From 534d80c35d19b11e07471ee0a358c9171648546e Mon Sep 17 00:00:00 2001
From: Riyyi <riyyi3@gmail.com>
Date: Sat, 6 May 2023 14:04:58 +0200
Subject: [PATCH] Reader: Prevent infinite loop during List and Vector creation

---
 README.org        |  4 +---
 src/functions.cpp |  1 -
 src/reader.cpp    | 12 ++++++++++--
 src/stepA_mal.cpp |  2 --
 4 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/README.org b/README.org
index c793f5b..2cfbbf0 100644
--- a/README.org
+++ b/README.org
@@ -3,12 +3,10 @@
 #+LANGUAGE: en
 #+OPTIONS: toc:nil
 
-This is my implementation of the [[https://github.com/kanaka/mal][Make A Lisp]] project, done in C++20.
+This is an implementation of the [[https://github.com/kanaka/mal][Make A Lisp]] project, done in C++20.
 
 ** Usage
 
-Change the ~#if 0~ macro at the top of the ~stepX.cpp~ to ~#if 1~.
-
 *** Run the REPL
 
 #+BEGIN_SRC shell-script
diff --git a/src/functions.cpp b/src/functions.cpp
index 875ab98..6e7f209 100644
--- a/src/functions.cpp
+++ b/src/functions.cpp
@@ -168,7 +168,6 @@ ADD_FUNCTION(
 		return makePtr<Constant>((result) ? Constant::True : Constant::False);
 	});
 
-// FIXME: (count {1}) infinite loop
 ADD_FUNCTION(
 	"count",
 	{
diff --git a/src/reader.cpp b/src/reader.cpp
index 037bb09..c21c466 100644
--- a/src/reader.cpp
+++ b/src/reader.cpp
@@ -146,7 +146,11 @@ ValuePtr Reader::readList()
 
 	auto list = makePtr<List>();
 	while (!isEOF() && peek().type != Token::Type::ParenClose) {
-		list->add(readImpl());
+		auto node = readImpl();
+		if (node == nullptr) {
+			return nullptr;
+		}
+		list->add(node);
 	}
 
 	if (!consumeSpecific(Token { .type = Token::Type::ParenClose })) { // )
@@ -163,7 +167,11 @@ ValuePtr Reader::readVector()
 
 	auto vector = makePtr<Vector>();
 	while (!isEOF() && peek().type != Token::Type::BracketClose) {
-		vector->add(readImpl());
+		auto node = readImpl();
+		if (node == nullptr) {
+			return nullptr;
+		}
+		vector->add(node);
 	}
 
 	if (!consumeSpecific(Token { .type = Token::Type::BracketClose })) { // ]
diff --git a/src/stepA_mal.cpp b/src/stepA_mal.cpp
index 4df9ff2..edd699d 100644
--- a/src/stepA_mal.cpp
+++ b/src/stepA_mal.cpp
@@ -24,7 +24,6 @@
 #include "readline.h"
 #include "settings.h"
 
-#if 1
 namespace blaze {
 
 static blaze::Readline s_readline;
@@ -178,4 +177,3 @@ auto main(int argc, char* argv[]) -> int
 
 	return 0;
 }
-#endif