From 8515d45b1e4d454ee0dda0e9c1d822d54d0d6b8b Mon Sep 17 00:00:00 2001
From: Konstantin Nazarov <mail@knazarov.com>
Date: Wed, 4 Sep 2024 23:18:57 +0100
Subject: [PATCH] Use recursion for reading lists

---
 src/reader.cpp | 65 +++++++++++++++++++++++++++-----------------------
 src/reader.hpp | 18 +++++++++-----
 test/dict.cpp  |  4 ++--
 3 files changed, 49 insertions(+), 38 deletions(-)

diff --git a/src/reader.cpp b/src/reader.cpp
index c773999..4a09ec5 100644
--- a/src/reader.cpp
+++ b/src/reader.cpp
@@ -88,31 +88,36 @@ Result<Value> Reader::read_multiple() {
   return ERROR(ReadError);
 }
 
-Result<Value> Reader::read_list() {
-  if (!match('(')) return ERROR(ReadError);
+Result<Value> Reader::read_list_rec(SourcePosition& end) {
+  forward_whitespace();
 
-  forward();
-
-  Value res = TRY(Nil::create());
-
-  while (1) {
-    forward_whitespace();
-
-    if (is_eof()) {
-      return ERROR(ReadError);
-    }
-
-    if (match(')')) {
-      forward();
-      return reverse(res);
-    }
-
-    auto val = TRY(read_one());
-
-    res = Value(TRY(Pair::create(val, res)));
+  if (is_eof()) {
+    return ERROR(ReadError);
   }
 
-  return ERROR(ReadError);
+  if (match(')')) {
+    forward();
+    end = position_;
+    return Value(TRY(Nil::create()));
+  }
+
+  auto val = TRY(read_one());
+  auto rest = TRY(read_list_rec(end));
+
+  auto res = Value(TRY(Pair::create(val, rest)));
+
+  return res;
+}
+
+Result<Value> Reader::read_list() {
+  if (!match('(')) return ERROR(ReadError);
+  // SourcePosition start = position_;
+  forward();
+
+  SourcePosition end = position_;
+  auto res = read_list_rec(end);
+
+  return res;
 }
 
 Result<Value> Reader::read_array_code() {
@@ -517,22 +522,22 @@ bool Reader::forward_exponent() {
   return forward_decimal_number();
 }
 
-Result<Value> read_one(const Value& value, bool as_code) {
+Result<Value> read_one(const Value& value, bool syntax, bool as_code) {
   if (!value.is<String>()) return ERROR(TypeMismatch);
-  auto r = Reader(*value.to<String>(), as_code);
+  auto r = Reader(*value.to<String>(), syntax, as_code);
   return r.read_one();
 }
-Result<Value> read_one(const String& value, bool as_code) {
-  auto r = Reader(value, as_code);
+Result<Value> read_one(const String& value, bool syntax, bool as_code) {
+  auto r = Reader(value, syntax, as_code);
   return r.read_one();
 }
-Result<Value> read_one(const char* value, bool as_code) {
+Result<Value> read_one(const char* value, bool syntax, bool as_code) {
   auto s = TRY(String::create(value));
-  auto r = Reader(s, as_code);
+  auto r = Reader(s, syntax, as_code);
   return r.read_one();
 }
 
-Result<Value> read_multiple(const String& value, bool as_code) {
-  auto r = Reader(value, as_code);
+Result<Value> read_multiple(const String& value, bool syntax, bool as_code) {
+  auto r = Reader(value, syntax, as_code);
   return r.read_multiple();
 }
diff --git a/src/reader.hpp b/src/reader.hpp
index 61c8e45..6fa28be 100644
--- a/src/reader.hpp
+++ b/src/reader.hpp
@@ -5,8 +5,8 @@
 
 class Reader {
  public:
-  Reader(const String& str, bool as_code = true)
-      : _str(str), _as_code(as_code) {}
+  Reader(const String& str, bool syntax = true, bool as_code = true)
+      : _str(str), _syntax(syntax), _as_code(as_code) {}
 
   Result<Value> read_one();
   Result<Value> read_multiple();
@@ -28,6 +28,7 @@ class Reader {
   bool is_string_start();
 
   Result<Value> read_list();
+  Result<Value> read_list_rec(SourcePosition& end);
   Result<Value> read_string();
   Result<Value> read_array();
   Result<Value> read_array_code();
@@ -45,12 +46,17 @@ class Reader {
   bool match(char c);
 
   const String& _str;
+  bool _syntax;
   bool _as_code;
   SourcePosition position_{1, 1, 0};
 };
 
-Result<Value> read_one(const Value& value, bool as_code = true);
-Result<Value> read_one(const String& value, bool as_code = true);
-Result<Value> read_one(const char* value, bool as_code = true);
+Result<Value> read_one(const Value& value, bool syntax = true,
+                       bool as_code = true);
+Result<Value> read_one(const String& value, bool syntax = true,
+                       bool as_code = true);
+Result<Value> read_one(const char* value, bool syntax = true,
+                       bool as_code = true);
 
-Result<Value> read_multiple(const String& value, bool as_code = true);
+Result<Value> read_multiple(const String& value, bool syntax = true,
+                            bool as_code = true);
diff --git a/test/dict.cpp b/test/dict.cpp
index 0909bb7..cc1e51f 100644
--- a/test/dict.cpp
+++ b/test/dict.cpp
@@ -26,11 +26,11 @@ TEST_CASE(dict_insert) {
 }
 
 TEST_CASE(dict_read) {
-  auto v = DIEX(read_one("{}", false));
+  auto v = DIEX(read_one("{}", false, false));
   auto s = DIEX(write_one(v));
   ASSERT_EQUALS(s, "{}");
 
-  v = DIEX(read_one("{1 2 3 4}", false));
+  v = DIEX(read_one("{1 2 3 4}", false, false));
   s = DIEX(write_one(v));
   ASSERT_EQUALS(s, "{1 2 3 4}");