# vi: ts=4 expandtab
#
#    Copyright (C) 2012 Yahoo! Inc.
#
#    Author: Joshua Harlow <harlowja@yahoo-inc.com>
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU General Public License version 3, as
#    published by the Free Software Foundation.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program.  If not, see <http://www.gnu.org/licenses/>.


class Merger(object):
    def __init__(self, merger, opts):
        self._merger = merger
        self._extend = 'extend' in opts

    def _on_tuple(self, value, merge_with):
        return self._on_list(list(value), merge_with)

    # On encountering a list or tuple type this action will be applied
    # a new list will be returned, if the value to merge with is itself
    # a list and we have been told to 'extend', then the value here will
    # be extended with the other list.
    def _on_list(self, value, merge_with):
        if not self._extend or not isinstance(merge_with, (tuple, list)):
            return merge_with
        # Leave the original list alone...
        value = list(value)
        return value.extend(merge_with)