| """Generate ast module from specification
|
|
|
| This script generates the ast module from a simple specification,
|
| which makes it easy to accomodate changes in the grammar. This
|
| 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
|
| the Node interface has changed more often than the grammar.
|
| """
|
|
|
| import fileinput
|
| import re
|
| import sys
|
| from StringIO import StringIO
|
|
|
| SPEC = "ast.txt"
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| COMMA = ", "
|
|
|
| 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
|
|
|
| def strip_default(arg):
|
| """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
|
| t = arg[:i].strip()
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| return t
|
|
|
| P_NODE = 1
|
| P_OTHER = 2
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| P_NESTED = 3
|
| P_NONE = 4
|
|
|
| class NodeInfo:
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| """Each instance describes a specific AST node"""
|
| 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):
|
| 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]
|
|
|
| def get_argprops(self):
|
| """Each argument can have a property like '*' or '!'
|
|
|
| XXX This method modifies the argnames in place!
|
| """
|
| d = {}
|
| hardest_arg = P_NODE
|
| for i in range(len(self.argnames)):
|
| arg = self.argnames[i]
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| if arg.endswith('*'):
|
| arg = self.argnames[i] = arg[:-1]
|
| d[arg] = P_OTHER
|
| hardest_arg = max(hardest_arg, P_OTHER)
|
| elif arg.endswith('!'):
|
| arg = self.argnames[i] = arg[:-1]
|
| d[arg] = P_NESTED
|
| hardest_arg = max(hardest_arg, P_NESTED)
|
| elif arg.endswith('&'):
|
| arg = self.argnames[i] = arg[:-1]
|
| d[arg] = P_NONE
|
| hardest_arg = max(hardest_arg, P_NONE)
|
| else:
|
| d[arg] = P_NODE
|
| self.hardest_arg = hardest_arg
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|
|
| if hardest_arg > P_NODE:
|
| self.args = self.args.replace('*', '')
|
| self.args = self.args.replace('!', '')
|
| self.args = self.args.replace('&', '')
|
|
|
| return d
|
|
|
| def gen_source(self):
|
| buf = StringIO()
|
| print >> buf, "class %s(Node):" % self.name
|
| 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
|
| self._gen_repr(buf)
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| buf.seek(0, 0)
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| return buf.read()
|
|
|
| def _gen_init(self, buf):
|
| if self.args:
|
| argtuple = '(' in self.args
|
| args = self.args if not argtuple else ''.join(self.argnames)
|
| print >> buf, " def __init__(self, %s, lineno=None):" % args
|
| else:
|
| print >> buf, " def __init__(self, lineno=None):"
|
| if self.argnames:
|
| if argtuple:
|
| for idx, name in enumerate(self.argnames):
|
| print >> buf, " self.%s = %s[%s]" % (name, args, idx)
|
| else:
|
| for name in self.argnames:
|
| print >> buf, " self.%s = %s" % (name, name)
|
| print >> buf, " self.lineno = lineno"
|
| # Copy the lines in self.init, indented four spaces. The rstrip()
|
| # business is to get rid of the four spaces if line happens to be
|
| # empty, so that reindent.py is happy with the output.
|
| for line in self.init:
|
| print >> buf, (" " + line).rstrip()
|
|
|
| def _gen_getChildren(self, buf):
|
| print >> buf, " def getChildren(self):"
|
| if len(self.argnames) == 0:
|
| print >> buf, " return ()"
|
| else:
|
| if self.hardest_arg < P_NESTED:
|
| clist = COMMA.join(["self.%s" % c
|
| for c in self.argnames])
|
| if self.nargs == 1:
|
| print >> buf, " return %s," % clist
|
| else:
|
| print >> buf, " return %s" % clist
|
| else:
|
| if len(self.argnames) == 1:
|
| print >> buf, " return tuple(flatten(self.%s))" % self.argnames[0]
|
| else:
|
| print >> buf, " children = []"
|
| template = " children.%s(%sself.%s%s)"
|
| for name in self.argnames:
|
| if self.argprops[name] == P_NESTED:
|
| print >> buf, template % ("extend", "flatten(",
