339 lines
10 KiB
Python
339 lines
10 KiB
Python
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#-----------------------------------------------------------------
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# _ast_gen.py
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#
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# Generates the AST Node classes from a specification given in
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# a configuration file
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#
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# The design of this module was inspired by astgen.py from the
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# Python 2.5 code-base.
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#
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# Eli Bendersky [https://eli.thegreenplace.net/]
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# License: BSD
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#-----------------------------------------------------------------
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import pprint
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from string import Template
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class ASTCodeGenerator(object):
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def __init__(self, cfg_filename='_c_ast.cfg'):
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""" Initialize the code generator from a configuration
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file.
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"""
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self.cfg_filename = cfg_filename
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self.node_cfg = [NodeCfg(name, contents)
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for (name, contents) in self.parse_cfgfile(cfg_filename)]
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def generate(self, file=None):
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""" Generates the code into file, an open file buffer.
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"""
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src = Template(_PROLOGUE_COMMENT).substitute(
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cfg_filename=self.cfg_filename)
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src += _PROLOGUE_CODE
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for node_cfg in self.node_cfg:
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src += node_cfg.generate_source() + '\n\n'
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file.write(src)
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def parse_cfgfile(self, filename):
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""" Parse the configuration file and yield pairs of
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(name, contents) for each node.
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"""
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with open(filename, "r") as f:
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for line in f:
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line = line.strip()
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if not line or line.startswith('#'):
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continue
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colon_i = line.find(':')
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lbracket_i = line.find('[')
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rbracket_i = line.find(']')
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if colon_i < 1 or lbracket_i <= colon_i or rbracket_i <= lbracket_i:
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raise RuntimeError("Invalid line in %s:\n%s\n" % (filename, line))
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name = line[:colon_i]
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val = line[lbracket_i + 1:rbracket_i]
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vallist = [v.strip() for v in val.split(',')] if val else []
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yield name, vallist
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class NodeCfg(object):
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""" Node configuration.
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name: node name
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contents: a list of contents - attributes and child nodes
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See comment at the top of the configuration file for details.
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"""
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def __init__(self, name, contents):
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self.name = name
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self.all_entries = []
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self.attr = []
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self.child = []
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self.seq_child = []
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for entry in contents:
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clean_entry = entry.rstrip('*')
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self.all_entries.append(clean_entry)
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if entry.endswith('**'):
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self.seq_child.append(clean_entry)
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elif entry.endswith('*'):
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self.child.append(clean_entry)
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else:
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self.attr.append(entry)
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def generate_source(self):
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src = self._gen_init()
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src += '\n' + self._gen_children()
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src += '\n' + self._gen_iter()
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src += '\n' + self._gen_attr_names()
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return src
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def _gen_init(self):
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src = "class %s(Node):\n" % self.name
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if self.all_entries:
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args = ', '.join(self.all_entries)
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slots = ', '.join("'{0}'".format(e) for e in self.all_entries)
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slots += ", 'coord', '__weakref__'"
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arglist = '(self, %s, coord=None)' % args
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else:
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slots = "'coord', '__weakref__'"
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arglist = '(self, coord=None)'
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src += " __slots__ = (%s)\n" % slots
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src += " def __init__%s:\n" % arglist
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for name in self.all_entries + ['coord']:
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src += " self.%s = %s\n" % (name, name)
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return src
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def _gen_children(self):
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src = ' def children(self):\n'
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if self.all_entries:
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src += ' nodelist = []\n'
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for child in self.child:
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src += (
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' if self.%(child)s is not None:' +
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' nodelist.append(("%(child)s", self.%(child)s))\n') % (
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dict(child=child))
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for seq_child in self.seq_child:
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src += (
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' for i, child in enumerate(self.%(child)s or []):\n'
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' nodelist.append(("%(child)s[%%d]" %% i, child))\n') % (
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dict(child=seq_child))
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src += ' return tuple(nodelist)\n'
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else:
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src += ' return ()\n'
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return src
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def _gen_iter(self):
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src = ' def __iter__(self):\n'
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if self.all_entries:
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for child in self.child:
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src += (
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' if self.%(child)s is not None:\n' +
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' yield self.%(child)s\n') % (dict(child=child))
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for seq_child in self.seq_child:
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src += (
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' for child in (self.%(child)s or []):\n'
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' yield child\n') % (dict(child=seq_child))
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if not (self.child or self.seq_child):
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# Empty generator
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src += (
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' return\n' +
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' yield\n')
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else:
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# Empty generator
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src += (
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' return\n' +
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' yield\n')
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return src
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def _gen_attr_names(self):
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src = " attr_names = (" + ''.join("%r, " % nm for nm in self.attr) + ')'
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return src
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_PROLOGUE_COMMENT = \
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r'''#-----------------------------------------------------------------
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# ** ATTENTION **
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# This code was automatically generated from the file:
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# $cfg_filename
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#
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# Do not modify it directly. Modify the configuration file and
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# run the generator again.
