * If the {@code ParseState} was {@link JSONStreamReader.ParseState#NUMBER_VALUE},
     * return the value as an int.
     * If the JSON value is not parseable as an int, as defined by the JSON
     * grammar, a {@code JSONException} will be thrown.</p>
     * This method advances the parser onto the next state.</p>
     * @return an int value
    @Override
    public int nextIntValue() throws JSONException {
        if ((state != ParseState.NUMBER_VALUE) || (objectStack.isEmpty())) {
            throw new JSONParseException("Invalid state", lexer.parsePosition());
        Token token = objectStack.pop();
        if (token == Token.NUMBER_VALUE) {
            state = ParseState.VALUE_SEPARATOR;
            StringBuilder sb = new StringBuilder();
            boolean isDbl = lexer.nextNumber(sb, mantissaDigits, exponentDigits);
            return decodeInt(sb.toString(), isDbl);
        } else {
            throw new JSONParseException("Invalid state", lexer.parsePosition());
     * If the {@code ParseState} was {@link JSONStreamReader.ParseState#NUMBER_VALUE},
     * return the value as a long.
     * If the JSON value is not parseable as a long, as defined by the JSON
     * grammar, a {@code JSONException} will be thrown.</p>
     * This method advances the parser onto the next state.</p>
     * @return a long value
    @Override
    public long nextLongValue() throws JSONException {
        if ((state != ParseState.NUMBER_VALUE) || (objectStack.isEmpty())) {
            throw new JSONParseException("Invalid state", lexer.parsePosition());
        Token token = objectStack.pop();
        if (token == Token.NUMBER_VALUE) {
            state = ParseState.VALUE_SEPARATOR;
            StringBuilder sb = new StringBuilder();
            boolean isDbl = lexer.nextNumber(sb, mantissaDigits, exponentDigits);
            return decodeLong(sb.toString(), isDbl);
        } else {
            throw new JSONParseException("Invalid state", lexer.parsePosition());
     * Returns a string representation of the stream reader, including its
     * current position in the source stream.
    @Override
    public String toString() {
        return "JSONSecStreamReader " + lexer.parsePosition().getPositionDetails();
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