#  ___________________________________________________________________________
#
#  Pyomo: Python Optimization Modeling Objects
#  Copyright 2017 National Technology and Engineering Solutions of Sandia, LLC
#  Under the terms of Contract DE-NA0003525 with National Technology and
#  Engineering Solutions of Sandia, LLC, the U.S. Government retains certain
#  rights in this software.
#  This software is distributed under the 3-clause BSD License.
#  ___________________________________________________________________________

__all__ = ['IndexedComponent', 'ActiveIndexedComponent']

import inspect
import logging
import sys

from pyomo.core.expr.expr_errors import TemplateExpressionError
from pyomo.core.expr.numvalue import native_types, NumericNDArray
from pyomo.core.base.indexed_component_slice import IndexedComponent_slice
from pyomo.core.base.initializer import Initializer
from pyomo.core.base.component import Component, ActiveComponent
from pyomo.core.base.config import PyomoOptions
from pyomo.core.base.global_set import UnindexedComponent_set
from pyomo.common import DeveloperError
from pyomo.common.dependencies import numpy as np, numpy_available
from pyomo.common.deprecation import deprecated, deprecation_warning
from pyomo.common.modeling import NOTSET

from collections.abc import Sequence

logger = logging.getLogger('pyomo.core')

sequence_types = {tuple, list}
def normalize_index(x):
    """Normalize a component index.

    This flattens nested sequences into a single tuple.  There is a
    "global" flag (normalize_index.flatten) that will turn off index
    flattening across Pyomo.

    Scalar values will be returned unchanged.  Tuples with a single
    value will be unpacked and returned as a single value.

    Returns
    -------
    scalar or tuple

    """
    if x.__class__ in native_types:
        return x
    elif x.__class__ in sequence_types:
        # Note that casting a tuple to a tuple is cheap (no copy, no
        # new object)
        x = tuple(x)
    else:
        x = (x,)

    x_len = len(x)
    i = 0
    while i < x_len:
        _xi_class = x[i].__class__
        if _xi_class in native_types:
            i += 1
        elif _xi_class in sequence_types:
            x_len += len(x[i]) - 1
            # Note that casting a tuple to a tuple is cheap (no copy, no
            # new object)
            x = x[:i] + tuple(x[i]) + x[i + 1:]
        elif issubclass(_xi_class, Sequence):
            if issubclass(_xi_class, str):
                # This is very difficult to get to: it would require a
                # user creating a custom derived string type
                native_types.add(_xi_class)
                i += 1
            else:
                sequence_types.add(_xi_class)
                x_len += len(x[i]) - 1
                x = x[:i] + tuple(x[i]) + x[i + 1:]
        else:
            i += 1

    if x_len == 1:
        return x[0]
    return x

# Pyomo will normalize indices by default
normalize_index.flatten = True


class _NotFound(object):
    pass
class _NotSpecified(object):
    pass

#
# Get the fully-qualified name for this index.  If there isn't anything
# in the _data dict (and there shouldn't be), then add something, get
# the name, and remove it.  This allows us to get the name of something
# that we haven't added yet without changing the state of the constraint
# object.
#
def _get_indexed_component_data_name(component, index):
    """Returns the fully-qualified component name for an unconstructed index.

    The ComponentData.name property assumes that the ComponentData has
    already been assigned to the owning Component.  This is a problem
    during the process of constructing a ComponentData instance, as we
    may need to throw an exception before the ComponentData is added to
    the owning component.  In those cases, we can use this function to
    generate the fully-qualified name without (permanently) adding the
    object to the Component.

    """
    if not component.is_indexed():
        return component.name
    elif index in component._data:
        ans = component._data[index].name
    else:
        for i in range(5):
            try:
                component._data[index] = component._ComponentDataClass(
                    *((None,)*i), component=component)
                i = None
                break
            except:
                pass
        if i is not None:
            # None of the generic positional arguments worked; raise an
            # exception
            component._data[index] = component._ComponentDataClass(
                component=component)
        try:
            ans = component._data[index].name
        except:
            ans = component.name + '[{unknown index}]'
        finally:
            del component._data[index]
    return ans

_rule_returned_none_error = """%s '%s': rule returned None.

