Source code for irfpy.npicommon.backend

''' Backend of NPI data set.
'''
import logging

from irfpy.util.julday import JdSeries

class NpiFileCommon:
    ''' NPI data file for the base of both MEX and VEX.

    This is a backend of the NPI database.
    The class is an abstract class, therefore, it should be
    impolemented according to MEX and VEX.

    :param filename:  File name to open.
    :param compress:  Force decompression.  ``None`` or "plain" or "gzip" or "bzip2".
        If ``None``'s case, one assumed the compression from the suffix.
    :param baseuriname:  If specified, ``self.filename`` is replaced by
        the baseuriname instead of the real file name.  This may be
        used if the open file is a temporal file (decompressed or network file).
    '''

    def __init__(self, filename, compress=None, baseuriname=None, loglevel=None):
        if baseuriname is None:
            self.filename = filename
        else:
            self.filename = baseuriname

        if loglevel is None:
            loglevel = logging.WARN

        self.logger = logging.getLogger("%s:%s" % (self.__class__.__name__, self.filename))
#        self.logger.setLevel(loglevel)

        self.npidata = JdSeries()

        fp = self.openfile(filename, compress=compress)
        self.loadfile(fp)
        fp.close()

    def openfile(self, filename, compress=None):
        cmp = None
        # compress switch.

        if compress is not None:
            if compress in ("gz", "gzip"):
                cmp = "gzip"
            elif compress in ('bz2', 'bzip2', 'bz', 'bzip'):
                cmp = "bzip2"
            elif compress in ('plain'):
                cmp = "plain"

        if cmp is None:
            if filename.endswith('.gz'):
                cmp = "gzip"
            elif filename.endswith('.bz2'):
                cmp = "bzip2"
            else:
                cmp = "plain"
        
        if cmp == "gzip":
            import gzip
            self.logger.debug('Using gzip')
            f = gzip.open(filename)
        if cmp == "bzip2":
            import bz2
            self.logger.debug('Using bzip2')
            f = bz2.BZ2File(filename, 'r')
        else:
            self.logger.debug('Using plain')
            f = open(filename, 'r')

        return f
        
    def loadfile(self, fp):
        ''' ABSTRACT: Read the data.

        Abstract method.  Load the file
        File should be loaded from the file pointer fp, and
        saved it into the ``JdSeries`` instance named ``self.npidata``.
        '''
        raise NotImplementedError(
            "The method loadfile in class %s should be overrided in the child class."
                                        % self.__class__.__name__)

    def getDataset(self):
        ''' Return the reference to the dataset, i.e. ``self.npidata``.
        '''
        return self.npidata