lighthouse/common/compare_fields/src/lib.rs
Michael Sproul 463e62e833 Generalise compare_fields to work with iterators (#4823)
## Proposed Changes

Add `compare_fields(as_iter)` as a field attribute to `compare_fields_derive`. This allows any iterable type to be compared in the same as a slice (by index). 

This is forwards-compatible with tree-states types like `List` and `Vector` which can not be cast to slices.
2023-10-18 12:59:53 +00:00

198 lines
5.4 KiB
Rust

//! Provides field-by-field comparisons for structs and vecs.
//!
//! Returns comparisons as data, without making assumptions about the desired equality (e.g.,
//! does not `panic!` on inequality).
//!
//! Note: `compare_fields_derive` requires `PartialEq` and `Debug` implementations.
//!
//! ## Example
//!
//! ```rust
//! use compare_fields::{CompareFields, Comparison, FieldComparison};
//! use compare_fields_derive::CompareFields;
//!
//! #[derive(PartialEq, Debug, CompareFields)]
//! pub struct Bar {
//! a: u64,
//! b: u16,
//! #[compare_fields(as_slice)]
//! c: Vec<Foo>
//! }
//!
//! #[derive(Clone, PartialEq, Debug, CompareFields)]
//! pub struct Foo {
//! d: String
//! }
//!
//! let cat = Foo {d: "cat".to_string()};
//! let dog = Foo {d: "dog".to_string()};
//! let chicken = Foo {d: "chicken".to_string()};
//!
//! let mut bar_a = Bar {
//! a: 42,
//! b: 12,
//! c: vec![ cat.clone(), dog.clone() ],
//! };
//!
//! let mut bar_b = Bar {
//! a: 42,
//! b: 99,
//! c: vec![ chicken.clone(), dog.clone()]
//! };
//!
//! let cat_dog = Comparison::Child(FieldComparison {
//! field_name: "d".to_string(),
//! equal: false,
//! a: "\"cat\"".to_string(),
//! b: "\"dog\"".to_string(),
//! });
//! assert_eq!(cat.compare_fields(&dog), vec![cat_dog]);
//!
//! let bar_a_b = vec![
//! Comparison::Child(FieldComparison {
//! field_name: "a".to_string(),
//! equal: true,
//! a: "42".to_string(),
//! b: "42".to_string(),
//! }),
//! Comparison::Child(FieldComparison {
//! field_name: "b".to_string(),
//! equal: false,
//! a: "12".to_string(),
//! b: "99".to_string(),
//! }),
//! Comparison::Parent{
//! field_name: "c".to_string(),
//! equal: false,
//! children: vec![
//! FieldComparison {
//! field_name: "0".to_string(),
//! equal: false,
//! a: "Some(Foo { d: \"cat\" })".to_string(),
//! b: "Some(Foo { d: \"chicken\" })".to_string(),
//! },
//! FieldComparison {
//! field_name: "1".to_string(),
//! equal: true,
//! a: "Some(Foo { d: \"dog\" })".to_string(),
//! b: "Some(Foo { d: \"dog\" })".to_string(),
//! }
//! ]
//! }
//! ];
//! assert_eq!(bar_a.compare_fields(&bar_b), bar_a_b);
//! ```
use itertools::{EitherOrBoth, Itertools};
use std::fmt::Debug;
#[derive(Debug, PartialEq, Clone)]
pub enum Comparison {
Child(FieldComparison),
Parent {
field_name: String,
equal: bool,
children: Vec<FieldComparison>,
},
}
impl Comparison {
pub fn child<T: Debug + PartialEq<T>>(field_name: String, a: &T, b: &T) -> Self {
Comparison::Child(FieldComparison::new(field_name, a, b))
}
pub fn parent(field_name: String, equal: bool, children: Vec<FieldComparison>) -> Self {
Comparison::Parent {
field_name,
equal,
children,
}
}
pub fn from_slice<T: Debug + PartialEq<T>>(field_name: String, a: &[T], b: &[T]) -> Self {
Self::from_iter(field_name, a.iter(), b.iter())
}
pub fn from_into_iter<'a, T: Debug + PartialEq + 'a>(
field_name: String,
a: impl IntoIterator<Item = &'a T>,
b: impl IntoIterator<Item = &'a T>,
) -> Self {
Self::from_iter(field_name, a.into_iter(), b.into_iter())
}
pub fn from_iter<'a, T: Debug + PartialEq + 'a>(
field_name: String,
a: impl Iterator<Item = &'a T>,
b: impl Iterator<Item = &'a T>,
) -> Self {
let mut children = vec![];
let mut all_equal = true;
for (i, entry) in a.zip_longest(b).enumerate() {
let comparison = match entry {
EitherOrBoth::Both(x, y) => {
FieldComparison::new(format!("{i}"), &Some(x), &Some(y))
}
EitherOrBoth::Left(x) => FieldComparison::new(format!("{i}"), &Some(x), &None),
EitherOrBoth::Right(y) => FieldComparison::new(format!("{i}"), &None, &Some(y)),
};
all_equal = all_equal && comparison.equal();
children.push(comparison);
}
Self::parent(field_name, all_equal, children)
}
pub fn retain_children<F>(&mut self, f: F)
where
F: FnMut(&FieldComparison) -> bool,
{
match self {
Comparison::Child(_) => (),
Comparison::Parent { children, .. } => children.retain(f),
}
}
pub fn equal(&self) -> bool {
match self {
Comparison::Child(fc) => fc.equal,
Comparison::Parent { equal, .. } => *equal,
}
}
pub fn not_equal(&self) -> bool {
!self.equal()
}
}
#[derive(Debug, PartialEq, Clone)]
pub struct FieldComparison {
pub field_name: String,
pub equal: bool,
pub a: String,
pub b: String,
}
pub trait CompareFields {
fn compare_fields(&self, b: &Self) -> Vec<Comparison>;
}
impl FieldComparison {
pub fn new<T: Debug + PartialEq<T>>(field_name: String, a: &T, b: &T) -> Self {
Self {
field_name,
equal: a == b,
a: format!("{a:?}"),
b: format!("{b:?}"),
}
}
pub fn equal(&self) -> bool {
self.equal
}
pub fn not_equal(&self) -> bool {
!self.equal()
}
}