def construct_params(self, params=None):
        """return a dictionary of bind parameter keys and values"""

        if params:
            params = util.column_dict(params)
            pd = {}
            for bindparam, name in self.bind_names.iteritems():
                for paramname in (bindparam.key, bindparam.shortname, name):
                    if paramname in params:
                        pd[name] = params[paramname]
                        break
                else:
                    if util.callable(bindparam.value):
                        pd[name] = bindparam.value()
                    else:
                        pd[name] = bindparam.value
            return pd
        else:
            pd = {}
            for bindparam in self.bind_names:
                if util.callable(bindparam.value):
                    pd[self.bind_names[bindparam]] = bindparam.value()
                else:
                    pd[self.bind_names[bindparam]] = bindparam.value
            return pd

    def as_predicate(cls, predicate, description=None):
        if isinstance(predicate, compound):
            return cls.as_predicate(predicate.fails.union(predicate.skips))

        elif isinstance(predicate, Predicate):
            if description and predicate.description is None:
                predicate.description = description
            return predicate
        elif isinstance(predicate, (list, set)):
            return OrPredicate(
                [cls.as_predicate(pred) for pred in predicate],
                description)
        elif isinstance(predicate, tuple):
            return SpecPredicate(*predicate)
        elif isinstance(predicate, compat.string_types):
            tokens = predicate.split(" ", 2)
            op = spec = None
            db = tokens.pop(0)
            if tokens:
                op = tokens.pop(0)
            if tokens:
                spec = tuple(int(d) for d in tokens.pop(0).split("."))
            return SpecPredicate(db, op, spec, description=description)
        elif util.callable(predicate):
            return LambdaPredicate(predicate, description)
        else:
            assert False, "unknown predicate type: %s" % predicate

    def process_cursor_execute(self, statement, parameters, context, executemany):
        if not context:
            return

        _received_parameters = context.compiled_parameters
        
        # recompile from the context, using the default dialect
        compiled = context.compiled.statement.\
                compile(dialect=DefaultDialect(), column_keys=context.compiled.column_keys)
                
        _received_statement = re.sub(r'\n', '', str(compiled))
        
        equivalent = self.statement == _received_statement
        if self.params:
            if util.callable(self.params):
                params = self.params(context)
            else:
                params = self.params

            if not isinstance(params, list):
                params = [params]
            
            # do a positive compare only
            for param, received in zip(params, _received_parameters):
                for k, v in param.iteritems():
                    if k not in received or received[k] != v:
                        equivalent = False
                        break
        else:
            params = {}

        self._result = equivalent
        if not self._result:
            self._errmsg = "Testing for compiled statement %r partial params %r, " \
                    "received %r with params %r" % (self.statement, params, _received_statement, _received_parameters)

    def process_cursor_execute(self, statement, parameters, context, executemany):
        if not context:
            return

        _received_statement = _process_engine_statement(context.unicode_statement, context)
        _received_parameters = context.compiled_parameters

        # TODO: remove this step once all unit tests
        # are migrated, as ExactSQL should really be *exact* SQL 
        sql = _process_assertion_statement(self.sql, context)

        equivalent = _received_statement == sql
        if self.params:
            if util.callable(self.params):
                params = self.params(context)
            else:
                params = self.params

            if not isinstance(params, list):
                params = [params]
            equivalent = equivalent and params == context.compiled_parameters
        else:
            params = {}


        self._result = equivalent
        if not self._result:
            self._errmsg = "Testing for exact statement %r exact params %r, " \
                "received %r with params %r" % (sql, params, _received_statement, _received_parameters)

    def visit_function(self, func, result_map=None, **kwargs):
        if result_map is not None:
            result_map[func.name.lower()] = (func.name, None, func.type)

        name = self.function_string(func)

        if util.callable(name):
            return name(*[self.process(x) for x in func.clauses])
        else:
            return ".".join(func.packagenames + [name]) % {'expr':self.function_argspec(func)}

