python/Tools/compiler/astgen.py at master · java66liu/python · GitHub

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"""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

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

python/Tools/compiler/astgen.py at master · java66liu/python · GitHub

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