From e425895a315d65ff9ca1e2d7911c2fd21d49fe5e Mon Sep 17 00:00:00 2001
From: Peter Mikkelsen <petermikkelsen10@gmail.com>
Date: Mon, 9 May 2022 18:59:23 +0000
Subject: =?UTF-8?q?Fix=20some=20nasty=20bugs=20with=20empty=20lines=20in?=
 =?UTF-8?q?=20dfns,=20and=20with=20stranding=20of=20=E2=8D=BA=20and=20?=
 =?UTF-8?q?=E2=8D=B5.?=
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---
 concurrency.c   |  5 ++++-
 error.c         |  2 +-
 eval.c          |  2 ++
 lexer.c         |  8 +++++++-
 tests/chain.apl |  7 ++++---
 tests/demo.apl  | 31 +++++++++++++++++++++++++++++++
 6 files changed, 49 insertions(+), 6 deletions(-)
 create mode 100644 tests/demo.apl

diff --git a/concurrency.c b/concurrency.c
index 81ff7b1..1d06a9c 100644
--- a/concurrency.c
+++ b/concurrency.c
@@ -49,7 +49,7 @@ spawnthread(Function f, Array *left, Array *right)
 	*/
 	Channel *setupdone = chancreate(sizeof(int), 0);
 	SpawnData *sp = emalloc(sizeof(SpawnData));
-	sp->func = f;
+	sp->func = dupfunction(f);
 	sp->left = left ? duparray(left) : nil;
 	sp->right = duparray(right);
 	sp->setupdone = setupdone;
@@ -87,6 +87,8 @@ messagesend(Array *a, int id)
 		td->lastmail = newmail;
 		rwakeup(&td->empty);
 		qunlock(&td->lock);
+	}else{
+		throwerror(L"Invalid thread id", EDomain);
 	}
 }
 
@@ -134,6 +136,7 @@ newprocfn(void *data)
 	unlock(&threadlock);
 	freearray(sp->left);
 	freearray(sp->right);
+	freefunction(sp->func);
 	free(sp);
 	free(td);
 }
diff --git a/error.c b/error.c
index ee6ffe9..e12318a 100644
--- a/error.c
+++ b/error.c
@@ -37,7 +37,7 @@ throwerror(Rune *msg, int err)
 	td->lasterror = err;
 	if(td->lasterrormsg)
 		free(td->lasterrormsg);
-	td->lasterrormsg = msg;
+	td->lasterrormsg = runestrdup(msg);
 
 	while(frame != nil){
 		for(ErrorGuard *eg = frame->errorguards; eg != nil; eg = eg->next){
diff --git a/eval.c b/eval.c
index 3174cd4..cfe5854 100644
--- a/eval.c
+++ b/eval.c
@@ -202,6 +202,7 @@ monadfun(Datum *left, Datum *right)
 {
 	traceprint("Monadic function application\n");
 	Datum *result = allocdatum(ArrayTag, 0);
+	SetStrand(right->array, 0);
 	result->array = runfunc(left->func, left->func.left, right->array);
 	return result;
 }
@@ -218,6 +219,7 @@ dyadfun(Datum *left, Datum *right)
 		result->func.code = right->hybrid;
 	}
 	result->func.left = fnSame(left->array);
+	SetStrand(result->func.left, 0);
 	return result;
 }
 
diff --git a/lexer.c b/lexer.c
index 4e9a4e4..9ce251a 100644
--- a/lexer.c
+++ b/lexer.c
@@ -72,8 +72,14 @@ lexline(InputStream *input, int toplevel)
 			case L'⋄':
 				if(stmt->ntoks == 0)
 					stmt = lexline(input, toplevel);
-				else
+				else{
 					stmt->next = lexline(input, toplevel);
+					if(stmt->next && stmt->next->ntoks == 0){ // Prevent empty statements
+						freestatement(*(stmt->next));
+						free(stmt->next);
+						stmt->next = nil;
+					}
+				}
 				goto end;
 			case L'⍝':
 				while(peek != '\n' && !inputEOF(input))
diff --git a/tests/chain.apl b/tests/chain.apl
index f6ab04b..aeeab52 100644
--- a/tests/chain.apl
+++ b/tests/chain.apl
@@ -1,8 +1,9 @@
 worker←{
-	msg←{1}⍇0
-	⎕←'Worker id ',(⍕⎕self),' got message: ',(⍕msg),' forwarding to ',⍕⍵
+	msg←1⍨⍇0
 	⍵≡⍬: ⎕←'DONE'
+	⎕←'Worker id ',(⍕⎕self),' got message: ',(⍕msg)
+	⎕←'Forwarding from ',(⍕⎕self), ' to ',⍕⍵
 	msg⍈⍵
 }
-last←worker&⍣100⊢⍬
+last←worker&⍣10⊢⍬
 'Hello there'⍈last
diff --git a/tests/demo.apl b/tests/demo.apl
new file mode 100644
index 0000000..7a6ddca
--- /dev/null
+++ b/tests/demo.apl
@@ -0,0 +1,31 @@
+⍝ The following demonstrates message passing between an 'iota sever',
+⍝ and a client (the user of the iota function). The client always initiates
+⍝ communication, and the server must be running, but the client should not
+⍝ be able to notice a difference between monadic ⍳ and the iota function,
+⍝ even though one does the computation in a different thread.
+
+iotaServer←{
+	msg←1⍨⍇0
+	msg≡'stop': ⎕←'Bye bye from indexer'
+	(from num)←msg
+	_←(⍳num)⍈from
+	∇⍵
+}
+
+id←0 ⍝ this is an invalid thread id, so it is a sane starting point
+
+start←{
+	id=0: iotaServer&⍬
+	id
+}
+
+stop←{
+	'stop'⍈id
+}
+
+iota←{
+	⍝ Sending messages to a nonexisting thread throws a domain error (11)
+	11::'Sorry, the iota server is not running'
+	_←(⎕self ⍵)⍈id
+	1⍨⍇0
+}
-- 
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