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251 lines
9.7 KiB
251 lines
9.7 KiB
6 years ago
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import hashlib
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import os
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from parso._compatibility import FileNotFoundError, is_pypy
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from parso.pgen2 import generate_grammar
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from parso.utils import split_lines, python_bytes_to_unicode, parse_version_string
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from parso.python.diff import DiffParser
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from parso.python.tokenize import tokenize_lines, tokenize
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from parso.python.token import PythonTokenTypes
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from parso.cache import parser_cache, load_module, save_module
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from parso.parser import BaseParser
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from parso.python.parser import Parser as PythonParser
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from parso.python.errors import ErrorFinderConfig
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from parso.python import pep8
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_loaded_grammars = {}
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class Grammar(object):
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"""
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:py:func:`parso.load_grammar` returns instances of this class.
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Creating custom none-python grammars by calling this is not supported, yet.
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"""
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#:param text: A BNF representation of your grammar.
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_error_normalizer_config = None
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_token_namespace = None
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_default_normalizer_config = pep8.PEP8NormalizerConfig()
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def __init__(self, text, tokenizer, parser=BaseParser, diff_parser=None):
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self._pgen_grammar = generate_grammar(
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text,
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token_namespace=self._get_token_namespace()
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)
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self._parser = parser
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self._tokenizer = tokenizer
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self._diff_parser = diff_parser
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self._hashed = hashlib.sha256(text.encode("utf-8")).hexdigest()
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def parse(self, code=None, **kwargs):
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"""
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If you want to parse a Python file you want to start here, most likely.
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If you need finer grained control over the parsed instance, there will be
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other ways to access it.
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:param str code: A unicode or bytes string. When it's not possible to
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decode bytes to a string, returns a
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:py:class:`UnicodeDecodeError`.
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:param bool error_recovery: If enabled, any code will be returned. If
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it is invalid, it will be returned as an error node. If disabled,
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you will get a ParseError when encountering syntax errors in your
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code.
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:param str start_symbol: The grammar rule (nonterminal) that you want
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to parse. Only allowed to be used when error_recovery is False.
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:param str path: The path to the file you want to open. Only needed for caching.
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:param bool cache: Keeps a copy of the parser tree in RAM and on disk
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if a path is given. Returns the cached trees if the corresponding
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files on disk have not changed.
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:param bool diff_cache: Diffs the cached python module against the new
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code and tries to parse only the parts that have changed. Returns
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the same (changed) module that is found in cache. Using this option
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requires you to not do anything anymore with the cached modules
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under that path, because the contents of it might change. This
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option is still somewhat experimental. If you want stability,
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please don't use it.
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:param bool cache_path: If given saves the parso cache in this
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directory. If not given, defaults to the default cache places on
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each platform.
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:return: A subclass of :py:class:`parso.tree.NodeOrLeaf`. Typically a
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:py:class:`parso.python.tree.Module`.
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"""
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if 'start_pos' in kwargs:
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raise TypeError("parse() got an unexpected keyword argument.")
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return self._parse(code=code, **kwargs)
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def _parse(self, code=None, error_recovery=True, path=None,
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start_symbol=None, cache=False, diff_cache=False,
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cache_path=None, start_pos=(1, 0)):
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"""
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Wanted python3.5 * operator and keyword only arguments. Therefore just
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wrap it all.
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start_pos here is just a parameter internally used. Might be public
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sometime in the future.
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"""
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if code is None and path is None:
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raise TypeError("Please provide either code or a path.")
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if start_symbol is None:
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start_symbol = self._start_nonterminal
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if error_recovery and start_symbol != 'file_input':
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raise NotImplementedError("This is currently not implemented.")
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if cache and path is not None:
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module_node = load_module(self._hashed, path, cache_path=cache_path)
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if module_node is not None:
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return module_node
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if code is None:
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with open(path, 'rb') as f:
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code = f.read()
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code = python_bytes_to_unicode(code)
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lines = split_lines(code, keepends=True)
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if diff_cache:
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if self._diff_parser is None:
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raise TypeError("You have to define a diff parser to be able "
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"to use this option.")
