calculation + conversion
cpc parses and evaluates strings of math, with support for units and conversion. 128-bit decimal floating points are used for high accuracy.
It also lets you mix units, so for example 1 km - 1m results in Number { value: 999, unit: Meter }.
Install using cargo:
cargo install cpc
To install it manually, grab the appropriate binary from the GitHub Releases page and place it wherever you normally place binaries on your OS.
cpc '2h/3 to min'
Add cpc as a dependency in Cargo.toml.
```rust use cpc::{eval}; use cpc::units::Unit;
match eval("3m + 1cm", true, Unit::Celsius, false) { Ok(answer) => { // answer: Number { value: 301, unit: Unit::Centimeter } println!("Evaluated value: {} {:?}", answer.value, answer.unit) }, Err(e) => { println!("{}", e) } } ```
``` 3 + 4 * 2
8 % 3
(4 + 1)km to light years
10m/2s * 5 trillion s
1 lightyear * 0.001mm in km2
1m/s + 1mi/h in kilometers per h
round(sqrt(2)^4)! liters
10% of abs(sin(pi)) horsepower to watts ```
cpc uses 128-bit Decimal Floating Point (d128) numbers instead of Binary Coded Decimals for better accuracy. The result cpc gives will still not always be 100% accurate. I would recommend rounding the result to 20 decimals or less.
It's pretty fast and scales well. In my case, it usually runs in under 0.1ms. The biggest performance hit is functions like log(). log(12345) evaluates in 0.12ms, and log(e) in 0.25ms.
To see how fast it is, you can pass the --debug flag in CLI, or the debug argument to eval().
cpc returns Results with basic strings as errors. Just to be safe, you may want to handle panics (You can do that using std::panic::catch_unwind).
Install Rust.
Run cpc with a CLI argument as input:
cargo run -- '100ms to s'
Run with debugging, which shows some extra logs:
cargo run -- '100ms to s' --debug
Run tests:
cargo test
Build:
cargo build
Nice resources for adding units: - https://github.com/ryantenney/gnu-units/blob/master/units.dat - https://support.google.com/websearch/answer/3284611 (unit list) - https://translatorscafe.com/unit-converter (unit conversion) - https://calculateme.com (unit conversion) - https://wikipedia.org
In src/units.rs, units are specified like this:
```rs
pub enum UnitType {
Time,
// etc
}
// ...
create_units!( Nanosecond: (Time, d128!(1)), Microsecond: (Time, d128!(1000)), // etc ) ```
The number associated with a unit is it's "weight". For example, if a second's weight is 1, then a minute's weight is 60.
I have found translatorscafe.com and calculateme.com to be good websites for unit conversion. Wikipedia is worth looking at as well.
Make sure to also add a test for each unit. The tests look like this:
rs
assert_eq!(convert_test(1000.0, Meter, Kilometer), 1.0);
Basically, 1000 Meter == 1 Kilometer.
Text is turned into tokens (some of which are units) in lexer.rs. Here's one example:
rs
// ...
match string {
"h" | "hr" | "hrs" | "hour" | "hours" => tokens.push(Token::Unit(Hour)),
// etc
}
// ...
For some reason cross stopped working for me in Rust 1.50 (rust-lang/rust#83154).
1. Install Docker
2. Install cross:
cargo install cross
3. Build for x86_64 macOS, Linux and Windows:
sh
cargo build --release --target x86_64-apple-darwin && cross build --release --target x86_64-unknown-linux-musl && cross build --release --target x86_64-pc-windows-gnu
- Building for x86_64-apple-darwin only works on macOS
- For more targets, check out the targets cross supports
- If you run cross build in parallel, you might get a cargo not found error
The compiled binaries will now be available inside target/<target>/release/. The filename will be either cpc or cpc.exe.
CHANGELOG.mdCargo.tomlcargo testv#.#.#cargo login and following the instructions
cargo publish --dry-run
cargo publish
cpc-v1.0.0-macos-x64