"""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