%s rules must return either a valid expression, numeric value, or
%s.Skip.  The most common cause of this error is forgetting to
include the "return" statement at the end of your rule.
"""

def rule_result_substituter(result_map):
    _map = result_map
    _map_types = set(type(key) for key in result_map)

    def rule_result_substituter_impl(rule, *args, **kwargs):
        if rule.__class__ in _map_types:
            #
            # The argument is a trivial type and will be mapped
            #
            value = rule
        else:
            #
            # Otherwise, the argument is a functor, so call it to
            # generate the rule result.
            #
            value = rule( *args, **kwargs )
        #
        # Map the returned value:
        #
        if value.__class__ in _map_types and value in _map:
            return _map[value]
        return value

    return rule_result_substituter_impl

_map_rule_funcdef = \
"""def wrapper_function%s:
    args, varargs, kwds, local_env = inspect.getargvalues(
        inspect.currentframe())
    args = tuple(local_env[_] for _ in args) + (varargs or ())
    return wrapping_fcn(rule, *args, **(kwds or {}))
"""

def rule_wrapper(rule, wrapping_fcn, positional_arg_map=None):
    """Wrap a rule with another function

    This utility method provides a way to wrap a function (rule) with
    another function while preserving the original function signature.
    This is important for rules, as the :py:func:`Initializer`
    argument processor relies on knowing the number of positional
    arguments.

    Parameters
    ----------
    rule: function
        The original rule being wrapped
    wrapping_fcn: function or Dict
        The wrapping function.  The `wrapping_fcn` will be called with
        ``(rule, *args, **kwargs)``.  For convenience, if a `dict` is
        passed as the `wrapping_fcn`, then the result of
        :py:func:`rule_result_substituter(wrapping_fcn)` is used as the
        wrapping function.
    positional_arg_map: iterable[int]
        An iterable of indices of rule positional arguments to expose in
        the wrapped function signature.  For example,
        `positional_arg_map=(2, 0)` and `rule=fcn(a, b, c)` would produce a
        wrapped function with a signature `wrapper_function(c, a)`

    """
    if isinstance(wrapping_fcn, dict):
        wrapping_fcn = rule_result_substituter(wrapping_fcn)
        if not inspect.isfunction(rule):
            return wrapping_fcn(rule)
    # Because some of our processing of initializer functions relies on
    # knowing the number of positional arguments, we will go to extra
    # effort here to preserve the original function signature.
    rule_sig = inspect.signature(rule)
    if positional_arg_map is not None:
        param = list(rule_sig.parameters.values())
        rule_sig = rule_sig.replace(
            parameters=(param[i] for i in positional_arg_map))
    _funcdef = _map_rule_funcdef % (str(rule_sig),)
    # Create the wrapper in a temporary environment that mimics this
    # function's environment.
    _env = dict(globals())
    _env.update(locals())
    exec(_funcdef, _env)
    return _env['wrapper_function']


class IndexedComponent(Component):
    """
    This is the base class for all indexed modeling components.
    This class stores a dictionary, self._data, that maps indices
    to component data objects.  The object self._index defines valid
    keys for this dictionary, and the dictionary keys may be a
    strict subset.

    The standard access and iteration methods iterate over the the
    keys of self._data.  This class supports a concept of a default
    component data value.  When enabled, the default does not
    change the access and iteration methods.

    IndexedComponent may be given a set over which indexing is restricted.
    Alternatively, IndexedComponent may be indexed over Any
    (pyomo.core.base.set_types.Any), in which case the IndexedComponent
    behaves like a dictionary - any hashable object can be used as a key
    and keys can be added on the fly.

