Implement expand last (\) and expand first (⍀)

2 files changed, 69 insertions, 2 deletions

diff --git a/apl9.h b/apl9.h
index 00075fd..83cee4a 100644
--- a/apl9.h
+++ b/apl9.h
@@ -375,7 +375,9 @@ Array *opSelfReference2(Datum *, Datum *, Array *, Array *);
 
 /* Dyadic functions from hybrids.c */
 Array *fnReplicateLast(Array *, Array *);
+Array *fnExpandLast(Array *, Array *);
 Array *fnReplicateFirst(Array *, Array *);
+Array *fnExpandFirst(Array *, Array *);
 
 /* Monadic operators from hybrids.c */
 Array *opReduceLast(Datum *, Array *, Array *);
diff --git a/hybrids.c b/hybrids.c
index da42e62..601898f 100644
--- a/hybrids.c
+++ b/hybrids.c
@@ -8,9 +8,9 @@ Rune primhybridnames[] = L"/\\⌿⍀";
 
 fndyad hybridfunctiondefs[] = {
 	fnReplicateLast, /* / */
-	0, /* \ */
+	fnExpandLast, /* \ */
 	fnReplicateFirst, /* ⌿ */
-	0, /* ⍀ */
+	fnExpandFirst, /* ⍀ */
 };
 
 opmonad hybridoperatordefs[] = {
@@ -28,6 +28,12 @@ fnReplicateLast(Array *left, Array *right)
 }
 
 Array *
+fnExpandLast(Array *left, Array *right)
+{
+	return rundfn(L"⍉⍺⍀⍉⍵", nil, nil, left, right);
+}
+
+Array *
 fnReplicateFirst(Array *left, Array *right)
 {
 	Rune *code =
@@ -38,6 +44,65 @@ fnReplicateFirst(Array *left, Array *right)
 	return rundfn(code, nil, nil, left, right);
 }
 
+Array *
+fnExpandFirst(Array *left, Array *right)
+{
+	if(left->type != AtypeInt)
+		throwerror(nil, EType);
+	if(left->rank > 1)
+		throwerror(nil, ERank);
+
+	right = right->rank == 0 ? fnRavel(right) : fnSame(right);
+
+	int npos = 0;
+	int nsize = 0;
+	int i;
+	for(i = 0; i < left->size; i++){
+		if(left->intdata[i] > 0)
+			npos++;
+		else if(left->intdata[i] == 0)
+			left->intdata[i] = -1;
+
+		vlong n = left->intdata[i];
+		nsize += n > 0 ? n : -n;
+	}
+
+	if(right->shape[0] != 1 && right->shape[0] != npos)
+		throwerror(nil, ELength);
+
+	vlong cellsize = right->shape[0] == 0 ? 1 : right->size / right->shape[0];
+	Array *result = allocarray(right->type, right->rank, nsize * cellsize);
+	result->shape[0] = nsize;
+	for(i = 1; i < result->rank; i++)
+		result->shape[i] = right->shape[i];
+
+	Array *fill = fillelement(right);
+	int from, to;
+	for(from = 0, to = 0, i = 0; to < nsize; i++, to += npos){
+		int neg = left->intdata[i] < 0;
+		npos = left->intdata[i];
+		if(neg){
+			npos = -npos;
+			for(int j = 0; j < npos*cellsize; j++)
+				memcpy(result->rawdata + (to*cellsize+j)*datasizes[result->type],
+					fill->rawdata, datasizes[result->type]);
+		}else{
+			for(int j = 0; j < npos; j++)
+				memcpy(result->rawdata + (to+j)*cellsize*datasizes[result->type],
+					right->rawdata + from*cellsize*datasizes[result->type],
+					cellsize*datasizes[result->type]);
+		}
+		if(result->type == AtypeArray)
+			for(int j = 0; j < npos*cellsize; j++)
+				incref(result->arraydata[to*cellsize+j]);
+		if(right->shape[0] != 1 && !neg)
+			from++;
+	}
+	freearray(fill);
+	freearray(right);
+	return result;
+}
+
 /* operator definitions */
 Array *
 opReduceLast(Datum *lefto, Array *left, Array *right)