public Chain()
{
myObjectTypes = new List <ObjectType>();
myPredecidedManyToOneFactTypeMappings = new FactTypeMappingList();
myPredecidedOneToOneFactTypeMappings = new FactTypeMappingList();
myUndecidedOneToOneFactTypeMappings = new FactTypeMappingListList();
myPossiblePermutations = new List <Permutation>();
mySmallestPermutationsInTermsOfConceptTypes = new List <Permutation>();
}
/// <summary>
/// Permutes the <see cref="FactTypeMapping"/>s, recursively.
/// </summary>
/// <param name="permutations">The collection containing <see cref="Permutation"/>s that have already been calculated, and to which newly calculated <see cref="Permutation"/>s are added.</param>
/// <param name="undecidedMappings">The list of potential <see cref="FactTypeMapping"/>s for each <see cref="FactType"/> that need to be permuted.</param>
/// <param name="decidedMappings">The <see cref="FactTypeMapping"/>s that have already been decided for this branch of the permutation. Should initially be empty.</param>
/// <param name="deeplyMappedObjectTypes"><see cref="ObjectType"/>s that already have some deep <see cref="FactTypeMapping"/> away from them.</param>
/// <param name="currentPosition">The index into <paramref name="undecidedMappings"/> that should be processed.</param>
private static void PermuteFactTypeMappings(IList<Permutation> permutations, FactTypeMappingListList undecidedMappings, FactTypeMappingList decidedMappings, Dictionary<ObjectType, object> deeplyMappedObjectTypes, int currentPosition)
{
int nextPosition = currentPosition + 1;
bool isLastUndecided = (nextPosition == undecidedMappings.Count);
foreach (FactTypeMapping potentialMapping in undecidedMappings[currentPosition])
{
if (potentialMapping.MappingDepth == MappingDepth.Deep && deeplyMappedObjectTypes.ContainsKey(potentialMapping.FromObjectType))
{
// We already have a deep mapping away from this object type, so we can skip this potential mapping (which would result in an illegal permutation).
continue;
}
// Put this potential mapping onto the stack of decided mappings.
decidedMappings.Add(potentialMapping);
if (isLastUndecided)
{
// This is the end of the list of undecided fact types, so we can create a permutation.
permutations.Add(new Permutation(new FactTypeMappingList(decidedMappings)));
}
else
{
if (potentialMapping.MappingDepth == MappingDepth.Deep)
{
// This is a deep mapping, so add the from object type to the set of deeply mapped object types.
deeplyMappedObjectTypes[potentialMapping.FromObjectType] = null;
}
// Go on to the potential mappings for the next undecided fact type.
PermuteFactTypeMappings(permutations, undecidedMappings, decidedMappings, deeplyMappedObjectTypes, nextPosition);
if (potentialMapping.MappingDepth == MappingDepth.Deep)
{
// Remove the from object type from the set of deeply mapped object types.
deeplyMappedObjectTypes.Remove(potentialMapping.FromObjectType);
}
}
// Pop this potential mapping off the stack of decided mappings so that we can go on to the next potential mapping.
decidedMappings.RemoveAt(decidedMappings.Count - 1);
}
}
/// <summary>
/// Returns the maximum number of <see cref="Permutation"/>s that could result for the specified set of undecided <see cref="FactTypeMapping"/>s.
/// </summary>
private static double CalculateMaxNumberOfPermutations(FactTypeMappingListList undecidedMappings)
{
double maxPermutations = 1;
foreach (FactTypeMappingList mappingList in undecidedMappings)
{
maxPermutations *= mappingList.Count;
}
return maxPermutations;
}
/// <summary>
/// If the number of undecided elements is unreasonably high,
/// then apply incrementally more stringent requirements for
/// deciding fact type mappings until we have a reasonable number.
