Implement rotate first (⊖) and rotate last (⌽)

1 files changed, 53 insertions, 2 deletions

diff --git a/functions.c b/functions.c
index d96deb6..997c1b4 100644
--- a/functions.c
+++ b/functions.c
@@ -110,8 +110,8 @@ fndyad dyadfunctiondefs[] = {
 	fnCatenateLast, /* , */
 	fnCatenateFirst, /* ⍪ */
 	fnReshape, /* ⍴ */
-	0, /* ⌽ */
-	0, /* ⊖ */
+	fnRotateLast, /* ⌽ */
+	fnRotateFirst, /* ⊖ */
 	0, /* ⍉ */
 	0, /* ⍎ */
 	0, /* ⍕ */
@@ -1328,6 +1328,57 @@ fnReshape(Array *left, Array *right)
 }
 
 Array *
+fnRotateLast(Array *left, Array *right)
+{
+	return rundfn(L"⍉(⍉⍺)⊖⍉⍵", nil, nil, left, right);
+}
+
+Array *
+fnRotateFirst(Array *left, Array *right)
+{
+	if(left->type != AtypeInt)
+		throwerror(nil, EType);
+
+	if(right->rank == 0 || right->size < 2)
+		return fnSame(right);
+
+	int i, j;
+	if(left->size == 1 && right->rank != 0){
+		vlong v = left->intdata[0];
+		left = allocarray(AtypeInt, right->rank-1, right->size / right->shape[0]);
+		for(i = 0; i < left->rank; i++)
+			left->shape[i] = right->shape[i+1];
+		for(i = 0; i < left->size; i++)
+			left->intdata[i] = v;
+	}else
+		left = fnSame(left);
+
+	if(left->rank != right->rank-1)
+		throwerror(nil, ERank);
+	for(i = 0; i < left->rank; i++)
+		if(left->shape[i] != right->shape[i+1])
+			throwerror(nil, EShape);
+
+	int n = right->shape[0];
+	for(i = 0; i < left->size; i++)
+		while(left->intdata[i] < 0)
+			left->intdata[i] += n;
+
+	Array *result = duparray(right);
+	for(i = 0; i < n; i++){
+		for(j = 0; j < left->size; j++){
+			vlong rot = left->intdata[j];
+			vlong from = j + ((i+rot)%n)*left->size;
+			vlong to = j + i*left->size;
+			memcpy(result->rawdata + to*datasizes[right->type],
+				right->rawdata + from*datasizes[right->type],
+				datasizes[right->type]);
+		}
+	}
+	return result;
+}
+
+Array *
 fnSelfReference2(Array *left, Array *right)
 {
 	DfnFrame *dfn = getcurrentdfn();