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002 * Licensed to the Apache Software Foundation (ASF) under one *
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005 * regarding copyright ownership. The ASF licenses this file *
006 * to you under the Apache License, Version 2.0 (the *
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008 * with the License. You may obtain a copy of the License at *
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010 * http://www.apache.org/licenses/LICENSE-2.0 *
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019
020 package org.apache.james.mime4j.stream;
021
022 import org.apache.james.mime4j.MimeException;
023 import org.apache.james.mime4j.util.ByteArrayBuffer;
024
025 /**
026 * Field builders are intended to construct {@link RawField} instances from multiple lines
027 * contained in {@link ByteArrayBuffer}s.
028 * <p/>
029 * Field builders are stateful and modal as they have to store intermediate results between
030 * method invocations and also rely on a particular sequence of method invocations
031 * (the mode of operation).
032 * <p/>
033 * Consumers are expected to interact with field builder in the following way:
034 * <ul>
035 * <li>Invoke {@link #reset()} method in order to reset builder's internal state and make it
036 * ready to start the process of building a new {@link RawField}.</li>
037 * <li>Invoke {@link #append(ByteArrayBuffer)} method one or multiple times in order to build
038 * an internal representation of a MIME field from individual lines of text.</li>
039 * <li>Optionally {@link #getRaw()} method can be invoked in order to get combined content
040 * of all lines processed so far. Please note builder implementations can return
041 * <code>null</code> if they do not retain original raw content.</li>
042 * <li>Invoke {@link #build()} method in order to generate a {@link RawField} instance
043 * based on the internal state of the builder.</li>
044 * </ul>
045 */
046 public interface FieldBuilder {
047
048 /**
049 * Resets the internal state of the builder making it ready to process new input.
050 */
051 void reset();
052
053 /**
054 * Updates builder's internal state by adding a new line of text.
055 */
056 void append(ByteArrayBuffer line) throws MimeException;
057
058 /**
059 * Builds an instance of {@link RawField} based on the internal state.
060 */
061 RawField build() throws MimeException;
062
063 /**
064 * Returns combined content of all lines processed so far or <code>null</code>
065 * if the builder does not retain original raw content.
066 */
067 ByteArrayBuffer getRaw();
068
069 }