/usr/lib/python2.7/dist-packages/py/_code/_assertionold.py is in python-py 1.4.20-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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import sys, inspect
from compiler import parse, ast, pycodegen
from py._code.assertion import BuiltinAssertionError, _format_explanation
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, py.std.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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