Support for generation of ast.py from simple description of node

structure (ast.txt).  Usage is python astgen.py > ast.py.

Tools/compiler/astgen.py

@@ -0,0 +1,182 @@
+"""Generate ast module from specification"""
+
+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
+    return arg[:i].strip()
+
+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.nargs = len(self.argnames)
+        self.children = COMMA.join(["self.%s" % c
+                                    for c in 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 gen_source(self):
+        buf = StringIO()
+        print >> buf, "class %s(Node):" % self.name
+        print >> buf, '    nodes["%s"] = "%s"' % (self.name.lower(), self.name)
+        self._gen_init(buf)
+        self._gen_getChildren(buf)
+        self._gen_repr(buf)
+        buf.seek(0, 0)
+        return buf.read()
+
+    def _gen_init(self, buf):
+        print >> buf, "    def __init__(self, %s):" % self.args
+        if self.argnames:
+            for name in self.argnames:
+                print >> buf, "        self.%s = %s" % (name, name)
+        else:
+            print >> buf, "        pass"
+        if self.init:
+            print >> buf, "".join(["    " + line for line in self.init])
+
+    def _gen_getChildren(self, buf):
+        print >> buf, "    def _getChildren(self):"
+        if self.argnames:
+            if self.nargs == 1:
+                print >> buf, "        return %s," % self.children
+            else:
+                print >> buf, "        return %s" % self.children
+        else:
+            print >> buf, "        return ()"
+
+    def _gen_repr(self, buf):
+        print >> buf, "    def __repr__(self):"
+        if self.argnames:
+            fmt = COMMA.join(["%s"] * self.nargs)
+            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):
+        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 classes.values()
+
+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.
+"""
+from types import TupleType, ListType
+from consts import CO_VARARGS, CO_VARKEYWORDS
+
+def flatten(list):
+    l = []
+    for elt in list:
+        t = type(elt)
+        if t is TupleType or t is ListType:
+            for elt2 in flatten(elt):
+                l.append(elt2)
+        else:
+            l.append(elt)
+    return l
+
+def asList(nodes):
+    l = []
+    for item in nodes:
+        if hasattr(item, "asList"):
+            l.append(item.asList())
+        else:
+            t = type(item)
+            if t is TupleType or t is ListType:
+                l.append(tuple(asList(item)))
+            else:
+                l.append(item)
+    return l
+
+nodes = {}
+
+class Node:
+    lineno = None
+    def getType(self):
+        pass
+    def getChildren(self):
+        # XXX It would be better to generate flat values to begin with
+        return flatten(self._getChildren())
+    def asList(self):
+        return tuple(asList(self.getChildren()))
+
+class EmptyNode(Node):
+    def __init__(self):
+        self.lineno = None
+
+### EPILOGUE
+klasses = globals()
+for k in nodes.keys():
+    nodes[k] = klasses[nodes[k]]