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- import py
- import sys, inspect
- from compiler import parse, ast, pycodegen
- from py._code.assertion import BuiltinAssertionError, _format_explanation
- import types
- passthroughex = py.builtin._sysex
- class Failure:
- def __init__(self, node):
- self.exc, self.value, self.tb = sys.exc_info()
- self.node = node
- class View(object):
- """View base class.
- If C is a subclass of View, then C(x) creates a proxy object around
- the object x. The actual class of the proxy is not C in general,
- but a *subclass* of C determined by the rules below. To avoid confusion
- we call view class the class of the proxy (a subclass of C, so of View)
- and object class the class of x.
- Attributes and methods not found in the proxy are automatically read on x.
- Other operations like setting attributes are performed on the proxy, as
- determined by its view class. The object x is available from the proxy
- as its __obj__ attribute.
- The view class selection is determined by the __view__ tuples and the
- optional __viewkey__ method. By default, the selected view class is the
- most specific subclass of C whose __view__ mentions the class of x.
- If no such subclass is found, the search proceeds with the parent
- object classes. For example, C(True) will first look for a subclass
- of C with __view__ = (..., bool, ...) and only if it doesn't find any
- look for one with __view__ = (..., int, ...), and then ..., object,...
- If everything fails the class C itself is considered to be the default.
- Alternatively, the view class selection can be driven by another aspect
- of the object x, instead of the class of x, by overriding __viewkey__.
- See last example at the end of this module.
- """
- _viewcache = {}
- __view__ = ()
- def __new__(rootclass, obj, *args, **kwds):
- self = object.__new__(rootclass)
- self.__obj__ = obj
- self.__rootclass__ = rootclass
- key = self.__viewkey__()
- try:
- self.__class__ = self._viewcache[key]
- except KeyError:
- self.__class__ = self._selectsubclass(key)
- return self
- def __getattr__(self, attr):
- # attributes not found in the normal hierarchy rooted on View
- # are looked up in the object's real class
- return getattr(self.__obj__, attr)
- def __viewkey__(self):
- return self.__obj__.__class__
- def __matchkey__(self, key, subclasses):
- if inspect.isclass(key):
- keys = inspect.getmro(key)
- else:
- keys = [key]
- for key in keys:
- result = [C for C in subclasses if key in C.__view__]
- if result:
- return result
- return []
- def _selectsubclass(self, key):
- subclasses = list(enumsubclasses(self.__rootclass__))
- for C in subclasses:
- if not isinstance(C.__view__, tuple):
- C.__view__ = (C.__view__,)
- choices = self.__matchkey__(key, subclasses)
- if not choices:
- return self.__rootclass__
- elif len(choices) == 1:
- return choices[0]
- else:
- # combine the multiple choices
- return type('?', tuple(choices), {})
- def __repr__(self):
- return '%s(%r)' % (self.__rootclass__.__name__, self.__obj__)
- def enumsubclasses(cls):
- for subcls in cls.__subclasses__():
- for subsubclass in enumsubclasses(subcls):
- yield subsubclass
- yield cls
- class Interpretable(View):
- """A parse tree node with a few extra methods."""
