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/**
 * Copyright (c) 2008, SnakeYAML
 *
 * Licensed 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.yaml.snakeyaml.scanner;

import org.yaml.snakeyaml.tokens.Token;

/**
 * This interface represents an input stream of {@link Token}s.
 * 
 * The parser and the scanner form together the 'Parse' step in the loading
 * process (see chapter 3.1 of the YAML
 * Specification).
 * 
 *
 * @see org.yaml.snakeyaml.tokens.Token
 */
public interface Scanner {

    /**
     * Check if the next token is one of the given types.
     *
     * @param choices
     *            token IDs.
     * @return true if the next token can be assigned to a variable
     *         of at least one of the given types. Returns false if
     *         no more tokens are available.
     * @throws ScannerException
     *             Thrown in case of malformed input.
     */
    boolean checkToken(Token.ID... choices);

    /**
     * Return the next token, but do not delete it from the stream.
     * The method must be called only after {@link #checkToken}.
     *
     * @return The token that will be returned on the next call to {@link #getToken}
     * @throws ScannerException          Thrown in case of malformed input.
     * @throws IndexOutOfBoundsException if no more token left
     */
    Token peekToken();

    /**
     * Returns the next token.
     * 
     * The token will be removed from the stream.
     * (Every invocation of this method must happen after calling {@link #checkToken}.
     * 
     *
     * @return the coming token
     * @throws ScannerException          Thrown in case of malformed input.
     * @throws IndexOutOfBoundsException if no more token left
     */
    Token getToken();
}