HashSet only implements the normal set. HashSet can not represent its complementary set when the complementary set is an infinite set.

FlagSet implemented as a tuple of a HashSet and a bool value. When the bool value is true, FlagSet represents the HashSet . When the bool value is true, FlagSet represents the the complementary set of HashSet .

As with the HashSet type, a FlagSet requires that the elements implement the Eq and Hash traits. In addition to operations of FlagSet, the elements also implement the Clone trait.

FlagSet also defines five kinds of operations of sets based on Binary Operations

A ∪B -> A + B

A ∩ B -> A & B

A - B -> A - B

A Xor B -> A ^ B

C_uA -> !A

Examples

```rust use std::collections::HashSet; use flag_set::FlagSet;

let a: HashSet<_> = vec![1, 2, 3].intoiter().collect(); let b: HashSet<_> = vec![2, 3, 4].intoiter().collect();

let flagap = FlagSet(a.clone(), true); let flagan = FlagSet(a.clone(), false); let flagbp = FlagSet(b.clone(), true); let flagbn = FlagSet(b.clone(), false);

// 用new方法创建实例 // use new method create an instance asserteq!(flagbn, FlagSet::new(vec![2, 3, 4], false));

// 测试并 // test union asserteq!(FlagSet::new(vec![1, 2, 3, 4], true), flagap.clone() + flagbp.clone()); asserteq!(FlagSet::new(vec![4], false), flagap.clone() + flagbn.clone()); asserteq!(FlagSet::new(vec![1], false), flagan.clone() + flagbp.clone()); asserteq!(FlagSet::new(vec![2, 3], false), flagan.clone() + flagbn.clone());

// 测试交 // test intersection asserteq!(FlagSet::new(vec![2, 3], true), flagap.clone() & flagbp.clone()); asserteq!(FlagSet::new(vec![1], true), flagap.clone() & flagbn.clone()); asserteq!(FlagSet::new(vec![4], true), flagan.clone() & flagbp.clone()); asserteq!(FlagSet::new(vec![1, 2, 3, 4], false), flagan.clone() & flagbn.clone());

// 测试减 // test substraction asserteq!(FlagSet::new(vec![1], true), flagap.clone() - flagbp.clone()); asserteq!(FlagSet::new(vec![2, 3], true), flagap.clone() - flagbn.clone()); asserteq!(FlagSet::new(vec![1, 2, 3, 4], false), flagan.clone() - flagbp.clone()); asserteq!(FlagSet::new(vec![4], true), flagan.clone() - flagbn.clone());

// 测试否 // test not asserteq!(FlagSet(a.clone(), true), !flagan.clone());

// 测试对称差 // test symmetric difference asserteq!(FlagSet::new(vec![1, 4], true), flagap.clone() ^ flag_bp.clone()); ```