fix issues andreaferretti#43, add backwardindex for vector

ippaveln · Apr 3, 2022 · 8033f79 · 8033f79
1 parent 39cde72
commit 8033f79
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diff --git a/neo/dense.nim b/neo/dense.nim
@@ -299,6 +299,15 @@ proc `[]=`*[A](m: var Matrix[A], i, j: int, val: A) {. inline .} =
   else:
     elRowMajor(mp, m, i, j) = val
 
+proc `[]`*[A](v: Vector[A], i: BackwardsIndex): A {. inline .} =
+  return v[v.len - i.int]
+
+proc `[]`*[A](v: var Vector[A], i: BackwardsIndex): var A {. inline .} =
+  return v[v.len - i.int]
+
+proc `[]=`*[A](v: Vector[A], i: BackwardsIndex, val: A) {. inline .} =
+  v[v.len - i.int] = val
+
 proc column*[A](m: Matrix[A], j: int): Vector[A] {. inline .} =
   checkBounds(j >= 0 and j < m.N)
   let mp = cast[CPointer[A]](m.fp)

diff --git a/tests/dense/daccess.nim b/tests/dense/daccess.nim
@@ -26,6 +26,13 @@ proc run() =
       check v[2] == 4.0
       check v[3] == 7.0
       check v[4] == 10.0
+    test "reading vector elements backwise index":
+      let v = makeVector(5, proc(i: int): float64 = (3 * i - 2).float64)
+      check v[^5] == -2.0
+      check v[^4] == 1.0
+      check v[^3] == 4.0
+      check v[^2] == 7.0
+      check v[^1] == 10.0
     test "mutating vector elements":
       var v = zeros(3)
       v[0] += 2.1