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python2.7
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parser
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unparse.py
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"Usage: unparse.py <path to source file>" import sys import ast import cStringIO import os # Large float and imaginary literals get turned into infinities in the AST. # We unparse those infinities to INFSTR. INFSTR = "1e" + repr(sys.float_info.max_10_exp + 1) def interleave(inter, f, seq): """Call f on each item in seq, calling inter() in between. """ seq = iter(seq) try: f(next(seq)) except StopIteration: pass else: for x in seq: inter() f(x) class Unparser: """Methods in this class recursively traverse an AST and output source code for the abstract syntax; original formatting is disregarded. """ def __init__(self, tree, file = sys.stdout): """Unparser(tree, file=sys.stdout) -> None. Print the source for tree to file.""" self.f = file self.future_imports = [] self._indent = 0 self.dispatch(tree) self.f.write("") self.f.flush() def fill(self, text = ""): "Indent a piece of text, according to the current indentation level" self.f.write("\n"+" "*self._indent + text) def write(self, text): "Append a piece of text to the current line." self.f.write(text) def enter(self): "Print ':', and increase the indentation." self.write(":") self._indent += 1 def leave(self): "Decrease the indentation level." self._indent -= 1 def dispatch(self, tree): "Dispatcher function, dispatching tree type T to method _T." if isinstance(tree, list): for t in tree: self.dispatch(t) return meth = getattr(self, "_"+tree.__class__.__name__) meth(tree) ############### Unparsing methods ###################### # There should be one method per concrete grammar type # # Constructors should be grouped by sum type. Ideally, # # this would follow the order in the grammar, but # # currently doesn't. # ######################################################## def _Module(self, tree): for stmt in tree.body: self.dispatch(stmt) # stmt def _Expr(self, tree): self.fill() self.dispatch(tree.value) def _Import(self, t): self.fill("import ") interleave(lambda: self.write(", "), self.dispatch, t.names) def _ImportFrom(self, t): # A from __future__ import may affect unparsing, so record it. if t.module and t.module == '__future__': self.future_imports.extend(n.name for n in t.names) self.fill("from ") self.write("." * t.level) if t.module: self.write(t.module) self.write(" import ") interleave(lambda: self.write(", "), self.dispatch, t.names) def _Assign(self, t): self.fill() for target in t.targets: self.dispatch(target) self.write(" = ") self.dispatch(t.value) def _AugAssign(self, t): self.fill() self.dispatch(t.target) self.write(" "+self.binop[t.op.__class__.__name__]+"= ") self.dispatch(t.value) def _Return(self, t): self.fill("return") if t.value: self.write(" ") self.dispatch(t.value) def _Pass(self, t): self.fill("pass") def _Break(self, t): self.fill("break") def _Continue(self, t): self.fill("continue") def _Delete(self, t): self.fill("del ") interleave(lambda: self.write(", "), self.dispatch, t.targets) def _Assert(self, t): self.fill("assert ") self.dispatch(t.test) if t.msg: self.write(", ") self.dispatch(t.msg) def _Exec(self, t): self.fill("exec ") self.dispatch(t.body) if t.globals: self.write(" in ") self.dispatch(t.globals) if t.locals: self.write(", ") self.dispatch(t.locals) def _Print(self, t): self.fill("print ") do_comma = False if t.dest: self.write(">>") self.dispatch(t.dest) do_comma = True for e in t.values: if do_comma:self.write(", ") else:do_comma=True self.dispatch(e) if not t.nl: self.write(",") def _Global(self, t): self.fill("global ") interleave(lambda: self.write(", "), self.write, t.names) def _Yield(self, t): self.write("(") self.write("yield") if t.value: self.write(" ") self.dispatch(t.value) self.write(")") def _Raise(self, t): self.fill('raise ') if t.type: self.dispatch(t.type) if t.inst: self.write(", ") self.dispatch(t.inst) if t.tback: self.write(", ") self.dispatch(t.tback) def _TryExcept(self, t): self.fill("try") self.enter() self.dispatch(t.body) self.leave() for ex in t.handlers: self.dispatch(ex) if t.orelse: self.fill("else") self.enter() self.dispatch(t.orelse) self.leave() def _TryFinally(self, t): if len(t.body) == 