public static string Hash(this IObject iObj, ComparisonConfig comparisonConfig = null, bool hashFromFragment = false)
{
if (iObj == null)
{
BH.Engine.Reflection.Compute.RecordError("Cannot query the hash of a null object.");
return("");
}
if (hashFromFragment && iObj is IBHoMObject)
{
// Instead of computing the Hash, first tryGet the hash in HashFragment
string hash = (iObj as IBHoMObject).FindFragment <HashFragment>()?.Hash;
if (!string.IsNullOrWhiteSpace(hash))
{
return(hash);
}
}
// ------ SET UP OF CONFIGURATION ------
// Make sure we always have a config object. Clone for immutability.
ComparisonConfig cc = comparisonConfig == null ? new ComparisonConfig() : comparisonConfig.DeepClone();
// Make sure that "BHoM_Guid" is added to the PropertyExceptions of the config.
cc.PropertyExceptions = cc.PropertyExceptions ?? new List <string>();
if (!cc.PropertyExceptions.Contains(nameof(BHoMObject.BHoM_Guid)))
{
cc.PropertyExceptions.Add(nameof(BHoMObject.BHoM_Guid));
}
// Process the "PropertiesToInclude" property.
if (cc.PropertiesToConsider?.Any() ?? false)
{
// The hash computation can only consider "exceptions".
// We need to retrieve all the object properties, intersect them with PropertiesToInclude, and treat all those remaining as "exceptions".
// Works only for top-level properties.
IEnumerable <string> exceptions = BH.Engine.Reflection.Query.PropertyNames(iObj).Except(cc.PropertiesToConsider);
cc.PropertyExceptions.AddRange(exceptions);
}
// Make sure that the single Property exceptions are either:
// - explicitly referring to a property in its "property path": e.g. Bar.StartNode.Point.X
// - OR if it's only a property name e.g. BHoM_Guid make sure that we prepend the wildcard so we can match the single property inside any property path: e.g. *BHoM_Guid
//cc.PropertyExceptions = cc.PropertyExceptions.Select(pe => pe = pe.Contains('.') ? pe : "*" + pe).ToList();
// Convert from the Numeric Tolerance to fractionalDigits (required for the hash).
int fractionalDigits = Math.Abs(Convert.ToInt32(Math.Log10(cc.NumericTolerance)));
// ----- SET UP OF INPUT OBJECT -----
// Copy the object for immutability
IObject iObj_copy = iObj.ShallowClone();
// Any HashFragment present on the object must not be considered when computing the Hash. Remove if present.
IBHoMObject bhomobj = iObj_copy as IBHoMObject;
if (bhomobj != null)
{
List <IHashFragment> hashFragments = bhomobj.GetAllFragments(typeof(IHashFragment)).OfType <IHashFragment>().ToList();
hashFragments.ForEach(f => bhomobj.Fragments.Remove(f.GetType()));
iObj_copy = bhomobj;
}
// ----- HASH -----
// Compute the defining string.
string hashString = DefiningString(iObj_copy, cc, fractionalDigits, 0);
if (string.IsNullOrWhiteSpace(hashString))
{
// This means that:
// - all properties of the input object were disregarded due to the settings specified in the ComparisonConfig, or
// - all properties of the input object that were not disregarded were null or empty,
// Since a hash has to be always returned, for this scenario we are forced to build a defining string out of the type full name.
hashString = iObj_copy.GetType().FullName;
}
// Return the SHA256 hash of the defining string.
return(SHA256Hash(hashString));
}
