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