- explanation = None
- def is_builtin(self, frame):
- return False
- def eval(self, frame):
- # fall-back for unknown expression nodes
- try:
- expr = ast.Expression(self.__obj__)
- expr.filename = '<eval>'
- self.__obj__.filename = '<eval>'
- co = pycodegen.ExpressionCodeGenerator(expr).getCode()
- result = frame.eval(co)
- except passthroughex:
- raise
- except:
- raise Failure(self)
- self.result = result
- self.explanation = self.explanation or frame.repr(self.result)
- def run(self, frame):
- # fall-back for unknown statement nodes
- try:
- expr = ast.Module(None, ast.Stmt([self.__obj__]))
- expr.filename = '<run>'
- co = pycodegen.ModuleCodeGenerator(expr).getCode()
- frame.exec_(co)
- except passthroughex:
- raise
- except:
- raise Failure(self)
- def nice_explanation(self):
- return _format_explanation(self.explanation)
- class Name(Interpretable):
- __view__ = ast.Name
- def is_local(self, frame):
- source = '%r in locals() is not globals()' % self.name
- try:
- return frame.is_true(frame.eval(source))
- except passthroughex:
- raise
- except:
- return False
- def is_global(self, frame):
- source = '%r in globals()' % self.name
- try:
- return frame.is_true(frame.eval(source))
- except passthroughex:
- raise
- except:
- return False
- def is_builtin(self, frame):
- source = '%r not in locals() and %r not in globals()' % (
- self.name, self.name)
- try:
- return frame.is_true(frame.eval(source))
- except passthroughex:
- raise
- except:
- return False
- def eval(self, frame):
- super(Name, self).eval(frame)
- if not self.is_local(frame):
- self.explanation = self.name
- class Compare(Interpretable):
- __view__ = ast.Compare
- def eval(self, frame):
- expr = Interpretable(self.expr)
- expr.eval(frame)
- for operation, expr2 in self.ops:
- if hasattr(self, 'result'):
- # shortcutting in chained expressions
- if not frame.is_true(self.result):
- break
- expr2 = Interpretable(expr2)
- expr2.eval(frame)
- self.explanation = "%s %s %s" % (
- expr.explanation, operation, expr2.explanation)
- source = "__exprinfo_left %s __exprinfo_right" % operation
- try:
- self.result = frame.eval(source,
- __exprinfo_left=expr.result,
- __exprinfo_right=expr2.result)
- except passthroughex:
- raise
- except:
- raise Failure(self)
- expr = expr2
- class And(Interpretable):
- __view__ = ast.And
- def eval(self, frame):
- explanations = []
- for expr in self.nodes:
- expr = Interpretable(expr)
- expr.eval(frame)
- explanations.append(expr.explanation)
- self.result = expr.result
- if not frame.is_true(expr.result):
- break
- self.explanation = '(' + ' and '.join(explanations) + ')'
- class Or(Interpretable):
- __view__ = ast.Or
- def eval(self, frame):
- explanations = []
- for expr in self.nodes:
- expr = Interpretable(expr)
- expr.eval(frame)
- explanations.append(expr.explanation)
- self.result = expr.result
- if frame.is_true(expr.result):
- break
- self.explanation = '(' + ' or '.join(explanations) + ')'
- # == Unary operations ==
- keepalive = []
- for astclass, astpattern in {
- ast.Not : 'not __exprinfo_expr',
- ast.Invert : '(~__exprinfo_expr)',
- }.items():
- class UnaryArith(Interpretable):
- __view__ = astclass
- def eval(self, frame, astpattern=astpattern):
- expr = Interpretable(self.expr)
- expr.eval(frame)
- self.explanation = astpattern.replace('__exprinfo_expr',
- expr.explanation)
- try:
- self.result = frame.eval(astpattern,
- __exprinfo_expr=expr.result)
- except passthroughex:
- raise
- except:
- raise Failure(self)
- keepalive.append(UnaryArith)
- # == Binary operations ==
- for astclass, astpattern in {
- ast.Add : '(__exprinfo_left + __exprinfo_right)',
