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#
# Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
# Use of this file is governed by the BSD 3-clause license that
# can be found in the LICENSE.txt file in the project root.
#
#
# Vacuum all input from a string and then treat it like a buffer.
#
from antlr4.Token import Token
class InputStream (object):
__slots__ = ('name', 'strdata', '_index', 'data', '_size')
def __init__(self, data: str):
self.name = "<empty>"
self.strdata = data
self._loadString()
def _loadString(self):
self._index = 0
self.data = [ord(c) for c in self.strdata]
self._size = len(self.data)
@property
def index(self):
return self._index
@property
def size(self):
return self._size
# Reset the stream so that it's in the same state it was
# when the object was created *except* the data array is not
# touched.
#
def reset(self):
self._index = 0
def consume(self):
if self._index >= self._size:
assert self.LA(1) == Token.EOF
raise Exception("cannot consume EOF")
self._index += 1
def LA(self, offset: int):
if offset==0:
return 0 # undefined
if offset<0:
offset += 1 # e.g., translate LA(-1) to use offset=0
pos = self._index + offset - 1
if pos < 0 or pos >= self._size: # invalid
return Token.EOF
return self.data[pos]
def LT(self, offset: int):
return self.LA(offset)
# mark/release do nothing; we have entire buffer
def mark(self):
return -1
def release(self, marker: int):
pass
# consume() ahead until p==_index; can't just set p=_index as we must
# update line and column. If we seek backwards, just set p
#
def seek(self, _index: int):
if _index<=self._index:
self._index = _index # just jump; don't update stream state (line, ...)
return
# seek forward
self._index = min(_index, self._size)
def getText(self, start :int, stop: int):
if stop >= self._size:
stop = self._size-1
if start >= self._size:
return ""
else:
return self.strdata[start:stop+1]
def __str__(self):
return self.strdata
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