    Constructor arguments:
        ctype       The class type for the derived subclass
        doc         A text string describing this component

    Private class attributes:
        _data               A dictionary from the index set to
                                component data objects
        _index              The set of valid indices
        _implicit_subsets   A temporary data element that stores
                                sets that are transfered to the model
    """

    class Skip(object): pass

    #
    # If an index is supplied for which there is not a _data entry
    # (specifically, in a get call), then this flag determines whether
    # a check is performed to see if the input index is in the
    # index set _index. This is extremely expensive, and so this flag
    # is provided to disable that feature globally.
    #
    _DEFAULT_INDEX_CHECKING_ENABLED = True

    def __init__(self, *args, **kwds):
        from pyomo.core.base.set import process_setarg
        #
        kwds.pop('noruleinit', None)
        Component.__init__(self, **kwds)
        #
        self._data = {}
        #
        if len(args) == 0 or (len(args) == 1 and
                              args[0] is UnindexedComponent_set):
            #
            # If no indexing sets are provided, generate a dummy index
            #
            self._implicit_subsets = None
            self._index = UnindexedComponent_set
        elif len(args) == 1:
            #
            # If a single indexing set is provided, just process it.
            #
            self._implicit_subsets = None
            self._index = process_setarg(args[0])
        else:
            #
            # If multiple indexing sets are provided, process them all,
            # and store the cross-product of these sets.  The individual
            # sets need to stored in the Pyomo model, so the
            # _implicit_subsets class data is used for this temporary
            # storage.
            #
            # Example:  Pyomo allows things like
            # "Param([1,2,3], range(100), initialize=0)".  This
            # needs to create *3* sets: two SetOf components and then
            # the SetProduct.  That means that the component needs to
            # hold on to the implicit SetOf objects until the component
            # is assigned to a model (where the implicit subsets can be
            # "transferred" to the model).
            #
            tmp = [process_setarg(x) for x in args]
            self._implicit_subsets = tmp
            self._index = tmp[0].cross(*tmp[1:])

    def __getstate__(self):
        # Special processing of getstate so that we never copy the
        # UnindexedComponent_set set
        state = super(IndexedComponent, self).__getstate__()
        if not self.is_indexed():
            state['_index'] = None
        return state

    def __setstate__(self, state):
        # Special processing of setstate so that we never copy the
        # UnindexedComponent_set set
        if state['_index'] is None:
            state['_index'] = UnindexedComponent_set
        super(IndexedComponent, self).__setstate__(state)

    def to_dense_data(self):
        """TODO"""
        for idx in self._index:
            if idx in self._data:
                continue
            try:
                self._getitem_when_not_present(idx)
            except KeyError:
                # Rule could have returned Skip, which we will silently ignore
                pass

    def clear(self):
        """Clear the data in this component"""
        if self.is_indexed():
            self._data = {}
        else:
            raise DeveloperError(
                "Derived scalar component %s failed to define clear()."
                % (self.__class__.__name__,))

    def index_set(self):
        """Return the index set"""
        return self._index

    def is_indexed(self):
        """Return true if this component is indexed"""
        return self._index is not UnindexedComponent_set

    def is_reference(self):
        """Return True if this component is a reference, where
        "reference" is interpreted as any component that does not
        own its own data.
        """
        return self._data is not None and type(self._data) is not dict

    def dim(self):
        """Return the dimension of the index"""
        if not self.is_indexed():
            return 0
        return self._index.dimen

    def __len__(self):
        """
        Return the number of component data objects stored by this
        component.
        """
        return len(self._data)

    def __contains__(self, idx):
        """Return true if the index is in the dictionary"""
        return idx in self._data

    # The default implementation is for keys() and __iter__ to be
    # synonyms.  The logic is implemented in keys() so that
    # keys/values/items continue to work for components that implement
    # other definitions for __iter__ (e.g., Set)
    def __iter__(self):
        """Return an iterator of the keys in the dictionary"""
        return self.keys()

    def keys(self):
        """Iterate over the keys in the dictionary"""

        if hasattr(self._index, 'isfinite') and not self._index.isfinite():
            #
            # If the index set is virtual (e.g., Any) then return the
            # data iterator.  Note that since we cannot check the length
            # of the underlying Set, there should be no warning if the
            # user iterates over the set when the _data dict is empty.
            #
            return self._data.__iter__()
        elif self.is_reference():
            return self._data.__iter__()
        elif len(self._data) == len(self._index):
            #
            # If the data is dense then return the index iterator.
            #
            return self._index.__iter__()
        else:
            if not self._data and self._index and PyomoOptions.paranoia_level:
                logger.warning(
"""Iterating over a Component (%s)
defined by a non-empty concrete set before any data objects have
actually been added to the Component.  The iterator will be empty.
This is usually caused by Concrete models where you declare the
component (e.g., a Var) and apply component-level operations (e.g.,
x.fix(0)) before you use the component members (in something like a
constraint).

