Merge pull request #9 from jangko/concat_operation

fixes #8, add concat operation

ranges/typedranges.nim

@@ -1,4 +1,4 @@
-import ./ptr_arith
+import ./ptr_arith, typetraits
 
 const rangesGCHoldEnabled = not defined(rangesDisableGCHold)
 const unsafeAPIEnabled = defined(rangesEnableUnsafeAPI)
@@ -145,3 +145,32 @@ proc `[]=`*[T, U, V](r: MutRange[T], s: HSlice[U, V], v: Range[T]) {.inline.} =
   r[s] = toOpenArray(v)
 
 proc baseAddr*[T](r: Range[T]): ptr T {.inline.} = r.start
+
+template toRange*[T](a: Range[T]): Range[T] = a
+
+# this preferred syntax doesn't work
+# see https://github.com/nim-lang/Nim/issues/7995
+#template copyRange[T](dest: seq[T], destOffset: int, src: Range[T]) =
+#  when supportsCopyMem(T):
+
+template copyRange[T](E: typedesc, dest: seq[T], destOffset: int, src: Range[T]) =
+  when supportsCopyMem(E):
+    if dest.len != 0 and src.len != 0:
+      copyMem(dest[destOffset].unsafeAddr, src.start, sizeof(T) * src.len)
+  else:
+    for i in 0..<src.len:
+      dest[i + destOffset] = src[i]
+
+proc concat*[T](v: varargs[Range[T], toRange]): seq[T] =
+  var len = 0
+  for c in v: inc(len, c.len)
+  result = newSeq[T](len)
+  len = 0
+  for c in v:
+    copyRange(T, result, len, c)
+    inc(len, c.len)
+
+proc `&`*[T](a, b: Range[T]): seq[T] =
+  result = newSeq[T](a.len + b.len)
+  copyRange(T, result, 0, a)
+  copyRange(T, result, a.len, b)

tests/ttypedranges.nim

@@ -26,3 +26,40 @@ suite "Typed ranges":
     var z = toRange(@[1, 2, 3, 4])
     check y == z
     check x != z
+
+  test "concat operation":
+    var a = toRange(@[1,2,3])
+    var b = toRange(@[4,5,6])
+    var c = toRange(@[7,8,9])
+    var d = @[1,2,3,4,5,6,7,8,9]
+    var e = @[1,2,3,4,5,6]
+    var f = @[4,5,6,7,8,9]
+    var x = concat(a, b, c)
+    var y = a & b
+    check x == d
+    check y == e
+    var z = concat(b, @[7,8,9])
+    check z == f
+
+    let u = toRange(newSeq[int](0))
+    let v = toRange(@[3])
+    check concat(u, v) == @[3]
+    check (v & u) == @[3]
+
+  test "complex types concat operation":
+    type
+      Jaeger = object
+        name: string
+        weight: int
+
+    var A = Jaeger(name: "Gipsy Avenger", weight: 2004)
+    var B = Jaeger(name: "Striker Eureka", weight: 1850)
+    var C = Jaeger(name: "Saber Athena", weight: 1628)
+    var D = Jaeger(name: "Cherno Alpha", weight: 2412)
+
+    var k = toRange(@[A, B])
+    var m = toRange(@[C, D])
+    var n = concat(k, m)
+    check n == @[A, B, C ,D]
+    check n != @[A, B, C ,C]
+