TokenConsumer.java

/*
 * TokenConsumer.java February 2007
 *
 * Copyright (C) 2007, Niall Gallagher <niallg@users.sf.net>
 *
 * 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.simpleframework.http.message;

import java.io.IOException;

import org.simpleframework.util.buffer.Allocator;
import org.simpleframework.util.buffer.Buffer;

/**
 * The <code>TokenConsumer</code> object is used to consume a token from the
 * cursor. Once the token has been consumed the consumer is finished and the
 * contents of the consumed token is appended to an allocated buffer so that it
 * can be extracted.
 * 
 * @author Niall Gallagher
 */
class TokenConsumer extends ArrayConsumer {

    /**
     * This is used to allocate a buffer to append the contents.
     */
    private Allocator allocator;

    /**
     * This is used to append the contents of consumed token.
     */
    private Buffer buffer;

    /**
     * This is the token that is to be consumed from the cursor.
     */
    private byte[] token;

    /**
     * This tracks the number of bytes that are read from the token.
     */
    private int seek;

    /**
     * This is the length of the token that is to be consumed.
     */
    private int length;

    /**
     * The <code>TokenConsumer</code> object is used to read a token from the
     * cursor. This tracks the bytes read from the cursor, when it has fully
     * read the token bytes correctly it will finish and append the consumed
     * bytes to a buffer.
     * 
     * @param allocator
     *            the allocator used to create a buffer
     * @param token
     *            this is the token that is to be consumed
     */
    public TokenConsumer(Allocator allocator, byte[] token) {
        this.allocator = allocator;
        this.length = token.length;
        this.token = token;
        this.chunk = this.length;
    }

    /**
     * This is used to append the consumed bytes to a created buffer so that it
     * can be used when he is finished. This allows the contents to be read from
     * an input stream or as a string.
     */
    @Override
    protected void process() throws IOException {
        if (this.buffer == null) {
            this.buffer = this.allocator.allocate(this.length);
        }
        this.buffer.append(this.token);
    }

    /**
     * This is used to scan the token from the array. Once the bytes have been
     * read from the consumed bytes this will return the number of bytes that
     * need to be reset within the buffer.
     * 
     * @return this returns the number of bytes to be reset
     */
    @Override
    protected int scan() throws IOException {
        int size = this.token.length;
        int pos = 0;

        if (this.count >= size) {
            while (this.seek < this.count) {
                if (this.array[this.seek++] != this.token[pos++])
                    throw new IOException("Invalid token");
            }
            this.done = true;
            return this.count - this.seek;
        }
        return 0;
    }
}