variant-rs

variant-rs is a Rust crate that provides idiomatic handling of COM VARIANT types. Rust supports discriminated union types out of the box, so although VARIANTs are usually a pain to work with, Rust makes it easy to encode and decode them.

The crate is designed to work with the VARIANT type from the winapi crate.

Basic usage

```rust use variant_rs::*;

fn main() { let v1 = Variant::I32(123); // manual instanciation let v2 = 123.tovariant(); // ToVariant trait let v3 = 123.into(); // From / Into traits asserteq!(v1, v2); assert_eq!(v1, v3);

let bstr: Variant = "Hello, world!".into();
let ptr: VARIANT = bstr.clone().try_into().unwrap(); // convert to COM VARIANT
let back: Variant = ptr.try_into().unwrap(); // convert back
assert_eq!(bstr, back);

} ```

Supported VARIANT types and corresponding types

| VARIANT type | Rust type | Rust type (BY_REF) | |----------------|---------------------|--------------------------------| | VT_EMPTY | () | N/A | | VT_NULL | () | N/A | | VT_I1 | i8 | PSTR | | VT_I2 | i16 | &'static mut i16 | | VT_I4 | i32 | &'static mut i32 | | VT_I8 | i64 | &'static mut i64 | | VT_UI1 | u8 | &'static mut u8 | | VT_UI2 | u16 | &'static mut u16 | | VT_UI4 | u32 | &'static mut u32 | | VT_UI8 | u64 | &'static mut u64 | | VT_INT | i32 | &'static mut i32 | | VT_UINT | u32 | &'static mut u32 | | VT_R4 | f32 | &'static mut f32 | | VT_R8 | f64 | &'static mut f64 | | VT_BOOL | bool | &'static mut ComBool | | VT_BSTR | BSTR | &'static mut BSTR | | VT_ERROR | HRESULT (i32) | &'static mut HRESULT (i32) | | VT_CY | Currency | &'static mut ComCurrency | | VT_DATE | NaiveDateTime | &'static mut ComDate | | VT_DECIMAL | Decimal | &'static mut ComDecimal | | VT_UNKNOWN | Option<IUnknown> | N/A | | VT_DISPATCH | Option<IDispatch> | N/A | | VT_VARIANT | N/A | PtrWrapper<VARIANT> |

Wrapper types

ComBool

i16-backed enum.

ComCurrency

Maps COM's i64 currency data CY to Decimal.

ComDecimal

Maps COM's 96-bit decimals DECIMAL to Decimal.

ComData

Maps COM's DATE (f64 milliseconds from 1899-12-30) to NaiveDateTime.

PtrWrapper

Safe wrapper around COM interface pointers.

Installation

Add this to your Cargo.toml: toml [dependencies] variant-rs = "0.2"

License

This project is licensed under either of * Apache License, Version 2.0, (LICENSE-APACHE or https://www.apache.org/licenses/LICENSE-2.0) * MIT license (LICENSE-MIT or https://opensource.org/licenses/MIT) at your option.