 def as_predicate(cls, predicate):
     if isinstance(predicate, Predicate):
         return predicate
     elif isinstance(predicate, list):
         return OrPredicate([cls.as_predicate(pred) for pred in predicate])
     elif isinstance(predicate, tuple):
         return SpecPredicate(*predicate)
     elif isinstance(predicate, basestring):
         return SpecPredicate(predicate, None, None)
     elif util.callable(predicate):
         return LambdaPredicate(predicate)
     else:
         assert False, "unknown predicate type: %s" % predicate

 def _apply_all(self, methods):
     for rec in self.proxy_refs:
         if rec is not None and rec.is_valid:
             try:
                 for name in methods:
                     if callable(name):
                         name(rec)
                     else:
                         getattr(rec, name)()
             except (SystemExit, KeyboardInterrupt):
                 raise
             except Exception, e:
                 # fixme
                 sys.stderr.write("\n" + str(e) + "\n")

 def _apply_all(self, methods):
     # must copy keys atomically
     for rec in self.proxy_refs.keys():
         if rec is not None and rec.is_valid:
             try:
                 for name in methods:
                     if callable(name):
                         name(rec)
                     else:
                         getattr(rec, name)()
             except (SystemExit, KeyboardInterrupt):
                 raise
             except Exception, e:
                 warnings.warn("testing_reaper couldn't close connection: %s" % e)

 def comparator(self):
     if util.callable(self._comparator):
         self._comparator = self._comparator()
     if self.adapter:
         self._comparator = self._comparator.adapted(self.adapter)
     return self._comparator

 def visit_binary(self, binary, **kwargs):
     op = self.operator_string(binary.operator)
     if util.callable(op):
         return op(self.process(binary.left), self.process(binary.right), **binary.modifiers)
     else:
         return self.process(binary.left) + " " + op + " " + self.process(binary.right)

def _instrument_class(cls):
    """Modify methods in a class and install instrumentation."""

    # TODO: more formally document this as a decoratorless/Python 2.3
    # option for specifying instrumentation.  (likely doc'd here in code only,
    # not in online docs.)  Useful for C types too.
    #
    # __instrumentation__ = {
    #   'rolename': 'methodname', # ...
    #   'methods': {
    #     'methodname': ('fire_{append,remove}_event', argspec,
    #                    'fire_{append,remove}_event'),
    #     'append': ('fire_append_event', 1, None),
    #     '__setitem__': ('fire_append_event', 1, 'fire_remove_event'),
    #     'pop': (None, None, 'fire_remove_event'),
    #     }
    #  }

    # In the normal call flow, a request for any of the 3 basic collection
    # types is transformed into one of our trivial subclasses
    # (e.g. InstrumentedList).  Catch anything else that sneaks in here...
    if cls.__module__ == '__builtin__':
        raise sa_exc.ArgumentError(
            "Can not instrument a built-in type. Use a "
            "subclass, even a trivial one.")

    collection_type = util.duck_type_collection(cls)
    if collection_type in __interfaces:
        roles = __interfaces[collection_type].copy()
        decorators = roles.pop('_decorators', {})
    else:
        roles, decorators = {}, {}

    if hasattr(cls, '__instrumentation__'):
        roles.update(copy.deepcopy(getattr(cls, '__instrumentation__')))

    methods = roles.pop('methods', {})

    for name in dir(cls):
        method = getattr(cls, name, None)
        if not util.callable(method):
            continue

        # note role declarations
        if hasattr(method, '_sa_instrument_role'):
            role = method._sa_instrument_role
            assert role in ('appender', 'remover', 'iterator',
                            'on_link', 'converter')
            roles[role] = name

        # transfer instrumentation requests from decorated function
        # to the combined queue
        before, after = None, None
        if hasattr(method, '_sa_instrument_before'):
            op, argument = method._sa_instrument_before
            assert op in ('fire_append_event', 'fire_remove_event')
            before = op, argument
        if hasattr(method, '_sa_instrument_after'):
            op = method._sa_instrument_after
            assert op in ('fire_append_event', 'fire_remove_event')
            after = op
        if before:
            methods[name] = before[0], before[1], after
        elif after:
            methods[name] = None, None, after

