Current File : //usr/lib/python3/dist-packages/blib2to3/pgen2/driver.py
# 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
from typing import (
Any,
cast,
IO,
Iterable,
List,
Optional,
Text,
Iterator,
Tuple,
TypeVar,
Generic,
Union,
)
from contextlib import contextmanager
from dataclasses import dataclass, field
# Pgen imports
from . import grammar, parse, token, tokenize, pgen
from logging import Logger
from blib2to3.pytree import NL
from blib2to3.pgen2.grammar import Grammar
from blib2to3.pgen2.tokenize import GoodTokenInfo
Path = Union[str, "os.PathLike[str]"]
@dataclass
class ReleaseRange:
start: int
end: Optional[int] = None
tokens: List[Any] = field(default_factory=list)
def lock(self) -> None:
total_eaten = len(self.tokens)
self.end = self.start + total_eaten
class TokenProxy:
def __init__(self, generator: Any) -> None:
self._tokens = generator
self._counter = 0
self._release_ranges: List[ReleaseRange] = []
@contextmanager
def release(self) -> Iterator["TokenProxy"]:
release_range = ReleaseRange(self._counter)
self._release_ranges.append(release_range)
try:
yield self
finally:
# Lock the last release range to the final position that
# has been eaten.
release_range.lock()
def eat(self, point: int) -> Any:
eaten_tokens = self._release_ranges[-1].tokens
if point < len(eaten_tokens):
return eaten_tokens[point]
else:
while point >= len(eaten_tokens):
token = next(self._tokens)
eaten_tokens.append(token)
return token
def __iter__(self) -> "TokenProxy":
return self
def __next__(self) -> Any:
# If the current position is already compromised (looked up)
# return the eaten token, if not just go further on the given
# token producer.
for release_range in self._release_ranges:
assert release_range.end is not None
start, end = release_range.start, release_range.end
if start <= self._counter < end:
token = release_range.tokens[self._counter - start]
break
else:
token = next(self._tokens)
self._counter += 1
return token
def can_advance(self, to: int) -> bool:
# Try to eat, fail if it can't. The eat operation is cached
# so there wont be any additional cost of eating here
try:
self.eat(to)
except StopIteration:
return False
else:
return True
class Driver(object):
def __init__(self, grammar: Grammar, logger: Optional[Logger] = None) -> None:
self.grammar = grammar
if logger is None:
logger = logging.getLogger(__name__)
self.logger = logger
def parse_tokens(self, tokens: Iterable[GoodTokenInfo], debug: bool = False) -> NL:
"""Parse a series of tokens and return the syntax tree."""
# XXX Move the prefix computation into a wrapper around tokenize.
proxy = TokenProxy(tokens)
p = parse.Parser(self.grammar)
p.setup(proxy=proxy)
lineno = 1
column = 0
indent_columns: List[int] = []
type = value = start = end = line_text = None
prefix = ""
for quintuple in proxy:
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:
assert type is not None
self.logger.debug(
"%s %r (prefix=%r)", token.tok_name[type], value, prefix
)
if type == token.INDENT:
indent_columns.append(len(value))
_prefix = prefix + value
prefix = ""
value = ""
elif type == token.DEDENT:
_indent_col = indent_columns.pop()
prefix, _prefix = self._partially_consume_prefix(prefix, _indent_col)
if p.addtoken(cast(int, type), value, (prefix, start)):
if debug:
self.logger.debug("Stop.")
break
prefix = ""
if type in {token.INDENT, token.DEDENT}:
prefix = _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???)
assert start is not None
raise parse.ParseError("incomplete input", type, value, (prefix, start))
assert p.rootnode is not None
return p.rootnode
def parse_stream_raw(self, stream: IO[Text], debug: bool = False) -> NL:
"""Parse a stream and return the syntax tree."""
tokens = tokenize.generate_tokens(stream.readline, grammar=self.grammar)
return self.parse_tokens(tokens, debug)
def parse_stream(self, stream: IO[Text], debug: bool = False) -> NL:
"""Parse a stream and return the syntax tree."""
return self.parse_stream_raw(stream, debug)
def parse_file(
self, filename: Path, encoding: Optional[Text] = None, debug: bool = False
) -> NL:
"""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: Text, debug: bool = False) -> NL:
"""Parse a string and return the syntax tree."""
tokens = tokenize.generate_tokens(
io.StringIO(text).readline, grammar=self.grammar
)
return self.parse_tokens(tokens, debug)
def _partially_consume_prefix(self, prefix: Text, column: int) -> Tuple[Text, Text]:
lines: List[str] = []
current_line = ""
current_column = 0
wait_for_nl = False
for char in prefix:
current_line += char
if wait_for_nl:
if char == "\n":
if current_line.strip() and current_column < column:
res = "".join(lines)
return res, prefix[len(res) :]
lines.append(current_line)
current_line = ""
current_column = 0
wait_for_nl = False
elif char in " \t":
current_column += 1
elif char == "\n":
# unexpected empty line
current_column = 0
else:
# indent is finished
wait_for_nl = True
return "".join(lines), current_line
def _generate_pickle_name(gt: Path, cache_dir: Optional[Path] = None) -> Text:
head, tail = os.path.splitext(gt)
if tail == ".txt":
tail = ""
name = head + tail + ".".join(map(str, sys.version_info)) + ".pickle"
if cache_dir:
return os.path.join(cache_dir, os.path.basename(name))
else:
return name
def load_grammar(
gt: Text = "Grammar.txt",
gp: Optional[Text] = None,
save: bool = True,
force: bool = False,
logger: Optional[Logger] = None,
) -> Grammar:
"""Load the grammar (maybe from a pickle)."""
if logger is None:
logger = logging.getLogger(__name__)
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: grammar.Grammar = 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: Text, b: Text) -> bool:
"""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: str, grammar_source: Text, cache_dir: Optional[Path] = None
) -> grammar.Grammar:
"""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):
gp = _generate_pickle_name(grammar_source, cache_dir) if cache_dir else None
return load_grammar(grammar_source, gp=gp)
pickled_name = _generate_pickle_name(os.path.basename(grammar_source), cache_dir)
data = pkgutil.get_data(package, pickled_name)
assert data is not None
g = grammar.Grammar()
g.loads(data)
return g
def main(*args: Text) -> bool:
"""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 = tuple(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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