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#![doc = include_str!("../README.md")]

pub mod default_impl;
pub mod holder;
pub mod cmp;

/// An item which state may change
///
/// Allows to keep track of the changes of the item
///
/// # Simple Mutation
/// ```
/// # use mutable::Mutable;
/// # use mutable_derive::Mutable;
/// #[derive(Mutable, Clone, Debug, PartialEq)]
///  struct Item {
///      size: usize,
/// }
///
/// let a0 = Item{ size: 0};
/// let a1 = Item{ size: 1};
///
/// assert_eq!(a0.cmp(&a1), vec![ItemMutation::Size((0, 1))]);
/// ```
///
/// # Nested mutation
/// ```
/// # use mutable::Mutable;
/// # use mutable_derive::Mutable;
/// #[derive(Mutable)]
/// struct Simple {
///     size: usize,
/// }
///
/// #[derive(Mutable)]
/// struct Complex{
///     id: String,
///     value: Simple,
/// }
///
/// # fn main(){
/// let mut c0 = Complex{ id: "a".to_string(), value: Simple { size: 32 } };
/// let c1 = Complex{ id: "b".to_string(), value: Simple { size: 64 } };
///
/// assert_eq!(c0.update(c1), vec![
///     ComplexMutation::Id(("a".to_string(), "b".to_string())),
///     ComplexMutation::Value(SimpleMutation::Size((32, 64)))
/// ]);
/// # }
/// ```
///
/// # Vec mutation
/// ```
/// # use mutable::Mutable;
/// # use mutable::cmp::SoftEq;
/// # use mutable_derive::{Mutable, SoftEq};
/// # use mutable::default_impl::VecMutation;
/// #[derive(Mutable, PartialEq, SoftEq, Debug, Clone)]
/// struct Item {
///     #[softeq(uid)]
///     id: String,
///     value: u32,
/// }
///
/// # fn main(){
/// let a0 = Item{id: "a".to_string(), value: 0};
/// let a1 = Item{id: "a".to_string(), value: 1};
/// let b = Item{id: "b".to_string(), value: 0};
///
/// let mut v0 = vec![a0];
/// let v1 = vec![a1, b];
///
/// assert_eq!(v0.update(v1), vec![
///     VecMutation::Update("a".to_string(), ItemMutation::Value((0, 1))),
///     VecMutation::Insertion("b".to_string())
/// ])
/// # }
/// ```
///
/// # Mutation generation
/// When derived through [mutable_derive::Mutable](../mutable_derive/derive.Mutable.html), the mutation type is generated as follow:
///
/// The mutation type is an enum, for which each variant correspond to a field of the struct.
/// Each of them as only one element, which is the mutation type of the attribute type
///
/// Example of result:
/// ```
/// struct Foo{
///     size: usize
/// }
///
/// // Generated
/// enum FooMutation{
///     Size((usize, usize)),
/// }
///
/// struct Item{
///     id: u32,
///     name: String,
///     value: Foo,
/// }
///
/// // Generated
/// enum ItemMutation{
///     Id((u32, u32)),
///     Name((String, String)),
///     Value(FooMutation),
/// }
/// ```

pub trait Mutable where Self: Sized {
    /// Type describing any changes that may happen to the item
    type Mutation: Clone;

    /// Compare self and other, and returns the list of changes to go from self to other. The order of the mutation in the returned vec is undefined\
    /// This should not be used outside of the Mutable implementation
    fn cmp(&self, other: &Self) -> Vec<Self::Mutation>;

    /// Mutate self into other, and returns the list of all mutations. The order of the mutation in the returned vec is undefined
    fn update(&mut self, other: Self) -> Vec<Self::Mutation> {
        let res = self.cmp(&other);
        *self = other;
        res
    }
}