You can silence this warning by one of three ways:
    1) Declare the component to be dense with the 'dense=True' option.
       This will cause all data objects to be immediately created and
       added to the Component.
    2) Defer component-level iteration until after the component data
       members have been added (through explicit use).
    3) If you intend to iterate over a component that may be empty, test
       if the component is empty first and avoid iteration in the case
       where it is empty.
""" % (self.name,) )

            if not hasattr(self._index, 'isordered') or not self._index.isordered():
                #
                # If the index set is not ordered, then return the
                # data iterator.  This is in an arbitrary order, which is
                # fine because the data is unordered.
                #
                return self._data.__iter__()
            else:
                #
                # Test each element of a sparse data with an ordered
                # index set in order.  This is potentially *slow*: if
                # the component is in fact very sparse, we could be
                # iterating over a huge (dense) index in order to sort a
                # small number of indices.  However, this provides a
                # consistent ordering that the user expects.
                #
                def _sparse_iter_gen(self):
                    for idx in self._index.__iter__():
                        if idx in self._data:
                            yield idx
                return _sparse_iter_gen(self)

    def values(self):
        """Return an iterator of the component data objects in the dictionary"""
        return (self[s] for s in self.keys())

    def items(self):
        """Return an iterator of (index,data) tuples from the dictionary"""
        return((s, self[s]) for s in self.keys())

    @deprecated('The iterkeys method is deprecated. Use dict.keys().',
                version='6.0')
    def iterkeys(self):
        """Return a list of keys in the dictionary"""
        return self.keys()

    @deprecated('The itervalues method is deprecated. Use dict.values().',
                version='6.0')
    def itervalues(self):
        """Return a list of the component data objects in the dictionary"""
        return self.values()

    @deprecated('The iteritems method is deprecated. Use dict.items().',
                version='6.0')
    def iteritems(self):
        """Return a list (index,data) tuples from the dictionary"""
        return self.items()

    def __getitem__(self, index):
        """
        This method returns the data corresponding to the given index.
        """
        if self._constructed is False:
            self._not_constructed_error(index)

        try:
            obj = self._data.get(index, _NotFound)
        except TypeError:
            try:
                index = self._processUnhashableIndex(index)
            except TypeError:
                # This index is really unhashable.  Set a flag so that
                # we can re-raise the original exception (not this one)
                index = TypeError
            if index is TypeError:
                raise
            if index.__class__ is IndexedComponent_slice:
                return index
            # The index could have contained constant but nonhashable
            # objects (e.g., scalar immutable Params).
            # _processUnhashableIndex will evaluate those constants, so
            # if it made any changes to the index, we need to re-check
            # the _data dict for membership.
            try:
                obj = self._data.get(index, _NotFound)
            except TypeError:
                obj = _NotFound

        if obj is _NotFound:
            # Not good: we have to defer this import to now
            # due to circular imports (expr imports _VarData
            # imports indexed_component, but we need expr
            # here
            from pyomo.core.expr import current as EXPR
            if index.__class__ is EXPR.GetItemExpression:
                return index
            validated_index = self._validate_index(index)
            if validated_index is not index:
                index = validated_index
                # _processUnhashableIndex could have found a slice, or
                # _validate could have found an Ellipsis and returned a
                # slicer
                if index.__class__ is IndexedComponent_slice:
                    return index
                obj = self._data.get(index, _NotFound)
            #
            # Call the _getitem_when_not_present helper to retrieve/return
            # the default value
            #
            if obj is _NotFound:
                return self._getitem_when_not_present(index)

