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//! Configuration
use once_cell;
use toml;
use std::iter;
use source;
/// A configuration
///
/// Can be used as global (but don't forget to initialize it somewhere!):
/// ```
/// static CONFIG: ezconf::Config = ezconf::INIT;
/// ```
#[derive(Debug)]
pub struct Config(once_cell::sync::OnceCell<toml::Value>);
/// Initial value for configs
pub const INIT: Config = Config(once_cell::sync::OnceCell::INIT);
impl Config {
/// Initialize this configuration.
///
/// Can only be called once, further calls will return `Err(())`.
///
/// `sources` should be an iterator of possible config sources that are tried in
/// order. The first one to load successfully will be used. If none of them
/// load, an empty default config will be used and `false` is returned.
///
/// # Example
/// ```
/// static CONFIG: ezconf::Config = ezconf::INIT;
///
/// fn main() {
/// CONFIG.init([ezconf::Source::File("config.toml")].iter()).unwrap();
/// }
/// ```
pub fn init<'a>(
&self,
sources: impl iter::Iterator<Item = &'a source::Source<'a>>,
) -> Result<bool, ()> {
let value = sources
.inspect(|s| info!("Trying config source {:?} ...", s))
.filter_map(|s| s.try_read().map(|v| (v, true)))
.inspect(|_| info!("Config loaded!"))
.next()
.unwrap_or_else(|| {
info!("Using empty (default) config!");
(toml::Value::Table(toml::value::Table::new()), false)
});
let res = value.1;
self.0.set(value.0)
.map(|()| res)
.map_err(|_: toml::Value| {
error!("Failed setting config cell. Maybe it was already initialized?");
})
}
/// Retrieve a value from this config.
///
/// Returns the value or `None` if it doesn't exist.
///
/// # Example
/// ```
/// static CONFIG: ezconf::Config = ezconf::INIT;
///
/// fn main() {
/// CONFIG.init([ezconf::Source::File("tests/test.toml")].iter()).unwrap();
///
/// let v = CONFIG.get::<f32>("float.a").unwrap();
/// assert_eq!(v, 1.4142135);
/// }
/// ```
pub fn get<'a, T: toml::macros::Deserialize<'a> + ::std::fmt::Debug>(
&self,
path: &str,
) -> Option<T> {
use toml_query::read::TomlValueReadExt;
self.0
.get()
.unwrap_or_else(|| {
error!("Failed opening config cell! Maybe it isn't initialized yet?");
panic!("Failed to open config cell");
})
.read(path)
.unwrap_or_else(|_| {
error!("Reading config value {:?} failed!", path);
panic!("Reading config value {:?} failed!", path);
})
.map(|v| {
v.clone().try_into::<T>().unwrap_or_else(|e| {
error!("Failed parsing value {:?}: {:?}", path, e);
panic!("Failed parsing value {:?}: {:?}", path, e);
})
})
.map(|v| {
debug!("{:?}: {:?}", path, v);
v
})
}
/// Retrieve a value from this config or return a default.
///
/// Returns the value or `def` if it doesn't exist.
///
/// # Example
/// ```
/// static CONFIG: ezconf::Config = ezconf::INIT;
///
/// fn main() {
/// CONFIG.init([ezconf::Source::File("tests/test.toml")].iter()).unwrap();
///
/// let v = CONFIG.get_or::<String>("string.foobar", "somestring".into());
/// assert_eq!(v, "somestring");
/// }
/// ```
pub fn get_or<'a, T: toml::macros::Deserialize<'a> + ::std::fmt::Debug>(
&self,
path: &str,
def: T,
) -> T {
self.get::<T>(path).unwrap_or_else(|| {
debug!("{:?}: {:?} (default)", path, def);
def
})
}
}