KDE 4.1 API Reference strigi/src/streams
JStreams
The JStreams classes provide a way of accessing streamed resources in manner similar to the Java interface java.io.InputStream.If you are writing an analyzer, you probably want to know about the Strigi::InputStream, which is just an (abstract) instance of Strigi::StreamBase, with char as the template parameter. This latter class is the one all Stream classes are derived from and implement the methods of.
In JStreams terminology (derived from the Java Streaming API terminology), an InputStream is a stream of raw bytes, and a Reader is a (Unicode) text stream.
Using JStreams
If you just want to use JStreams to read from files, there's very little you need to know. The documentation for Strigi::StreamBase should give you information on the basic stream-reading functionality.Strigi::InputStream is the interface for reading a raw stream of bytes. If you need the decoded contents of a text file, you should use Strigi::InputStreamReader to convert a Strigi::InputStream to a Strigi::Reader, which is an interface for reading a stream of Unicode characters.
JStreams also provides several implementations of Strigi::InputStream that facilitate opening files. For example, Strigi::FileInputStream will open a Strigi::InputStream to read the contents of a file.
Strigi::StringStream allows you to access in-memory data as a stream. Strigi::StringInputStream and Strigi::StringReader are types of Strigi::StringStream for byte (char) arrays and Unicode (wchar_t) strings.
Substreams
One of the most useful features of JStreams is the ability to split a stream into substreams. For example, you might have a stream for a tar archive. A Strigi::SubStreamProvider for this could give you a stream for each file in the archive.Writing New Stream Providers
If you want to write a new stream that allows you to, for example, read a file from the internet over HTTP, you need to derive it from Strigi::StreamBase. Almost certainly you will want to derive from Strigi::InputStream, for a simple raw stream of bytes, or from Strigi::BufferedInputStream, for buffered stream.If your stream returns Unicode characters, the classes you want are Strigi::Reader and Strigi::BufferedReader. Don't forget that you can use Strigi::InputStreamReader to decode a text Strigi::InputStream.
Stream Providers for Analyzers
The main reason you might want to write a stream provider is for use in a Strigi::StreamThroughAnalyzer. This could take a Strigi::InputStream as an argument to the constructor, and operate on the data as it is read.To do this, you should inherit from either Strigi::InputStream or Strigi::BufferedInputStream. In the former case, you need to implement Strigi::InputStream::read(), Strigi::InputStream::reset() and Strigi::InputStream::skip(). reset and skip should just call the same methods in the underlying source stream, whereas read should operate on the data read from the source stream as it is requested.
If you inherit from Strigi::BufferedInputStream, you need to implement Strigi::BufferedInputStream::fillBuffer(), and this should again read from the source stream and operate on the data as it is read.
