__file__ = 'ky_token.py'
__usage__ = '''<identifier> = token( token type, token value, column index, line number, previous token, next token )
    token type  - eg. token.NUMBER, token.IDENT, etc.
    token val   - eg. 12, 'test', ie. any arbitrary value
    column idx  - eg. 3 ie. lexical position of token
    line num    - eg. 2 ie. line # of token
    previous    - previous token in stream
    next        - next token in stream'''

__description__ = '''This class is the basic token class returned by the
lexical scanner.  This may become a base class whereby all
tokens are sub classes.  Basically just a data storage class.'''

__author__ = 'Timothy Wakeham (timmeh)'
__contact__ = 'timmeh@hiddenworlds.org'
__updated__ = '28-03-2008 @ 14:57:40'

__todo__ = None

#start
class Token:

    ID = 'KY_TOKEN'

    NUMBER = 1
    LBRACKET = 2
    RBRACKET = 3
    OPERATOR = 4
    IDENT = 5
    KEYWORD = 6
    UNKNOWN = 7
    EOF = 8
    UNOP = 9

    END = 0

    MAPPING = ['End', 'Number', 'Left Bracket', 'Right Bracket', 'Operator',
               'Identifier', 'Keyword', 'Unknown', 'EOF', 'Unary Op']

    def __init__(self, tok_type, tok_val, idx=None, line=None, prev=None, next=None):

        # token details
        self.token_type = tok_type
        self.token_value = tok_val

        # lexer state
        self.idx = idx
        self.line = line

        # pointers to context tokens
        self.prev = prev
        self.next= next

    def next(self):
        return self.next

    def previous(self):
        return self.prev

    def __str__(self):
        return '<Token type:%s value:%s>' % (Token.MAPPING[self.token_type], self.token_value)