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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()))
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