Refactor a bit

src/coverage.rs

@@ -2,21 +2,17 @@ use bit_vec::BitVec;
 
 #[derive(Debug)]
 pub struct Coverage {
+    n: usize,
     rows: BitVec,
     cols: BitVec,
 }
 
 impl Coverage {
-    // XXX: Is this needed?
+    pub fn n(&self) -> usize { self.n }
-    pub fn n(&self) -> usize {
-        let n1 = self.rows.len();
-        let n2 = self.cols.len();
-        assert!(n1 == n2);
-        return n1;
-    }
 
     pub fn new(n: usize) -> Coverage {
         Coverage {
+            n: n,
             rows: BitVec::from_elem(n, false),
             cols: BitVec::from_elem(n, false),
         }

src/lib.rs

@@ -39,6 +39,7 @@ impl<T> WeightNum for T
 where T: PartialOrd + Copy + Sub<Output=T> + Add<Output=T> + Zero { }
 
 #[derive(Debug)]
+// TODO: A WeightMatrix trait
 pub struct WeightMatrix<T: WeightNum> {
     c: SquareMatrix<T>,
 }
@@ -59,11 +60,19 @@ impl<T: WeightNum> WeightMatrix<T> {
         self.c.n()
     }
 
-    #[inline(always)]
+    #[inline]
     fn is_element_zero(&self, pos: (usize, usize)) -> bool {
         self.c[pos].partial_cmp(&T::zero()) == Some(Ordering::Equal)
     }
 
+    // for each row, subtracts the minimum of that row from each other value in the row.
+    pub fn sub_min_of_each_row(&mut self) {
+        for row in 0..self.n() {
+            let min = self.min_of_row(row);
+            self.sub_row(row, min);
+        }
+    }
+
     /// Return the minimum element of row `row`.
     fn min_of_row(&self, row: usize) -> T {
         let row_slice = self.c.row_slice(row);
@@ -92,6 +101,7 @@ impl<T: WeightNum> WeightMatrix<T> {
     }
 
     /// Find the first uncovered element with value 0 `find_a_zero`
+    /// TODO: Move into Coverage as iter_uncovered()
     fn find_uncovered_zero(&self, cov: &Coverage) -> Option<(usize, usize)> {
         let n = self.n();
 
@@ -153,17 +163,10 @@ enum Step {
 /// For each row of the matrix, find the smallest element and
 /// subtract it from every element in its row. Go to Step 2.
 fn step1<T: WeightNum>(c: &mut WeightMatrix<T>) -> Step {
-    let n = c.n();
+    c.sub_min_of_each_row();
-
-    for row in 0..n {
-        let min = c.min_of_row(row);
-        c.sub_row(row, min);
-    }
-
     return Step::Step2;
 }
 
-
 /// Find a zero (Z) in the resulting matrix. If there is no starred
 /// zero in its row or column, star Z. Repeat for each element in the
 /// matrix. Go to Step 3.