[js] Make nqp::decode changed the VMArray instead of returning a hack…

…ed NQPArray.

src/vm/js/nqp-runtime/core.js

@@ -596,8 +596,6 @@ function renameEncoding(encoding) {
 exports.renameEncoding = renameEncoding;
 
 function byteSize(buf) {
-  if (buf.bytes) return buf.bytes;
-
   var bits = buf._STable.REPR.type._STable.REPR.bits;
 
   if (bits % 8) {
@@ -607,9 +605,6 @@ function byteSize(buf) {
   return bits / 8;
 }
 
-// HACK should be using buf instead of creating a new one
-// TODO needs to be fixed after an Array handling refactor
-
 op.encode = function(str, encoding_, buf) {
   var encoding = renameEncoding(encoding_);
 
@@ -621,13 +616,11 @@ op.encode = function(str, encoding_, buf) {
 
   var offset = 0;
   for (var i = 0; i < buffer.length / elementSize; i++) {
-    ret[i] = buffer.readIntLE(offset, elementSize);
+    buf.array[i] = buffer.readIntLE(offset, elementSize);
     offset += elementSize;
   }
 
-  ret = new NQPArray(ret);
-  ret.bytes = elementSize;
-  return ret;
+  return buf;
 };
 
 op.decode = function(buf, encoding_) {

src/vm/js/nqp-runtime/reprs.js

@@ -744,6 +744,26 @@ class VMArray extends REPR {
       return value;
     });
 
+    /* TODO test how things should be converted */
+
+    STable.addInternalMethod('$$atpos_s', function(index) {
+      var value = this.array[index < 0 ? this.array.length + index : index];
+      if (value === undefined) return null_s;
+      return value;
+    });
+
+    STable.addInternalMethod('$$atpos_n', function(index) {
+      var value = this.array[index < 0 ? this.array.length + index : index];
+      if (value === undefined) return 0.0;
+      return value;
+    });
+
+    STable.addInternalMethod('$$atpos_i', function(index) {
+      var value = this.array[index < 0 ? this.array.length + index : index];
+      if (value === undefined) return 0;
+      return value;
+    });
+
     STable.addInternalMethod('$$bindpos', function(index, value) {
       return this.array[index < 0 ? this.array.length + index : index] = value;
     });