added toOpenArray builtin for zero-copy slices; syntax sugar yet to come

1 files changed, 17 insertions, 0 deletions

diff --git a/compiler/ccgexprs.nim b/compiler/ccgexprs.nim
index 6ea56d71d..dc06c8482 100644
--- a/compiler/ccgexprs.nim
+++ b/compiler/ccgexprs.nim
@@ -880,6 +880,23 @@ proc genCStringElem(p: BProc, n, x, y: PNode, d: var TLoc) =
   putIntoDest(p, d, n,
               rfmt(nil, "$1[$2]", rdLoc(a), rdCharLoc(b)), a.storage)
 
+proc genIndexCheck(p: BProc; arr, idx: TLoc) =
+  let ty = skipTypes(arr.t, abstractVarRange)
+  case ty.kind
+  of tyOpenArray, tyVarargs:
+    linefmt(p, cpsStmts, "if ((NU)($1) >= (NU)($2Len_0)) #raiseIndexError();$n",
+            rdLoc(idx), rdLoc(arr))
+  of tyArray:
+    let first = intLiteral(firstOrd(ty))
+    if tfUncheckedArray notin ty.flags:
+      linefmt(p, cpsStmts, "if ($1 < $2 || $1 > $3) #raiseIndexError();$n",
+              rdCharLoc(idx), first, intLiteral(lastOrd(ty)))
+  of tySequence, tyString:
+    linefmt(p, cpsStmts,
+          "if ((NU)($1) >= (NU)($2->$3)) #raiseIndexError();$n",
+          rdLoc(idx), rdLoc(arr), lenField(p))
+  else: discard
+
 proc genOpenArrayElem(p: BProc, n, x, y: PNode, d: var TLoc) =
   var a, b: TLoc
   initLocExpr(p, x, a)