Trait VersionSet

Source

pub trait VersionSet:
    Debug
    + Display
    + Clone
    + Eq {
    type V: Debug + Display + Clone + Ord;

    // Required methods
    fn empty() -> Self;
    fn singleton(v: Self::V) -> Self;
    fn complement(&self) -> Self;
    fn intersection(&self, other: &Self) -> Self;
    fn contains(&self, v: &Self::V) -> bool;

    // Provided methods
    fn full() -> Self { ... }
    fn union(&self, other: &Self) -> Self { ... }
    fn is_disjoint(&self, other: &Self) -> bool { ... }
    fn subset_of(&self, other: &Self) -> bool { ... }
}

Expand description

A set of versions.

See Ranges for an implementation.

The methods with default implementations can be overwritten for better performance, but their output must be equal to the default implementation.

§Equality

It is important that the Eq trait is implemented so that if two sets contain the same versions, they are equal under Eq. In particular, you can only use #[derive(Eq, PartialEq)] if Eq is strictly equivalent to the structural equality, i.e. if version sets are always stored in a canonical representations. Such problems may arise if your implementations of complement() and intersection() do not return canonical representations.

For example, >=1,<4 || >=2,<5 and >=1,<4 || >=3,<5 are equal, because they can both be normalized to >=1,<5.

Note that pubgrub does not know which versions actually exist for a package, the contract is about upholding the mathematical properties of set operations, assuming all versions are possible. This is required for the solver to determine the relationship of version sets to each other.