From 71e1c529203d88e97d9aa477d11feb62bf22b2a9 Mon Sep 17 00:00:00 2001
From: nicoo <nicoo@debian.org>
Date: Fri, 19 Jun 2020 13:58:11 +0200
Subject: [PATCH 1/3] factor::Factors: Rename new() to one()

---
 src/uu/factor/src/factor.rs | 4 ++--
 src/uu/factor/src/rho.rs    | 2 +-
 src/uu/factor/src/table.rs  | 2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/uu/factor/src/factor.rs b/src/uu/factor/src/factor.rs
index 3ba471d73..8ee77e5bb 100644
--- a/src/uu/factor/src/factor.rs
+++ b/src/uu/factor/src/factor.rs
@@ -32,7 +32,7 @@ struct Factors {
 }
 
 impl Factors {
-    fn new() -> Factors {
+    fn one() -> Factors {
         Factors { f: BTreeMap::new() }
     }
 
@@ -75,7 +75,7 @@ impl fmt::Display for Factors {
 }
 
 fn factor(mut n: u64) -> Factors {
-    let mut factors = Factors::new();
+    let mut factors = Factors::one();
 
     if n < 2 {
         factors.push(n);
diff --git a/src/uu/factor/src/rho.rs b/src/uu/factor/src/rho.rs
index e9076144b..93b1943bc 100644
--- a/src/uu/factor/src/rho.rs
+++ b/src/uu/factor/src/rho.rs
@@ -55,7 +55,7 @@ fn _factor<A: Arithmetic>(num: u64) -> Factors {
         _factor::<A>(n)
     };
 
-    let mut factors = Factors::new();
+    let mut factors = Factors::one();
     if num == 1 {
         return factors;
     }
diff --git a/src/uu/factor/src/table.rs b/src/uu/factor/src/table.rs
index 6c59d3f07..e11b7198b 100644
--- a/src/uu/factor/src/table.rs
+++ b/src/uu/factor/src/table.rs
@@ -15,7 +15,7 @@ use crate::Factors;
 include!(concat!(env!("OUT_DIR"), "/prime_table.rs"));
 
 pub(crate) fn factor(mut num: u64) -> (Factors, u64) {
-    let mut factors = Factors::new();
+    let mut factors = Factors::one();
     for &(prime, inv, ceil) in P_INVS_U64 {
         if num == 1 {
             break;

From dacee413dbb8abac36be6eb4389a07781609207e Mon Sep 17 00:00:00 2001
From: nicoo <nicoo@debian.org>
Date: Fri, 19 Jun 2020 14:03:11 +0200
Subject: [PATCH 2/3] factor::rho: Refactor to avoid unnecessary allocations

---
 src/uu/factor/src/factor.rs | 7 +++++++
 src/uu/factor/src/rho.rs    | 8 +++-----
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/src/uu/factor/src/factor.rs b/src/uu/factor/src/factor.rs
index 8ee77e5bb..d56488793 100644
--- a/src/uu/factor/src/factor.rs
+++ b/src/uu/factor/src/factor.rs
@@ -36,6 +36,13 @@ impl Factors {
         Factors { f: BTreeMap::new() }
     }
 
+    fn prime(p: u64) -> Factors {
+        debug_assert!(miller_rabin::is_prime(p));
+        let mut f = Factors::one();
+        f.push(p);
+        f
+    }
+
     fn add(&mut self, prime: u64, exp: u8) {
         debug_assert!(exp > 0);
         let n = *self.f.get(&prime).unwrap_or(&0);
diff --git a/src/uu/factor/src/rho.rs b/src/uu/factor/src/rho.rs
index 93b1943bc..4dfa33b07 100644
--- a/src/uu/factor/src/rho.rs
+++ b/src/uu/factor/src/rho.rs
@@ -55,17 +55,15 @@ fn _factor<A: Arithmetic>(num: u64) -> Factors {
         _factor::<A>(n)
     };
 
-    let mut factors = Factors::one();
     if num == 1 {
-        return factors;
+        return Factors::one();
     }
 
     let n = A::new(num);
     let divisor;
     match miller_rabin::test::<A>(n) {
         Prime => {
-            factors.push(num);
-            return factors;
+            return Factors::prime(num);
         }
 
         Composite(d) => {
@@ -77,7 +75,7 @@ fn _factor<A: Arithmetic>(num: u64) -> Factors {
         }
     };
 
-    factors *= _factor(divisor);
+    let mut factors = _factor(divisor);
     factors *= _factor(num / divisor);
     factors
 }

From 0518e06053282505d98936c612bf1202609d27ce Mon Sep 17 00:00:00 2001
From: nicoo <nicoo@debian.org>
Date: Fri, 19 Jun 2020 14:10:34 +0200
Subject: [PATCH 3/3] factor::rho: Minor refactor for readability

---
 src/uu/factor/src/rho.rs | 12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/src/uu/factor/src/rho.rs b/src/uu/factor/src/rho.rs
index 4dfa33b07..9a53a40f4 100644
--- a/src/uu/factor/src/rho.rs
+++ b/src/uu/factor/src/rho.rs
@@ -60,19 +60,13 @@ fn _factor<A: Arithmetic>(num: u64) -> Factors {
     }
 
     let n = A::new(num);
-    let divisor;
-    match miller_rabin::test::<A>(n) {
+    let divisor = match miller_rabin::test::<A>(n) {
         Prime => {
             return Factors::prime(num);
         }
 
-        Composite(d) => {
-            divisor = d;
-        }
-
-        Pseudoprime => {
-            divisor = find_divisor::<A>(n);
-        }
+        Composite(d) => d,
+        Pseudoprime => find_divisor::<A>(n),
     };
 
     let mut factors = _factor(divisor);