1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
|
"""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
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()
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 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, " 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:"
" 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.
"""
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 flatten_nodes(list):
return [n for n in flatten(list) if isinstance(n, Node)]
def asList(nodearg):
l = []
for item in nodearg:
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: # an abstract base class
lineno = None # provide a lineno for nodes that don't have one
def getType(self):
pass # implemented by subclass
def getChildren(self):
pass # implemented by subclasses
def asList(self):
return tuple(asList(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
klasses = globals()
for k in nodes.keys():
nodes[k] = klasses[nodes[k]]
|
