codekingpro/portable-devtools

1#-----------------------------------------------------------------2# plyparser.py3#4# PLYParser class and other utilities for simplifying programming5# parsers with PLY6#7# Eli Bendersky [https://eli.thegreenplace.net/]8# License: BSD9#-----------------------------------------------------------------10 11import warnings12 13class Coord(object):14    """ Coordinates of a syntactic element. Consists of:15            - File name16            - Line number17            - (optional) column number, for the Lexer18    """19    __slots__ = ('file', 'line', 'column', '__weakref__')20    def __init__(self, file, line, column=None):21        self.file = file22        self.line = line23        self.column = column24 25    def __str__(self):26        str = "%s:%s" % (self.file, self.line)27        if self.column: str += ":%s" % self.column28        return str29 30 31class ParseError(Exception): pass32 33 34class PLYParser(object):35    def _create_opt_rule(self, rulename):36        """ Given a rule name, creates an optional ply.yacc rule37            for it. The name of the optional rule is38            <rulename>_opt39        """40        optname = rulename + '_opt'41 42        def optrule(self, p):43            p[0] = p[1]44 45        optrule.__doc__ = '%s : empty\n| %s' % (optname, rulename)46        optrule.__name__ = 'p_%s' % optname47        setattr(self.__class__, optrule.__name__, optrule)48 49    def _coord(self, lineno, column=None):50        return Coord(51                file=self.clex.filename,52                line=lineno,53                column=column)54 55    def _token_coord(self, p, token_idx):56        """ Returns the coordinates for the YaccProduction object 'p' indexed57            with 'token_idx'. The coordinate includes the 'lineno' and58            'column'. Both follow the lex semantic, starting from 1.59        """60        last_cr = p.lexer.lexer.lexdata.rfind('\n', 0, p.lexpos(token_idx))61        if last_cr < 0:62            last_cr = -163        column = (p.lexpos(token_idx) - (last_cr))64        return self._coord(p.lineno(token_idx), column)65 66    def _parse_error(self, msg, coord):67        raise ParseError("%s: %s" % (coord, msg))68 69 70def parameterized(*params):71    """ Decorator to create parameterized rules.72 73    Parameterized rule methods must be named starting with 'p_' and contain74    'xxx', and their docstrings may contain 'xxx' and 'yyy'. These will be75    replaced by the given parameter tuples. For example, ``p_xxx_rule()`` with76    docstring 'xxx_rule  : yyy' when decorated with77    ``@parameterized(('id', 'ID'))`` produces ``p_id_rule()`` with the docstring78    'id_rule  : ID'. Using multiple tuples produces multiple rules.79    """80    def decorate(rule_func):81        rule_func._params = params82        return rule_func83    return decorate84 85 86def template(cls):87    """ Class decorator to generate rules from parameterized rule templates.88 89    See `parameterized` for more information on parameterized rules.90    """91    issued_nodoc_warning = False92    for attr_name in dir(cls):93        if attr_name.startswith('p_'):94            method = getattr(cls, attr_name)95            if hasattr(method, '_params'):96                # Remove the template method97                delattr(cls, attr_name)98                # Create parameterized rules from this method; only run this if99                # the method has a docstring. This is to address an issue when100                # pycparser's users are installed in -OO mode which strips101                # docstrings away.102                # See: https://github.com/eliben/pycparser/pull/198/ and103                #      https://github.com/eliben/pycparser/issues/197104                # for discussion.105                if method.__doc__ is not None:106                    _create_param_rules(cls, method)107                elif not issued_nodoc_warning:108                    warnings.warn(109                        'parsing methods must have __doc__ for pycparser to work properly',110                        RuntimeWarning,111                        stacklevel=2)112                    issued_nodoc_warning = True113    return cls114 115 116def _create_param_rules(cls, func):117    """ Create ply.yacc rules based on a parameterized rule function118 119    Generates new methods (one per each pair of parameters) based on the120    template rule function `func`, and attaches them to `cls`. The rule121    function's parameters must be accessible via its `_params` attribute.122    """123    for xxx, yyy in func._params:124        # Use the template method's body for each new method125        def param_rule(self, p):126            func(self, p)127 128        # Substitute in the params for the grammar rule and function name129        param_rule.__doc__ = func.__doc__.replace('xxx', xxx).replace('yyy', yyy)130        param_rule.__name__ = func.__name__.replace('xxx', xxx)131 132        # Attach the new method to the class133        setattr(cls, param_rule.__name__, param_rule)134