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try:
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module_cache_item = parser_cache[self._hashed][path]
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except KeyError:
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pass
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else:
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module_node = module_cache_item.node
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old_lines = module_cache_item.lines
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if old_lines == lines:
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return module_node
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new_node = self._diff_parser(
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self._pgen_grammar, self._tokenizer, module_node
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).update(
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old_lines=old_lines,
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new_lines=lines
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)
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save_module(self._hashed, path, new_node, lines,
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# Never pickle in pypy, it's slow as hell.
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pickling=cache and not is_pypy,
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cache_path=cache_path)
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return new_node
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tokens = self._tokenizer(lines, start_pos)
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p = self._parser(
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self._pgen_grammar,
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error_recovery=error_recovery,
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start_nonterminal=start_symbol
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)
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root_node = p.parse(tokens=tokens)
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if cache or diff_cache:
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save_module(self._hashed, path, root_node, lines,
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# Never pickle in pypy, it's slow as hell.
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pickling=cache and not is_pypy,
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cache_path=cache_path)
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return root_node
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def _get_token_namespace(self):
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ns = self._token_namespace
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if ns is None:
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raise ValueError("The token namespace should be set.")
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return ns
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def iter_errors(self, node):
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"""
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Given a :py:class:`parso.tree.NodeOrLeaf` returns a generator of
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:py:class:`parso.normalizer.Issue` objects. For Python this is
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a list of syntax/indentation errors.
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"""
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if self._error_normalizer_config is None:
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raise ValueError("No error normalizer specified for this grammar.")
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return self._get_normalizer_issues(node, self._error_normalizer_config)
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def _get_normalizer(self, normalizer_config):
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if normalizer_config is None:
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normalizer_config = self._default_normalizer_config
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if normalizer_config is None:
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raise ValueError("You need to specify a normalizer, because "
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"there's no default normalizer for this tree.")
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return normalizer_config.create_normalizer(self)
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def _normalize(self, node, normalizer_config=None):
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"""
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TODO this is not public, yet.
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The returned code will be normalized, e.g. PEP8 for Python.
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"""
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normalizer = self._get_normalizer(normalizer_config)
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return normalizer.walk(node)
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def _get_normalizer_issues(self, node, normalizer_config=None):
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normalizer = self._get_normalizer(normalizer_config)
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normalizer.walk(node)
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return normalizer.issues
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def __repr__(self):
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nonterminals = self._pgen_grammar.nonterminal_to_dfas.keys()
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txt = ' '.join(list(nonterminals)[:3]) + ' ...'
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return '<%s:%s>' % (self.__class__.__name__, txt)
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class PythonGrammar(Grammar):
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_error_normalizer_config = ErrorFinderConfig()
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_token_namespace = PythonTokenTypes
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_start_nonterminal = 'file_input'
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def __init__(self, version_info, bnf_text):
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super(PythonGrammar, self).__init__(
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bnf_text,
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tokenizer=self._tokenize_lines,
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parser=PythonParser,
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diff_parser=DiffParser
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)
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self.version_info = version_info
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def _tokenize_lines(self, lines, start_pos):
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return tokenize_lines(lines, self.version_info, start_pos=start_pos)
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def _tokenize(self, code):
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# Used by Jedi.
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return tokenize(code, self.version_info)
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def load_grammar(**kwargs):
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"""
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Loads a :py:class:`parso.Grammar`. The default version is the current Python
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version.
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:param str version: A python version string, e.g. ``version='3.3'``.
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:param str path: A path to a grammar file
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"""
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def load_grammar(language='python', version=None, path=None):
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if language == 'python':
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version_info = parse_version_string(version)
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file = path or os.path.join(
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'python',
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'grammar%s%s.txt' % (version_info.major, version_info.minor)
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)
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global _loaded_grammars
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path = os.path.join(os.path.dirname(__file__), file)
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try:
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return _loaded_grammars[path]
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except KeyError:
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try:
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with open(path) as f:
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bnf_text = f.read()
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grammar = PythonGrammar(version_info, bnf_text)
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return _loaded_grammars.setdefault(path, grammar)
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except FileNotFoundError:
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message = "Python version %s is currently not supported." % version
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raise NotImplementedError(message)
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else:
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raise NotImplementedError("No support for language %s." % language)
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return load_grammar(**kwargs)
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