//! This module implements configuration related stuff.
use std::fmt;
use std::env;
use std::io::Read;
use std::fs::File;
use std::path::Path;
use std::collections::BTreeMap;
use rustc_serialize::json::{Object, Json};
/// The pencil `Config` type, We provide ways to fill it from JSON files:
///
/// ```rust,no_run
/// let mut app = pencil::Pencil::new("/demo");
/// app.config.from_jsonfile("yourconfig.json")
/// ```
///
/// You can also load configurations from an environment variable
/// pointing to a file:
///
/// ```rust,no_run
/// let mut app = pencil::Pencil::new("/demo");
/// app.config.from_envvar("YOURAPPLICATION_SETTINGS")
/// ```
///
/// In this case, you have to set this environment variable to the file
/// you want to use. On Linux and OS X you can use the export statement:
///
/// ```bash
/// export YOURAPPLICATION_SETTINGS="/path/to/config/file"
/// ```
#[derive(Clone)]
pub struct Config {
config: Object,
}
impl Default for Config {
fn default() -> Config {
Config::new()
}
}
impl Config {
/// Create a `Config` object.
pub fn new() -> Config {
let json_object: Object = BTreeMap::new();
Config {
config: json_object,
}
}
/// Set a value for the key.
pub fn set(&mut self, key: &str, value: Json) {
self.config.insert(key.to_string(), value);
}
/// Returns a reference to the value corresponding to the key.
pub fn get(&self, key: &str) -> Option<&Json> {
self.config.get(&key.to_string())
}
/// Get a boolean configuration value. If the key doesn't exist
/// or the value is not a `Json::Boolean`, the default value
/// will be returned.
pub fn get_boolean(&self, key: &str, default: bool) -> bool {
match self.get(key) {
Some(value) => {
match *value {
Json::Boolean(value) => value,
_ => default
}
},
None => default
}
}
/// Loads a configuration from an environment variable pointing to
/// a JSON configuration file.
pub fn from_envvar(&mut self, variable_name: &str) {
match env::var(variable_name) {
Ok(value) => self.from_jsonfile(&value),
Err(_) => panic!("The environment variable {} is not set.", variable_name),
}
}
/// Updates the values in the config from a JSON file.
pub fn from_jsonfile(&mut self, filepath: &str) {
let path = Path::new(filepath);
let mut file = File::open(&path).unwrap();
let mut content = String::new();
file.read_to_string(&mut content).unwrap();
let object: Json = Json::from_str(&content).unwrap();
match object {
Json::Object(object) => { self.from_object(object); },
_ => { panic!("The configuration file is not an JSON object."); }
}
}
/// Updates the values from the given `Object`.
pub fn from_object(&mut self, object: Object) {
for (key, value) in &object {
self.set(&key, value.clone());
}
}
}
impl fmt::Debug for Config {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "<Pencil Config {:?}>", self.config)
}
}