From 4939a12089e160471590e3812d4533bae34dd64d Mon Sep 17 00:00:00 2001
From: Peter Mikkelsen <petermikkelsen10@gmail.com>
Date: Wed, 2 Feb 2022 14:30:28 +0000
Subject: =?UTF-8?q?Implement=20find=20=E2=8D=B7?=
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---
 apl9.h      |  1 +
 functions.c | 29 ++++++++++++++++++++++++++++-
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/apl9.h b/apl9.h
index 3b77423..e9a6cb7 100644
--- a/apl9.h
+++ b/apl9.h
@@ -357,6 +357,7 @@ Array *fnIndex(Array *, Array *);
 Array *fnIndexOf(Array *, Array *);
 Array *fnIntervalIndex(Array *, Array *);
 Array *fnMembership(Array *, Array *);
+Array *fnFind(Array *, Array *);
 Array *fnUnion(Array *, Array *);
 Array *fnIntersection(Array *, Array *);
 Array *fnExcluding(Array *, Array *);
diff --git a/functions.c b/functions.c
index e3020f9..f1c4b0d 100644
--- a/functions.c
+++ b/functions.c
@@ -103,7 +103,7 @@ fndyad dyadfunctiondefs[] = {
 	fnIndexOf, /* ⍳ */
 	fnIntervalIndex, /* ⍸ */
 	fnMembership, /* ∊ */
-	0, /* ⍷ */
+	fnFind, /* ⍷ */
 	fnUnion, /* ∪ */
 	fnIntersection, /* ∩ */
 	fnExcluding, /* ~ */
@@ -1585,6 +1585,33 @@ fnMembership(Array *left, Array *right)
 	return rundfn(L"∨/⍺≡⌾⍵", nil, nil, left, right);
 }
 
+Array *
+fnFind(Array *left, Array *right)
+{
+	int i,j;
+	if(left->rank > right->rank){
+		print("Left rank larger\n");
+		return rundfn(L"(⍴⍵)⍴0", nil, nil, nil, right);
+	}
+
+	if(left->rank < right->rank){
+		Array *newleft = allocarray(left->type, right->rank, left->size);
+		for(i = 0; i < right->rank - left->rank; i++)
+			newleft->shape[i] = 1;
+		for(j = 0; j < left->rank; j++)
+			newleft->shape[i+j] = left->shape[j]; 
+		memcpy(newleft->rawdata, left->rawdata, datasizes[left->type] * left->size);
+		if(left->type == AtypeArray)
+			for(i = 0; i < left->size; i++)
+				incref(newleft->arraydata[i]);
+		left = newleft;
+	}else
+		left = fnSame(left);
+	Array *result = rundfn(L"⎕io←0 ⋄ (⍴⍵)↑(⍺{⍶≡(⍴⍶)↑⍵↓⍹}⍵)¨⍳1+⍵-⍥⍴⍺", nil, nil, left, right);
+	freearray(left);
+	return result;
+}
+
 Array *
 fnUnion(Array *left, Array *right)
 {
-- 
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