Crate collections_fromstr[−][src]
Expand description
This crate provides a FromStr
derive for newtypes on iterable collections on single types, such Vec<T>
or HashSet<T>
. The element is parsed by splitting the input along a pattern that you specify though the #[item_separator]
attribute. The individual items are then parsed using their respective FromStr
implementations.
Requirements
- The macro will take the first field in your struct that has a type with a path argument
<T>
and assume that it is the inner type. It will assume thatT
in this example is the item type. - The item type
T
must not be an actual type (no trait type) that implementsFromStr
. - As inner type you can use any type that implements
FromIterator<Item = T>
(likeVec<T>
orHashSet<T>
). From
needs to be implemented between your newtype and its inner type. Crates likederive_more
take easy care of that.
Example
use collections_fromstr::FromStr; use derive_more::From; use std::str::FromStr; #[derive(From, FromStr, PartialEq)] #[item_separator = ","] struct NewVec(Vec<i32>); static VALUES: &str = "1,2,3,-3,-2,-1"; assert!(NewVec::from_str(VALUES).unwrap() == NewVec(vec![1,2,3,-3,-2,-1]));
Wait… you know that I could just use Iterator::split
for this, right?
Okay, hear me out. Say you’ve got data like this:
1-3:B,I,U//43-60:I//83-87:I,U//99-104: B,I// [etc.]
Let’s say this data represents text markup: You’ve got character ranges on the left of the colon :
, and highlighting information on the right side (B
= bold, I
= italics, U
= underline, but you’ll probably expand it later once you get that hedgefund money), of which there might be multiple, separated by commas ,
. Each markup is separated by double slashes //
.
… Now look at the magic of FromStr
doing its thing:
use std::collections::HashSet; use derive_more::From; use std::ops::Range; #[derive(parse_display::FromStr)] #[display("{0.start}-{0.end}")] struct CharRange(#[from_str(default)] Range<u32>); #[derive(parse_display::FromStr, Hash, PartialEq, Eq)] #[non_exhaustive] enum MarkupOperation { #[display("B")] Bold, #[display("I")] Italics, #[display("U")] Underline, } #[derive(From, collections_fromstr::FromStr)] #[item_separator=","] struct Operations(HashSet<MarkupOperation>); #[derive(parse_display::FromStr)] #[display("{range}:{operations}")] struct Markup{ range: CharRange, operations: Operations, } #[derive(From, collections_fromstr::FromStr)] #[item_separator="//"] struct MarkupVec(Vec<Markup>);
Look at this code. It’s. So. Clean. 🥺 And you’ll be less likely to produce bugs, like forgetting about the case of an empty input string.
License
collections-fromstr
is distributed under the terms of both the MIT license and the Apache License (Version 2.0).
See LICENSE-APACHE
and LICENSE-MIT
for details.
Derive Macros
FromStr | Derives |