/
main.rs
91 lines (69 loc) · 2.15 KB
/
main.rs
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use std::marker::PhantomData;
fn main() {
println!("Hello, world!");
}
// traits
pub trait BookIterator<'a>: Iterator<Item=f64> {}
pub trait BookSide<'a> {
type BookIteratorType: BookIterator<'a>;
fn book_iterator(&self) -> Self::BookIteratorType;
}
// implementation 1: stateful
pub struct ArrayBookSide {
quotes: Vec<f64>,
}
pub struct ArrayBookSideIterator<'a> {
quotes_iter: std::slice::Iter<'a, f64>,
}
impl<'a> BookSide<'a> for ArrayBookSide {
type BookIteratorType = ArrayBookSideIterator<'a>;
fn book_iterator(&self) -> Self::BookIteratorType {
ArrayBookSideIterator { quotes_iter: self.quotes.iter() }
}
}
impl<'a> Iterator for ArrayBookSideIterator<'a> {
type Item = f64;
fn next(&mut self) -> Option<Self::Item> {
self.quotes_iter.next().map(|"e| quote)
}
}
impl<'a> BookIterator<'a> for ArrayBookSideIterator<'a> {}
// implementation 2: delegating
pub struct CommissionBookSide<'a, B>
where B: BookSide<'a> {
base_book_side: B,
multiplier: f64,
_marker: PhantomData<&'a B>,
}
impl<'a, B> CommissionBookSide<'a, B>
where B: BookSide<'a> {
pub fn new(base_book_side: B) -> CommissionBookSide<'a, B> {
CommissionBookSide { base_book_side, multiplier: 1.1, _marker: PhantomData {} }
}
}
impl<'a, B> BookSide<'a> for CommissionBookSide<'a, B>
where B: BookSide<'a> {
type BookIteratorType = CommissionIterator<'a, B::BookIteratorType>;
fn book_iterator(&self) -> Self::BookIteratorType {
CommissionIterator {
base_iterator: self.base_book_side.book_iterator(),
multiplier: self.multiplier,
_marker: PhantomData {},
}
}
}
pub struct CommissionIterator<'a, BI>
where BI: BookIterator<'a> {
base_iterator: BI,
multiplier: f64,
_marker: PhantomData<&'a BI>,
}
impl<'a, BI> Iterator for CommissionIterator<'a, BI>
where BI: BookIterator<'a> {
type Item = BI::Item;
fn next(&mut self) -> Option<Self::Item> {
self.base_iterator.next().map(|quote| quote * self.multiplier)
}
}
impl<'a, BI> BookIterator<'a> for CommissionIterator<'a, BI>
where BI: BookIterator<'a> {}