# Copyright (C) 2008 Andi Albrecht, albrecht.andi@gmail.com
#
# This module is part of python-sqlparse and is released under
# the BSD License: http://www.opensource.org/licenses/bsd-license.php.

# The Token implementation is based on pygment's token system written
# by Georg Brandl.
# http://pygments.org/

"""Tokens"""

try:
    set
except NameError:
    from sets import Set as set


class _TokenType(tuple):
    parent = None

    def split(self):
        buf = []
        node = self
        while node is not None:
            buf.append(node)
            node = node.parent
        buf.reverse()
        return buf

    def __init__(self, *args):
        # no need to call super.__init__
        self.subtypes = set()

    def __contains__(self, val):
        return self is val or (
            type(val) is self.__class__ and
            val[:len(self)] == self
        )

    def __getattr__(self, val):
        if not val or not val[0].isupper():
            return tuple.__getattribute__(self, val)
        new = _TokenType(self + (val,))
        setattr(self, val, new)
        self.subtypes.add(new)
        new.parent = self
        return new

    def __hash__(self):
        return hash(tuple(self))

    def __repr__(self):
        return 'Token' + (self and '.' or '') + '.'.join(self)


Token       = _TokenType()

# Special token types
Text        = Token.Text
Whitespace  = Text.Whitespace
Newline     = Whitespace.Newline
Error       = Token.Error
# Text that doesn't belong to this lexer (e.g. HTML in PHP)
Other       = Token.Other

# Common token types for source code
Keyword     = Token.Keyword
Name        = Token.Name
Literal     = Token.Literal
String      = Literal.String
Number      = Literal.Number
Punctuation = Token.Punctuation
Operator    = Token.Operator
Wildcard    = Token.Wildcard
Comment     = Token.Comment
Assignment  = Token.Assignement

# Generic types for non-source code
Generic     = Token.Generic

# String and some others are not direct childs of Token.
# alias them:
Token.Token = Token
Token.String = String
Token.Number = Number

# SQL specific tokens
DML = Keyword.DML
DDL = Keyword.DDL
Command = Keyword.Command

Group = Token.Group
Group.Parenthesis = Token.Group.Parenthesis
Group.Comment = Token.Group.Comment
Group.Where = Token.Group.Where


def is_token_subtype(ttype, other):
    """
    Return True if ``ttype`` is a subtype of ``other``.

    exists for backwards compatibility. use ``ttype in other`` now.
    """
    return ttype in other


def string_to_tokentype(s):
    """
    Convert a string into a token type::

        >>> string_to_token('String.Double')
        Token.Literal.String.Double
        >>> string_to_token('Token.Literal.Number')
        Token.Literal.Number
        >>> string_to_token('')
        Token

    Tokens that are already tokens are returned unchanged:

        >>> string_to_token(String)
        Token.Literal.String
    """
    if isinstance(s, _TokenType):
        return s
    if not s:
        return Token
    node = Token
    for item in s.split('.'):
        node = getattr(node, item)
    return node

