From 6262cd9aab04bce1c98fd5f6ab19cd5da814dfc7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juan=20Manuel=20Tom=C3=A1s?= <jtomas1815@gmail.com>
Date: Mon, 11 Jan 2021 08:42:04 -0300
Subject: Implement add and sub for P

---
 src/poly.rs | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 62 insertions(+), 1 deletion(-)

(limited to 'src/poly.rs')

diff --git a/src/poly.rs b/src/poly.rs
index 2128d38..34444b3 100644
--- a/src/poly.rs
+++ b/src/poly.rs
@@ -1,6 +1,53 @@
+mod iter;
+
+use crate::number::Number;
+use iter::Iter;
+use std::cmp;
 use std::cmp::Ordering;
+use std::ops::{Add, Sub};
+use std::iter::{Zip, Take};
+
+#[derive(PartialEq, Debug)]
+pub struct P(Vec<Number>);
+
+impl P {
+    fn degree(&self) -> usize {
+        let mut i = self.0.len() - 1;
+        while self.0[i] == 0.0 && i > 0 {
+            i -= 1;
+        }
+        i
+    }
+
+    fn iter(&self) -> Iter {
+        Iter::new(self.0.clone())
+    }
+
+    fn zip(&self, other: &Self) -> Zip<Take<Iter>, Take<Iter>> {
+        let deg = cmp::max(self.degree(), other.degree()) + 1;
+        let a = self.iter().take(deg);
+        let b = other.iter().take(deg);
+        a.zip(b)
+    }
+}
+
+impl Add for &P {
+    type Output = P;
+
+    fn add(self, other: Self) -> P {
+        P(self.zip(other).map(|(x, y)| {x + y}).collect())
+    }
+}
+
+impl Sub for &P {
+    type Output = P;
+
+    fn sub(self, other: Self) -> P {
+        P(self.zip(other).map(|(x, y)| {x - y}).collect())
+    }
+}
 
-pub type Number = f32;
+//****************************REFACTORING************************************
 
 pub type Poly = Vec<Number>;
 
@@ -87,6 +134,20 @@ pub fn gcd(a: &Poly, b: &Poly) -> Poly {
 mod tests {
     use super::*;
 
+    #[test]
+    fn add_test() {
+        let a = P(vec![1.0]);
+        let b = P(vec![0.0, 0.0, 0.0, 1.0]);
+        assert_eq!(&a + &b, P(vec![1.0, 0.0, 0.0, 1.0]));
+    }
+
+    #[test]
+    fn sub_test() {
+        let a = P(vec![1.0, 2.0, 3.0]);
+        let b = P(vec![1.0]);
+        assert_eq!(&a - &b, P(vec![0.0, 2.0, 3.0]));
+    }
+
     #[test]
     fn poly_is_zero() {
         let p = vec![0.0; 5];
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