mirror of
https://github.com/python/cpython
synced 2024-10-16 21:24:34 +00:00
ca4d08b6d3
happy with the output as-is. This incidentally also gets rid of "an extra" blank line at the end of the output block that probably wasn't intended (although it doesn't matter one way or the other).
290 lines
9.3 KiB
Python
290 lines
9.3 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 = max(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 = max(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 = max(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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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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if self.args:
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print >> buf, " def __init__(self, %s, lineno=None):" % self.args
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else:
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print >> buf, " def __init__(self, lineno=None):"
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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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print >> buf, " self.lineno = lineno"
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# Copy the lines in self.init, indented four spaces. The rstrip()
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# business is to get rid of the four spaces if line happens to be
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# empty, so that reindent.py is happy with the output.
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for line in self.init:
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print >> buf, (" " + line).rstrip()
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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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if len(self.argnames) == 1:
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print >> buf, " return tuple(flatten(self.%s))" % self.argnames[0]
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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, " nodelist = []"
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template = " nodelist.%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:\n"
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" nodelist.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(nodelist)"
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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 sorted(classes.values(), key=lambda n: n.name)
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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 by Tools/compiler/astgen.py
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"""
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from consts import CO_VARARGS, CO_VARKEYWORDS
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def flatten(seq):
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l = []
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for elt in seq:
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t = type(elt)
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if t is tuple or t is list:
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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(seq):
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return [n for n in flatten(seq) if isinstance(n, Node)]
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nodes = {}
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class Node:
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"""Abstract base class for ast nodes."""
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def getChildren(self):
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pass # implemented by subclasses
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def __iter__(self):
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for n in self.getChildren():
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yield n
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def asList(self): # for backwards compatibility
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return 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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class Expression(Node):
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# Expression is an artificial node class to support "eval"
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nodes["expression"] = "Expression"
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def __init__(self, node):
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self.node = node
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def getChildren(self):
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return self.node,
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def getChildNodes(self):
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return self.node,
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def __repr__(self):
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return "Expression(%s)" % (repr(self.node))
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### EPILOGUE
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for name, obj in globals().items():
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if isinstance(obj, type) and issubclass(obj, Node):
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nodes[name.lower()] = obj
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