        return obj

    def __setitem__(self, index, val):
        #
        # Set the value: This relies on _setitem_when_not_present() to
        # insert the correct ComponentData into the _data dictionary
        # when it is not present and _setitem_impl to update an existing
        # entry.
        #
        # Note: it is important that we check _constructed is False and not
        # just evaluates to false: when constructing immutable Params,
        # _constructed will be None during the construction process when
        # setting the value is valid.
        #
        if self._constructed is False:
            self._not_constructed_error(index)

        try:
            obj = self._data.get(index, _NotFound)
        except TypeError:
            obj = _NotFound
            index = self._processUnhashableIndex(index)

        if obj is _NotFound:
            # If we didn't find the index in the data, then we need to
            # validate it against the underlying set (as long as
            # _processUnhashableIndex didn't return a slicer)
            if index.__class__ is not IndexedComponent_slice:
                index = self._validate_index(index)
        else:
            return self._setitem_impl(index, obj, val)
        #
        # Call the _setitem_impl helper to populate the _data
        # dictionary and set the value
        #
        # Note that we need to RECHECK the class against
        # IndexedComponent_slice, as _validate_index could have found
        # an Ellipsis (which is hashable) and returned a slicer
        #
        if index.__class__ is IndexedComponent_slice:
            # support "m.x[:,1] = 5" through a simple recursive call.
            #
            # Assert that this slice was just generated
            assert len(index._call_stack) == 1
            #
            # Note that the slicer will only slice over *existing*
            # entries, but they may not be in the data dictionary.  Make
            # a copy of the slicer items *before* we start iterating
            # over it in case the setter changes the _data dictionary.
            for idx, obj in list(index.expanded_items()):
                self._setitem_impl(idx, obj, val)
        else:
            obj = self._data.get(index, _NotFound)
            if obj is _NotFound:
                return self._setitem_when_not_present(index, val)
            else:
                return self._setitem_impl(index, obj, val)

    def __delitem__(self, index):
        if self._constructed is False:
            self._not_constructed_error(index)

        try:
            obj = self._data.get(index, _NotFound)
        except TypeError:
            obj = _NotFound
            index = self._processUnhashableIndex(index)

        if obj is _NotFound:
            if index.__class__ is not IndexedComponent_slice:
                index = self._validate_index(index)

        # this supports "del m.x[:,1]" through a simple recursive call
        if index.__class__ is IndexedComponent_slice:
            # Assert that this slice ws just generated
            assert len(index._call_stack) == 1
            # Make a copy of the slicer items *before* we start
            # iterating over it (since we will be removing items!).
            for idx in list(index.expanded_keys()):
                del self[idx]
        else:
            # Handle the normal deletion operation
            if self.is_indexed():
                # Remove reference to this object
                self._data[index]._component = None
            del self._data[index]

    def _pop_from_kwargs(self, name, kwargs, namelist, notset=None):
        args = [arg for arg in (kwargs.pop(name, notset) for name in namelist)
                if arg is not notset]
        if len(args) == 1:
            return args[0]
        elif not args:
            return notset
        else:
            argnames = "%s%s '%s='" % (
                ', '.join("'%s='" % _ for _ in namelist[:-1]),
                ',' if len(namelist) > 2 else '',
                namelist[-1]
            )
            raise ValueError(
                "Duplicate initialization: %s() only accepts one of %s" %
                (name, argnames))

    def _construct_from_rule_using_setitem(self):
        if self._rule is None:
            return
        index = None
        rule = self._rule
        block = self.parent_block()
        try:
            if rule.constant() and self.is_indexed():
                # A constant rule could return a dict-like thing or
                # matrix that we would then want to process with
                # Initializer().  If the rule actually returned a
                # constant, then this is just a little overhead.
                self._rule = rule = Initializer(
                    rule(block, None),
                    treat_sequences_as_mappings=False,
                    arg_not_specified=NOTSET
                )

