Implement the rank operator

1 files changed, 37 insertions, 8 deletions

diff --git a/operators.c b/operators.c
index 202667c..f6066d9 100644
--- a/operators.c
+++ b/operators.c
@@ -244,16 +244,45 @@ opAtop(Datum *lefto, Datum *righto, Array *left, Array *right)
 		default:
 			p = q = r = 0;
 		}
-		print("Running %S with ranks %d %d %d\n", ppdatum(*lefto), p, q, r);
-		if(left)
-			throwerror(nil, ENotImplemented);
-		else{
-			
+
+		/* "Normalize" the ranks (remove negatives, and ranks above the array's ranks */
+		if(left){
+			q = q < 0 ? left->rank + q : q;
+			q = q < 0 ? 0 : q;
+			q = q > left->rank ? left->rank : q;
 		}
-		throwerror(nil, ENotImplemented);
-		return nil;
-	}else
+		p = p < 0 ? right->rank + p : p;
+		p = p < 0 ? 0 : p;
+		p = p > right->rank ? right->rank : p;
+		r = r < 0 ? right->rank + r : r;
+		r = r < 0 ? 0 : r;
+		r = r > right->rank ? right->rank : r;
+
+		Array *result;
+		if(left){
+			Array *cellrankl = mkscalarint(q);
+			Array *cellrankr = mkscalarint(r);
+			Array *lefts = rundfn(L"(⌷∘⍵)¨⍳(-⍺)↓⍴⍵", nil, nil, cellrankl, left);
+			Array *rights = rundfn(L"(⌷∘⍵)¨⍳(-⍺)↓⍴⍵", nil, nil, cellrankr, right);
+			result = rundfn(L"↑⍺⍶¨⍵", lefto, nil, lefts, rights);
+			freearray(cellrankl);
+			freearray(cellrankr);
+			freearray(lefts);
+			freearray(rights);
+		}else{
+			if(right->rank == p)
+				result = runfunc(lefto->func, nil, right);
+			else{
+				Array *cellrank = mkscalarint(p);
+				result = rundfn(L"↑⍶¨(⌷∘⍵)¨⍳(-⍺)↓⍴⍵", lefto, nil, cellrank, right);
+				freearray(cellrank);
+			}
+		}
+		return result;
+	}else{
+		throwerror(L"Unknown combination of operands to ⍤", ENotImplemented);
 		return nil;
+	}
 }
 
 Array *