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use std::collections::hash_map::HashMap;
use std::fs::File;
use std::io::Read;
use std::fmt::{Display, Formatter, Error};
#[derive(Clone)]
pub enum ConfigValue {
Str(String),
UInt(usize)
}
impl Display for ConfigValue {
fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error> {
match self {
ConfigValue::Str(s) => write!(f, "{}", s),
ConfigValue::UInt(u) => write!(f, "{}", u)
}
}
}
struct ConfigItem {
default_value: ConfigValue,
parse_func: Box<dyn Fn(String) -> Option<ConfigValue>>,
}
pub struct Config {
v: HashMap<String, ConfigValue>,
}
fn stripped_str(s: String) -> Option<ConfigValue> {
Some(ConfigValue::Str(String::from(s.trim())))
}
fn parse_usize(s: String) -> Option<ConfigValue> {
if let Ok(r) = usize::from_str_radix(&s, 10) {
Some(ConfigValue::UInt(r))
} else { None }
}
pub fn split_at_first<'a, 'b>(s: &'a str, sp: &'b str) -> (&'a str, &'a str) {
if let Some(p) = s.find(sp) {
(&s[.. p], &s[p + sp.len()..])
} else { (s, "") }
}
impl Config {
fn items() -> HashMap<&'static str, ConfigItem> {
HashMap::from([
("SERVED_DATA_ROOT", ConfigItem{default_value: ConfigValue::Str(String::from("")), parse_func: Box::new(stripped_str)}),
("POSTS_PER_PAGE", ConfigItem{default_value: ConfigValue::UInt(20), parse_func: Box::new(parse_usize)}),
("DISPLAY_TIMEZONE", ConfigItem{default_value: ConfigValue::Str(String::from("UTC")), parse_func: Box::new(stripped_str)}),
("VERSION_STRING", ConfigItem{default_value: ConfigValue::Str(String::from("1.0")), parse_func: Box::new(stripped_str)}),
])
}
pub fn parse_config(filename: &str) -> Config {
let mut v = HashMap::from_iter(
Config::items().iter()
.map(|(k, v)| {(String::from(*k), v.default_value.clone())})
);
let mut f = File::open(filename).unwrap();
let mut s = String::new();
if let Ok(_) = f.read_to_string(&mut s) {
for l in s.split("\n") {
let (sname, svalue) = split_at_first(l, "=");
if let Some(ConfigItem{default_value: _, parse_func}) = Config::items().get(sname) {
if let Some(value) = parse_func(String::from(svalue)) {
v.insert(String::from(sname), value);
}
}
}
}
Config { v }
}
pub fn get(&self, key: &str) -> ConfigValue {
self.v.get(&String::from(key)).unwrap().clone()
}
pub fn get_str(&self, key: &str) -> String {
if let ConfigValue::Str(s) = self.get(key) {
s
} else { String::from("") }
}
}
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