Start implementations of basic arithmatic operators

src/bigint.rs

@@ -1,18 +1,15 @@
 //! \[WIP\] Arbitrarily large integers
 //!
 //! Traits to implement:
-//! * Add
-//! * AddAssign
-//! * Div
-//! * DivAssign
-//! * Mul
-//! * MulAssign
 //! * Neg
 //! * Rem
 //! * RemAssign
 //! * Sub
 //! * SubAssign
 use crate::num::*;
+use core::ops::{
+    Add, AddAssign, Div, DivAssign, Mul, MulAssign, Neg, Not, Rem, RemAssign, Sub, SubAssign,
+};
 
 #[derive(Clone, Debug)]
 pub struct BigInt {
@@ -37,64 +34,19 @@ macro_rules! impl_from_smaller {
 
 #[cfg(target_pointer_width = "16")]
 impl_from_smaller!(u8, u16);
-
 #[cfg(target_pointer_width = "16")]
 static BITS:usize = 16;
 
 #[cfg(target_pointer_width = "32")]
 impl_from_smaller!(u8, u16, u32);
-
 #[cfg(target_pointer_width = "32")]
 static BITS:usize = 32;
 
 #[cfg(target_pointer_width = "64")]
 impl_from_smaller!(u8, u16, u32, u64);
-
 #[cfg(target_pointer_width = "64")]
 static BITS:usize = 64;
 
-fn add(u: BigInt, v: BigInt) -> BigInt {
-    let mut out = BigInt::default();
-
-    let u_digits = u.inner.len();
-    let v_digits = v.inner.len();
-
-    let digits = if v_digits > u_digits {
-        v_digits
-    } else {
-        u_digits
-    };
-
-    let mut carry = 0usize;
-    for i in 0..=digits {
-        let a = *u.inner.get(i).unwrap_or(&0usize);
-        let b = *v.inner.get(i).unwrap_or(&0usize);
-
-        let (res, overflowed) = a.overflowing_add(b);
-        // assert!(!overflowed, "Expected to overflow: {:#?}", (res, overflowed));
-        if overflowed {
-            if i == 0 {
-               out.inner[i] = res;
-            } else {
-                out.inner.push(res);
-            }
-            carry = core::usize::MAX - res;
-        } else {
-            if res < core::usize::MAX {
-                out.inner.push(res + carry);
-                carry = 0;
-            } else {
-                out.inner.push(0usize);
-                carry = 1;
-            }
-
-            carry = 0;
-        }
-    }
-
-    out
-}
-
 impl Default for BigInt {
     fn default() -> Self {
         Self {
@@ -114,14 +66,14 @@ impl From<usize> for BigInt {
 }
 
 impl From<&str> for BigInt {
-    fn from(_: &str) -> Self {
-        unimplemented!()
+    fn from(s: &str) -> Self {
+        Self::from_str_radix(s, 10)
     }
 }
 
 impl From<String> for BigInt {
-    fn from(_: String) -> Self {
-        unimplemented!()
+    fn from(s: String) -> Self {
+        Self::from_str_radix(s, 10)
     }
 }
 
@@ -134,11 +86,130 @@ impl BigInt {
         todo!();
     }
 
-    pub fn from_str_radix<T: ToString>(s: T, radix: usize) {
+    pub fn from_str_radix<T: ToString>(s: T, radix: usize) -> BigInt {
         todo!();
     }
 }
 
+impl Add for BigInt {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self::Output {
+        let mut out = BigInt::default();
+
+        let u_digits = self.inner.len();
+        let v_digits = rhs.inner.len();
+
+        let digits = if v_digits > u_digits {
+            v_digits
+        } else {
+            u_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);
+
+            let (res, overflowed) = a.overflowing_add(b);
+            // assert!(!overflowed, "Expected to overflow: {:#?}", (res, overflowed));
+            if overflowed {
+                if i == 0 {
+                    out.inner[i] = res;
+                } else {
+                    out.inner.push(res);
+                }
+                carry = core::usize::MAX - res;
+            } else {
+                if res < core::usize::MAX {
+                    out.inner.push(res + carry);
+                    carry = 0;
+                } else {
+                    out.inner.push(0usize);
+                    carry = 1;
+                }
+
+                carry = 0;
+            }
+        }
+
+        out
+    }
+}
+
+impl Sub for BigInt {
+    type Output = Self;
+
+    fn sub(self, rhs: Self) -> Self::Output {
+        unimplemented!()
+    }
+}
+
+impl Mul for BigInt {
+    type Output = Self;
+
+    fn mul(self, rhs: Self) -> Self::Output {
+        unimplemented!()
+    }
+}
+
+impl Div for BigInt {
+    type Output = Self;
+
+    fn div(self, rhs: Self) -> Self::Output {
+        unimplemented!()
+    }
+}
+
+impl Rem for BigInt {
+    type Output = Self;
+
+    fn rem(self, rhs: Self) -> Self::Output {
+        unimplemented!()
+    }
+}
+
+impl AddAssign for BigInt {
+    fn add_assign(&mut self, rhs: Self) {
+        *self = self.clone() + rhs;
+    }
+}
+
+impl SubAssign for BigInt {
+    fn sub_assign(&mut self, rhs: Self) {
+        *self = self.clone() - rhs;
+    }
+}
+
+impl MulAssign for BigInt {
+    fn mul_assign(&mut self, rhs: Self) {
+        *self = self.clone() * rhs;
+    }
+}
+
+impl DivAssign for BigInt {
+    fn div_assign(&mut self, rhs: Self) {
+        *self = self.clone() / rhs;
+    }
+}
+
+impl RemAssign for BigInt {
+    fn rem_assign(&mut self, rhs: Self) {
+        *self = self.clone() % rhs;
+    }
+}
+
+impl Neg for BigInt {
+    type Output = Self;
+
+    fn neg(self) -> Self::Output {
+        let mut output = self.clone();
+        output.sign = !output.sign;
+
+        output
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -158,11 +229,28 @@ mod tests {
         let a = BigInt::from(core::usize::MAX);
         let b = BigInt::from(core::usize::MAX);
 
-        let sum = add(a, b);
+        let sum = a + b;
 
-        assert_eq!(sum.inner[0], core::usize::MAX - 1, "least significant place should be MAX - 1");
+        assert_eq!(
+            sum.inner[0],
+            core::usize::MAX - 1,
+            "least significant place should be MAX - 1"
+        );
         assert_eq!(sum.inner[1], 1usize, "most significant place should be 1");
+    }
 
-        // assert!(false, "{:#?} should have inner equal to {:?}", sum, core::u64::MAX as u128 + core::u64::MAX as u128);
+    #[test]
+    fn test_add_assign() {
+        let mut a = BigInt::from(core::usize::MAX);
+        let b = BigInt::from(core::usize::MAX);
+
+        a += b;
+
+        assert_eq!(
+            a.inner[0],
+            core::usize::MAX - 1,
+            "least significant place should be MAX - 1"
+        );
+        assert_eq!(a.inner[1], 1usize, "most significant place should be 1");
     }
 }