ref: 57d690c482c7e5f57608befe7cb04797b1bff153
dir: /sys/src/cmd/python/Tools/compiler/astgen.py/
"""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 getopt 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