/// <inheritdoc />
public int GetHashCode(
object obj)
{
return(HashCodeHelper.Initialize().Hash(obj).Value);
}
/// <summary>
/// Adds the hash code for the given item to the current hash code and returns the new hash code.
/// </summary>
/// <typeparam name="T">The type of the item being hashed.</typeparam>
/// <param name="item">The item to hash.</param>
/// <returns>The new hash code.</returns>
public HashCodeHelper Hash <T>(
T item)
{
unchecked
{
HashCodeHelper result;
var declaredType = typeof(T);
var runtimeType = item?.GetType();
if ((declaredType == typeof(object)) && (runtimeType != null))
{
// If the declared type is object and item is not null
// (if it's null then it will will eventually hit the else statement at the bottom,
// either in this pass, or thru HashDictionary(), etc. which will come back thru
// the front door using Hash<object>(null)
if (runtimeType == typeof(object))
{
// new object().GetHashCode() != new object().GetHashCode() so we need to solve for that here.
var hashCode = this.Value;
hashCode = (hashCode * HashCodeMultiplier) + ObjectHashCode;
result = new HashCodeHelper(hashCode);
}
else
{
// Use the runtime type as the declared type and come back thru the front door.
result = (HashCodeHelper)HashGenericMethodInfo.MakeGenericMethod(runtimeType).Invoke(this, new object[] { item });
}
}
else if (declaredType.IsClosedSystemDictionaryType())
{
var methodInfo = declaredType.GetGenericTypeDefinition() == typeof(IDictionary <,>)
? HashDictionaryGenericMethodInfo
: HashReadOnlyDictionaryGenericMethodInfo;
result = (HashCodeHelper)methodInfo.MakeGenericMethod(declaredType.GenericTypeArguments).Invoke(this, new object[] { item });
}
else if (declaredType.IsClosedSystemCollectionType())
{
if (declaredType.IsClosedSystemOrderedCollectionType())
{
result = (HashCodeHelper)HashOrderedCollectionGenericMethodInfo.MakeGenericMethod(declaredType.GenericTypeArguments).Invoke(this, new object[] { item });
}
else
{
result = (HashCodeHelper)HashUnorderedCollectionGenericMethodInfo.MakeGenericMethod(declaredType.GenericTypeArguments).Invoke(this, new object[] { item });
}
}
else if (declaredType.IsArray)
{
var genericArguments = declaredType.GetElementType();
result = (HashCodeHelper)HashOrderedCollectionGenericMethodInfo.MakeGenericMethod(genericArguments).Invoke(this, new object[] { item });
}
else if (declaredType.IsClosedSystemEnumerableType())
{
result = (HashCodeHelper)HashUnorderedCollectionGenericMethodInfo.MakeGenericMethod(declaredType.GenericTypeArguments).Invoke(this, new object[] { item });
}
else if ((declaredType == typeof(DateTime)) || (declaredType == typeof(DateTime?)))
{
var hashCode = this.Value;
hashCode = (hashCode * HashCodeMultiplier) + (item?.GetHashCode() ?? 0);
if (item != null)
{
hashCode = (hashCode * HashCodeMultiplier) + ((DateTime)(object)item).Kind.GetHashCode();
}
result = new HashCodeHelper(hashCode);
}
else if ((declaredType == typeof(Color)) || (declaredType == typeof(Color?)))
{
if (item == null)
{
result = this.Hash((object)null);
}
else
{
var color = (Color)(object)item;
result = this.Hash(color.A).Hash(color.R).Hash(color.G).Hash(color.B);
}
}
else
{
var hashCode = (this.Value * HashCodeMultiplier) + (item?.GetHashCode() ?? 0);
result = new HashCodeHelper(hashCode);
}
return(result);
}
}
/// <summary>
/// Adds the hash code for the given item to the current hash code and returns the new hash code.
/// </summary>
/// <typeparam name="T">The type of the item being hashed.</typeparam>
/// <param name="item">The item to hash.</param>
/// <returns>The new hash code.</returns>
public HashCodeHelper Hash <T>(
T item)
{
unchecked
{
HashCodeHelper result;
var valueType = typeof(T);
if (valueType.IsClosedSystemDictionaryType())
{
var methodInfo = valueType.GetGenericTypeDefinition() == typeof(IDictionary <,>)
? HashDictionaryMethodInfo
: HashReadOnlyDictionaryMethodInfo;
result = (HashCodeHelper)methodInfo.MakeGenericMethod(valueType.GenericTypeArguments).Invoke(this, new[] { (object)item });
}
else if (valueType.IsClosedSystemCollectionType())
{
if (valueType.IsClosedSystemOrderedCollectionType())
{
result = (HashCodeHelper)HashOrderedCollectionMethodInfo.MakeGenericMethod(valueType.GenericTypeArguments).Invoke(this, new[] { (object)item });
}
else
{
result = (HashCodeHelper)HashUnorderedCollectionMethodInfo.MakeGenericMethod(valueType.GenericTypeArguments).Invoke(this, new[] { (object)item });
}
}
else if (valueType.IsArray)
{
var genericArguments = valueType.GetElementType();
result = (HashCodeHelper)HashOrderedCollectionMethodInfo.MakeGenericMethod(genericArguments).Invoke(this, new[] { (object)item });
}
else if (valueType.IsClosedSystemEnumerableType())
{
result = (HashCodeHelper)HashUnorderedCollectionMethodInfo.MakeGenericMethod(valueType.GenericTypeArguments).Invoke(this, new[] { (object)item });
}
else if ((valueType == typeof(DateTime)) || (valueType == typeof(DateTime?)))
{
var hashCode = this.Value;
hashCode = (hashCode * HashCodeMultiplier) + (item?.GetHashCode() ?? 0);
if (item != null)
{
hashCode = (hashCode * HashCodeMultiplier) + ((DateTime)(object)item).Kind.GetHashCode();
}
result = new HashCodeHelper(hashCode);
}
else
{
var hashCode = (this.Value * HashCodeMultiplier) + (item?.GetHashCode() ?? 0);
result = new HashCodeHelper(hashCode);
}
return(result);
}
}