Partially implement multiplication, code formatting

README.md

@@ -2,3 +2,10 @@
 
 Playing around with numeric types in Rust.
 
+[![Build Status](https://jenkins.timshome.page/buildStatus/icon?job=timw4mail%2Frusty-numbers%2Fmaster)](https://jenkins.timshome.page/job/timw4mail/job/rusty-numbers/job/master/)
+
+## Components
+
+* Rational (fraction) type, which overloads arithmatic operators
+* Various fibonacci/factorial implementations for native numeric types
+* BigInt (high precision integer) type, overloading arithmatic operators

benches/stock_functions.rs

@@ -102,6 +102,10 @@ mod sf {
     }
 }
 
-criterion_group!(benches, sf::bench_factorial, sf::bench_fibonacci, sf::bench_gcd);
+criterion_group!(
+    benches,
+    sf::bench_factorial,
+    sf::bench_fibonacci,
+    sf::bench_gcd
+);
 criterion_main!(benches);
-

src/bigint.rs

@@ -1,7 +1,7 @@
 #![allow(unused_variables)]
 //! \[WIP\] Arbitrarily large integers
-use crate::num::*;
 use crate::num::Sign::*;
+use crate::num::*;
 use core::ops::{
     Add, AddAssign, Div, DivAssign, Mul, MulAssign, Neg, Not, Rem, RemAssign, Sub, SubAssign,
 };
@@ -59,19 +59,27 @@ impl BigInt {
         }
     }
 
+    /// Create a new BigInt, with the specified inner capacity
+    pub fn with_capacity(size: usize) -> Self {
+        Self {
+            inner: Vec::with_capacity(size),
+            sign: Positive,
+        }
+    }
+
     /// Remove digits that are zero from the internal representation.
     ///
     /// Similar to 007 -> 7 in base 10
     pub fn trim_zeros(&mut self) {
         let current_len = self.inner.len();
         if current_len < 2 {
-            return
+            return;
         }
 
         let mut trailing_zeros = 0usize;
         for val in self.inner.iter().rev() {
             if *val != 0 {
-                break
+                break;
             }
 
             trailing_zeros += 1;
@@ -121,15 +129,14 @@ impl BigInt {
 impl Add for BigInt {
     type Output = Self;
 
-    fn add(self, rhs: Self) -> Self::Output {
     // @TODO: handle signs
+    fn add(self, rhs: Self) -> Self::Output {
         if self.sign == Positive && rhs.sign == Negative {
             return self - -rhs;
         }
 
-        let mut out = BigInt::new_empty();
-
         let digits = Self::get_digit_count(&self, &rhs) + 1;
+        let mut out = BigInt::with_capacity(digits);
 
         let mut carry = 0usize;
         for i in 0..digits {
@@ -164,11 +171,10 @@ impl Add for BigInt {
 impl Sub for BigInt {
     type Output = Self;
 
-    fn sub(self, rhs: Self) -> Self::Output {
     // @TODO: handle signs
-        let mut out = BigInt::new_empty();
-
+    fn sub(self, rhs: Self) -> Self::Output {
         let digits = Self::get_digit_count(&self, &rhs);
+        let mut out = BigInt::with_capacity(digits);
 
         let mut borrow = 0usize;
         for i in 0..digits {
@@ -204,7 +210,41 @@ impl Mul for BigInt {
     type Output = Self;
 
     fn mul(self, rhs: Self) -> Self::Output {
+        // Multiplication can result in twice the number of digits
+        let digits = Self::get_digit_count(&self, &rhs) * 2;
+        let mut out = BigInt::with_capacity(digits);
+
+        let mut carry = 0usize;
+        for i in 0..digits {
+            let a = *self.inner.get(i).unwrap_or(&0usize);
+            let b = *rhs.inner.get(i).unwrap_or(&0usize);
+
+            if a == 0 || b == 0 {
+                out.inner.push(0);
+                continue;
+            }
+
+            let (res, overflowed) = a.overflowing_mul(b);
+
+            if overflowed {
                 todo!()
+            } else {
+                match res.checked_add(carry) {
+                    Some(res) => {
+                        out.inner.push(res);
+                        carry = 0;
+                    }
+                    None => {
+                        // Well, we have to deal with overflow again
+                        todo!();
+                    }
+                }
+            }
+        }
+
+        out.trim_zeros();
+
+        out
     }
 }
 
@@ -258,11 +298,10 @@ impl Neg for BigInt {
     type Output = Self;
 
     /// Flip the sign of the current `BigInt` value
-    fn neg(self) -> Self::Output {
-        let mut output = self.clone();
-        output.sign = !output.sign;
+    fn neg(mut self) -> Self::Output {
+        self.sign = !self.sign;
 
-        output
+        self
     }
 }
 
@@ -373,7 +412,7 @@ mod tests {
     fn test_trim_zeros() {
         let mut lotsoftrailing = BigInt {
             inner: vec![1, 0, 0, 0, 0, 0, 0, 0, 0],
-            sign: Positive
+            sign: Positive,
         };
 
         lotsoftrailing.trim_zeros();
@@ -423,32 +462,26 @@ mod tests {
     fn test_sub_borrow() {
         let a = BigInt {
             inner: vec![0, 1],
-            sign: Positive
+            sign: Positive,
         };
 
         let b = BigInt::from(2);
         let diff = a - b;
         assert_eq!(diff.clone().inner.len(), 1, "{:#?}", diff.clone());
-        assert_eq!(
-            diff.inner[0],
-            core::usize::MAX - 1
-        );
+        assert_eq!(diff.inner[0], core::usize::MAX - 1);
     }
 
     #[test]
     fn test_sub_assign() {
         let mut a = BigInt {
             inner: vec![1, 0, 1],
-            sign: Positive
+            sign: Positive,
         };
         let b = BigInt::from(2);
 
         a -= b;
 
-        assert_eq!(
-            a.inner,
-            vec![core::usize::MAX, core::usize::MAX]
-        );
+        assert_eq!(a.inner, vec![core::usize::MAX, core::usize::MAX]);
     }
 
     #[test]