|
| name, ")")
|
| else:
|
| print >> buf, template % ("append", "", name, "")
|
| print >> buf, " return tuple(children)"
|
|
|
| def _gen_getChildNodes(self, buf):
|
| print >> buf, " def getChildNodes(self):"
|
| if len(self.argnames) == 0:
|
| print >> buf, " return ()"
|
| else:
|
| if self.hardest_arg < P_NESTED:
|
| clist = ["self.%s" % c
|
| for c in self.argnames
|
| if self.argprops[c] == P_NODE]
|
| if len(clist) == 0:
|
| print >> buf, " return ()"
|
| elif len(clist) == 1:
|
| print >> buf, " return %s," % clist[0]
|
| else:
|
| print >> buf, " return %s" % COMMA.join(clist)
|
| else:
|
| print >> buf, " nodelist = []"
|
| template = " nodelist.%s(%sself.%s%s)"
|
| for name in self.argnames:
|
| if self.argprops[name] == P_NONE:
|
| tmp = (" if self.%s is not None:\n"
|
| " nodelist.append(self.%s)")
|
| print >> buf, tmp % (name, name)
|
| elif self.argprops[name] == P_NESTED:
|
| print >> buf, template % ("extend", "flatten_nodes(",
|
| name, ")")
|
| elif self.argprops[name] == P_NODE:
|
| print >> buf, template % ("append", "", name, "")
|
| print >> buf, " return tuple(nodelist)"
|
|
|
| def _gen_repr(self, buf):
|
| print >> buf, " def __repr__(self):"
|
| if self.argnames:
|
| fmt = COMMA.join(["%s"] * self.nargs)
|
| if '(' in self.args:
|
| fmt = '(%s)' % fmt
|
| vals = ["repr(self.%s)" % name for name in self.argnames]
|
| vals = COMMA.join(vals)
|
| if self.nargs == 1:
|
| vals = vals + ","
|
| print >> buf, ' return "%s(%s)" %% (%s)' % \
|
| (self.name, fmt, vals)
|
| else:
|
| print >> buf, ' return "%s()"' % self.name
|
|
|
| rx_init = re.compile('init\((.*)\):')
|
|
|
| def parse_spec(file):
|
| classes = {}
|
| cur = None
|
| for line in fileinput.input(file):
|
| if line.strip().startswith('#'):
|
| continue
|
| mo = rx_init.search(line)
|
| if mo is None:
|
| if cur is None:
|
| # a normal entry
|
| try:
|
| name, args = line.split(':')
|
| except ValueError:
|
| continue
|
| classes[name] = NodeInfo(name, args)
|
| cur = None
|
| else:
|
| # some code for the __init__ method
|
| cur.init.append(line)
|
| else:
|
| # some extra code for a Node's __init__ method
|
| name = mo.group(1)
|
| cur = classes[name]
|
| return sorted(classes.values(), key=lambda n: n.name)
|
|
|
| def main():
|
| prologue, epilogue = load_boilerplate(sys.argv[-1])
|
| print prologue
|
| print
|
| classes = parse_spec(SPEC)
|
| for info in classes:
|
| print info.gen_source()
|
| print epilogue
|
|
|
| if __name__ == "__main__":
|
| main()
|
| sys.exit(0)
|
|
|
| ### PROLOGUE
|
| """Python abstract syntax node definitions
|
|
|
| This file is automatically generated by Tools/compiler/astgen.py
|
| """
|
| from consts import CO_VARARGS, CO_VARKEYWORDS
|
|
|
| def flatten(seq):
|
| l = []
|
| for elt in seq:
|
| t = type(elt)
|
| if t is tuple or t is list:
|
| for elt2 in flatten(elt):
|
| l.append(elt2)
|
| else:
|
| l.append(elt)
|
| return l
|
|
|
| def flatten_nodes(seq):
|
| return [n for n in flatten(seq) if isinstance(n, Node)]
|
|
|
| nodes = {}
|
|
|
| class Node:
|
| """Abstract base class for ast nodes."""
|
| def getChildren(self):
|
| pass # implemented by subclasses
|
| def __iter__(self):
|
| for n in self.getChildren():
|
| yield n
|
| def asList(self): # for backwards compatibility
|
| return self.getChildren()
|
| def getChildNodes(self):
|
| pass # implemented by subclasses
|
|
|
| class EmptyNode(Node):
|
| pass
|
|
|
| class Expression(Node):
|
| # Expression is an artificial node class to support "eval"
|
| nodes["expression"] = "Expression"
|
| def __init__(self, node):
|
| self.node = node
|
|
|
| def getChildren(self):
|
| return self.node,
|
|
|
| def getChildNodes(self):
|
| return self.node,
|
|
|
| def __repr__(self):
|
| return "Expression(%s)" % (repr(self.node))
|
|
|
| ### EPILOGUE
|
| for name, obj in globals().items():
|
| if isinstance(obj, type) and issubclass(obj, Node):
|
| nodes[name.lower()] = obj
|