- ast.Sub : '(__exprinfo_left - __exprinfo_right)',
- ast.Mul : '(__exprinfo_left * __exprinfo_right)',
- ast.Div : '(__exprinfo_left / __exprinfo_right)',
- ast.Mod : '(__exprinfo_left % __exprinfo_right)',
- ast.Power : '(__exprinfo_left ** __exprinfo_right)',
- }.items():
- class BinaryArith(Interpretable):
- __view__ = astclass
- def eval(self, frame, astpattern=astpattern):
- left = Interpretable(self.left)
- left.eval(frame)
- right = Interpretable(self.right)
- right.eval(frame)
- self.explanation = (astpattern
- .replace('__exprinfo_left', left .explanation)
- .replace('__exprinfo_right', right.explanation))
- try:
- self.result = frame.eval(astpattern,
- __exprinfo_left=left.result,
- __exprinfo_right=right.result)
- except passthroughex:
- raise
- except:
- raise Failure(self)
- keepalive.append(BinaryArith)
- class CallFunc(Interpretable):
- __view__ = ast.CallFunc
- def is_bool(self, frame):
- source = 'isinstance(__exprinfo_value, bool)'
- try:
- return frame.is_true(frame.eval(source,
- __exprinfo_value=self.result))
- except passthroughex:
- raise
- except:
- return False
- def eval(self, frame):
- node = Interpretable(self.node)
- node.eval(frame)
- explanations = []
- vars = {'__exprinfo_fn': node.result}
- source = '__exprinfo_fn('
- for a in self.args:
- if isinstance(a, ast.Keyword):
- keyword = a.name
- a = a.expr
- else:
- keyword = None
- a = Interpretable(a)
- a.eval(frame)
- argname = '__exprinfo_%d' % len(vars)
- vars[argname] = a.result
- if keyword is None:
- source += argname + ','
- explanations.append(a.explanation)
- else:
- source += '%s=%s,' % (keyword, argname)
- explanations.append('%s=%s' % (keyword, a.explanation))
- if self.star_args:
- star_args = Interpretable(self.star_args)
- star_args.eval(frame)
- argname = '__exprinfo_star'
- vars[argname] = star_args.result
- source += '*' + argname + ','
- explanations.append('*' + star_args.explanation)
- if self.dstar_args:
- dstar_args = Interpretable(self.dstar_args)
- dstar_args.eval(frame)
- argname = '__exprinfo_kwds'
- vars[argname] = dstar_args.result
- source += '**' + argname + ','
- explanations.append('**' + dstar_args.explanation)
- self.explanation = "%s(%s)" % (
- node.explanation, ', '.join(explanations))
- if source.endswith(','):
- source = source[:-1]
- source += ')'
- try:
- self.result = frame.eval(source, **vars)
- except passthroughex:
- raise
- except:
- raise Failure(self)
- if not node.is_builtin(frame) or not self.is_bool(frame):
- r = frame.repr(self.result)
- self.explanation = '%s\n{%s = %s\n}' % (r, r, self.explanation)
- class Getattr(Interpretable):
- __view__ = ast.Getattr
- def eval(self, frame):
- expr = Interpretable(self.expr)
- expr.eval(frame)
- source = '__exprinfo_expr.%s' % self.attrname
- try:
- self.result = frame.eval(source, __exprinfo_expr=expr.result)
- except passthroughex:
- raise
- except:
- raise Failure(self)
- self.explanation = '%s.%s' % (expr.explanation, self.attrname)
- # if the attribute comes from the instance, its value is interesting
- source = ('hasattr(__exprinfo_expr, "__dict__") and '
- '%r in __exprinfo_expr.__dict__' % self.attrname)
- try:
- from_instance = frame.is_true(
- frame.eval(source, __exprinfo_expr=expr.result))
- except passthroughex:
- raise
- except:
- from_instance = True
- if from_instance:
- r = frame.repr(self.result)
- self.explanation = '%s\n{%s = %s\n}' % (r, r, self.explanation)
- # == Re-interpretation of full statements ==
- class Assert(Interpretable):
- __view__ = ast.Assert
- def run(self, frame):
- test = Interpretable(self.test)
- test.eval(frame)
- # simplify 'assert False where False = ...'
