Ah, yes I see your issue. The > and < operators (comparison) assume that
A < B OR B <= A will always be true. When you're talking about sets,
A may not be a subset of B AND B might not be a subset of A. So I
suppose the less than/ greater than does not really equate to subset
notation. You could use leftShift and rightShift...
Try this?
class MySet {
def items = []
public boolean leftShift(other) {
if( ! (other instanceof MySet) ) return false
(this.items - other.items).size == 0
}
public boolean rightShift(other) {
if( ! (other instanceof MySet) ) return -1
(other.items - this.items).size == 0
}
public boolean equals( other ) {
if( ! (other instanceof MySet) ) return -1
(other.items - this.items).size == 0 &&
(this.items - other.items).size == 0
}
}
def set1 = new MySet( items:[1,2,3] )
def set2 = new MySet( items:[1,2,3] )
assert set1 == set2
assert set1 << set2 && set2 << set1
assert set1 >> set2 && set2 >> set1
set2.items -= 3 //set2 == [1,2]
assert set1 != set2
assert set2 << set1 && set1 >> set2
assert !(set1 << set2) && !(set2 >> set1)
set3 = new MySet( items:[1,8] )
assert !( set1 >> set3 ) && !( set3 >> set1 )
assert !( set1 << set3 ) && !( set3 << set1 )
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