            if rule.contains_indices():
                # The index is coming in externally; we need to validate it
                for index in rule.indices():
                    self[index] = rule(block, index)
            elif not self.index_set().isfinite():
                # If the index is not finite, then we cannot iterate
                # over it.  Since the rule doesn't provide explicit
                # indices, then there is nothing we can do (the
                # assumption is that the user will trigger specific
                # indices to be created at a later time).
                pass
            elif rule.constant():
                # Slight optimization: if the initializer is known to be
                # constant, then only call the rule once.
                val = rule(block, None)
                for index in self.index_set():
                    self._setitem_when_not_present(index, val)
            else:
                for index in self.index_set():
                    self._setitem_when_not_present(index, rule(block, index))
        except:
            err = sys.exc_info()[1]
            logger.error(
                "Rule failed for %s '%s' with index %s:\n%s: %s"
                % (self.ctype.__name__,
                   self.name,
                   str(index),
                   type(err).__name__,
                   err))
            raise

    def _not_constructed_error(self, idx):
        # Generate an error because the component is not constructed
        if not self.is_indexed():
            idx_str = ''
        elif idx.__class__ is tuple:
            idx_str = "[" + ",".join(str(i) for i in idx) + "]"
        else:
            idx_str = "[" + str(idx) + "]"
        raise ValueError(
            "Error retrieving component %s%s: The component has "
            "not been constructed." % (self.name, idx_str,))

    def _validate_index(self, idx):
        if not IndexedComponent._DEFAULT_INDEX_CHECKING_ENABLED:
            # Return whatever index was provided if the global flag dictates
            # that we should bypass all index checking and domain validation
            return idx

        # This is only called through __{get,set,del}item__, which has
        # already trapped unhashable objects.
        validated_idx = self._index.get(idx, _NotFound)
        if validated_idx is not _NotFound:
            # If the index is in the underlying index set, then return it
            #  Note: This check is potentially expensive (e.g., when the
            # indexing set is a complex set operation)!
            return validated_idx

        if idx.__class__ is IndexedComponent_slice:
            return idx

        if normalize_index.flatten:
            # Now we normalize the index and check again.  Usually,
            # indices will be already be normalized, so we defer the
            # "automatic" call to normalize_index until now for the
            # sake of efficiency.
            normalized_idx = normalize_index(idx)
            if normalized_idx is not idx:
                idx = normalized_idx
                if idx in self._data:
                    return idx
                if idx in self._index:
                    return idx
        # There is the chance that the index contains an Ellipsis,
        # so we should generate a slicer
        if idx is Ellipsis or idx.__class__ is tuple and Ellipsis in idx:
            return self._processUnhashableIndex(idx)
        #
        # Generate different errors, depending on the state of the index.
        #
        if not self.is_indexed():
            raise KeyError(
                "Cannot treat the scalar component '%s' "
                "as an indexed component" % ( self.name, ))
        #
        # Raise an exception
        #
        raise KeyError(
            "Index '%s' is not valid for indexed component '%s'"
            % ( idx, self.name, ))

    def _processUnhashableIndex(self, idx):
        """Process a call to __getitem__ with unhashable elements

        There are three basic ways to get here:
          1) the index contains one or more slices or ellipsis
          2) the index contains an unhashable type (e.g., a Pyomo
             (Simple)Component
          3) the index contains an IndexTemplate
        """
        from pyomo.core.expr import current as EXPR
        #
        # Iterate through the index and look for slices and constant
        # components
        #
        fixed = {}
        sliced = {}
        ellipsis = None
        _found_numeric = False
        #
        # Setup the slice template (in fixed)
        #
        if normalize_index.flatten:
            idx = normalize_index(idx)
        if idx.__class__ is not tuple:
            idx = (idx,)

        for i,val in enumerate(idx):
            if type(val) is slice:
                if val.start is not None or val.stop is not None:
                    raise IndexError(
                        "Indexed components can only be indexed with simple "
                        "slices: start and stop values are not allowed.")
                if val.step is not None:
                    deprecation_warning(
                        "The special wildcard slice (::0) is deprecated.  "
                        "Please use an ellipsis (...) to indicate "
                        "'0 or more' indices", version='4.4')
                    val = Ellipsis
                else:
                    if ellipsis is None:
                        sliced[i] = val
                    else:
                        sliced[i-len(idx)] = val
                    continue

            if val is Ellipsis:
                if ellipsis is not None:
                    raise IndexError(
                        "Indexed components can only be indexed with simple "
                        "slices: the Pyomo wildcard slice (Ellipsis; "
                        "e.g., '...') can only appear once")
                ellipsis = i
                continue

