mirror of https://github.com/apache/cassandra
108 lines
4.1 KiB
Python
108 lines
4.1 KiB
Python
# Licensed to the Apache Software Foundation (ASF) under one
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# or more contributor license agreements. See the NOTICE file
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# distributed with this work for additional information
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# regarding copyright ownership. The ASF licenses this file
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# to you under the Apache License, Version 2.0 (the
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# "License"); you may not use this file except in compliance
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# with the License. You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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# SaferScanner is just like re.Scanner, but it neuters any grouping in the lexicon
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# regular expressions and throws an error on group references, named groups, or
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# regex in-pattern flags. Any of those can break correct operation of Scanner.
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import re
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try:
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from sre_constants import BRANCH, SUBPATTERN, GROUPREF, GROUPREF_IGNORE, GROUPREF_EXISTS
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except ImportError:
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from re._constants import BRANCH, SUBPATTERN, GROUPREF, GROUPREF_IGNORE, GROUPREF_EXISTS
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from sys import version_info
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class SaferScannerBase(re.Scanner):
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@classmethod
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def subpat(cls, phrase, flags):
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return cls.scrub_sub(re.sre_parse.parse(phrase, flags), flags)
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@classmethod
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def scrub_sub(cls, sub, flags):
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scrubbedsub = []
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seqtypes = (type(()), type([]))
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for op, arg in sub.data:
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if type(arg) in seqtypes:
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arg = [cls.scrub_sub(a, flags) if isinstance(a, re.sre_parse.SubPattern) else a
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for a in arg]
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if op in (BRANCH, SUBPATTERN):
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arg = [None] + arg[1:]
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if op in (GROUPREF, GROUPREF_IGNORE, GROUPREF_EXISTS):
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raise ValueError("Group references not allowed in SaferScanner lexicon")
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scrubbedsub.append((op, arg))
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if sub.pattern.groupdict:
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raise ValueError("Named captures not allowed in SaferScanner lexicon")
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if sub.pattern.flags ^ flags:
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raise ValueError("RE flag setting not allowed in SaferScanner lexicon (%s)" % (bin(sub.pattern.flags),))
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return re.sre_parse.SubPattern(sub.pattern, scrubbedsub)
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class Py36SaferScanner(SaferScannerBase):
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def __init__(self, lexicon, flags=0):
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self.lexicon = lexicon
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p = []
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s = re.sre_parse.Pattern()
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s.flags = flags
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for phrase, action in lexicon:
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gid = s.opengroup()
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p.append(re.sre_parse.SubPattern(s, [(SUBPATTERN, (gid, 0, 0, re.sre_parse.parse(phrase, flags))), ]))
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s.closegroup(gid, p[-1])
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p = re.sre_parse.SubPattern(s, [(BRANCH, (None, p))])
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self.p = p
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self.scanner = re.sre_compile.compile(p)
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class Py38SaferScanner(SaferScannerBase):
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def __init__(self, lexicon, flags=0):
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self.lexicon = lexicon
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p = []
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s = re.sre_parse.State()
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s.flags = flags
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for phrase, action in lexicon:
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gid = s.opengroup()
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p.append(re.sre_parse.SubPattern(s, [(SUBPATTERN, (gid, 0, 0, re.sre_parse.parse(phrase, flags))), ]))
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s.closegroup(gid, p[-1])
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p = re.sre_parse.SubPattern(s, [(BRANCH, (None, p))])
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self.p = p
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self.scanner = re.sre_compile.compile(p)
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class Py311SaferScanner(SaferScannerBase):
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def __init__(self, lexicon, flags=0):
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self.lexicon = lexicon
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p = []
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s = re._parser.State()
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s.flags = flags
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for phrase, action in lexicon:
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gid = s.opengroup()
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p.append(re._parser.SubPattern(s, [(SUBPATTERN, (gid, 0, 0, re._parser.parse(phrase, flags))), ]))
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s.closegroup(gid, p[-1])
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p = re._parser.SubPattern(s, [(BRANCH, (None, p))])
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self.p = p
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self.scanner = re._compiler.compile(p)
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SaferScanner = Py36SaferScanner
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if version_info >= (3, 11):
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SaferScanner = Py311SaferScanner
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elif version_info >= (3, 8):
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SaferScanner = Py38SaferScanner
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