/// </summary>
public void EnsureReasonablePermutations(FactTypeMappingListDictionary allUndecidedMappings, FactTypeMappingDictionary allPredecidedMappings, FactTypeMappingDictionary allDecidedMappings)
{
FactTypeMappingListList undecidedMappings = myUndecidedOneToOneFactTypeMappings;
double maxPermutations = CalculateMaxNumberOfPermutations(undecidedMappings);
if (maxPermutations > MaxReasonablePermutations)
{
int undecidedMappingCount = undecidedMappings.Count;
Predicate <FactTypeMapping>[] reductionConditions = ReductionConditions;
if (reductionConditions == null)
{
// Note that there is intentionally a lot of duplication in
// these routines. An earlier design attempted to call previous
// conditions along with later ones, but this resulted in a much
// more complicated algorithm and multiple calls. The algorithm
// was simplified in exchange for making these condition routines
// more complicated.
reductionConditions = new Predicate <FactTypeMapping>[] {
delegate(FactTypeMapping mapping)
{
// If the fact type has a single non-mandatory value type
// then do not map towards the value type.
FactTypeMappingFlags mappingFlags = mapping.Flags;
if ((mappingFlags & (FactTypeMappingFlags.TowardsValueType | FactTypeMappingFlags.FromValueType)) == (FactTypeMappingFlags.TowardsValueType))
{
if (0 != (mappingFlags & FactTypeMappingFlags.TowardsRoleMandatory))
{
return(0 != (mappingFlags & FactTypeMappingFlags.TowardsRoleImpliedMandatory));
}
return(true);
}
return(false);
},
delegate(FactTypeMapping mapping)
{
// If the fact type has an unbalanced mandatory and is not a subtype,
// then map towards the mandatory.
FactTypeMappingFlags mappingFlags = mapping.Flags;
if (FactTypeMappingFlags.FromRoleMandatory == (mappingFlags & (FactTypeMappingFlags.FromRoleMandatory | FactTypeMappingFlags.FromRoleImpliedMandatory)) &&
0 == (mappingFlags & FactTypeMappingFlags.Subtype) &&
FactTypeMappingFlags.TowardsRoleMandatory != (mappingFlags & (FactTypeMappingFlags.TowardsRoleMandatory | FactTypeMappingFlags.TowardsRoleImpliedMandatory)))
{
return(true);
}
// Duplicate previous ValueType check
if ((mappingFlags & (FactTypeMappingFlags.TowardsValueType | FactTypeMappingFlags.FromValueType)) == (FactTypeMappingFlags.TowardsValueType))
{
if (0 != (mappingFlags & FactTypeMappingFlags.TowardsRoleMandatory))
{
return(0 != (mappingFlags & FactTypeMappingFlags.TowardsRoleImpliedMandatory));
}
return(true);
}
return(false);
},
delegate(FactTypeMapping mapping)
{
// Map away from a preferred identifier. This is not a cumulative test, and is ignored for later conditions.
FactTypeMappingFlags mappingFlags = mapping.Flags;
if (0 == (mappingFlags & FactTypeMappingFlags.FromPreferredIdentifier))
{
return(true);
}
// Duplicate unbalanced ValueType and unbalanced mandatory checks
if (FactTypeMappingFlags.FromRoleMandatory == (mappingFlags & (FactTypeMappingFlags.FromRoleMandatory | FactTypeMappingFlags.FromRoleImpliedMandatory)) &&
0 == (mappingFlags & FactTypeMappingFlags.Subtype) &&
FactTypeMappingFlags.TowardsRoleMandatory != (mappingFlags & (FactTypeMappingFlags.TowardsRoleMandatory | FactTypeMappingFlags.TowardsRoleImpliedMandatory)))
{
return(true);
}
if ((mappingFlags & (FactTypeMappingFlags.TowardsValueType | FactTypeMappingFlags.FromValueType)) == (FactTypeMappingFlags.TowardsValueType))
{
if (0 != (mappingFlags & FactTypeMappingFlags.TowardsRoleMandatory))
{
return(0 != (mappingFlags & FactTypeMappingFlags.TowardsRoleImpliedMandatory));
}
return(true);
}
return(false);
},
delegate(FactTypeMapping mapping)
{
// Prefer a shallow mapping.
