feature-check - query a program for supported features
======================================================
The `feature-check` library helps programs obtain the list of supported
features from a program via various methods (e.g. running it with
the `--features` command-line option) and check for the presence and,
possibly, versions of specific features.
List a program's features
-------------------------
Use the default `List` mode of operation in the configuration object,
specify the program name and, possibly, the command-line option to use and
the string that the feature list line should start with:
use std::error::Error;
use feature_check::defs::{Config, Obtained};
use feature_check::obtain as fobtain;
fn main() -> Result<(), Box<dyn Error>> {
let config = Config {
program: "curl".to_string(),
option_name: "--version".to_string(),
..Config::default()
};
match fobtain::obtain_features(&config)? {
Obtained::Failed(err) => eprintln!("Could not obtain the features: {}", err),
Obtained::NotSupported => eprintln!("Querying features not supported"),
Obtained::Features(res) => println!("{} features", res.len()),
};
Ok(())
}
Compare a single feature against a version number
-------------------------------------------------
Once the list of features has been queried, use an expression previously
obtained from the `expr::parse_simple()` function:
use std::error;
use feature_check::defs::{Config, Obtained};
use feature_check::expr::{self as fexpr, CalcResult};
use feature_check::obtain as fobtain;
fn main() -> Result<(), Box<dyn error::Error>> {
let query = "feature-check >= 0.2";
let expr = fexpr::parse_simple(&query)?;
let config = Config {
program: "feature-check".to_string(),
..Config::default()
};
match fobtain::obtain_features(&config)? {
Obtained::Failed(err) => eprintln!(
"Could not obtain the features for {}: {}",
config.program, err
),
Obtained::NotSupported => eprintln!("Querying features not supported"),
Obtained::Features(res) => {
println!("{} features", res.len());
match res.contains_key("feature-check") {
false => eprintln!("No 'feature-check' in the features list"),
true => match expr.get_value(&res)? {
CalcResult::Bool(value) => println!("{}: {}", query, value),
other => eprintln!("Unexpected result: {:?}", other),
},
};
}
};
Ok(())
}
For the crate's change history, see
the [changelog](https://gitlab.com/ppentchev/feature-check/-/blob/master/docs/changes.md)
file in the source distribution.