- if (test.explanation.startswith('False\n{False = ') and
- test.explanation.endswith('\n}')):
- test.explanation = test.explanation[15:-2]
- # print the result as 'assert <explanation>'
- self.result = test.result
- self.explanation = 'assert ' + test.explanation
- if not frame.is_true(test.result):
- try:
- raise BuiltinAssertionError
- except passthroughex:
- raise
- except:
- raise Failure(self)
- class Assign(Interpretable):
- __view__ = ast.Assign
- def run(self, frame):
- expr = Interpretable(self.expr)
- expr.eval(frame)
- self.result = expr.result
- self.explanation = '... = ' + expr.explanation
- # fall-back-run the rest of the assignment
- ass = ast.Assign(self.nodes, ast.Name('__exprinfo_expr'))
- mod = ast.Module(None, ast.Stmt([ass]))
- mod.filename = '<run>'
- co = pycodegen.ModuleCodeGenerator(mod).getCode()
- try:
- frame.exec_(co, __exprinfo_expr=expr.result)
- except passthroughex:
- raise
- except:
- raise Failure(self)
- class Discard(Interpretable):
- __view__ = ast.Discard
- def run(self, frame):
- expr = Interpretable(self.expr)
- expr.eval(frame)
- self.result = expr.result
- self.explanation = expr.explanation
- class Stmt(Interpretable):
- __view__ = ast.Stmt
- def run(self, frame):
- for stmt in self.nodes:
- stmt = Interpretable(stmt)
- stmt.run(frame)
- def report_failure(e):
- explanation = e.node.nice_explanation()
- if explanation:
- explanation = ", in: " + explanation
- else:
- explanation = ""
- sys.stdout.write("%s: %s%s\n" % (e.exc.__name__, e.value, explanation))
- def check(s, frame=None):
- if frame is None:
- frame = sys._getframe(1)
- frame = py.code.Frame(frame)
- expr = parse(s, 'eval')
- assert isinstance(expr, ast.Expression)
- node = Interpretable(expr.node)
- try:
- node.eval(frame)
- except passthroughex:
- raise
- except Failure:
- e = sys.exc_info()[1]
- report_failure(e)
- else:
- if not frame.is_true(node.result):
- sys.stderr.write("assertion failed: %s\n" % node.nice_explanation())
- ###########################################################
- # API / Entry points
- # #########################################################
- def interpret(source, frame, should_fail=False):
- module = Interpretable(parse(source, 'exec').node)
- #print "got module", module
- if isinstance(frame, types.FrameType):
- frame = py.code.Frame(frame)
- try:
- module.run(frame)
- except Failure:
- e = sys.exc_info()[1]
- return getfailure(e)
- except passthroughex:
- raise
- except:
- import traceback
- traceback.print_exc()
- if should_fail:
- return ("(assertion failed, but when it was re-run for "
- "printing intermediate values, it did not fail. Suggestions: "
- "compute assert expression before the assert or use --nomagic)")
- else:
- return None
- def getmsg(excinfo):
- if isinstance(excinfo, tuple):
- excinfo = py.code.ExceptionInfo(excinfo)
- #frame, line = gettbline(tb)
- #frame = py.code.Frame(frame)
- #return interpret(line, frame)
- tb = excinfo.traceback[-1]
- source = str(tb.statement).strip()
- x = interpret(source, tb.frame, should_fail=True)
- if not isinstance(x, str):
- raise TypeError("interpret returned non-string %r" % (x,))
- return x
- def getfailure(e):
- explanation = e.node.nice_explanation()
- if str(e.value):
- lines = explanation.split('\n')
- lines[0] += " << %s" % (e.value,)
- explanation = '\n'.join(lines)
- text = "%s: %s" % (e.exc.__name__, explanation)
- if text.startswith('AssertionError: assert '):
- text = text[16:]
- return text
- def run(s, frame=None):
- if frame is None:
- frame = sys._getframe(1)
- frame = py.code.Frame(frame)
- module = Interpretable(parse(s, 'exec').node)
- try:
- module.run(frame)
- except Failure:
- e = sys.exc_info()[1]
- report_failure(e)
- if __name__ == '__main__':
- # example:
- def f():
- return 5
- def g():
- return 3
- def h(x):
- return 'never'
- check("f() * g() == 5")
- check("not f()")
- check("not (f() and g() or 0)")
- check("f() == g()")
- i = 4
- check("i == f()")
- check("len(f()) == 0")
- check("isinstance(2+3+4, float)")
- run("x = i")
- check("x == 5")
- run("assert not f(), 'oops'")
- run("a, b, c = 1, 2")
- run("a, b, c = f()")
- check("max([f(),g()]) == 4")
- check("'hello'[g()] == 'h'")
- run("'guk%d' % h(f())")
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