dom/src/main/java/org/apache/james/mime4j/field/LenientFieldParser.java

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package org.apache.james.mime4j.field;

import org.apache.james.mime4j.MimeException;
import org.apache.james.mime4j.codec.DecodeMonitor;
import org.apache.james.mime4j.dom.FieldParser;
import org.apache.james.mime4j.dom.field.AddressListField;
import org.apache.james.mime4j.dom.field.ContentDescriptionField;
import org.apache.james.mime4j.dom.field.ContentDispositionField;
import org.apache.james.mime4j.dom.field.ContentIdField;
import org.apache.james.mime4j.dom.field.ContentLanguageField;
import org.apache.james.mime4j.dom.field.ContentLengthField;
import org.apache.james.mime4j.dom.field.ContentLocationField;
import org.apache.james.mime4j.dom.field.ContentMD5Field;
import org.apache.james.mime4j.dom.field.ContentTransferEncodingField;
import org.apache.james.mime4j.dom.field.ContentTypeField;
import org.apache.james.mime4j.dom.field.DateTimeField;
import org.apache.james.mime4j.dom.field.FieldName;
import org.apache.james.mime4j.dom.field.MailboxField;
import org.apache.james.mime4j.dom.field.MailboxListField;
import org.apache.james.mime4j.dom.field.MimeVersionField;
import org.apache.james.mime4j.dom.field.ParsedField;
import org.apache.james.mime4j.dom.field.UnstructuredField;
import org.apache.james.mime4j.stream.Field;
import org.apache.james.mime4j.stream.RawField;
import org.apache.james.mime4j.stream.RawFieldParser;
import org.apache.james.mime4j.util.ByteSequence;
import org.apache.james.mime4j.util.ContentUtil;

/**
 * Lenient implementation of the {@link FieldParser} interface with a high degree of tolerance
 * to non-severe MIME field format violations. 
 */
public class LenientFieldParser extends DelegatingFieldParser {

    private static final FieldParser<ParsedField> PARSER = new LenientFieldParser();

    /**
     * Gets the default instance of this class.
     *
     * @return the default instance
     */
    public static FieldParser<ParsedField> getParser() {
        return PARSER;
    }

    /**
     * Parses the given byte sequence and returns an instance of the {@link ParsedField} class. 
     * The type of the class returned depends on the field name; see {@link #parse(String)} for 
     * a table of field names and their corresponding classes.
     *
     * @param raw the bytes to parse.
     * @param monitor decoding monitor used while parsing/decoding.
     * @return a parsed field.
     * @throws MimeException if the raw string cannot be split into field name and body.
     */
    public static ParsedField parse(
            final ByteSequence raw,
            final DecodeMonitor monitor) throws MimeException {
        Field rawField = RawFieldParser.DEFAULT.parseField(raw);
        return PARSER.parse(rawField, monitor);
    }

    /**
     * Parses the given string and returns an instance of the <code>Field</code> class.
     * The type of the class returned depends on the field name.
     *
     * @param rawStr the string to parse.
     * @param monitor a DecodeMonitor object used while parsing/decoding.
     * @return a <code>ParsedField</code> instance.
     * @throws MimeException if the raw string cannot be split into field name and body.
     */
    public static ParsedField parse(
            final String rawStr,
            final DecodeMonitor monitor) throws MimeException {
        ByteSequence raw = ContentUtil.encode(rawStr);
        RawField rawField = RawFieldParser.DEFAULT.parseField(raw);
        // Do not retain the original raw representation as the field
        // may require folding
        return PARSER.parse(rawField, monitor);
    }

