1 files changed, 133 insertions, 0 deletions
diff --git a/pycparser/plyparser.py b/pycparser/plyparser.py
new file mode 100644
index 0000000..6222c0e
--- /dev/null
+++ b/pycparser/plyparser.py
@@ -0,0 +1,133 @@
+#-----------------------------------------------------------------
+# plyparser.py
+#
+# PLYParser class and other utilites for simplifying programming
+# parsers with PLY
+#
+# Eli Bendersky [https://eli.thegreenplace.net/]
+# License: BSD
+#-----------------------------------------------------------------
+
+import warnings
+
+class Coord(object):
+    """ Coordinates of a syntactic element. Consists of:
+            - File name
+            - Line number
+            - (optional) column number, for the Lexer
+    """
+    __slots__ = ('file', 'line', 'column', '__weakref__')
+    def __init__(self, file, line, column=None):
+        self.file = file
+        self.line = line
+        self.column = column
+
+    def __str__(self):
+        str = "%s:%s" % (self.file, self.line)
+        if self.column: str += ":%s" % self.column
+        return str
+
+
+class ParseError(Exception): pass
+
+
+class PLYParser(object):
+    def _create_opt_rule(self, rulename):
+        """ Given a rule name, creates an optional ply.yacc rule
+            for it. The name of the optional rule is
+            <rulename>_opt
+        """
+        optname = rulename + '_opt'
+
+        def optrule(self, p):
+            p[0] = p[1]
+
+        optrule.__doc__ = '%s : empty\n| %s' % (optname, rulename)
+        optrule.__name__ = 'p_%s' % optname
+        setattr(self.__class__, optrule.__name__, optrule)
+
+    def _coord(self, lineno, column=None):
+        return Coord(
+                file=self.clex.filename,
+                line=lineno,
+                column=column)
+
+    def _token_coord(self, p, token_idx):
+        """ Returns the coordinates for the YaccProduction objet 'p' indexed
+            with 'token_idx'. The coordinate includes the 'lineno' and
+            'column'. Both follow the lex semantic, starting from 1.
+        """
+        last_cr = p.lexer.lexer.lexdata.rfind('\n', 0, p.lexpos(token_idx))
+        if last_cr < 0:
+            last_cr = -1
+        column = (p.lexpos(token_idx) - (last_cr))
+        return self._coord(p.lineno(token_idx), column)
+
+    def _parse_error(self, msg, coord):
+        raise ParseError("%s: %s" % (coord, msg))
+
+
+def parameterized(*params):
+    """ Decorator to create parameterized rules.
+
+    Parameterized rule methods must be named starting with 'p_' and contain
+    'xxx', and their docstrings may contain 'xxx' and 'yyy'. These will be
+    replaced by the given parameter tuples. For example, ``p_xxx_rule()`` with
+    docstring 'xxx_rule  : yyy' when decorated with
+    ``@parameterized(('id', 'ID'))`` produces ``p_id_rule()`` with the docstring
+    'id_rule  : ID'. Using multiple tuples produces multiple rules.
+    """
+    def decorate(rule_func):
+        rule_func._params = params
+        return rule_func
+    return decorate
+
+
+def template(cls):
+    """ Class decorator to generate rules from parameterized rule templates.
+
+    See `parameterized` for more information on parameterized rules.
+    """
+    issued_nodoc_warning = False
+    for attr_name in dir(cls):
+        if attr_name.startswith('p_'):
+            method = getattr(cls, attr_name)
+            if hasattr(method, '_params'):
+                # Remove the template method
+                delattr(cls, attr_name)
+                # Create parameterized rules from this method; only run this if
+                # the method has a docstring. This is to address an issue when
+                # pycparser's users are installed in -OO mode which strips
+                # docstrings away.
+                # See: https://github.com/eliben/pycparser/pull/198/ and
+                #      https://github.com/eliben/pycparser/issues/197
+                # for discussion.
+                if method.__doc__ is not None:
+                    _create_param_rules(cls, method)
+                elif not issued_nodoc_warning:
+                    warnings.warn(
+                        'parsing methods must have __doc__ for pycparser to work properly',
+                        RuntimeWarning,
+                        stacklevel=2)
+                    issued_nodoc_warning = True
+    return cls
+
+
+def _create_param_rules(cls, func):
+    """ Create ply.yacc rules based on a parameterized rule function
+
+    Generates new methods (one per each pair of parameters) based on the
+    template rule function `func`, and attaches them to `cls`. The rule
+    function's parameters must be accessible via its `_params` attribute.
+    """
+    for xxx, yyy in func._params:
+        # Use the template method's body for each new method
+        def param_rule(self, p):
+            func(self, p)
+
+        # Substitute in the params for the grammar rule and function name
+        param_rule.__doc__ = func.__doc__.replace('xxx', xxx).replace('yyy', yyy)
+        param_rule.__name__ = func.__name__.replace('xxx', xxx)
+
+        # Attach the new method to the class
+        setattr(cls, param_rule.__name__, param_rule)