            if hasattr(val, 'is_expression_type'):
                _num_val = val
                # Attempt to retrieve the numeric value .. if this
                # is a template expression generation, then it
                # should raise a TemplateExpressionError
                try:
                    val = EXPR.evaluate_expression(val, constant=True)
                    _found_numeric = True

                except TemplateExpressionError:
                    #
                    # The index is a template expression, so return the
                    # templatized expression.
                    #
                    from pyomo.core.expr import current as EXPR
                    return EXPR.GetItemExpression((self,) + tuple(idx))

                except EXPR.NonConstantExpressionError:
                    #
                    # The expression contains an unfixed variable
                    #
                    raise RuntimeError(
"""Error retrieving the value of an indexed item %s:
index %s is not a constant value.  This is likely not what you meant to
do, as if you later change the fixed value of the object this lookup
will not change.  If you understand the implications of using
non-constant values, you can get the current value of the object using
the value() function.""" % ( self.name, i ))

                except EXPR.FixedExpressionError:
                    #
                    # The expression contains a fixed variable
                    #
                    raise RuntimeError(
"""Error retrieving the value of an indexed item %s:
index %s is a fixed but not constant value.  This is likely not what you
meant to do, as if you later change the fixed value of the object this
lookup will not change.  If you understand the implications of using
fixed but not constant values, you can get the current value using the
value() function.""" % ( self.name, i ))
                #
                # There are other ways we could get an exception such as
                # evaluating a Param / Var that is not initialized.
                # These exceptions will continue up the call stack.
                #

            # verify that the value is hashable
            hash(val)
            if ellipsis is None:
                fixed[i] = val
            else:
                fixed[i - len(idx)] = val

        if sliced or ellipsis is not None:
            slice_dim = len(idx)
            if ellipsis is not None:
                slice_dim -= 1
            if normalize_index.flatten:
                set_dim = self.dim()
            elif self._implicit_subsets is None:
                # Scalar component.
                set_dim = 0
            else:
                set_dim = len(self._implicit_subsets)

            structurally_valid = False
            if slice_dim == set_dim or set_dim is None:
                structurally_valid = True
            elif ellipsis is not None and slice_dim < set_dim:
                structurally_valid = True
            elif set_dim == 0 and idx == (slice(None),):
                # If dim == 0 and idx is slice(None), the component was
                # a scalar passed a single slice. Since scalar components
                # can be accessed with a "1-dimensional" index of None,
                # this behavior is allowed.
                #
                # Note that x[...] is caught above, as slice_dim will be
                # 0 in that case
                structurally_valid = True

            if not structurally_valid:
                raise IndexError(
                    "Index %s contains an invalid number of entries for "
                    "component %s. Expected %s, got %s."
                    % (idx, self.name, set_dim, slice_dim))
            return IndexedComponent_slice(self, fixed, sliced, ellipsis)
        elif _found_numeric:
            if len(idx) == 1:
                return fixed[0]
            else:
                return tuple( fixed[i] for i in range(len(idx)) )
        else:
            raise DeveloperError(
                "Unknown problem encountered when trying to retrieve "
                "index for component %s" % (self.name,) )

    def _getitem_when_not_present(self, index):
        """Returns/initializes a value when the index is not in the _data dict.

        Override this method if the component allows implicit member
        construction.  For classes that do not support a 'default' (at
        this point, everything except Param and Var), requesting
        _getitem_when_not_present will generate a KeyError (just like a
        normal dict).

        Implementations may assume that the index has already been validated
        and is a legitimate entry in the _data dict.

        """
        raise KeyError(index)

    def _setitem_impl(self, index, obj, value):
        """Perform the fundamental object value storage

        Components that want to implement a nonstandard storage mechanism
        should override this method.

        Implementations may assume that the index has already been
        validated and is a legitimate pre-existing entry in the _data
        dict.

        """
        if value is IndexedComponent.Skip:
            del self[index]
            return None
        else:
            obj.set_value(value)
        return obj

    def _setitem_when_not_present(self, index, value=_NotSpecified):
        """Perform the fundamental component item creation and storage.