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# ** ** *** ** **
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#
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# pycparser: c_ast.py
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#
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# AST Node classes.
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#
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# Eli Bendersky [https://eli.thegreenplace.net/]
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# License: BSD
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#-----------------------------------------------------------------
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'''
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_PROLOGUE_CODE = r'''
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import sys
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def _repr(obj):
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"""
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Get the representation of an object, with dedicated pprint-like format for lists.
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"""
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if isinstance(obj, list):
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return '[' + (',\n '.join((_repr(e).replace('\n', '\n ') for e in obj))) + '\n]'
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else:
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return repr(obj)
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class Node(object):
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__slots__ = ()
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""" Abstract base class for AST nodes.
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"""
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def __repr__(self):
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""" Generates a python representation of the current node
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"""
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result = self.__class__.__name__ + '('
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indent = ''
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separator = ''
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for name in self.__slots__[:-2]:
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result += separator
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result += indent
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result += name + '=' + (_repr(getattr(self, name)).replace('\n', '\n ' + (' ' * (len(name) + len(self.__class__.__name__)))))
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separator = ','
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indent = '\n ' + (' ' * len(self.__class__.__name__))
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result += indent + ')'
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return result
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def children(self):
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""" A sequence of all children that are Nodes
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"""
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pass
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def show(self, buf=sys.stdout, offset=0, attrnames=False, nodenames=False, showcoord=False, _my_node_name=None):
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""" Pretty print the Node and all its attributes and
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children (recursively) to a buffer.
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buf:
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Open IO buffer into which the Node is printed.
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offset:
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Initial offset (amount of leading spaces)
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attrnames:
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True if you want to see the attribute names in
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name=value pairs. False to only see the values.
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nodenames:
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True if you want to see the actual node names
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within their parents.
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showcoord:
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Do you want the coordinates of each Node to be
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displayed.
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"""
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lead = ' ' * offset
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if nodenames and _my_node_name is not None:
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buf.write(lead + self.__class__.__name__+ ' <' + _my_node_name + '>: ')
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else:
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buf.write(lead + self.__class__.__name__+ ': ')
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if self.attr_names:
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if attrnames:
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nvlist = [(n, getattr(self,n)) for n in self.attr_names]
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attrstr = ', '.join('%s=%s' % nv for nv in nvlist)
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else:
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vlist = [getattr(self, n) for n in self.attr_names]
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attrstr = ', '.join('%s' % v for v in vlist)
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buf.write(attrstr)
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if showcoord:
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buf.write(' (at %s)' % self.coord)
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buf.write('\n')
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for (child_name, child) in self.children():
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child.show(
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buf,
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offset=offset + 2,
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attrnames=attrnames,
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nodenames=nodenames,
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showcoord=showcoord,
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_my_node_name=child_name)
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class NodeVisitor(object):
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""" A base NodeVisitor class for visiting c_ast nodes.
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Subclass it and define your own visit_XXX methods, where
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XXX is the class name you want to visit with these
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methods.
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For example:
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class ConstantVisitor(NodeVisitor):
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def __init__(self):
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self.values = []
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def visit_Constant(self, node):
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self.values.append(node.value)
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Creates a list of values of all the constant nodes
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encountered below the given node. To use it:
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cv = ConstantVisitor()
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cv.visit(node)
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Notes:
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* generic_visit() will be called for AST nodes for which
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no visit_XXX method was defined.
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* The children of nodes for which a visit_XXX was
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defined will not be visited - if you need this, call
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generic_visit() on the node.
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You can use:
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NodeVisitor.generic_visit(self, node)
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* Modeled after Python's own AST visiting facilities
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(the ast module of Python 3.0)
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"""
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_method_cache = None
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def visit(self, node):
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""" Visit a node.
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"""
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if self._method_cache is None:
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self._method_cache = {}
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visitor = self._method_cache.get(node.__class__.__name__, None)
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if visitor is None:
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method = 'visit_' + node.__class__.__name__
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visitor = getattr(self, method, self.generic_visit)
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self._method_cache[node.__class__.__name__] = visitor
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return visitor(node)
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def generic_visit(self, node):
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""" Called if no explicit visitor function exists for a
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node. Implements preorder visiting of the node.
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"""
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for c in node:
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self.visit(c)
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'''
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