/Demo/parser/unparse.py

  1"Usage: unparse.py <path to source file>"
  2import sys
  3import _ast
  4import cStringIO
  5import os
  6
  7def interleave(inter, f, seq):
  8    """Call f on each item in seq, calling inter() in between.
  9    """
 10    seq = iter(seq)
 11    try:
 12        f(seq.next())
 13    except StopIteration:
 14        pass
 15    else:
 16        for x in seq:
 17            inter()
 18            f(x)
 19
 20class Unparser:
 21    """Methods in this class recursively traverse an AST and
 22    output source code for the abstract syntax; original formatting
 23    is disregarged. """
 24
 25    def __init__(self, tree, file = sys.stdout):
 26        """Unparser(tree, file=sys.stdout) -> None.
 27         Print the source for tree to file."""
 28        self.f = file
 29        self._indent = 0
 30        self.dispatch(tree)
 31        print >>self.f,""
 32        self.f.flush()
 33
 34    def fill(self, text = ""):
 35        "Indent a piece of text, according to the current indentation level"
 36        self.f.write("\n"+"    "*self._indent + text)
 37
 38    def write(self, text):
 39        "Append a piece of text to the current line."
 40        self.f.write(text)
 41
 42    def enter(self):
 43        "Print ':', and increase the indentation."
 44        self.write(":")
 45        self._indent += 1
 46
 47    def leave(self):
 48        "Decrease the indentation level."
 49        self._indent -= 1
 50
 51    def dispatch(self, tree):
 52        "Dispatcher function, dispatching tree type T to method _T."
 53        if isinstance(tree, list):
 54            for t in tree:
 55                self.dispatch(t)
 56            return
 57        meth = getattr(self, "_"+tree.__class__.__name__)
 58        meth(tree)
 59
 60
 61    ############### Unparsing methods ######################
 62    # There should be one method per concrete grammar type #
 63    # Constructors should be grouped by sum type. Ideally, #
 64    # this would follow the order in the grammar, but      #
 65    # currently doesn't.                                   #
 66    ########################################################
 67
 68    def _Module(self, tree):
 69        for stmt in tree.body:
 70            self.dispatch(stmt)
 71
 72    # stmt
 73    def _Expr(self, tree):
 74        self.fill()
 75        self.dispatch(tree.value)
 76
 77    def _Import(self, t):
 78        self.fill("import ")
 79        interleave(lambda: self.write(", "), self.dispatch, t.names)
 80
 81    def _ImportFrom(self, t):
 82        self.fill("from ")
 83        self.write(t.module)
 84        self.write(" import ")
 85        interleave(lambda: self.write(", "), self.dispatch, t.names)
 86        # XXX(jpe) what is level for?
 87
 88    def _Assign(self, t):
 89        self.fill()
 90        for target in t.targets:
 91            self.dispatch(target)
 92            self.write(" = ")
 93        self.dispatch(t.value)
 94
 95    def _AugAssign(self, t):
 96        self.fill()
 97        self.dispatch(t.target)
 98        self.write(" "+self.binop[t.op.__class__.__name__]+"= ")
 99        self.dispatch(t.value)
100
101    def _Return(self, t):
102        self.fill("return")
103        if t.value:
104            self.write(" ")
105            self.dispatch(t.value)
106
107    def _Pass(self, t):
108        self.fill("pass")
109
110    def _Break(self, t):
111        self.fill("break")
112
113    def _Continue(self, t):
114        self.fill("continue")
115
116    def _Delete(self, t):
117        self.fill("del ")
118        self.dispatch(t.targets)
119
120    def _Assert(self, t):
121        self.fill("assert ")
122        self.dispatch(t.test)
123        if t.msg:
124            self.write(", ")
125            self.dispatch(t.msg)
126
127    def _Exec(self, t):
128        self.fill("exec ")
129        self.dispatch(t.body)
130        if t.globals:
131            self.write(" in ")
132            self.dispatch(t.globals)
133        if t.locals:
134            self.write(", ")
135            self.dispatch(t.locals)
136
137    def _Print(self, t):
138        self.fill("print ")
139        do_comma = False
140        if t.dest:
141            self.write(">>")
142            self.dispatch(t.dest)
143            do_comma = True
144        for e in t.values:
145            if do_comma:self.write(", ")
146            else:do_comma=True
147            self.dispatch(e)
148        if not t.nl:
149            self.write(",")
150
151    def _Global(self, t):
152        self.fill("global ")
153        interleave(lambda: self.write(", "), self.write, t.names)
154
155    def _Yield(self, t):
156        self.write("(")
157        self.write("yield")
158        if t.value:
159            self.write(" ")
160            self.dispatch(t.value)
161        self.write(")")
162
163    def _Raise(self, t):
164        self.fill('raise ')
165        if t.type:
166            self.dispatch(t.type)
167        if t.inst:
168            self.write(", ")
169            self.dispatch(t.inst)
170        if t.tback:
171            self.write(", ")
172            self.dispatch(t.tback)
173
174    def _TryExcept(self, t):
175        self.fill("try")
176        self.enter()
177        self.dispatch(t.body)
178        self.leave()
179
180        for ex in t.handlers:
181            self.dispatch(ex)
182        if t.orelse:
183            self.fill("else")
184            self.enter()
185            self.dispatch(t.orelse)
186            self.leave()
187
188    def _TryFinally(self, t):
189        self.fill("try")
190        self.enter()
191        self.dispatch(t.body)
192        self.leave()
193
194        self.fill("finally")
195        self.enter()
196        self.dispatch(t.finalbody)
197        self.leave()
198
199    def _ExceptHandler(self, t):
200        self.fill("except")
