diff options
Diffstat (limited to 'Tools/compiler/astgen.py')
| -rw-r--r-- | Tools/compiler/astgen.py | 130 |
1 files changed, 112 insertions, 18 deletions
diff --git a/Tools/compiler/astgen.py b/Tools/compiler/astgen.py index c0eb464..245eebd 100644 --- a/Tools/compiler/astgen.py +++ b/Tools/compiler/astgen.py @@ -1,4 +1,11 @@ -"""Generate ast module from specification""" +"""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 @@ -24,7 +31,13 @@ def strip_default(arg): i = arg.find('=') if i == -1: return arg - return arg[:i].strip() + 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""" @@ -32,9 +45,8 @@ class NodeInfo: self.name = name self.args = args.strip() self.argnames = self.get_argnames() + self.argprops = self.get_argprops() self.nargs = len(self.argnames) - self.children = COMMA.join(["self.%s" % c - for c in self.argnames]) self.init = [] def get_argnames(self): @@ -47,12 +59,48 @@ class NodeInfo: 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 = P_OTHER + elif arg.endswith('!'): + arg = self.argnames[i] = arg[:-1] + d[arg] = P_NESTED + hardest_arg = P_NESTED + elif arg.endswith('&'): + arg = self.argnames[i] = arg[:-1] + d[arg] = P_NONE + 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 print >> buf, ' nodes["%s"] = "%s"' % (self.name.lower(), 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() @@ -68,14 +116,57 @@ class NodeInfo: 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 + 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: + 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, " nodes = []" + template = " nodes.%s(%sself.%s%s)" + for name in self.argnames: + if self.argprops[name] == P_NONE: + tmp = (" if self.%s is not None:" + " nodes.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(nodes)" def _gen_repr(self, buf): print >> buf, " def __repr__(self):" @@ -98,6 +189,8 @@ 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: @@ -149,6 +242,9 @@ def flatten(list): l.append(elt) return l +def flatten_nodes(list): + return [n for n in flatten(list) if isinstance(n, Node)] + def asList(nodes): l = [] for item in nodes: @@ -164,21 +260,19 @@ def asList(nodes): nodes = {} -class Node: - lineno = None +class Node: # an abstract base class + lineno = None # provide a lineno for nodes that don't have one def getType(self): - pass + pass # implemented by subclass def getChildren(self): - # XXX It would be better to generate flat values to begin with - return flatten(self._getChildren()) + pass # implemented by subclasses def asList(self): return tuple(asList(self.getChildren())) def getChildNodes(self): - return [n for n in self.getChildren() if isinstance(n, Node)] + pass # implemented by subclasses class EmptyNode(Node): - def __init__(self): - self.lineno = None + pass ### EPILOGUE klasses = globals() |