The Fortress Language Specification - CiteSeerX

38.2 The Trait Fortress.Standard.TotalComparison
The comparison operator CMP , when applied to values belonging to a total order, typically returns a value of type
TotalComparison. The three values of type TotalComparison are called LessThan, EqualTo, and GreaterThan.
This trait supports an associative operator LEXICO that is useful for supporting lexicographic comparison of ordered
sequences; the trick is to compare the sequences elementwise and then to use the LEXICO operator to reduce the
sequence of comparison results. Note that EqualTo is the identity for LEXICO , and all other comparison values are
left zeroes for LEXICO .
value trait TotalComparison
extends { Comparison,
AssociativeTotalComparison,LEXICO,
HasIdentityTotalComparison,LEXICO,
HasLeftZeroesTotalComparison,LEXICO,isLeftZeroForLEXICO }
comprises { LessThan, EqualTo, GreaterThan }
opr LEXICO(self,other: TotalComparison): TotalComparison
isLeftZeroForLEXICO(self):Boolean
opr =(self,other: TotalComparison): Boolean
getter hashCode(): Z64
toString():String
end
LessThan: TotalComparison
EqualTo: TotalComparison
GreaterThan: TotalComparison
38.2.1 opr LEXICO(self,other: TotalComparison):TotalComparison
The operator LEXICO returns its right argument if the left argument is EqualTo; otherwise it returns its left argument.
The LEXICO operator as applied to total comparison values may be described by this table:
LEXICO LessThan EqualTo GreaterThan
LessThan LessThan LessThan LessThan
EqualTo LessThan EqualTo GreaterThan
GreaterThan GreaterThan GreaterThan GreaterThan
38.2.2 isLeftZeroForLEXICO(self):Boolean
This method returns false for EqualTo and true for all other total comparison values.
38.2.3 opr =(self,other: TotalComparison):Boolean
Two total comparison values are strictly equivalent if and only if they are the same.
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