Procedural macro library for converting between Rust struct types and associative containers.
One concern that I've repeatedly come upon when writing Rust is the lack of operability between converting highly structured types, and more "raw" map structures. This may be the case for instances where we want to represent structured data in a more tabulated format, or the other way around, without resorting to long conditional pattern matching:
```rust // converting between a struct like ... struct SomeData { key: String }
// ... and an associative map type like ...
let somedata_hm: HashMap
Using metaprogramming and code generation capabilities supported by Rust's support for procedural macros, I decided to implement this crate to simply provide conversion support between structs (abstractly known as product types), and associative containers, including HashMaps and BTreeMaps (TODO).
This was largely inspired by previous work done by @ameo, linked in his blog here, but extends on it to support conversion both ways. This crate contains code that is supported for Rust 2018, and includes updated dependencies for AST parsing and code generation. It includes one subcrate, structmap-derive, which implements the actual procedural macro.
In your Cargo.toml file, include the crate as so:
[dependencies]
structmap = "0.1.0"
Now let's demonstrate conversion! Note that your struct type should extend the Default trait for type conversion to account for uninitialized attributes.
```rust use structmap::FromHashMap; use structmap_derive::FromHashMap;
struct TestStruct { name: String, value: String, }
impl Default for TestStruct { fn default() -> Self { Self { name: String::new(), value: String::new(), } } }
fn main() { // create a hashmap with key-value pairs let mut hm = HashMap::new(); hm.insert(String::from("name"), String::from("example")); hm.insert(String::from("value"), String::from("some_value"));
// convert hashmap to struct, and check attributes
let test: TestStruct = TestStruct::from_hashmap(hm);
assert!(test.name == "example");
assert!(test.value == "some_value");
} ```
```rust use structmap::ToHashMap; use structmap_derive::ToHashMap;
struct TestStruct { name: String, value: String, }
// impl Default ...
fn main() { let teststruct = TestStruct { name: String::from("example"), value: String::from("somevalue"), };
// convert struct to hashmap, and check attributes
let hm: HashMap<String, String> = TestStruct::to_hashmap(test_struct);
assert!(hm.get("name").unwrap() == "example");
assert!(hm.get("value").unwrap() == "some_value");
} ```
This is still a WIP crate, and will mostly be used for personal projects, but feel free to let me know if there are any outstanding features that should be implemented!