From fbcb1cad3eca5ca670f623bdb25a78b8fe54af1b Mon Sep 17 00:00:00 2001
From: Peter Mikkelsen <petermikkelsen10@gmail.com>
Date: Wed, 19 Jan 2022 10:42:21 +0000
Subject: =?UTF-8?q?Add=20dyadic=20=E2=89=A1=20match?=
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---
 apl9.h      |  2 ++
 array.c     | 38 ++++++++++++++++++++++++++++++++++++++
 functions.c |  9 ++++++++-
 3 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/apl9.h b/apl9.h
index 4bb1296..2320bb2 100644
--- a/apl9.h
+++ b/apl9.h
@@ -169,6 +169,7 @@ int scalarextend(Array *, Array *, Array **, Array **);
 int commontype(Array *, Array *, Array **, Array **, int);
 Array *arrayitem(Array *, int);
 Array *simplifyarray(Array *);
+int comparearray(Array *, Array *);
 
 /* eval.c */
 Datum *eval(Statement *);
@@ -214,6 +215,7 @@ Array *fnPower(Array *, Array *);
 Array *fnLogarithm(Array *, Array *);
 Array *fnLeft(Array *, Array *);
 Array *fnRight(Array *, Array *);
+Array *fnMatch(Array *, Array *);
 Array *fnCatenateFirst(Array *, Array *);
 Array *fnReshape(Array *, Array *);
 
diff --git a/array.c b/array.c
index 5fb2a32..cf5a7f3 100644
--- a/array.c
+++ b/array.c
@@ -209,4 +209,42 @@ simplifyarray(Array *a)
 		return b;
 	}else
 		return fnSame(a);
+}
+
+int
+comparearray(Array *a, Array *b)
+{
+	/* returns -1 if a < b, 0 if a == b and 1 if a > b.
+	   Only correctly handles test for equality right now,
+	   and returns 1 for unequal data. */
+
+	if(a->type != b->type)
+		return 1;
+	if(a->rank != b->rank)
+		return 1;
+	if(a->size != b->size)
+		return 1;
+	for(int i = 0; i < a->rank; i++)
+		if(a->shape[i] != b->shape[i])
+			return 1;
+	for(int i = 0; i < a->size; i++){
+		if(a->type == AtypeArray){
+			/* do something recursive here */
+			int sub = comparearray(a->arraydata[i], b->arraydata[i]);
+			if(sub != 0)
+				return sub;
+		}else{
+			int sub = memcmp(
+					a->rawdata + i * datasizes[a->type],
+					b->rawdata + i * datasizes[a->type],
+					datasizes[a->type]);
+			if(sub < 0)
+				return -1;
+			else if(sub > 0)
+				return 1;	
+		}
+	}
+
+	/* if we get here, the arrays are equal */
+	return 0;
 }
\ No newline at end of file
diff --git a/functions.c b/functions.c
index 353ad88..90bb3fb 100644
--- a/functions.c
+++ b/functions.c
@@ -85,7 +85,7 @@ fndyad dyadfunctiondefs[] = {
 	0, /* < */
 	0, /* > */
 	0, /* ≥ */
-	0, /* ≡ */
+	fnMatch, /* ≡ */
 	0, /* ≢ */
 	0, /* ∨ */
 	0, /* ∧ */
@@ -508,6 +508,13 @@ fnRight(Array *left, Array *right)
 	return right;
 }
 
+Array *
+fnMatch(Array *left, Array *right)
+{
+	int cmp = comparearray(left, right);
+	return mkscalarint(cmp == 0);
+}
+
 Array *
 fnCatenateFirst(Array *left, Array *right)
 {
-- 
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