# Copyright (c) 2011, Thomas Paviot (tpaviot@gmail.com)
# All rights reserved.

# This file is part of the StepClassLibrary (SCL).
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
#   Redistributions of source code must retain the above copyright notice,
#   this list of conditions and the following disclaimer.
#
#   Redistributions in binary form must reproduce the above copyright notice,
#   this list of conditions and the following disclaimer in the documentation
#   and/or other materials provided with the distribution.
#
#   Neither the name of the <ORGANIZATION> nor the names of its contributors may
#   be used to endorse or promote products derived from this software without
#   specific prior written permission.

# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED.
# IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY
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import sys
import BaseType

class EnumerationId(object):
    """
    EXPRESS definition:
    ===================
    An enumeration data type has as its domain an ordered set of names. The names represent
    values of the enumeration data type. These names are designated by enumeration_ids and are
    referred to as enumeration items.
    """
    pass

class ENUMERATION(object):
    """
    EXPRESS definition:
    ===================
    An ENUMERATION data type has as its domain an ordered set of names. The names represent
    values of the enumeration data type.
    
    Python implementation:
    ======================
    An enumeration is initialized from strings defining the types.
    For instance, some EXPRESS definition:
    TYPE ahead_or_behind = ENUMERATION OF
      (ahead,
       behind);
    END_TYPE; -- ahead_or_behind
    
    is implemented in python with the line:
    >>> ahead_of_behind = ENUMERATION('ahead','behind', the_current_scope)
    >>> ahead_or_behind.ahead
    >>> ahead_of_behind.behind
    
    And, if and only if ahead and/or behind are not in scope (e.g. they are not entity names,
    and/or many enums define the same enumeration identifier):
    >>> ahead
    >>> behind
    """
    def __init__(self,*kargs,**args):
        # first defining the scope
        if 'scope' in args:
            self._scope = args['scope']
        else:
            self._scope = None
        # store passed enum identifiers
        self._enum_id_names = list(kargs)
        self._enum_ids = []
        # we create enums id from names, and create attributes
        # for instance, from the identifier name 'ahead',
        # we create an attribute ahead with which is a new
        # instance of EnumerationId
        for enum_id_name in self._enum_id_names:
            setattr(self,enum_id_name,EnumerationId())
            # we store this new attributes to the enum_ids list, which
            # will be accessed by the type checker with the get_enum_ids method
            self._enum_ids.append(self.__getattribute__(enum_id_name))
        #
        # Then we check if the enums names can be added to the current scope:
        # if the name is already in the scope, then another enums id or select
        # has the same name -> we do nothing, enums will be called 
        # with ahead_of_behind.ahead or ahead_or_behind.behind.
        # otherwise, they can be called as only ahead or behind
        # Note: since ENUMERATIONS are defined *before* entities, if an entity
        # has the same name as an enum id, it will replace it in the current scope.
        #
        for enum_id_name in self._enum_id_names:
            if enum_id_name not in vars(self._scope):
                vars(self._scope)[enum_id_name] = self.__getattribute__(enum_id_name)

    def get_enum_ids(self):
        return self._enum_ids
        
class SELECT(object):
    """ A select data type has as its domain the union of the domains of the named data types in
    its select list. The select data type is a generalization of each of the named data types in its
    select list.
    """
    def __init__(self,*kargs,**args):
        # first defining the scope
        if 'scope' in args:
            self._scope = args['scope']
        else:
            self._scope = None
        # create the types from the list of arguments
        self._base_types = []
        for types in list(kargs):
            new_type = BaseType.Type(types,self._scope)
            self._base_types.append(new_type)
 
    def get_allowed_types(self):
        _auth_types = []
        for types in self._base_types:
            _auth_types.append(types.get_type())
        return _auth_types

    def get_allowed_basic_types(self):
        ''' if a select contains some subselect, goes down through the different
        sublayers until there is no more '''
        b = []
        _auth_types = self.get_allowed_types()
        for _auth_type in _auth_types:
            if isinstance(_auth_type,SELECT) or isinstance(_auth_type,ENUMERATION):
                h = _auth_type.get_allowed_types()
                b.extend(h)
            else:
                b = _auth_types
        return b
