cmp_wrap

Have you ever needed to compare the same data by different fields, depending on context? If so, this crate is for you!

The main feature of this crate is a lightweight wrapper around types which lets you compare them after a mappeing (keying) function, meaning the parital_cmp operators ( < , > , == ...) are applied on the result of the keying function.

There are two main modules in this crate: [permissive] and [strict]. The permissive lets you compare different types as long as the keying function returns comparable types.

The strict implementation woun't let you compare different types, and will save you from comparing by two different contexts.

Examples

Using context

You probably have some kind of context in which you would like to compare your values, such as length of vectors or the first value.

```rust use cmp_wrap::permissive::KeyCmpContext;

let by_length = KeyCmpContext::new(|v: &Vec<_>| v.len());

let longvec = bylength.wrap(vec![1,2,3,4]); let shortvec = bylength.wrap(vec![1,2]);

assert!(longvec > shortvec, "The vec {:?} is longer then {:?}", longvec, shortvec);

```

One might want to use multiple contexts for the same data

```rust use cmp_wrap::strict::KeyCmpContext;

let longvec = vec![1,2,3,4]; let shortvec = vec![4,2];

let bylength = KeyCmpContext::new(|v: &&Vec<_>| v.len()); let byfirst_element = KeyCmpContext::new(|v: &&Vec<_>| v[0]);

let bylengthlong = bylength.wrap(&longvec); let bylengthshort = bylength.wrap(&shortvec);

let byfirstelementlong = byfirstelement.wrap(&longvec); let byfirstelementshort = byfirstelement.wrap(&shortvec);

assert!(bylengthlong > bylengthshort, "The vec {:?} is longer then {:?}", longvec, shortvec); assert!(byfirstelementlong < byfirstelementshort, "The vec's {:?} first element is smaller then {:?}'s", longvec, shortvec);

```

By direct creation

you can define the key function on a "case by case" basis. This is not recommended. ```rust use cmp_wrap::permissive::CmpByKey;

let lenaskey = |v: &Vec<_>| v.len();

let longvec = CmpByKey::new(vec![1,2,3,4], &lenaskey); let shortvec = CmpByKey::new(vec![1,2], &lenaskey);

assert!(longvec > shortvec, "The vector {:?} is longer then {:?}", longvec, shortvec); ```

License: MIT