1 and isinstance(t.body[0], ast.TryExcept): # try-except-finally self.dispatch(t.body) else: self.fill("try") self.enter() self.dispatch(t.body) self.leave() self.fill("finally") self.enter() self.dispatch(t.finalbody) self.leave() def _ExceptHandler(self, t): self.fill("except") if t.type: self.write(" ") self.dispatch(t.type) if t.name: self.write(" as ") self.dispatch(t.name) self.enter() self.dispatch(t.body) self.leave() def _ClassDef(self, t): self.write("\n") for deco in t.decorator_list: self.fill("@") self.dispatch(deco) self.fill("class "+t.name) if t.bases: self.write("(") for a in t.bases: self.dispatch(a) self.write(", ") self.write(")") self.enter() self.dispatch(t.body) self.leave() def _FunctionDef(self, t): self.write("\n") for deco in t.decorator_list: self.fill("@") self.dispatch(deco) self.fill("def "+t.name + "(") self.dispatch(t.args) self.write(")") self.enter() self.dispatch(t.body) self.leave() def _For(self, t): self.fill("for ") self.dispatch(t.target) self.write(" in ") self.dispatch(t.iter) self.enter() self.dispatch(t.body) self.leave() if t.orelse: self.fill("else") self.enter() self.dispatch(t.orelse) self.leave() def _If(self, t): self.fill("if ") self.dispatch(t.test) self.enter() self.dispatch(t.body) self.leave() # collapse nested ifs into equivalent elifs. while (t.orelse and len(t.orelse) == 1 and isinstance(t.orelse[0], ast.If)): t = t.orelse[0] self.fill("elif ") self.dispatch(t.test) self.enter() self.dispatch(t.body) self.leave() # final else if t.orelse: self.fill("else") self.enter() self.dispatch(t.orelse) self.leave() def _While(self, t): self.fill("while ") self.dispatch(t.test) self.enter() self.dispatch(t.body) self.leave() if t.orelse: self.fill("else") self.enter() self.dispatch(t.orelse) self.leave() def _With(self, t): self.fill("with ") self.dispatch(t.context_expr) if t.optional_vars: self.write(" as ") self.dispatch(t.optional_vars) self.enter() self.dispatch(t.body) self.leave() # expr def _Str(self, tree): # if from __future__ import unicode_literals is in effect, # then we want to output string literals using a 'b' prefix # and unicode literals with no prefix. if "unicode_literals" not in self.future_imports: self.write(repr(tree.s)) elif isinstance(tree.s, str): self.write("b" + repr(tree.s)) elif isinstance(tree.s, unicode): self.write(repr(tree.s).lstrip("u")) else: assert False, "shouldn't get here" def _Name(self, t): self.write(t.id) def _Repr(self, t): self.write("`") self.dispatch(t.value) self.write("`") def _Num(self, t): repr_n = repr(t.n) # Parenthesize negative numbers, to avoid turning (-1)**2 into -1**2. if repr_n.startswith("-"): self.write("(") # Substitute overflowing decimal literal for AST infinities. self.write(repr_n.replace("inf", INFSTR)) if repr_n.startswith("-"): self.write(")") def _List(self, t): self.write("[") interleave(lambda: self.write(", "), self.dispatch, t.elts) self.write("]") def _ListComp(self, t): self.write("[") self.dispatch(t.elt) for gen in t.generators: self.dispatch(gen) self.write("]") def _GeneratorExp(self, t): self.write("(") self.dispatch(t.elt) for gen in t.generators: self.dispatch(gen) self.write(")") def _SetComp(self, t): self.write("{") self.dispatch(t.elt) for gen in t.generators: self.dispatch(gen) self.write("}") def _DictComp(self, t): self.write("{") self.dispatch(t.key) self.write(": ") self.dispatch(t.value) for gen in t.generators: self.dispatch(gen) self.write("}") def _comprehension(self, t): self.write(" for ") self.dispatch(t.target) self.write(" in ") self.dispatch(t.iter) for if_clause in t.ifs: self.write(" if ") self.dispatch(if_clause) def _IfExp(self, t): self.write("(") self.dispatch(t.body) self.write(" if ") self.dispatch(t.test) self.write(" else ") self.dispatch(t.orelse) self.write(")") def _Set(self, t): assert(t.elts) # should be at least one element self.write("{") interleave(lambda: self.write(", "), self.dispatch, t.elts) self.write("}") def _Dict(self, t): self.write("{") def write_pair(pair): (k, v) = pair self.dispatch(k) self.write(": ") self.dispatch(v) interleave(lambda: self.write(", "), write_pair, zip(t.keys, t.values)) self.write("}") def _Tuple(self, t): self.write("(") if len(t.elts) == 1: (elt,) = t.elts self.dispatch(elt) self.write(",") else: interleave(lambda: self.write(", "), self.dispatch, t.elts) self.write(")") unop = {"Invert":"~", "Not": "not", "UAdd":"+", "USub":"-"} def _UnaryOp(self, t): self.write("(") self.write(self.unop[t.op.