    # apply ABC auto-decoration to methods that need it
    for method, decorator in decorators.items():
        fn = getattr(cls, method, None)
        if (fn and method not in methods and
            not hasattr(fn, '_sa_instrumented')):
            setattr(cls, method, decorator(fn))

    # ensure all roles are present, and apply implicit instrumentation if
    # needed
    if 'appender' not in roles or not hasattr(cls, roles['appender']):
        raise sa_exc.ArgumentError(
            "Type %s must elect an appender method to be "
            "a collection class" % cls.__name__)
    elif (roles['appender'] not in methods and
          not hasattr(getattr(cls, roles['appender']), '_sa_instrumented')):
        methods[roles['appender']] = ('fire_append_event', 1, None)

    if 'remover' not in roles or not hasattr(cls, roles['remover']):
        raise sa_exc.ArgumentError(
            "Type %s must elect a remover method to be "
            "a collection class" % cls.__name__)
    elif (roles['remover'] not in methods and
          not hasattr(getattr(cls, roles['remover']), '_sa_instrumented')):
        methods[roles['remover']] = ('fire_remove_event', 1, None)

    if 'iterator' not in roles or not hasattr(cls, roles['iterator']):
        raise sa_exc.ArgumentError(
            "Type %s must elect an iterator method to be "
            "a collection class" % cls.__name__)

    # apply ad-hoc instrumentation from decorators, class-level defaults
    # and implicit role declarations
    for method, (before, argument, after) in methods.items():
        setattr(cls, method,
#.........这里部分代码省略.........

    def _determine_targets(self):
        if isinstance(self.argument, type):
            self.mapper = mapper.class_mapper(self.argument, compile=False)
        elif isinstance(self.argument, mapper.Mapper):
            self.mapper = self.argument
        elif util.callable(self.argument):
            # accept a callable to suit various deferred-configurational schemes
            self.mapper = mapper.class_mapper(self.argument(), compile=False)
        else:
            raise sa_exc.ArgumentError(
                "relation '%s' expects a class or a mapper argument (received: %s)" % (self.key, type(self.argument))
            )
        assert isinstance(self.mapper, mapper.Mapper), self.mapper

        # accept callables for other attributes which may require deferred initialization
        for attr in ("order_by", "primaryjoin", "secondaryjoin", "secondary", "_foreign_keys", "remote_side"):
            if util.callable(getattr(self, attr)):
                setattr(self, attr, getattr(self, attr)())

        # in the case that InstrumentedAttributes were used to construct
        # primaryjoin or secondaryjoin, remove the "_orm_adapt" annotation so these
        # interact with Query in the same way as the original Table-bound Column objects
        for attr in ("primaryjoin", "secondaryjoin"):
            val = getattr(self, attr)
            if val is not None:
                util.assert_arg_type(val, sql.ClauseElement, attr)
                setattr(self, attr, _orm_deannotate(val))

        if self.order_by:
            self.order_by = [expression._literal_as_column(x) for x in util.to_list(self.order_by)]

        self._foreign_keys = util.column_set(
            expression._literal_as_column(x) for x in util.to_column_set(self._foreign_keys)
        )
        self.remote_side = util.column_set(
            expression._literal_as_column(x) for x in util.to_column_set(self.remote_side)
        )

        if not self.parent.concrete:
            for inheriting in self.parent.iterate_to_root():
                if inheriting is not self.parent and inheriting._get_property(self.key, raiseerr=False):
                    util.warn(
                        (
                            "Warning: relation '%s' on mapper '%s' supercedes "
                            "the same relation on inherited mapper '%s'; this "
                            "can cause dependency issues during flush"
                        )
                        % (self.key, self.parent, inheriting)
                    )

        # TODO: remove 'self.table'
        self.target = self.table = self.mapper.mapped_table

        if self.cascade.delete_orphan:
            if self.parent.class_ is self.mapper.class_:
                raise sa_exc.ArgumentError(
                    "In relationship '%s', can't establish 'delete-orphan' cascade "
                    "rule on a self-referential relationship.  "
                    "You probably want cascade='all', which includes delete cascading but not orphan detection."
                    % (str(self))
                )
            self.mapper.primary_mapper().delete_orphans.append((self.key, self.parent.class_))