/// <summary>
/// Structural equality testing. Objects are equal if they are of the same type
/// and if each field (given by the enumeration <see cref="FieldValues" />) is equal
/// for the two values.
/// </summary>
/// <param name="obj">The value to compare to this value</param>
/// <returns>True if the values are equal, false otherwise.</returns>
public override bool Equals(object /*?*/ obj)
{
CompoundValue other = obj as CompoundValue;
if ((object)other == null)
{
return(false);
}
if ((object)this == obj)
{
return(true);
}
if (this.GetType() != obj.GetType())
{
return(false);
}
IEnumerator <IComparable> fields1 = this.FieldValues().GetEnumerator();
IEnumerator <IComparable> fields2 = other.FieldValues().GetEnumerator();
while (true)
{
bool hasNext1 = fields1.MoveNext();
bool hasNext2 = fields2.MoveNext();
if (hasNext1 ^ hasNext2)
{
return(false); // differing lengths
}
if (!hasNext1)
{
return(true);
}
if (!Object.Equals(fields1.Current, fields2.Current))
{
return(false);
}
}
}
/// <summary>
/// Term order. Comparision is based on type and recursively on fields.
/// </summary>
/// <param name="obj"></param>
/// <returns>-1 if less than, 0 if equal, 1 if greater than</returns>
/// <exception cref="System.ArgumentException">Thrown if <paramref name="obj"/> is nonnull but is not an <c>CompoundValue</c>.</exception>
public override int CompareTo(object /*?*/ obj)
//^ requires obj != null ==> obj is IComparable;
//^ ensures result == 0 <==> Object.Equals(this, obj);
//^ ensures result == -1 || result == 0 || result == 1;
{
// Case 1: other obj is null
if (obj == null)
{
return(1); // nonnull is bigger than null
}
CompoundValue other = obj as CompoundValue;
if ((object)other == null)
{
throw new ArgumentException(MessageStrings.LocalizedFormat(MessageStrings.CompoundValueRequired, obj.GetType().ToString()));
}
// Case 2: types aren't the same, do type comparison in dictionary order
Type t1 = this.GetType();
Type t2 = obj.GetType();
if (t1 != t2)
{
return(t1.ToString().CompareTo(t2.ToString()));
}
// Case 3: types are the same, look for first field that is not equal
IEnumerator <IComparable> fields1 = this.FieldValues().GetEnumerator();
IEnumerator <IComparable> fields2 = other.FieldValues().GetEnumerator();
while (true)
{
bool hasNext1 = fields1.MoveNext();
bool hasNext2 = fields2.MoveNext();
if (hasNext1 & !hasNext2)
{
return(1); // longer comes after shorter
}
if (!hasNext1 & hasNext2)
{
return(-1); // shorter comes before longer
}
if (!hasNext1)
{
return(0); // items are equal
}
IComparable c1 = fields1.Current as IComparable;
IComparable c2 = fields2.Current as IComparable;
if (fields1.Current != null && c1 == null)
{
throw new ArgumentException(MessageStrings.LocalizedFormat(MessageStrings.ComparableTypeRequired, fields1.Current.GetType().ToString()));
}
if (fields2.Current != null && c2 == null)
{
throw new ArgumentException(MessageStrings.LocalizedFormat(MessageStrings.ComparableTypeRequired, fields2.Current.GetType().ToString()));
}
int fieldCompare = HashAlgorithms.CompareValues(c1, c2);
if (fieldCompare != 0)
{
return(fieldCompare);
}
}
}