201        if t.type:
202            self.write(" ")
203            self.dispatch(t.type)
204        if t.name:
205            self.write(", ")
206            self.dispatch(t.name)
207        self.enter()
208        self.dispatch(t.body)
209        self.leave()
210
211    def _ClassDef(self, t):
212        self.write("\n")
213        self.fill("class "+t.name)
214        if t.bases:
215            self.write("(")
216            for a in t.bases:
217                self.dispatch(a)
218                self.write(", ")
219            self.write(")")
220        self.enter()
221        self.dispatch(t.body)
222        self.leave()
223
224    def _FunctionDef(self, t):
225        self.write("\n")
226        for deco in t.decorator_list:
227            self.fill("@")
228            self.dispatch(deco)
229        self.fill("def "+t.name + "(")
230        self.dispatch(t.args)
231        self.write(")")
232        self.enter()
233        self.dispatch(t.body)
234        self.leave()
235
236    def _For(self, t):
237        self.fill("for ")
238        self.dispatch(t.target)
239        self.write(" in ")
240        self.dispatch(t.iter)
241        self.enter()
242        self.dispatch(t.body)
243        self.leave()
244        if t.orelse:
245            self.fill("else")
246            self.enter()
247            self.dispatch(t.orelse)
248            self.leave
249
250    def _If(self, t):
251        self.fill("if ")
252        self.dispatch(t.test)
253        self.enter()
254        # XXX elif?
255        self.dispatch(t.body)
256        self.leave()
257        if t.orelse:
258            self.fill("else")
259            self.enter()
260            self.dispatch(t.orelse)
261            self.leave()
262
263    def _While(self, t):
264        self.fill("while ")
265        self.dispatch(t.test)
266        self.enter()
267        self.dispatch(t.body)
268        self.leave()
269        if t.orelse:
270            self.fill("else")
271            self.enter()
272            self.dispatch(t.orelse)
273            self.leave
274
275    def _With(self, t):
276        self.fill("with ")
277        self.dispatch(t.context_expr)
278        if t.optional_vars:
279            self.write(" as ")
280            self.dispatch(t.optional_vars)
281        self.enter()
282        self.dispatch(t.body)
283        self.leave()
284
285    # expr
286    def _Str(self, tree):
287        self.write(repr(tree.s))
288
289    def _Name(self, t):
290        self.write(t.id)
291
292    def _Repr(self, t):
293        self.write("`")
294        self.dispatch(t.value)
295        self.write("`")
296
297    def _Num(self, t):
298        self.write(repr(t.n))
299
300    def _List(self, t):
301        self.write("[")
302        interleave(lambda: self.write(", "), self.dispatch, t.elts)
303        self.write("]")
304
305    def _ListComp(self, t):
306        self.write("[")
307        self.dispatch(t.elt)
308        for gen in t.generators:
309            self.dispatch(gen)
310        self.write("]")
311
312    def _GeneratorExp(self, t):
313        self.write("(")
314        self.dispatch(t.elt)
315        for gen in t.generators:
316            self.dispatch(gen)
317        self.write(")")
318
319    def _comprehension(self, t):
320        self.write(" for ")
321        self.dispatch(t.target)
322        self.write(" in ")
323        self.dispatch(t.iter)
324        for if_clause in t.ifs:
325            self.write(" if ")
326            self.dispatch(if_clause)
327
328    def _IfExp(self, t):
329        self.write("(")
330        self.dispatch(t.body)
331        self.write(" if ")
332        self.dispatch(t.test)
333        self.write(" else ")
334        self.dispatch(t.orelse)
335        self.write(")")
336
337    def _Dict(self, t):
338        self.write("{")
339        def writem((k, v)):
340            self.dispatch(k)
341            self.write(": ")
342            self.dispatch(v)
343        interleave(lambda: self.write(", "), writem, zip(t.keys, t.values))
344        self.write("}")
345
346    def _Tuple(self, t):
347        self.write("(")
348        if len(t.elts) == 1:
349            (elt,) = t.elts
350            self.dispatch(elt)
351            self.write(",")
352        else:
353            interleave(lambda: self.write(", "), self.dispatch, t.elts)
354        self.write(")")
355
356    unop = {"Invert":"~", "Not": "not", "UAdd":"+", "USub":"-"}
357    def _UnaryOp(self, t):
358        self.write(self.unop[t.op.__class__.__name__])
359        self.write("(")
360        self.dispatch(t.operand)
361        self.write(")")
362
363    binop = { "Add":"+", "Sub":"-", "Mult":"*", "Div":"/", "Mod":"%",
364                    "LShift":">>", "RShift":"<<", "BitOr":"|", "BitXor":"^", "BitAnd":"&",
365                    "FloorDiv":"//", "Pow": "**"}
366    def _BinOp(self, t):
367        self.write("(")
368        self.dispatch(t.left)
369        self.write(" " + self.binop[t.op.__class__.__name__] + " ")
370        self.dispatch(t.right)
371        self.write(")")
372
373    cmpops = {"Eq":"==", "NotEq":"!=", "Lt":"<", "LtE":"<=", "Gt":">", "GtE":">=",
374                        "Is":"is", "IsNot":"is not", "In":"in", "NotIn":"not in"}
375    def _Compare(self, t):
376        self.write("(")
377        self.dispatch(t.left)
378        for o, e in zip(t.ops, t.comparators):
379            self.write(" " + self.cmpops[o.__class__.__name__] + " ")
380            self.dispatch(e)
381            self.write(")")
382
383    boolops = {_ast.And: 'and', _ast.Or: 'or'}
384    def _BoolOp(self, t):
385        self.write("(")
386        s = " %s " % self.boolops[t.op.__class__]
387        interleave(lambda: self.write(s), self.dispatch, t.values)
388        self.write(")")
389
390    def _Attribute(self,t):
391        self.dispatch(t.value)
392        self.write(".")
