Interface TableBuilder

    • Method Summary

      All Methods Instance Methods Abstract Methods 
      Modifier and Type Method Description
      boolean canImport​(java.awt.datatransfer.DataFlavor flavor)
      Indicates whether this builder is able to turn a resource of media type indicated by flavor into a table.
      java.lang.String getFormatName()
      Returns the name of the format which can be read by this handler.
      StarTable makeStarTable​(uk.ac.starlink.util.DataSource datsrc, boolean wantRandom, StoragePolicy storagePolicy)
      Constructs a StarTable based on a given DataSource.
      void streamStarTable​(java.io.InputStream istrm, TableSink sink, java.lang.String pos)
      Reads a table from an input stream and writes it a row at a time to a sink.
    • Method Detail

      • makeStarTable

        StarTable makeStarTable​(uk.ac.starlink.util.DataSource datsrc,
                                boolean wantRandom,
                                StoragePolicy storagePolicy)
                         throws java.io.IOException
        Constructs a StarTable based on a given DataSource. If the source is not recognised or this builder does not know how to construct a table from it, then a TableFormatException should be thrown. If this builder thinks it should be able to handle the source but an error occurs during processing, an IOException can be thrown.

        The wantRandom parameter is used to indicate whether, ideally, a random-access table should be returned. There is no requirement for the builder to honour this request, but if it knows how to make both random and non-random tables, it can use this flag to decide which to return.

        Note: the presence of the wantRandom parameter is somewhat misleading. TableBuilder implementations usually should, and do, ignore it (it would be removed from the interface if it were not for backward compatibility issues). Regardless of the value of this parameter, implementations should return a random-access table only if it is easy for them to do so; in particular they should not use the supplied storagePolicy, or any other resource-expensive measure, to randomise a sequential table just because the wantRandom parameter is true.

        Parameters:
        datsrc - the DataSource containing the table resource
        wantRandom - whether, preferentially, a random access table should be returned
        storagePolicy - a StoragePolicy object which may be used to supply scratch storage if the builder needs it
        Returns:
        a StarTable made out of datsrc
        Throws:
        TableFormatException - if the table is not of a kind that can be handled by this handler
        java.io.IOException - if an unexpected I/O error occurs during processing
      • streamStarTable

        void streamStarTable​(java.io.InputStream istrm,
                             TableSink sink,
                             java.lang.String pos)
                      throws java.io.IOException
        Reads a table from an input stream and writes it a row at a time to a sink. Not all implementations will be able to do this; for instance, extracting the table from the data may be a two-pass process. Implementations which are unable to perform this function should throw a TableFormatException.

        The input stream should be prepared for use prior to calling this method, so implementations should not in general attempt to decompress or buffer istrm.

        Parameters:
        istrm - input stream containing table data
        sink - destination of the table
        pos - position identifier describing the location of the table within the stream; see DataSource.getPosition() (may be null)
        Throws:
        TableFormatException - if the table can't be streamed or the data is malformed
        java.io.IOException - if some other error occurs
      • canImport

        boolean canImport​(java.awt.datatransfer.DataFlavor flavor)
        Indicates whether this builder is able to turn a resource of media type indicated by flavor into a table. It should return true if it thinks that its streamStarTable(java.io.InputStream, uk.ac.starlink.table.TableSink, java.lang.String) method stands a reasonable chance of successfully constructing a StarTable from a DataSource whose input stream is described by the DataFlavor flavor. It will typically make this determination based on the flavor's MIME type.

        This method should only return true if the flavor looks like it is targeted at this builder; for instance a builder which uses a text-based format should return false for a flavor which indicates a MIME type of text/plain.

        This method is used in supporting drag and drop functionality (see StarTableFactory.canImport(java.awt.datatransfer.DataFlavor[])).

        Parameters:
        flavor - the DataFlavor whose suitability as stream input is to be assessed
        Returns:
        true iff this builder reckons it stands a good chance of turning a stream of type flavor into a StarTable
      • getFormatName

        java.lang.String getFormatName()
        Returns the name of the format which can be read by this handler. Matching against this string may be used by callers to identify or select this handler from a list.
        Returns:
        one-word description of this handler's format