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An embeddable C Preprocessor for the JVM.
There is a newer version: 1.4.14
/*
 * Anarres C Preprocessor
 * Copyright (c) 2007-2015, Shevek
 *
 * 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.anarres.cpp;

import java.io.IOException;
import java.util.Iterator;
import java.util.NoSuchElementException;
import javax.annotation.Nonnull;
import static org.anarres.cpp.Token.EOF;

/**
 * An Iterator for {@link Source Sources},
 * returning {@link Token Tokens}.
 */
public class SourceIterator implements Iterator {

    private final Source source;
    private Token tok;

    public SourceIterator(@Nonnull Source s) {
        this.source = s;
        this.tok = null;
    }

    /**
     * Rethrows IOException inside IllegalStateException.
     */
    private void advance() {
        try {
            if (tok == null)
                tok = source.token();
        } catch (LexerException e) {
            throw new IllegalStateException(e);
        } catch (IOException e) {
            throw new IllegalStateException(e);
        }
    }

    /**
     * Returns true if the enclosed Source has more tokens.
     *
     * The EOF token is never returned by the iterator.
     * @throws IllegalStateException if the Source
     *		throws a LexerException or IOException
     */
    @Override
    public boolean hasNext() {
        advance();
        return tok.getType() != EOF;
    }

    /**
     * Returns the next token from the enclosed Source.
     *
     * The EOF token is never returned by the iterator.
     * @throws IllegalStateException if the Source
     *		throws a LexerException or IOException
     */
    @Override
    public Token next() {
        if (!hasNext())
            throw new NoSuchElementException();
        Token t = this.tok;
        this.tok = null;
        return t;
    }

    /**
     * Not supported.
     *
     * @throws UnsupportedOperationException unconditionally.
     */
    @Override
    public void remove() {
        throw new UnsupportedOperationException();
    }
}