393        self.write(t.attr)
394
395    def _Call(self, t):
396        self.dispatch(t.func)
397        self.write("(")
398        comma = False
399        for e in t.args:
400            if comma: self.write(", ")
401            else: comma = True
402            self.dispatch(e)
403        for e in t.keywords:
404            if comma: self.write(", ")
405            else: comma = True
406            self.dispatch(e)
407        if t.starargs:
408            if comma: self.write(", ")
409            else: comma = True
410            self.write("*")
411            self.dispatch(t.starargs)
412        if t.kwargs:
413            if comma: self.write(", ")
414            else: comma = True
415            self.write("**")
416            self.dispatch(t.kwargs)
417        self.write(")")
418
419    def _Subscript(self, t):
420        self.dispatch(t.value)
421        self.write("[")
422        self.dispatch(t.slice)
423        self.write("]")
424
425    # slice
426    def _Ellipsis(self, t):
427        self.write("...")
428
429    def _Index(self, t):
430        self.dispatch(t.value)
431
432    def _Slice(self, t):
433        if t.lower:
434            self.dispatch(t.lower)
435        self.write(":")
436        if t.upper:
437            self.dispatch(t.upper)
438        if t.step:
439            self.write(":")
440            self.dispatch(t.step)
441
442    def _ExtSlice(self, t):
443        interleave(lambda: self.write(', '), self.dispatch, t.dims)
444
445    # others
446    def _arguments(self, t):
447        first = True
448        nonDef = len(t.args)-len(t.defaults)
449        for a in t.args[0:nonDef]:
450            if first:first = False
451            else: self.write(", ")
452            self.dispatch(a)
453        for a,d in zip(t.args[nonDef:], t.defaults):
454            if first:first = False
455            else: self.write(", ")
456            self.dispatch(a),
457            self.write("=")
458            self.dispatch(d)
459        if t.vararg:
460            if first:first = False
461            else: self.write(", ")
462            self.write("*"+t.vararg)
463        if t.kwarg:
464            if first:first = False
465            else: self.write(", ")
466            self.write("**"+t.kwarg)
467
468    def _keyword(self, t):
469        self.write(t.arg)
470        self.write("=")
471        self.dispatch(t.value)
472
473    def _Lambda(self, t):
474        self.write("lambda ")
475        self.dispatch(t.args)
476        self.write(": ")
477        self.dispatch(t.body)
478
479    def _alias(self, t):
480        self.write(t.name)
481        if t.asname:
482            self.write(" as "+t.asname)
483
484def roundtrip(filename, output=sys.stdout):
485    source = open(filename).read()
486    tree = compile(source, filename, "exec", _ast.PyCF_ONLY_AST)
487    Unparser(tree, output)
488
489
490
491def testdir(a):
492    try:
493        names = [n for n in os.listdir(a) if n.endswith('.py')]
494    except OSError:
495        print >> sys.stderr, "Directory not readable: %s" % a
496    else:
497        for n in names:
498            fullname = os.path.join(a, n)
499            if os.path.isfile(fullname):
500                output = cStringIO.StringIO()
501                print 'Testing %s' % fullname
502                try:
503                    roundtrip(fullname, output)
504                except Exception, e:
505                    print '  Failed to compile, exception is %s' % repr(e)
506            elif os.path.isdir(fullname):
507                testdir(fullname)
508
509def main(args):
510    if args[0] == '--testdir':
511        for a in args[1:]:
512            testdir(a)
513    else:
514        for a in args:
515            roundtrip(a)
516
517if __name__=='__main__':
518    main(sys.argv[1:])