source: vendor/python/2.5/Tools/compiler/astgen.py

Last change on this file was 3225, checked in by bird, 18 years ago

Python 2.5
File size: 9.3 KB
Line 
1"""Generate ast module from specification
2
3This script generates the ast module from a simple specification,
4which makes it easy to accomodate changes in the grammar. This
5approach would be quite reasonable if the grammar changed often.
6Instead, it is rather complex to generate the appropriate code. And
7the Node interface has changed more often than the grammar.
8"""
9
10import fileinput
11import getopt
12import re
13import sys
14from StringIO import StringIO
15
16SPEC = "ast.txt"
17COMMA = ", "
18
19def load_boilerplate(file):
20 f = open(file)
21 buf = f.read()
22 f.close()
23 i = buf.find('### ''PROLOGUE')
24 j = buf.find('### ''EPILOGUE')
25 pro = buf[i+12:j].strip()
26 epi = buf[j+12:].strip()
27 return pro, epi
28
29def strip_default(arg):
30 """Return the argname from an 'arg = default' string"""
31 i = arg.find('=')
32 if i == -1:
33 return arg
34 t = arg[:i].strip()
35 return t
36
37P_NODE = 1
38P_OTHER = 2
39P_NESTED = 3
40P_NONE = 4
41
42class NodeInfo:
43 """Each instance describes a specific AST node"""
44 def __init__(self, name, args):
45 self.name = name
46 self.args = args.strip()
47 self.argnames = self.get_argnames()
48 self.argprops = self.get_argprops()
49 self.nargs = len(self.argnames)
50 self.init = []
51
52 def get_argnames(self):
53 if '(' in self.args:
54 i = self.args.find('(')
55 j = self.args.rfind(')')
56 args = self.args[i+1:j]
57 else:
58 args = self.args
59 return [strip_default(arg.strip())
60 for arg in args.split(',') if arg]
61
62 def get_argprops(self):
63 """Each argument can have a property like '*' or '!'
64
65 XXX This method modifies the argnames in place!
66 """
67 d = {}
68 hardest_arg = P_NODE
69 for i in range(len(self.argnames)):
70 arg = self.argnames[i]
71 if arg.endswith('*'):
72 arg = self.argnames[i] = arg[:-1]
73 d[arg] = P_OTHER
74 hardest_arg = max(hardest_arg, P_OTHER)
75 elif arg.endswith('!'):
76 arg = self.argnames[i] = arg[:-1]
77 d[arg] = P_NESTED
78 hardest_arg = max(hardest_arg, P_NESTED)
79 elif arg.endswith('&'):
80 arg = self.argnames[i] = arg[:-1]
81 d[arg] = P_NONE
82 hardest_arg = max(hardest_arg, P_NONE)
83 else:
84 d[arg] = P_NODE
85 self.hardest_arg = hardest_arg
86
87 if hardest_arg > P_NODE:
88 self.args = self.args.replace('*', '')
89 self.args = self.args.replace('!', '')
90 self.args = self.args.replace('&', '')
91
92 return d
93
94 def gen_source(self):
95 buf = StringIO()
96 print >> buf, "class %s(Node):" % self.name
97 self._gen_init(buf)
98 print >> buf
99 self._gen_getChildren(buf)
100 print >> buf
101 self._gen_getChildNodes(buf)
102 print >> buf
103 self._gen_repr(buf)
104 buf.seek(0, 0)
105 return buf.read()
106
107 def _gen_init(self, buf):
108 if self.args:
109 print >> buf, " def __init__(self, %s, lineno=None):" % self.args
110 else:
111 print >> buf, " def __init__(self, lineno=None):"
112 if self.argnames:
113 for name in self.argnames:
114 print >> buf, " self.%s = %s" % (name, name)
115 print >> buf, " self.lineno = lineno"
116 # Copy the lines in self.init, indented four spaces. The rstrip()
117 # business is to get rid of the four spaces if line happens to be
118 # empty, so that reindent.py is happy with the output.
