"""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.
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"
COMMA = ", "

def load_boilerplate(file):
 f = open(file)
 buf = f.read()
 f.close()
 i = buf.find('### ''PROLOGUE')
 j = buf.find('### ''EPILOGUE')
 pro = buf[i+12:j].strip()
 epi = buf[j+12:].strip()
 return pro, epi

def strip_default(arg):
 """Return the argname from an 'arg = default' string"""
 i = arg.find('=')
 if i == -1:
 return arg
 t = arg[:i].strip()
 return t

P_NODE = 1
P_OTHER = 2
P_NESTED = 3
P_NONE = 4

class NodeInfo:
 """Each instance describes a specific AST node"""
 def __init__(self, name, args):
 self.name = name
 self.args = args.strip()
 self.argnames = self.get_argnames()
 self.argprops = self.get_argprops()
 self.nargs = len(self.argnames)
 self.init = []

 def get_argnames(self):
 if '(' in self.args:
 i = self.args.find('(')
 j = self.args.rfind(')')
 args = self.args[i+1:j]
 else:
 args = self.args
 return [strip_default(arg.strip())
 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]
 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

 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)
 print >> buf
 self._gen_getChildren(buf)
 print >> buf
 self._gen_getChildNodes(buf)
 print >> buf
 self._gen_repr(buf)
 buf.seek(0, 0)
 return buf.read()

 def _gen_init(self, buf):
 if self.args:
 print >> buf, " def __init__(self, %s, lineno=None):" % self.args
 else:
 print >> buf, " def __init__(self, lineno=None):"
 if self.argnames:
 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