Crate ref_map 

Convenience methods when dealing with references of Options and Results.

This crate introduces a pair of traits OptionRefMap and ResultRefMap, which add methods to their respective standard library enums to avoid needing to add .as_ref() before any .map() methods on their value.

This is useful when you want to borrow from an Option or Result but want to avoid the boilerplate of first getting the references to the values contained inside.

use ref_map::*;

let string: Option<String> = Some("hello world\n".into());

// Without ref-map:
// the .as_ref() is necessary because otherwise it tries to consume the String
let message: Option<&str> = string.as_ref().map(|s| s.trim());

// With ref-map:
let message: Option<&str> = string.ref_map(|s| s.trim());

Similarly, .ref_map() and .ref_map_err() are available for Results to mimic their .map() and .map_err() methods:

let answer: Result<PathBuf, String> = Ok(PathBuf::from("/test"));

// Mapping borrowed Ok(_) to another type
let path: Result<&Path, &String> = answer.ref_map(|p| p.as_path());

// Mapping borrower Err(_)
let error: Result<&PathBuf, &str> = answer.ref_map_err(|e| e.as_str());

Additionally, the crate provides the OptionStringRef trait, which allows painlessly borrowing a Option<String> or Option<Cow<str>> as Option<&str>:

// Easily get a borrowed version for use
let string_one: Option<String> = Some(String::from("foo"));
let borrowed: Option<&str> = string_one.as_str();

// Same deal with Cow<str>
let string_two: Option<Cow<str>> = Some(Cow::Owned(String::from("bar")));
let borrowed: Option<&str> = string_two.as_str();

Traits

OptionRefMap

Extension trait for Option. Adds the ref_map() extension method onto Option.

OptionStringRef

Extension trait for optional string types. Adds the as_str() extension method onto owned string Option values.

ResultRefMap

Extension trait for Result. Adds the ref_map() and ref_map_err() extension methods onto Result.