# -*- coding: utf-8 -*-
from __future__ import unicode_literals
import itertools
from copy import copy
from typing import Any
from typing import Optional
from typing import Tuple
from typing import Type
from ._compat import PY2
from ._compat import unicode
from .exceptions import UnexpectedEofError
from .exceptions import UnexpectedCharError
from .exceptions import ParseError
from .toml_char import TOMLChar
class _State:
def __init__(
self, source, save_marker=False, restore=False
): # type: (_Source, Optional[bool], Optional[bool]) -> None
self._source = source
self._save_marker = save_marker
self.restore = restore
def __enter__(self): # type: () -> None
# Entering this context manager - save the state
if PY2:
# Python 2.7 does not allow to directly copy
# an iterator, so we have to make tees of the original
# chars iterator.
self._source._chars, self._chars = itertools.tee(self._source._chars)
else:
self._chars = copy(self._source._chars)
self._idx = self._source._idx
self._current = self._source._current
self._marker = self._source._marker
return self
def __exit__(self, exception_type, exception_val, trace):
# Exiting this context manager - restore the prior state
if self.restore or exception_type:
self._source._chars = self._chars
self._source._idx = self._idx
self._source._current = self._current
if self._save_marker:
self._source._marker = self._marker
class _StateHandler:
"""
State preserver for the Parser.
"""
def __init__(self, source): # type: (Source) -> None
self._source = source
self._states = []
def __call__(self, *args, **kwargs):
return _State(self._source, *args, **kwargs)
def __enter__(self): # type: () -> None
state = self()
self._states.append(state)
return state.__enter__()
def __exit__(self, exception_type, exception_val, trace):
state = self._states.pop()
return state.__exit__(exception_type, exception_val, trace)
class Source(unicode):
EOF = TOMLChar("\0")
def __init__(self, _): # type: (unicode) -> None
super(Source, self).__init__()
# Collection of TOMLChars
self._chars = iter([(i, TOMLChar(c)) for i, c in enumerate(self)])
self._idx = 0
self._marker = 0
self._current = TOMLChar("")
self._state = _StateHandler(self)
self.inc()
def reset(self):
# initialize both idx and current
self.inc()
# reset marker
self.mark()
@property
def state(self): # type: () -> _StateHandler
return self._state
@property
def idx(self): # type: () -> int
return self._idx
@property
def current(self): # type: () -> TOMLChar
return self._current
@property
def marker(self): # type: () -> int
return self._marker
def extract(self): # type: () -> unicode
"""
Extracts the value between marker and index
"""
return self[self._marker : self._idx]
def inc(self, exception=None): # type: (Optional[Type[ParseError]]) -> bool
"""
Increments the parser if the end of the input has not been reached.
Returns whether or not it was able to advance.
"""
try:
self._idx, self._current = next(self._chars)
return True
except StopIteration:
self._idx = len(self)
self._current = self.EOF
if exception:
raise self.parse_error(exception)
return False
def inc_n(self, n, exception=None): # type: (int, Exception) -> bool
"""
Increments the parser by n characters
if the end of the input has not been reached.
"""
for _ in range(n):
if not self.inc(exception=exception):
return False
return True
def consume(self, chars, min=0, max=-1):
"""
Consume chars until min/max is satisfied is valid.
"""
while self.current in chars and max != 0:
min -= 1
max -= 1
if not self.inc():
break
# failed to consume minimum number of characters
if min > 0:
self.parse_error(UnexpectedCharError)
def end(self): # type: () -> bool
"""
Returns True if the parser has reached the end of the input.
"""
return self._current is self.EOF
def mark(self): # type: () -> None
"""
Sets the marker to the index's current position
"""
self._marker = self._idx
def parse_error(
self, exception=ParseError, *args
): # type: (Type[ParseError], Any) -> ParseError
"""
Creates a generic "parse error" at the current position.
"""
line, col = self._to_linecol()
return exception(line, col, *args)
def _to_linecol(self): # type: () -> Tuple[int, int]
cur = 0
for i, line in enumerate(self.splitlines()):
if cur + len(line) + 1 > self.idx:
return (i + 1, self.idx - cur)
cur += len(line) + 1
return len(self.splitlines()), 0
