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| # Copyright 2004-2005 Elemental Security, Inc. All Rights Reserved. | |
| # Licensed to PSF under a Contributor Agreement. | |
| # Modifications: | |
| # Copyright 2006 Google, Inc. All Rights Reserved. | |
| # Licensed to PSF under a Contributor Agreement. | |
| """Parser driver. | |
| This provides a high-level interface to parse a file into a syntax tree. | |
| """ | |
| __author__ = "Guido van Rossum <guido@python.org>" | |
| __all__ = ["Driver", "load_grammar"] | |
| # Python imports | |
| import io | |
| import os | |
| import logging | |
| import pkgutil | |
| import sys | |
| # Pgen imports | |
| from . import grammar, parse, token, tokenize, pgen | |
| class Driver(object): | |
| def __init__(self, grammar, convert=None, logger=None): | |
| self.grammar = grammar | |
| if logger is None: | |
| logger = logging.getLogger() | |
| self.logger = logger | |
| self.convert = convert | |
| def parse_tokens(self, tokens, debug=False): | |
| """Parse a series of tokens and return the syntax tree.""" | |
| # XXX Move the prefix computation into a wrapper around tokenize. | |
| p = parse.Parser(self.grammar, self.convert) | |
| p.setup() | |
| lineno = 1 | |
| column = 0 | |
| type = value = start = end = line_text = None | |
| prefix = "" | |
| for quintuple in tokens: | |
| type, value, start, end, line_text = quintuple | |
| if start != (lineno, column): | |
| assert (lineno, column) <= start, ((lineno, column), start) | |
| s_lineno, s_column = start | |
| if lineno < s_lineno: | |
| prefix += "\n" * (s_lineno - lineno) | |
| lineno = s_lineno | |
| column = 0 | |
| if column < s_column: | |
| prefix += line_text[column:s_column] | |
| column = s_column | |
| if type in (tokenize.COMMENT, tokenize.NL): | |
| prefix += value | |
| lineno, column = end | |
| if value.endswith("\n"): | |
| lineno += 1 | |
| column = 0 | |
| continue | |
| if type == token.OP: | |
| type = grammar.opmap[value] | |
| if debug: | |
| self.logger.debug("%s %r (prefix=%r)", | |
| token.tok_name[type], value, prefix) | |
| if p.addtoken(type, value, (prefix, start)): | |
| if debug: | |
| self.logger.debug("Stop.") | |
| break | |
| prefix = "" | |
| lineno, column = end | |
| if value.endswith("\n"): | |
| lineno += 1 | |
| column = 0 | |
| else: | |
| # We never broke out -- EOF is too soon (how can this happen???) | |
| raise parse.ParseError("incomplete input", | |
| type, value, (prefix, start)) | |
| return p.rootnode | |
| def parse_stream_raw(self, stream, debug=False): | |
| """Parse a stream and return the syntax tree.""" | |
| tokens = tokenize.generate_tokens(stream.readline) | |
| return self.parse_tokens(tokens, debug) | |
| def parse_stream(self, stream, debug=False): | |
| """Parse a stream and return the syntax tree.""" | |
| return self.parse_stream_raw(stream, debug) | |
| def parse_file(self, filename, encoding=None, debug=False): | |
| """Parse a file and return the syntax tree.""" | |
| with io.open(filename, "r", encoding=encoding) as stream: | |
| return self.parse_stream(stream, debug) | |
| def parse_string(self, text, debug=False): | |
| """Parse a string and return the syntax tree.""" | |
| tokens = tokenize.generate_tokens(io.StringIO(text).readline) | |
| return self.parse_tokens(tokens, debug) | |
| def _generate_pickle_name(gt): | |
| head, tail = os.path.splitext(gt) | |
| if tail == ".txt": | |
| tail = "" | |
| return head + tail + ".".join(map(str, sys.version_info)) + ".pickle" | |
| def load_grammar(gt="Grammar.txt", gp=None, | |
| save=True, force=False, logger=None): | |
| """Load the grammar (maybe from a pickle).""" | |
| if logger is None: | |
| logger = logging.getLogger() | |
| gp = _generate_pickle_name(gt) if gp is None else gp | |
| if force or not _newer(gp, gt): | |
| logger.info("Generating grammar tables from %s", gt) | |
| g = pgen.generate_grammar(gt) | |
| if save: | |
| logger.info("Writing grammar tables to %s", gp) | |
| try: | |
| g.dump(gp) | |
| except OSError as e: | |
| logger.info("Writing failed: %s", e) | |
| else: | |
| g = grammar.Grammar() | |
| g.load(gp) | |
| return g | |
| def _newer(a, b): | |
| """Inquire whether file a was written since file b.""" | |
| if not os.path.exists(a): | |
| return False | |
| if not os.path.exists(b): | |
| return True | |
| return os.path.getmtime(a) >= os.path.getmtime(b) | |
| def load_packaged_grammar(package, grammar_source): | |
| """Normally, loads a pickled grammar by doing | |
| pkgutil.get_data(package, pickled_grammar) | |
| where *pickled_grammar* is computed from *grammar_source* by adding the | |
| Python version and using a ``.pickle`` extension. | |
| However, if *grammar_source* is an extant file, load_grammar(grammar_source) | |
| is called instead. This facilitates using a packaged grammar file when needed | |
| but preserves load_grammar's automatic regeneration behavior when possible. | |
| """ | |
| if os.path.isfile(grammar_source): | |
| return load_grammar(grammar_source) | |
| pickled_name = _generate_pickle_name(os.path.basename(grammar_source)) | |
| data = pkgutil.get_data(package, pickled_name) | |
| g = grammar.Grammar() | |
| g.loads(data) | |
| return g | |
| def main(*args): | |
| """Main program, when run as a script: produce grammar pickle files. | |
| Calls load_grammar for each argument, a path to a grammar text file. | |
| """ | |
| if not args: | |
| args = sys.argv[1:] | |
| logging.basicConfig(level=logging.INFO, stream=sys.stdout, | |
| format='%(message)s') | |
| for gt in args: | |
| load_grammar(gt, save=True, force=True) | |
| return True | |
| if __name__ == "__main__": | |
| sys.exit(int(not main())) | |