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"""

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    Parse log data into log_events

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"""

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import datetime

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import log_line

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from log_line import LogTypes

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class LogParser (object) :

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    """

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        Abstract interface

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    """

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    def __init__ (self, tz, timestamp_fmt="%H:%M:%S") :

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        """

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            Setup the parser to use the given format for line timestamps, which are of the given timezone

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        """

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        self.tz = tz

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        self.timestamp_fmt = timestamp_fmt

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    def parse_lines (self, lines, date=None, starting_offset=None) :

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        """

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            Parse the given (iterable) lines of unicode text into a LogEvent, no trailing newline.

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            Offset is the starting offset, and may be None to not use it.

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            Giving date lets the parser build full timestamps, otherwise, unless line timestamps have full date

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            information, event timestamps will have a date component of 1900/1/1.

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        """

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        abstract

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class IrssiParser (LogParser) :

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    """

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        A parser for irssi logfiles

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    """

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    def parse_lines (self, lines, date=None, starting_offset=None) :

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        """

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            Parse the given lines, yielding LogEvents. 

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        """

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        for offset, line in enumerate(lines) :

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            # offset?

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            if starting_offset :

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                offset = starting_offset + offset

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            else :

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                offset = None

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            # try and parse

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            try :

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                line = self.parse_line(line, date, offset)

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            except Exception, e :

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                raise Exception("Parsing line failed: %r@%d: %s" % (line, offset, e))

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            else :

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                # yield unless None

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                if line :

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                    yield line

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    def parse_line (self, line, date, offset=None) :

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        """

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            Parse a single line, and return the resulting LogLine, or None, to ignore the line

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        """

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        # empty line

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        if not line :

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            return

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        # status lines

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        elif line.startswith('---') :

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            # XXX: handle these

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            return

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        # normal lines

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        else :

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            # XXX: only parse timestamps for now

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            timestamp, data = line.split(' ', 1)

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            # parse timestamp into naive datetime

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            dt = datetime.datetime.strptime(timestamp, self.timestamp_fmt)

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            # override date?

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            if date :

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                dt = dt.replace(year=date.year, month=date.month, day=date.day)

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            # now localize with timezone

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            dtz = self.tz.localize(dt)

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            # build raw event

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            return log_line.LogLine(offset, LogTypes.RAW, dtz, None, data)

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