    /**
     * <p>
     * Parses the given string and returns an instance of the {@link ParsedField} class. 
     * The type of the class returned depends on the field name:
     * </p>
     * <table summary="Field names and corresponding classes">
     *   <tr><th>Class returned</th><th>Field names</th></tr>
     *   <tr><td>{@link ContentTypeField}</td><td>Content-Type</td></tr>
     *   <tr><td>{@link ContentLengthField}</td><td>Content-Length</td></tr>
     *   <tr><td>{@link ContentTransferEncodingField}</td><td>Content-Transfer-Encoding</td></tr>
     *   <tr><td>{@link ContentDispositionField}</td><td>Content-Disposition</td></tr>
     *   <tr><td>{@link ContentDescriptionField}</td><td>Content-Description</td></tr>
     *   <tr><td>{@link ContentIdField}</td><td>Content-ID</td></tr>
     *   <tr><td>{@link ContentMD5Field}</td><td>Content-MD5</td></tr>
     *   <tr><td>{@link ContentLanguageField}</td><td>Content-Language</td></tr>
     *   <tr><td>{@link ContentLocationField}</td><td>Content-Location</td></tr>
     *   <tr><td>{@link MimeVersionField}</td><td>MIME-Version</td></tr>
     *   <tr><td>{@link DateTimeField}</td><td>Date, Resent-Date</td></tr>
     *   <tr><td>{@link MailboxField}</td><td>Sender, Resent-Sender</td></tr>
     *   <tr><td>{@link MailboxListField}</td><td>From, Resent-From</td></tr>
     *   <tr><td>{@link AddressListField}</td><td>To, Cc, Bcc, Reply-To, Resent-To, Resent-Cc, Resent-Bcc</td></tr>
     *   <tr><td>{@link UnstructuredField}</td><td>Subject and others</td></tr>
     * </table>
     *
     * @param rawStr the string to parse.
     * @return a parsed field.
     * @throws MimeException if the raw string cannot be split into field name and body.
     */
    public static ParsedField parse(final String rawStr) throws MimeException {
        return parse(rawStr, DecodeMonitor.SILENT);
    }

    public LenientFieldParser() {
        super(UnstructuredFieldImpl.PARSER);
        setFieldParser(FieldName.CONTENT_TYPE,
                ContentTypeFieldLenientImpl.PARSER);        // lenient
        setFieldParser(FieldName.CONTENT_LENGTH,
                ContentLengthFieldImpl.PARSER);             // default
        setFieldParser(FieldName.CONTENT_TRANSFER_ENCODING,
                ContentTransferEncodingFieldImpl.PARSER);   // default
        setFieldParser(FieldName.CONTENT_DISPOSITION,
                ContentDispositionFieldLenientImpl.PARSER); // lenient
        setFieldParser(FieldName.CONTENT_ID,
                ContentIdFieldImpl.PARSER);                 // default
        setFieldParser(FieldName.CONTENT_MD5,
                ContentMD5FieldImpl.PARSER);                // default
        setFieldParser(FieldName.CONTENT_DESCRIPTION,
                ContentDescriptionFieldImpl.PARSER);        // default
        setFieldParser(FieldName.CONTENT_LANGUAGE,
                ContentLanguageFieldLenientImpl.PARSER);    // lenient
        setFieldParser(FieldName.CONTENT_LOCATION,
                ContentLocationFieldLenientImpl.PARSER);    // lenient
        setFieldParser(FieldName.MIME_VERSION,
                MimeVersionFieldImpl.PARSER);               // lenient

        FieldParser<DateTimeField> dateTimeParser = DateTimeFieldLenientImpl.PARSER;
        setFieldParser(FieldName.DATE, dateTimeParser);
        setFieldParser(FieldName.RESENT_DATE, dateTimeParser);

        FieldParser<MailboxListField> mailboxListParser = MailboxListFieldLenientImpl.PARSER;
        setFieldParser(FieldName.FROM, mailboxListParser);
        setFieldParser(FieldName.RESENT_FROM, mailboxListParser);

        FieldParser<MailboxField> mailboxParser = MailboxFieldLenientImpl.PARSER;
        setFieldParser(FieldName.SENDER, mailboxParser);
        setFieldParser(FieldName.RESENT_SENDER, mailboxParser);

        FieldParser<AddressListField> addressListParser = AddressListFieldLenientImpl.PARSER;
        setFieldParser(FieldName.TO, addressListParser);
        setFieldParser(FieldName.RESENT_TO, addressListParser);
        setFieldParser(FieldName.CC, addressListParser);
        setFieldParser(FieldName.RESENT_CC, addressListParser);
        setFieldParser(FieldName.BCC, addressListParser);
        setFieldParser(FieldName.RESENT_BCC, addressListParser);
        setFieldParser(FieldName.REPLY_TO, addressListParser);
    }

}