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5477f529d6
Add support for floor division (// and //=) The implementation of getChildren() and getChildNodes() is intended to be faster, because it avoids calling flatten() on every return value. But it's not clear that it is a lot faster, because constructing a tuple with just the right values ends up being slow. (Too many attribute lookups probably.) The ast.txt file is much more complicated, with funny characters at the ends of names (*, &, !) to indicate the types of each child node. The astgen script is also much more complex, making me wonder if it's still useful.
280 lines
8.7 KiB
Python
280 lines
8.7 KiB
Python
"""Generate ast module from specification
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This script generates the ast module from a simple specification,
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which makes it easy to accomodate changes in the grammar. This
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approach would be quite reasonable if the grammar changed often.
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Instead, it is rather complex to generate the appropriate code. And
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the Node interface has changed more often than the grammar.
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"""
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import fileinput
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import getopt
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import re
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import sys
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from StringIO import StringIO
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SPEC = "ast.txt"
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COMMA = ", "
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def load_boilerplate(file):
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f = open(file)
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buf = f.read()
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f.close()
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i = buf.find('### ''PROLOGUE')
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j = buf.find('### ''EPILOGUE')
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pro = buf[i+12:j].strip()
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epi = buf[j+12:].strip()
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return pro, epi
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def strip_default(arg):
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"""Return the argname from an 'arg = default' string"""
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i = arg.find('=')
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if i == -1:
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return arg
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t = arg[:i].strip()
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return t
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P_NODE = 1
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P_OTHER = 2
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P_NESTED = 3
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P_NONE = 4
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class NodeInfo:
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"""Each instance describes a specific AST node"""
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def __init__(self, name, args):
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self.name = name
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self.args = args.strip()
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self.argnames = self.get_argnames()
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self.argprops = self.get_argprops()
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self.nargs = len(self.argnames)
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self.init = []
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def get_argnames(self):
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if '(' in self.args:
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i = self.args.find('(')
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j = self.args.rfind(')')
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args = self.args[i+1:j]
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else:
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args = self.args
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return [strip_default(arg.strip())
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for arg in args.split(',') if arg]
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def get_argprops(self):
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"""Each argument can have a property like '*' or '!'
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XXX This method modifies the argnames in place!
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"""
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d = {}
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hardest_arg = P_NODE
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for i in range(len(self.argnames)):
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arg = self.argnames[i]
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if arg.endswith('*'):
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arg = self.argnames[i] = arg[:-1]
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d[arg] = P_OTHER
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hardest_arg = P_OTHER
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elif arg.endswith('!'):
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arg = self.argnames[i] = arg[:-1]
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d[arg] = P_NESTED
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hardest_arg = P_NESTED
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elif arg.endswith('&'):
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arg = self.argnames[i] = arg[:-1]
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d[arg] = P_NONE
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hardest_arg = P_NONE
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else:
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d[arg] = P_NODE
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self.hardest_arg = hardest_arg
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if hardest_arg > P_NODE:
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self.args = self.args.replace('*', '')
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self.args = self.args.replace('!', '')
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self.args = self.args.replace('&', '')
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return d
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def gen_source(self):
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buf = StringIO()
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print >> buf, "class %s(Node):" % self.name
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print >> buf, ' nodes["%s"] = "%s"' % (self.name.lower(), self.name)
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self._gen_init(buf)
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print >> buf
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self._gen_getChildren(buf)
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print >> buf
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self._gen_getChildNodes(buf)
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print >> buf
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self._gen_repr(buf)
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buf.seek(0, 0)
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return buf.read()
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def _gen_init(self, buf):
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print >> buf, " def __init__(self, %s):" % self.args
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if self.argnames:
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for name in self.argnames:
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print >> buf, " self.%s = %s" % (name, name)
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else:
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print >> buf, " pass"
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if self.init:
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print >> buf, "".join([" " + line for line in self.init])
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def _gen_getChildren(self, buf):
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print >> buf, " def getChildren(self):"
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if len(self.argnames) == 0:
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print >> buf, " return ()"
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else:
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if self.hardest_arg < P_NESTED:
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clist = COMMA.join(["self.%s" % c
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for c in self.argnames])
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if self.nargs == 1:
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print >> buf, " return %s," % clist
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else:
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print >> buf, " return %s" % clist
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else:
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print >> buf, " children = []"
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template = " children.%s(%sself.%s%s)"
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for name in self.argnames:
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if self.argprops[name] == P_NESTED:
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print >> buf, template % ("extend", "flatten(",
