Trait Annotate

Source

pub trait Annotate<A>: Sized {
    type Annotation;

    // Required method
    fn annotated(self, annotation: Self::Annotation) -> Annotated<Self, A>;
}

Expand description

Some Semigroup such as crate::op::Coalesce can have an annotation. Annotate trait will be derived by Semigroup. The annotated value is represented by a type Annotated.

§Examples

§constructed semigroup

use semigroup::{op::Coalesce, Annotate, Semigroup};

let a = Coalesce(Some(1)).annotated("first");
let b = Coalesce(None).annotated("second");
let c = Coalesce(Some(3)).annotated("third");

let ab = a.semigroup(b);
assert_eq!(ab.value(), &Coalesce(Some(1)));
assert_eq!(ab.annotation(), &"first");

let bc = b.semigroup(c);
assert_eq!(bc.value(), &Coalesce(Some(3)));
assert_eq!(bc.annotation(), &"third");

let ca = c.semigroup(a);
assert_eq!(ca.value(), &Coalesce(Some(3)));
assert_eq!(ca.annotation(), &"third");

§derived semigroup

use semigroup::{op::Coalesce, Annotate, Annotated, Semigroup};

#[derive(Debug, Clone, Copy, PartialEq, Semigroup)]
#[semigroup(annotated, with = "semigroup::op::Coalesce")]
struct ExampleStruct<'a> {
    num: Option<u32>,
    str: Option<&'a str>,
    #[semigroup(with = "semigroup::op::Overwrite")]
    boolean: bool,
}

let a = ExampleStruct { num: Some(1), str: None, boolean: true }.annotated("first");
let b = ExampleStruct { num: None, str: Some("ten"), boolean: false }.annotated("second");
let c = ExampleStruct { num: Some(100), str: None, boolean: false }.annotated("third");

let ab = a.semigroup(b);
assert_eq!(ab.value(), &ExampleStruct { num: Some(1), str: Some("ten"), boolean: false });
assert_eq!(ab.annotation().num, "first");
assert_eq!(ab.annotation().str, "second");
assert_eq!(ab.annotation().boolean, "second");
assert_eq!(ab.annotation(), &ExampleStructAnnotation{ num: "first", str: "second", boolean: "second" });

let bc = b.semigroup(c);
assert_eq!(bc.value(), &ExampleStruct { num: Some(100), str: Some("ten"), boolean: false });
assert_eq!(bc.annotation().num, "third");
assert_eq!(bc.annotation().str, "second");
assert_eq!(bc.annotation().boolean, "third");
assert_eq!(bc.annotation(), &ExampleStructAnnotation{ num: "third", str: "second", boolean: "third" });

let ca = c.semigroup(a);
assert_eq!(ca.value(), &ExampleStruct { num: Some(100), str: None, boolean: true });
assert_eq!(ca.annotation().num, "third");
assert_eq!(ca.annotation().str, "third");
assert_eq!(ca.annotation().boolean, "first");
assert_eq!(ca.annotation(), &ExampleStructAnnotation{ num: "third", str: "third", boolean: "first" });