JsonTokenizer.java

/*
 * MIT License
 *
 * Copyright (c) 2017 Konrad Kleczkowski
 *
 * 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 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 com.github.repaj.libjson.io;

/**
 * An interface describing JSON tokenizer.
 * <p>
 * Tokenizer is a facility to break some input into parts called <em>tokens</em>.
 * Tokenizer should check if returned tokens are consistent, but does not need to
 * check consistency of output in context of JSON grammar.
 * <p>
 * Tokenizers are low-level classes that should be used as back-end of reading
 * stuff like parsers, stream readers, etc.
 * <p>
 * If an I/O error will occur, all methods throws unchecked I/O exceptions
 * during operation, in this case {@link java.io.IOException} is wrapped in
 * {@link JsonIOException}.
 *
 * @author Konrad Kleczkowski
 */
public interface JsonTokenizer {
    /**
     * Returns the line number that is proceed by this tokenizer.
     * If this tokenizer does not support line numbering,
     * then <code>-1</code> is returned.
     *
     * @return the line number that is proceed by this tokenizer if this feature
     * is supported, otherwise <code>-1</code>.
     */
    default int getLine() {
        return -1;
    }

    /**
     * Returns <code>true</code> if pending token is of specified type.
     *
     * @param tokenType expected type of pending token
     * @return <code>true</code> if pending token is of specified type, otherwise <code>false</code>
     * @throws JsonIOException      if I/O error occurs
     * @throws NullPointerException if <code>tokenType</code> is null
     */
    boolean hasNext(JsonTokenType tokenType);

    /**
     * If token type is the same as pending token, returns that token
     * and removes it from input.
     *
     * @param tokenType expected type of pending token
     * @return pending token it token type is the same as specified.
     * @throws JsonParseException   if expected and actual token types are mismatched
     * @throws JsonIOException      if I/O error occurs
     * @throws NullPointerException if <code>tokenType</code> is null
     */
    String next(JsonTokenType tokenType) throws JsonParseException;
}