__class__.__name__]) self.write(" ") # If we're applying unary minus to a number, parenthesize the number. # This is necessary: -2147483648 is different from -(2147483648) on # a 32-bit machine (the first is an int, the second a long), and # -7j is different from -(7j). (The first has real part 0.0, the second # has real part -0.0.) if isinstance(t.op, ast.USub) and isinstance(t.operand, ast.Num): self.write("(") self.dispatch(t.operand) self.write(")") else: self.dispatch(t.operand) self.write(")") binop = { "Add":"+", "Sub":"-", "Mult":"*", "Div":"/", "Mod":"%", "LShift":"<<", "RShift":">>", "BitOr":"|", "BitXor":"^", "BitAnd":"&", "FloorDiv":"//", "Pow": "**"} def _BinOp(self, t): self.write("(") self.dispatch(t.left) self.write(" " + self.binop[t.op.__class__.__name__] + " ") self.dispatch(t.right) self.write(")") cmpops = {"Eq":"==", "NotEq":"!=", "Lt":"<", "LtE":"<=", "Gt":">", "GtE":">=", "Is":"is", "IsNot":"is not", "In":"in", "NotIn":"not in"} def _Compare(self, t): self.write("(") self.dispatch(t.left) for o, e in zip(t.ops, t.comparators): self.write(" " + self.cmpops[o.__class__.__name__] + " ") self.dispatch(e) self.write(")") boolops = {ast.And: 'and', ast.Or: 'or'} def _BoolOp(self, t): self.write("(") s = " %s " % self.boolops[t.op.__class__] interleave(lambda: self.write(s), self.dispatch, t.values) self.write(")") def _Attribute(self,t): self.dispatch(t.value) # Special case: 3.__abs__() is a syntax error, so if t.value # is an integer literal then we need to either parenthesize # it or add an extra space to get 3 .__abs__(). if isinstance(t.value, ast.Num) and isinstance(t.value.n, int): self.write(" ") self.write(".") self.write(t.attr) def _Call(self, t): self.dispatch(t.func) self.write("(") comma = False for e in t.args: if comma: self.write(", ") else: comma = True self.dispatch(e) for e in t.keywords: if comma: self.write(", ") else: comma = True self.dispatch(e) if t.starargs: if comma: self.write(", ") else: comma = True self.write("*") self.dispatch(t.starargs) if t.kwargs: if comma: self.write(", ") else: comma = True self.write("**") self.dispatch(t.kwargs) self.write(")") def _Subscript(self, t): self.dispatch(t.value) self.write("[") self.dispatch(t.slice) self.write("]") # slice def _Ellipsis(self, t): self.write("...") def _Index(self, t): self.dispatch(t.value) def _Slice(self, t): if t.lower: self.dispatch(t.lower) self.write(":") if t.upper: self.dispatch(t.upper) if t.step: self.write(":") self.dispatch(t.step) def _ExtSlice(self, t): interleave(lambda: self.write(', '), self.dispatch, t.dims) # others def _arguments(self, t): first = True # normal arguments defaults = [None] * (len(t.args) - len(t.defaults)) + t.defaults for a,d in zip(t.args, defaults): if first:first = False else: self.write(", ") self.dispatch(a), if d: self.write("=") self.dispatch(d) # varargs if t.vararg: if first:first = False else: self.write(", ") self.write("*") self.write(t.vararg) # kwargs if t.kwarg: if first:first = False else: self.write(", ") self.write("**"+t.kwarg) def _keyword(self, t): self.write(t.arg) self.write("=") self.dispatch(t.value) def _Lambda(self, t): self.write("(") self.write("lambda ") self.dispatch(t.args) self.write(": ") self.dispatch(t.body) self.write(")") def _alias(self, t): self.write(t.name) if t.asname: self.write(" as "+t.asname) def roundtrip(filename, output=sys.stdout): with open(filename, "r") as pyfile: source = pyfile.read() tree = compile(source, filename, "exec", ast.PyCF_ONLY_AST) Unparser(tree, output) def testdir(a): try: names = [n for n in os.listdir(a) if n.endswith('.py')] except OSError: sys.stderr.write("Directory not readable: %s" % a) else: for n in names: fullname = os.path.join(a, n) if os.path.isfile(fullname): output = cStringIO.StringIO() print 'Testing %s' % fullname try: roundtrip(fullname, output) except Exception as e: print ' Failed to compile, exception is %s' % repr(e) elif os.path.isdir(fullname): testdir(fullname) def main(args): if args[0] == '--testdir': for a in args[1:]: testdir(a) else: for a in args: roundtrip(a) if __name__=='__main__': main(sys.argv[1:])
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