        Components that want to implement a nonstandard storage mechanism
        should override this method.

        Implementations may assume that the index has already been
        validated and is a legitimate entry in the _data dict.
        """
        # If the value is "Skip" do not add anything
        if value is IndexedComponent.Skip:
            return None
        #
        # If we are a scalar, then idx will be None (_validate_index ensures
        # this)
        if index is None and not self.is_indexed():
            obj = self._data[index] = self
        else:
            obj = self._data[index] = self._ComponentDataClass(component=self)
        try:
            if value is not _NotSpecified:
                obj.set_value(value)
        except:
            self._data.pop(index, None)
            raise
        return obj

    def set_value(self, value):
        """Set the value of a scalar component."""
        if self.is_indexed():
            raise ValueError(
                "Cannot set the value for the indexed component '%s' "
                "without specifying an index value.\n"
                "\tFor example, model.%s[i] = value"
                % (self.name, self.name))
        else:
            raise DeveloperError(
                "Derived component %s failed to define set_value() "
                "for scalar instances."
                % (self.__class__.__name__,))

    def _pprint(self):
        """Print component information."""
        return ( [("Size", len(self)),
                  ("Index", self._index if self.is_indexed() else None),
                  ],
                 self._data.items(),
                 ( "Object",),
                 lambda k, v: [ type(v) ]
                 )

    def id_index_map(self):
        """
        Return an dictionary id->index for
        all ComponentData instances.
        """
        result = {}
        for index, component_data in self.items():
            result[id(component_data)] = index
        return result


class ActiveIndexedComponent(IndexedComponent, ActiveComponent):
    """
    This is the base class for all indexed modeling components
    whose data members are subclasses of ActiveComponentData, e.g.,
    can be activated or deactivated.

    The activate and deactivate methods activate both the
    component as well as all component data values.
    """

    def __init__(self, *args, **kwds):
        IndexedComponent.__init__(self, *args, **kwds)
        # Replicate the ActiveComponent.__init__() here.  We don't want
        # to use super, because that will run afoul of certain
        # assumptions for derived SimpleComponents' __init__()
        #
        # FIXME: eliminate multiple inheritance of SimpleComponents
        self._active = True

    def activate(self):
        """Set the active attribute to True"""
        super(ActiveIndexedComponent, self).activate()
        if self.is_indexed():
            for component_data in self.values():
                component_data.activate()

    def deactivate(self):
        """Set the active attribute to False"""
        super(ActiveIndexedComponent, self).deactivate()
        if self.is_indexed():
            for component_data in self.values():
                component_data.deactivate()


# Ideally, this would inherit from np.lib.mixins.NDArrayOperatorsMixin,
# but doing so overrides things like __contains__ in addition to the
# operators that we are interested in.
class IndexedComponent_NDArrayMixin(object):
    """Support using IndexedComponent with numpy.ndarray

    This IndexedComponent mixin class adds support for implicitly using
    the IndexedComponent as a term in an expression with numpy ndarray
    objects.

    """

    def __array__(self, dtype=None):
        if not self.is_indexed():
            ans = NumericNDArray(shape=(1,), dtype=object)
            ans[0] = self
            return ans

        _dim = self.dim()
        if _dim is None:
            raise TypeError(
                "Cannot convert a non-dimensioned Pyomo IndexedComponent "
                "(%s) into a numpy array" % (self,))
        bounds = self.index_set().bounds()
        if not isinstance(bounds[0], Sequence):
            bounds = ((bounds[0],), (bounds[1],))
        if any(b != 0 for b in bounds[0]):
            raise TypeError(
                "Cannot convert a Pyomo IndexedComponent "
                "(%s) with bounds [%s, %s] into a numpy array" % (
                    self, bounds[0], bounds[1]))
        shape = tuple(b+1 for b in bounds[1])
        ans = NumericNDArray(shape=shape, dtype=object)
        for k, v in self.items():
            ans[k] = v
        return ans

    def __array_ufunc__(self, ufunc, method, *inputs, **kwargs):
        return NumericNDArray.__array_ufunc__(
            None, ufunc, method, *inputs, **kwargs)
