From cca34a1ad7656dd0f9a50fddbf79ba390a4822e5 Mon Sep 17 00:00:00 2001
From: Johannes Kapfhammer <jkapfham@ethz.ch>
Date: Sun, 6 Oct 2019 21:17:37 +0200
Subject: [PATCH] dbg: allow empty argument list

---
 example.cpp              |  3 ++-
 include/bits/soi-dbg.hpp | 30 +++++++++++++++++++++++++-----
 2 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/example.cpp b/example.cpp
index b2c81d9..b7b3195 100644
--- a/example.cpp
+++ b/example.cpp
@@ -5,6 +5,7 @@ signed main() {
   dbg("hi");
   string s="world";
   dbg(s);
+  dbg();
   dbg(false);
   dbg(true);
   dbg('c');
@@ -17,5 +18,5 @@ signed main() {
   dbg(map<int, string>{{3,"three"},{1,"one"}});
   dbg(unordered_map<int, string>{{3,"three"},{1,"one"}});
   dbg(unordered_set<int>{3,1,4});
-  cout << "hi\n";
+  dbg();
 }
diff --git a/include/bits/soi-dbg.hpp b/include/bits/soi-dbg.hpp
index 346b3ee..7da31f9 100644
--- a/include/bits/soi-dbg.hpp
+++ b/include/bits/soi-dbg.hpp
@@ -183,6 +183,11 @@ auto dbg_print(const char (&msg)[N], std::string const &, char const *file,
   return msg;
 }
 
+void dbg_print_status(char const *file, int line, char const *function_name) {
+  std::cerr << ANSI_VALUE << "[" << file << ":" << line << " (" << function_name
+            << ")]" << ANSI_VALUE << '\n';
+}
+
 template <typename T> T &&identity(T &&t) { return std::forward<T>(t); }
 
 } // end namespace detail
@@ -192,11 +197,26 @@ template <typename T> T &&identity(T &&t) { return std::forward<T>(t); }
 #ifdef SOI_RELEASE
 #define dbg(...) dbg_macro::identity(__VA_ARGS__)
 #else
-#define dbg(...)                                                               \
-  soi::detail::dbg_print(                                                      \
-      (__VA_ARGS__),                                                           \
-      soi::detail::sanitized_type_name<decltype(__VA_ARGS__)>(), __FILE__,     \
-      __LINE__, __func__, #__VA_ARGS__)
+
+#define SOI_ARG16(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, ...) _15
+#define SOI_IS_NONEMPTY(...) SOI_ARG16(1, ##__VA_ARGS__, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0)
+
+#define SOI_DBG_IMPL_0()                                \
+  soi::detail::dbg_print_status(__FILE__, __LINE__, __func__)
+#define SOI_DBG_IMPL_1(...)                                             \
+  soi::detail::dbg_print((__VA_ARGS__),                                 \
+                         soi::detail::sanitized_type_name<decltype(__VA_ARGS__)>(), __FILE__, \
+                         __LINE__, __func__, #__VA_ARGS__)
+
+
+#define SOI_CAT(a, ...) PRIMITIVE_CAT(a, __VA_ARGS__)
+#define SOI_PRIMITIVE_CAT(a, ...) a ## __VA_ARGS__
+
+#define SOI_DBG_IMPL(is_nonempty, ...)                          \
+  SOI_PRIMITIVE_CAT(SOI_DBG_IMPL_, is_nonempty)(__VA_ARGS__)
+
+#define dbg(...)                                                       \
+  SOI_DBG_IMPL(SOI_IS_NONEMPTY(__VA_ARGS__), __VA_ARGS__)
 #endif
 
 #endif // SOI_DBG