byteutils: lexicographical less than

stew/byteutils.nim

@@ -129,3 +129,12 @@ func toBytes*(s: string): seq[byte] =
   ## nim essentially are byte sequences without any particular encoding, this
   ## is almost a noop
   cast[seq[byte]](s)
+
+func `<`*(a, b: openArray[byte]): bool =
+  ## Lexicographical compare of two byte arrays
+  let minlen = min(a.len, b.len)
+
+  for i in 0..<minlen:
+    if a[i] != b[i]: return a[i] < b[i]
+
+  a.len < b.len

tests/test_byteutils.nim

@@ -59,3 +59,25 @@ suite "Byte utils":
     block:
       expect AssertionError:
         let a = hexToPaddedByteArray[2]("0x12345")
+
+  test "lessThan":
+    let
+      a = [0'u8, 1, 2]
+      b = [2'u8, 1, 0]
+      c = [0'u8, 1, 2, 3]
+      d = [0'u8, 1, 3, 3]
+
+    check:
+      not (a < a)
+
+      a < b
+      not (b < a)
+
+      c < b
+      not (b < c)
+
+      a < c
+      not (c < a)
+
+      c < d
+      not (d < c)