From 0b0823837fd6a73e1fda0bdbf0b65d51a5e7b770 Mon Sep 17 00:00:00 2001
From: Alexandre Plateau <lexplt.dev@gmail.com>
Date: Sun, 20 Oct 2024 22:37:36 +0200
Subject: [PATCH] fix(macro processor): empty\? should work with nil when
 evaluated as a macro

tail also works in macros with non-list nodes
---
 src/arkreactor/Compiler/Macros/Processor.cpp  | 20 ++++++++++---------
 .../resources/LangSuite/macro-tests.ark       | 19 ++++++++++++++++--
 2 files changed, 28 insertions(+), 11 deletions(-)

diff --git a/src/arkreactor/Compiler/Macros/Processor.cpp b/src/arkreactor/Compiler/Macros/Processor.cpp
index 032b5a4d8..1574859b5 100644
--- a/src/arkreactor/Compiler/Macros/Processor.cpp
+++ b/src/arkreactor/Compiler/Macros/Processor.cpp
@@ -396,16 +396,16 @@ namespace Ark::internal
             {
                 if (node.list().size() > 2)
                     throwMacroProcessingError(fmt::format("When expanding `empty?' inside a macro, got {} arguments, expected 1", argcount), node);
-                if (Node& lst = node.list()[1]; lst.nodeType() == NodeType::List)  // only apply len at compile time if we can
+                if (Node& lst = node.list()[1]; lst.nodeType() == NodeType::List && isConstEval(lst))
                 {
-                    if (isConstEval(lst))
-                    {
-                        if (!lst.list().empty() && lst.list()[0] == getListNode())
-                            setWithFileAttributes(node, node, lst.list().size() - 1 == 0 ? getTrueNode() : getFalseNode());
-                        else
-                            setWithFileAttributes(node, node, lst.list().size() == 0 ? getTrueNode() : getFalseNode());
-                    }
+                    // only apply len at compile time if we can
+                    if (!lst.list().empty() && lst.list()[0] == getListNode())
+                        setWithFileAttributes(node, node, lst.list().size() - 1 == 0 ? getTrueNode() : getFalseNode());
+                    else
+                        setWithFileAttributes(node, node, lst.list().empty() ? getTrueNode() : getFalseNode());
                 }
+                else if (lst == getNilNode())
+                    setWithFileAttributes(node, node, getTrueNode());
             }
             else if (name == "@")
             {
@@ -487,6 +487,7 @@ namespace Ark::internal
                     else if (!sublist.list().empty())
                     {
                         sublist.list().erase(sublist.constList().begin());
+                        sublist.list().insert(sublist.list().begin(), getListNode());
                         setWithFileAttributes(node, node, sublist);
                     }
                     else
@@ -692,7 +693,8 @@ namespace Ark::internal
                 return it != Language::operators.end() ||
                     it2 != Builtins::builtins.end() ||
                     findNearestMacro(node.string()) != nullptr ||
-                    node.string() == "list";
+                    node.string() == "list" ||
+                    node.string() == "nil";
             }
 
             case NodeType::List:
diff --git a/tests/unittests/resources/LangSuite/macro-tests.ark b/tests/unittests/resources/LangSuite/macro-tests.ark
index d33598b78..faef3ddf5 100644
--- a/tests/unittests/resources/LangSuite/macro-tests.ark
+++ b/tests/unittests/resources/LangSuite/macro-tests.ark
@@ -27,8 +27,23 @@
         (test:eq (add_two 1 2) 3)
         (test:eq (add_two nice_value 2) 14)
 
-        ($ c (* 4 (/ 10 2)))
-        (test:eq c 20) })
+        ($ c (a b) (* a b))
+        (test:eq (c 4 10) 40)
+
+        ($ d (a b) (/ a b))
+        (test:eq (d 10 2) 5) })
+
+    (test:case "node manipulation" {
+        ($ node_tail () (tail (begin 1 2 3)))
+        ($ length () (len (fun () 5)))
+        ($ not_empty_node () (empty? (fun () ())))
+        ($ empty_node () (empty? ()))
+
+        (test:eq (length) 3)
+        (test:eq (not_empty_node) false)
+        (test:eq (empty_node) true)
+        # because it removes the "begin"
+        (test:eq (node_tail) [1 2 3]) })
 
     (test:case "conditional macros" {
         (test:expect ($if (and true true) true false))