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Revise implementations of getChildren() and getChildNodes().
Add support for floor division (// and //=) The implementation of getChildren() and getChildNodes() is intended to be faster, because it avoids calling flatten() on every return value. But it's not clear that it is a lot faster, because constructing a tuple with just the right values ends up being slow. (Too many attribute lookups probably.) The ast.txt file is much more complicated, with funny characters at the ends of names (*, &, !) to indicate the types of each child node. The astgen script is also much more complex, making me wonder if it's still useful.
This commit is contained in:
Jeremy Hylton
parent
96d68d57be
commit
5477f529d6
6 changed files with 1530 additions and 320 deletions
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@ -1,4 +1,11 @@
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"""Generate ast module from specification"""
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"""Generate ast module from specification
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This script generates the ast module from a simple specification,
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which makes it easy to accomodate changes in the grammar. This
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approach would be quite reasonable if the grammar changed often.
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Instead, it is rather complex to generate the appropriate code. And
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the Node interface has changed more often than the grammar.
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"""
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import fileinput
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import getopt
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@ -24,7 +31,13 @@ def strip_default(arg):
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i = arg.find('=')
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if i == -1:
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return arg
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return arg[:i].strip()
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t = arg[:i].strip()
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return t
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P_NODE = 1
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P_OTHER = 2
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P_NESTED = 3
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P_NONE = 4
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class NodeInfo:
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"""Each instance describes a specific AST node"""
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@ -32,9 +45,8 @@ class NodeInfo:
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self.name = name
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self.args = args.strip()
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self.argnames = self.get_argnames()
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self.argprops = self.get_argprops()
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self.nargs = len(self.argnames)
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self.children = COMMA.join(["self.%s" % c
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for c in self.argnames])
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self.init = []
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def get_argnames(self):
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@ -47,12 +59,48 @@ class NodeInfo:
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return [strip_default(arg.strip())
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for arg in args.split(',') if arg]
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def get_argprops(self):
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"""Each argument can have a property like '*' or '!'
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XXX This method modifies the argnames in place!
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"""
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d = {}
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hardest_arg = P_NODE
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for i in range(len(self.argnames)):
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arg = self.argnames[i]
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if arg.endswith('*'):
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arg = self.argnames[i] = arg[:-1]
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d[arg] = P_OTHER
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hardest_arg = P_OTHER
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elif arg.endswith('!'):
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arg = self.argnames[i] = arg[:-1]
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d[arg] = P_NESTED
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hardest_arg = P_NESTED
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elif arg.endswith('&'):
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arg = self.argnames[i] = arg[:-1]
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d[arg] = P_NONE
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hardest_arg = P_NONE
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else:
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d[arg] = P_NODE
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self.hardest_arg = hardest_arg
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if hardest_arg > P_NODE:
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self.args = self.args.replace('*', '')
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self.args = self.args.replace('!', '')
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self.args = self.args.replace('&', '')
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return d
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def gen_source(self):
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buf = StringIO()
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print >> buf, "class %s(Node):" % self.name
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print >> buf, ' nodes["%s"] = "%s"' % (self.name.lower(), self.name)
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self._gen_init(buf)
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print >> buf
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self._gen_getChildren(buf)
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print >> buf
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self._gen_getChildNodes(buf)
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print >> buf
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self._gen_repr(buf)
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buf.seek(0, 0)
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return buf.read()
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@ -68,14 +116,57 @@ class NodeInfo:
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print >> buf, "".join([" " + line for line in self.init])
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def _gen_getChildren(self, buf):
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print >> buf, " def _getChildren(self):"
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if self.argnames:
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if self.nargs == 1:
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print >> buf, " return %s," % self.children
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else:
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print >> buf, " return %s" % self.children
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else:
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print >> buf, " def getChildren(self):"
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if len(self.argnames) == 0:
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print >> buf, " return ()"
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else:
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if self.hardest_arg < P_NESTED:
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clist = COMMA.join(["self.%s" % c
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for c in self.argnames])
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if self.nargs == 1:
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print >> buf, " return %s," % clist
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else:
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print >> buf, " return %s" % clist
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else:
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print >> buf, " children = []"
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template = " children.%s(%sself.%s%s)"
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for name in self.argnames:
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if self.argprops[name] == P_NESTED:
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print >> buf, template % ("extend", "flatten(",
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name, ")")
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else:
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print >> buf, template % ("append", "", name, "")
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print >> buf, " return tuple(children)"
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def _gen_getChildNodes(self, buf):
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print >> buf, " def getChildNodes(self):"
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if len(self.argnames) == 0:
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print >> buf, " return ()"
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else:
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if self.hardest_arg < P_NESTED:
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clist = ["self.%s" % c
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for c in self.argnames
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if self.argprops[c] == P_NODE]
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if len(clist) == 0:
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print >> buf, " return ()"
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elif len(clist) == 1:
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print >> buf, " return %s," % clist[0]
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else:
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print >> buf, " return %s" % COMMA.join(clist)
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else:
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print >> buf, " nodes = []"
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template = " nodes.%s(%sself.%s%s)"
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for name in self.argnames:
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if self.argprops[name] == P_NONE:
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tmp = (" if self.%s is not None:"
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" nodes.append(self.%s)")
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print >> buf, tmp % (name, name)
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elif self.argprops[name] == P_NESTED:
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print >> buf, template % ("extend", "flatten_nodes(",
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name, ")")
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elif self.argprops[name] == P_NODE:
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print >> buf, template % ("append", "", name, "")
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print >> buf, " return tuple(nodes)"
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def _gen_repr(self, buf):
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print >> buf, " def __repr__(self):"
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@ -98,6 +189,8 @@ def parse_spec(file):
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classes = {}
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cur = None
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for line in fileinput.input(file):
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if line.strip().startswith('#'):
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continue
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mo = rx_init.search(line)
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if mo is None:
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if cur is None:
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@ -149,6 +242,9 @@ def flatten(list):
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l.append(elt)
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return l
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def flatten_nodes(list):
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return [n for n in flatten(list) if isinstance(n, Node)]
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def asList(nodes):
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l = []
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for item in nodes:
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@ -164,21 +260,19 @@ def asList(nodes):
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nodes = {}
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class Node:
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lineno = None
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class Node: # an abstract base class
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lineno = None # provide a lineno for nodes that don't have one
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def getType(self):
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pass
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pass # implemented by subclass
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def getChildren(self):
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# XXX It would be better to generate flat values to begin with
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return flatten(self._getChildren())
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pass # implemented by subclasses
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def asList(self):
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return tuple(asList(self.getChildren()))
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def getChildNodes(self):
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return [n for n in self.getChildren() if isinstance(n, Node)]
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pass # implemented by subclasses
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class EmptyNode(Node):
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def __init__(self):
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self.lineno = None
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pass
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### EPILOGUE
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klasses = globals()
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