7 releases
0.1.6 | Oct 16, 2022 |
---|---|
0.1.5 | May 24, 2021 |
0.1.4 | Apr 24, 2021 |
0.1.3 | Jan 7, 2021 |
0.1.0 | Sep 1, 2020 |
#2055 in Rust patterns
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11KB
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structmap
Procedural macro crate for converting between Rust struct
types and associative containers.
use std::collections::BTreeMap;
// converting between a struct like ...
struct SomeData {
key: String
}
// ... and a BTreeMap like ...
let somedata_hm: BTreeMap<String, String> = BTreeMap::new();
This removes the need to pattern match on attributes and keys when making a conversion.
This was largely inspired by previous work done by @Ameobea, but extends on it much further to support conversion both ways, generic value types, and Rust 2018 conventions.
Usage
In your Cargo.toml
file, include the crate as so:
[dependencies]
structmap = "0.1"
Now let's demonstrate conversion! Note that your struct
type should extend the Default
trait for type conversion to account for uninitialized attributes.
structmap supports conversion between two types of map aliases:
StringMap
- Strings for both keys and values. Conversion is supported only one-way at the moment from struct to BTreeMap, but not the other way around.GenericMap
- Generic serde-styleValue
s as values. Conversion is supported both ways, but limited.
Map to Struct
use structmap::FromMap;
use structmap_derive::FromMap;
#[derive(FromMap)]
struct TestStruct {
name: String,
value: i64,
}
impl Default for TestStruct {
fn default() -> Self {
Self {
name: String::new(),
value: 0
}
}
}
fn main() {
// create a hashmap with key-value pairs
let mut hm = GenericMap::new();
// `Value` is an enum wrapper to support genericized types, to support structs
// with varying types for their fields.
hm.insert(String::from("name"), Value::new(String::from("example")));
hm.insert(String::from("value"), Value::new(0_i64));
// convert hashmap to struct, and check attributes
let test: TestStruct = TestStruct::from_genericmap(hm);
assert!(test.name == "example");
assert!(test.value == 0);
}
Struct to Map
use structmap::{ToMap, value::Value};
use structmap_derive::ToMap;
use std::collections::BTreeMap;
#[derive(ToMap, Default)]
struct TestStruct {
name: String,
value: i64,
}
// impl Default ...
fn main() {
let test_struct = TestStruct {
name: String::from("example"),
value: 0,
};
// convert struct to generic map, and check attributes
let hm: BTreeMap<String, Value> = TestStruct::to_genericmap(test_struct);
assert!(hm.get("name").unwrap().String().unwrap() == "example");
assert!(hm.get("value").unwrap().i64().unwrap() == 0);
let test_struct = TestStruct {
name: String::from("example"),
value: 0,
};
// convert struct to string map, and check attributes
let hm: BTreeMap<String, String> = TestStruct::to_stringmap(test_struct);
assert!(hm.get("name").unwrap() == "example");
assert!(hm.get("value").unwrap() == "0");
}
Need a different key name when converting from a struct
to a map container? Use #[rename]
for
struct attributes!
use structmap::ToMap;
use structmap_derive::ToMap;
#[derive(ToMap, Default)]
struct TestStruct {
#[rename(name = "Full Name")]
name: String,
#[rename(name = "Data")]
value: String,
}
Contributions
All complex types, include dynamic arrays, Option
s, Result
s and data structures are not yet
supported (which you can help implement!).
Feel free to let me know if there are any outstanding features that should be implemented!
Big thanks to the following contributors:
License
Dependencies
~1.5MB
~35K SLoC