119 for line in self.init:
120 print >> buf, (" " + line).rstrip()
121
122 def _gen_getChildren(self, buf):
123 print >> buf, " def getChildren(self):"
124 if len(self.argnames) == 0:
125 print >> buf, " return ()"
126 else:
127 if self.hardest_arg < P_NESTED:
128 clist = COMMA.join(["self.%s" % c
129 for c in self.argnames])
130 if self.nargs == 1:
131 print >> buf, " return %s," % clist
132 else:
133 print >> buf, " return %s" % clist
134 else:
135 if len(self.argnames) == 1:
136 print >> buf, " return tuple(flatten(self.%s))" % self.argnames[0]
137 else:
138 print >> buf, " children = []"
139 template = " children.%s(%sself.%s%s)"
140 for name in self.argnames:
141 if self.argprops[name] == P_NESTED:
142 print >> buf, template % ("extend", "flatten(",
143 name, ")")
144 else:
145 print >> buf, template % ("append", "", name, "")
146 print >> buf, " return tuple(children)"
147
148 def _gen_getChildNodes(self, buf):
149 print >> buf, " def getChildNodes(self):"
150 if len(self.argnames) == 0:
151 print >> buf, " return ()"
152 else:
153 if self.hardest_arg < P_NESTED:
154 clist = ["self.%s" % c
155 for c in self.argnames
156 if self.argprops[c] == P_NODE]
157 if len(clist) == 0:
158 print >> buf, " return ()"
159 elif len(clist) == 1:
160 print >> buf, " return %s," % clist[0]
161 else:
162 print >> buf, " return %s" % COMMA.join(clist)
163 else:
164 print >> buf, " nodelist = []"
165 template = " nodelist.%s(%sself.%s%s)"
166 for name in self.argnames:
167 if self.argprops[name] == P_NONE:
168 tmp = (" if self.%s is not None:\n"
169 " nodelist.append(self.%s)")
170 print >> buf, tmp % (name, name)
171 elif self.argprops[name] == P_NESTED:
172 print >> buf, template % ("extend", "flatten_nodes(",
173 name, ")")
174 elif self.argprops[name] == P_NODE:
175 print >> buf, template % ("append", "", name, "")
176 print >> buf, " return tuple(nodelist)"
177
178 def _gen_repr(self, buf):
179 print >> buf, " def __repr__(self):"
180 if self.argnames:
181 fmt = COMMA.join(["%s"] * self.nargs)
182 if '(' in self.args:
183 fmt = '(%s)' % fmt
184 vals = ["repr(self.%s)" % name for name in self.argnames]
185 vals = COMMA.join(vals)
186 if self.nargs == 1:
187 vals = vals + ","
188 print >> buf, ' return "%s(%s)" %% (%s)' % \
189 (self.name, fmt, vals)
190 else:
191 print >> buf, ' return "%s()"' % self.name
192
193rx_init = re.compile('init\((.*)\):')
194
195def parse_spec(file):
196 classes = {}
197 cur = None
198 for line in fileinput.input(file):
199 if line.strip().startswith('#'):
200 continue
201 mo = rx_init.search(line)
202 if mo is None:
203 if cur is None:
204 # a normal entry
205 try:
206 name, args = line.split(':')
207 except ValueError:
208 continue
209 classes[name] = NodeInfo(name, args)
210 cur = None
211 else:
212 # some code for the __init__ method
213 cur.init.append(line)
214 else:
215 # some extra code for a Node's __init__ method
216 name = mo.group(1)
217 cur = classes[name]
218 return sorted(classes.values(), key=lambda n: n.name)
219
220def main():
221 prologue, epilogue = load_boilerplate(sys.argv[-1])
222 print prologue
223 print
224 classes = parse_spec(SPEC)
225 for info in classes:
226 print info.gen_source()
227 print epilogue
228
229if __name__ == "__main__":
230 main()
231 sys.exit(0)
232
233### PROLOGUE
234"""Python abstract syntax node definitions
235
236This file is automatically generated by Tools/compiler/astgen.py
237"""
238from consts import CO_VARARGS, CO_VARKEYWORDS
239
240def flatten(seq):
241 l = []
242 for elt in seq:
243 t = type(elt)
244 if t is tuple or t is list:
245 for elt2 in flatten(elt):
246 l.append(elt2)
247 else:
248 l.append(elt)
249 return l
250
251def flatten_nodes(seq):
252 return [n for n in flatten(seq) if isinstance(n, Node)]
253
254nodes = {}
255
256class Node:
257 """Abstract base class for ast nodes."""
258 def getChildren(self):
259 pass # implemented by subclasses
260 def __iter__(self):
261 for n in self.getChildren():
262 yield n
263 def asList(self): # for backwards compatibility
264 return self.getChildren()
265 def getChildNodes(self):
266 pass # implemented by subclasses
267
268class EmptyNode(Node):
269 pass
270
271class Expression(Node):
272 # Expression is an artificial node class to support "eval"
273 nodes["expression"] = "Expression"
274 def __init__(self, node):
275 self.node = node
276
277 def getChildren(self):
278 return self.node,
279
280 def getChildNodes(self):
281 return self.node,
282
283 def __repr__(self):
284 return "Expression(%s)" % (repr(self.node))
285
286### EPILOGUE
287for name, obj in globals().items():
288 if isinstance(obj, type) and issubclass(obj, Node):
289 nodes[name.lower()] = obj
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