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|
| | """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"] |
| |
|
| | |
| | import io |
| | import os |
| | import logging |
| | import pkgutil |
| | import sys |
| |
|
| | |
| | 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.""" |
| | |
| | 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: |
| | |
| | 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())) |
| |
|