source: python/vendor/Python-2.6.5/Tools/compiler/astgen.py

Last change on this file was 2, checked in by Yuri Dario, 15 years ago

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