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|
use std::fmt::Display;
use std::marker::PhantomData;
pub struct Namer<T, F> {
make_name: F,
counter: u64,
_phantom: PhantomData<T>,
}
impl<T, F> Namer<T, F> {
pub fn new(make_name: F) -> Self {
Namer {
make_name,
counter: 0,
_phantom: PhantomData,
}
}
}
impl Namer<String, Box<dyn Fn(u64) -> String>> {
pub fn with_prefix<T>(prefix: T) -> Self
where
T: Display + 'static,
{
Namer::new(move |i| format!("{}{}", prefix, i)).boxed()
}
pub fn with_suffix<T>(suffix: T) -> Self
where
T: Display + 'static,
{
Namer::new(move |i| format!("{}{}", i, suffix)).boxed()
}
pub fn alphabetic() -> Self {
Namer::new(|i| {
if i <= 26 {
std::char::from_u32((i + 96) as u32).unwrap().to_string()
} else {
format!(
"{}{}",
std::char::from_u32(((i % 26) + 96) as u32).unwrap(),
i - 26
)
}
})
.boxed()
}
}
impl<T, F> Namer<T, F>
where
F: Fn(u64) -> T,
{
pub fn make_name(&mut self) -> T {
self.counter += 1;
(self.make_name)(self.counter)
}
pub fn boxed(self) -> NamerOf<T>
where
F: 'static,
{
Namer {
make_name: Box::new(self.make_name),
counter: self.counter,
_phantom: self._phantom,
}
}
pub fn map<G, U>(self, f: G) -> NamerOf<U>
where
G: Fn(T) -> U + 'static,
T: 'static,
F: 'static,
{
Namer {
counter: self.counter,
make_name: Box::new(move |x| f((self.make_name)(x))),
_phantom: PhantomData,
}
}
}
pub type NamerOf<T> = Namer<T, Box<dyn Fn(u64) -> T>>;
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn prefix() {
let mut namer = Namer::with_prefix("t");
assert_eq!(namer.make_name(), "t1");
assert_eq!(namer.make_name(), "t2");
}
#[test]
fn suffix() {
let mut namer = Namer::with_suffix("t");
assert_eq!(namer.make_name(), "1t");
assert_eq!(namer.make_name(), "2t");
}
#[test]
fn alphabetic() {
let mut namer = Namer::alphabetic();
assert_eq!(namer.make_name(), "a");
assert_eq!(namer.make_name(), "b");
(0..25).for_each(|_| {
namer.make_name();
});
assert_eq!(namer.make_name(), "b2");
}
#[test]
fn custom_callback() {
let mut namer = Namer::new(|n| n + 1);
assert_eq!(namer.make_name(), 2);
assert_eq!(namer.make_name(), 3);
}
}
|