FactTypeMappingFlags mappingFlags = mapping.Flags;
if (0 != (mappingFlags & FactTypeMappingFlags.DeepMapping))
{
return(true);
}
// Duplicate unbalanced ValueType and unbalanced mandatory checks
if (FactTypeMappingFlags.FromRoleMandatory == (mappingFlags & (FactTypeMappingFlags.FromRoleMandatory | FactTypeMappingFlags.FromRoleImpliedMandatory)) &&
0 == (mappingFlags & FactTypeMappingFlags.Subtype) &&
FactTypeMappingFlags.TowardsRoleMandatory != (mappingFlags & (FactTypeMappingFlags.TowardsRoleMandatory | FactTypeMappingFlags.TowardsRoleImpliedMandatory)))
{
return(true);
}
if ((mappingFlags & (FactTypeMappingFlags.TowardsValueType | FactTypeMappingFlags.FromValueType)) == (FactTypeMappingFlags.TowardsValueType))
{
if (0 != (mappingFlags & FactTypeMappingFlags.TowardsRoleMandatory))
{
return(0 != (mappingFlags & FactTypeMappingFlags.TowardsRoleImpliedMandatory));
}
return(true);
}
return(false);
},
delegate(FactTypeMapping mapping)
{
// If we have too many permutations then just map towards the first role.
// Yes, this is completely arbitrary, but getting anywhere past item 2 on
// this list will be extremely rarely and represents truly pathological cases.
// Perform previous flag-based checks first.
FactTypeMappingFlags mappingFlags = mapping.Flags;
if (0 != (mappingFlags & FactTypeMappingFlags.DeepMapping))
{
return(true);
}
if (FactTypeMappingFlags.FromRoleMandatory == (mappingFlags & (FactTypeMappingFlags.FromRoleMandatory | FactTypeMappingFlags.FromRoleImpliedMandatory)) &&
0 == (mappingFlags & FactTypeMappingFlags.Subtype) &&
FactTypeMappingFlags.TowardsRoleMandatory != (mappingFlags & (FactTypeMappingFlags.TowardsRoleMandatory | FactTypeMappingFlags.TowardsRoleImpliedMandatory)))
{
return(true);
}
if ((mappingFlags & (FactTypeMappingFlags.TowardsValueType | FactTypeMappingFlags.FromValueType)) == (FactTypeMappingFlags.TowardsValueType))
{
if (0 != (mappingFlags & FactTypeMappingFlags.TowardsRoleMandatory))
{
return(0 != (mappingFlags & FactTypeMappingFlags.TowardsRoleImpliedMandatory));
}
return(true);
}
Role role = mapping.TowardsRole;
return(0 != mapping.FactType.RoleCollection.IndexOf((RoleBase)role.Proxy ?? role));
},
};
ReductionConditions = reductionConditions;
}
FactTypeMappingList decidedMappings = myPredecidedOneToOneFactTypeMappings;
for (int maxReduction = 0; maxReduction < reductionConditions.Length; ++maxReduction)
{
for (int undecidedMappingIndex = undecidedMappingCount - 1; undecidedMappingIndex >= 0; --undecidedMappingIndex)
{
FactTypeMappingList testMappings = undecidedMappings[undecidedMappingIndex];
int testMappingCount = testMappings.Count;
// Note that the max length of this list is four (shallow and deep both directions)
FactTypeMapping singleMapping = null;
for (int i = 0; i < testMappingCount; ++i)
{
FactTypeMapping testMapping = testMappings[i];
if (!reductionConditions[maxReduction](testMapping))
{
// This test mapping is not filtered, allow it
if (singleMapping == null)
{
singleMapping = testMapping;
}
else
{
singleMapping = null;
break;
}
}
}
if (singleMapping != null)
{
decidedMappings.Add(singleMapping);
undecidedMappings.RemoveAt(undecidedMappingIndex);
--undecidedMappingCount;
maxPermutations /= testMappingCount;
FactType factTypeKey = singleMapping.FactType;
allUndecidedMappings.Remove(factTypeKey);
allPredecidedMappings.Add(factTypeKey, singleMapping);
allDecidedMappings.Add(factTypeKey, singleMapping);
}
}
if (maxPermutations <= MaxReasonablePermutations)
{
break;
}
}
}
}