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name, ")")
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else:
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print >> buf, template % ("append", "", name, "")
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print >> buf, " return tuple(children)"
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def _gen_getChildNodes(self, buf):
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print >> buf, " def getChildNodes(self):"
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if len(self.argnames) == 0:
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print >> buf, " return ()"
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else:
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if self.hardest_arg < P_NESTED:
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clist = ["self.%s" % c
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for c in self.argnames
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if self.argprops[c] == P_NODE]
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if len(clist) == 0:
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print >> buf, " return ()"
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elif len(clist) == 1:
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print >> buf, " return %s," % clist[0]
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else:
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print >> buf, " return %s" % COMMA.join(clist)
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else:
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print >> buf, " nodes = []"
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template = " nodes.%s(%sself.%s%s)"
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for name in self.argnames:
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if self.argprops[name] == P_NONE:
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tmp = (" if self.%s is not None:"
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" nodes.append(self.%s)")
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print >> buf, tmp % (name, name)
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elif self.argprops[name] == P_NESTED:
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print >> buf, template % ("extend", "flatten_nodes(",
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name, ")")
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elif self.argprops[name] == P_NODE:
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print >> buf, template % ("append", "", name, "")
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print >> buf, " return tuple(nodes)"
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def _gen_repr(self, buf):
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print >> buf, " def __repr__(self):"
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if self.argnames:
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fmt = COMMA.join(["%s"] * self.nargs)
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if '(' in self.args:
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fmt = '(%s)' % fmt
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vals = ["repr(self.%s)" % name for name in self.argnames]
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vals = COMMA.join(vals)
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if self.nargs == 1:
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vals = vals + ","
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print >> buf, ' return "%s(%s)" %% (%s)' % \
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(self.name, fmt, vals)
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else:
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print >> buf, ' return "%s()"' % self.name
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rx_init = re.compile('init\((.*)\):')
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def parse_spec(file):
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classes = {}
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cur = None
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for line in fileinput.input(file):
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if line.strip().startswith('#'):
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continue
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mo = rx_init.search(line)
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if mo is None:
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if cur is None:
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# a normal entry
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try:
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name, args = line.split(':')
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except ValueError:
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continue
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classes[name] = NodeInfo(name, args)
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cur = None
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else:
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# some code for the __init__ method
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cur.init.append(line)
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else:
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# some extra code for a Node's __init__ method
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name = mo.group(1)
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cur = classes[name]
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return classes.values()
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def main():
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prologue, epilogue = load_boilerplate(sys.argv[-1])
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print prologue
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print
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classes = parse_spec(SPEC)
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for info in classes:
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print info.gen_source()
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print epilogue
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if __name__ == "__main__":
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main()
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sys.exit(0)
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### PROLOGUE
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"""Python abstract syntax node definitions
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This file is automatically generated.
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"""
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from types import TupleType, ListType
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from consts import CO_VARARGS, CO_VARKEYWORDS
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def flatten(list):
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l = []
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for elt in list:
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t = type(elt)
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if t is TupleType or t is ListType:
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for elt2 in flatten(elt):
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l.append(elt2)
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else:
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l.append(elt)
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return l
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def flatten_nodes(list):
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return [n for n in flatten(list) if isinstance(n, Node)]
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def asList(nodes):
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l = []
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for item in nodes:
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if hasattr(item, "asList"):
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l.append(item.asList())
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else:
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t = type(item)
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if t is TupleType or t is ListType:
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l.append(tuple(asList(item)))
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else:
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l.append(item)
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return l
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nodes = {}
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class Node: # an abstract base class
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lineno = None # provide a lineno for nodes that don't have one
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def getType(self):
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pass # implemented by subclass
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def getChildren(self):
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pass # implemented by subclasses
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def asList(self):
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return tuple(asList(self.getChildren()))
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def getChildNodes(self):
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pass # implemented by subclasses
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class EmptyNode(Node):
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pass
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### EPILOGUE
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klasses = globals()
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for k in nodes.keys():
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nodes[k] = klasses[nodes[k]]
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