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#############################################################################
# Copyright (c) 2015-2016 Balabit
#
# This program is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License version 2 as published
# by the Free Software Foundation, or (at your option) any later version.
#
# 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, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
#
# As an additional exemption you are allowed to compile & link against the
# OpenSSL libraries as published by the OpenSSL project. See the file
# COPYING for details.
#
#############################################################################
from .lexertoken import LexerToken
from .lexer import Lexer
class TabLexer(Lexer):
def __init__(self, lexer):
self._lexer = lexer
self._current_token = None
self._end_of_tokens = False
self._replaced_token = None
self._buffered_tokens = None
self._buffer_count = 0
self._is_last_token = False
def input(self, text):
self._lexer.input(text)
self._end_of_tokens = False
self._buffered_tokens = None
self._replaced_token = None
def get_replaced_token(self):
return self._replaced_token
def set_drop_last_token(self, value):
if value:
self._buffer_count = 1
else:
self._buffer_count = 0
def token(self):
if self._end_of_tokens:
return None
if not self._is_buffer_initialized():
self._fill_buffer()
self._shift_and_inject_tab()
return self._current_token
def get_position(self):
# This method is not implemented as it would require to look ahead
# to the next token we may or may not have, making the code more
# difficult. We are not using this anyway.
raise NotImplementedError
def _shift_and_inject_tab(self):
self._shift_from_buffer()
if self._is_last_token or self._is_current_token_partial():
self._end_of_tokens = True
self._replaced_token = self._current_token
self._current_token = self._constuct_tab_token()
def _is_current_token_partial(self):
return (self._current_token is not None and
(hasattr(self._current_token, 'partial') and
self._current_token.partial))
def _is_buffer_initialized(self):
return self._buffered_tokens is not None
def _constuct_tab_token(self):
if self._replaced_token is not None:
lexpos = self._replaced_token.lexpos
else:
lexpos = self._lexer.get_position()
return LexerToken(type="TAB", lexpos=lexpos)
def _shift_from_buffer(self):
self._fetch_token_to_buffer()
self._is_last_token = len(self._buffered_tokens) <= self._buffer_count
self._current_token = self._get_token_from_buffer()
def _fill_buffer(self):
self._buffered_tokens = []
for _ in range(self._buffer_count):
self._fetch_token_to_buffer()
def _fetch_token_to_buffer(self):
token = self._lexer.token()
if token is not None:
self._buffered_tokens.append(token)
def _get_token_from_buffer(self):
try:
token = self._buffered_tokens[0]
self._buffered_tokens = self._buffered_tokens[1:]
return token
except IndexError:
return None
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