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