Package it.unimi.di.big.mg4j.document

Class InputStreamDocumentSequence

    • Constructor Detail

      • InputStreamDocumentSequence

        public InputStreamDocumentSequence​(InputStream inputStream,
                                   int separator,
                                   DocumentFactory factory,
                                   int maxDocs)
        Creates a new document sequence based on a given input stream and separator; the sequence will not return more than the given number of documents.
        Parameters:
        inputStream - the input stream containing all documents.
        separator - the separator.
        factory - the factory that will be used to create documents.
        maxDocs - the maximum number of documents returned.

      • InputStreamDocumentSequence

        public InputStreamDocumentSequence​(InputStream inputStream,
                                   int separator,
                                   DocumentFactory factory)
        Creates a new document sequence based on a given input stream and separator.
        Parameters:
        inputStream - the input stream containing all documents.
        separator - the separator.
        factory - the factory that will be used to create documents.

    • Method Detail

      • iterator

        public DocumentIterator iterator()
        Description copied from interface: DocumentSequence
        Returns an iterator over the sequence of documents.

        Warning: this method can be safely called just one time. For instance, implementations based on standard input will usually throw an exception if this method is called twice.

        Implementations may decide to override this restriction (in particular, if they implement DocumentCollection). Usually, however, it is not possible to obtain two iterators at the same time on a collection.

        Specified by:
        iterator in interface DocumentSequence
        Returns:
        an iterator over the sequence of documents.
        See Also:
        DocumentCollection

      • factory

        public DocumentFactory factory()
        Description copied from interface: DocumentSequence
        Returns the factory used by this sequence.

        Every document sequence is based on a document factory that transforms raw bytes into a sequence of characters. The factory contains useful information such as the number of fields.

        Specified by:
        factory in interface DocumentSequence
        Returns:
        the factory used by this sequence.

      • mark

        public void mark​(int readlimit)
        Overrides:
        mark in class InputStream

      • available

        public int available()
              throws IOException
        Returns one if there is an available byte which is not a separator, zero otherwise.

        This behaviour tries to avoid calls to InputStream.available()s, which are unbelievably slow. Stream decoders presently require just to know whether it is possible to read a character in a nonblocking way or not.

        Overrides:
        available in class FastBufferedInputStream
        Returns:
        one if there is an available byte which is not a separator, zero otherwise.
        Throws:
        IOException

      • close

        public void close()
           throws IOException
        Description copied from interface: DocumentSequence
        Closes this document sequence, releasing all resources.

        You should always call this method after having finished with this document sequence. Implementations are invited to call this method in a finaliser as a safety net (even better, implement SafelyCloseable), but since there is no guarantee as to when finalisers are invoked, you should not depend on this behaviour.

        Specified by:
        close in interface AutoCloseable
        Specified by:
        close in interface Closeable
        Specified by:
        close in interface DocumentSequence
        Overrides:
        close in class FastBufferedInputStream
        Throws:
        IOException

      • filename

        public void filename​(CharSequence filename)
              throws IOException
        Description copied from interface: DocumentSequence
        Sets the filename of this document sequence.

        Several document sequences (or collections) are stored using Java's standard serialisation mechanism; nonetheless, they require access to files that are stored as serialised filenames inside the instance. If all pieces are in the current directory, this works as expected. However, if the sequence was specified using a complete pathname, during deserialisation it will be impossible to recover the associated files. In this case, the class expects that this method is invoked over the newly deserialised instance so that pathnames can be relativised to the given filename. Classes that need this mechanism should not fail upon deserialisation if they do not find some support file, but rather wait for the first access.

        In several cases, this method can be a no-op (e.g., for an InputStreamDocumentSequence or a FileSetDocumentCollection). Other implementations, such as SimpleCompressedDocumentCollection or ZipDocumentCollection, require a specific treatment. AbstractDocumentSequence implements this method as a no-op.

        Specified by:
        filename in interface DocumentSequence
        Parameters:
        filename - the filename of this document sequence.
        Throws:
        IOException