fix: [log] adjust code interface and fix bugs

benchmark/benchmark_log.cpp

@@ -5,6 +5,13 @@
 
 namespace {
 
+void BM_imp_log_no_output(benchmark::State& state) {
+  imp::log::gripper log {{}, __func__};
+  for (auto _ : state) {
+    log.debug("hello log.");
+  }
+}
+
 void BM_imp_log_gripper(benchmark::State& state) {
   imp::log::gripper log {{}, __func__};
   for (auto _ : state) {
@@ -14,4 +21,5 @@ void BM_imp_log_gripper(benchmark::State& state) {
 
 } // namespace
 
+BENCHMARK(BM_imp_log_no_output);
 BENCHMARK(BM_imp_log_gripper);

include/libimp/log.h

@@ -16,108 +16,9 @@
 #include "libimp/def.h"
 #include "libimp/detect_plat.h"
 #include "libimp/export.h"
+#include "libimp/enum_cast.h"
 
 LIBIMP_NAMESPACE_BEG_
-
-namespace detail_log {
-
-template <typename T>
-class has_fn_info {
-  static std::false_type check(...);
-  template <typename U>
-  static auto check(U *u) -> decltype(u->info(std::declval<std::string>()), std::true_type{});
-
-public:
-  using type = decltype(check(static_cast<T *>(nullptr)));
-};
-
-template <typename T>
-constexpr bool has_fn_info_v = has_fn_info<T>::type::value;
-
-template <typename T>
-class has_fn_error {
-  static std::false_type check(...);
-  template <typename U>
-  static auto check(U *u) -> decltype(u->error(std::declval<std::string>()), std::true_type{});
-
-public:
-  using type = decltype(check(static_cast<T *>(nullptr)));
-};
-
-template <typename T>
-constexpr bool has_fn_error_v = has_fn_error<T>::type::value;
-
-struct vtable_t {
-  void (*info )(void *, std::string &&);
-  void (*error)(void *, std::string &&);
-};
-
-template <typename T>
-class traits {
-  template <typename U>
-  static auto make_fn_info() noexcept
-    -> std::enable_if_t<has_fn_info_v<U>, void (*)(void *, std::string &&)> {
-    return [](void *p, std::string &&s) {
-      static_cast<U *>(p)->info(std::move(s));
-    };
-  }
-  template <typename U>
-  static auto make_fn_info() noexcept
-    -> std::enable_if_t<!has_fn_info_v<U>, void (*)(void *, std::string &&)> {
-    return [](void *, std::string &&) {};
-  }
-
-  template <typename U>
-  static auto make_fn_error() noexcept
-    -> std::enable_if_t<has_fn_error_v<U>, void (*)(void *, std::string &&)> {
-    return [](void *p, std::string &&s) {
-      static_cast<U *>(p)->error(std::move(s));
-    };
-  }
-  template <typename U>
-  static auto make_fn_error() noexcept
-    -> std::enable_if_t<!has_fn_error_v<U>, void (*)(void *, std::string &&)> {
-    return [](void *, std::string &&) {};
-  }
-
-public:
-  static auto make_vtable() noexcept {
-    static vtable_t vt {
-      make_fn_info <T>(),
-      make_fn_error<T>(),
-    };
-    return &vt;
-  }
-};
-
-} // namespace detail_log
-
-class LIBIMP_EXPORT log_printer {
-  void *objp_ {nullptr};
-  detail_log::vtable_t *vtable_ {nullptr};
-
-public:
-  log_printer() noexcept = default;
-
-  template <typename T>
-  log_printer(T &p) noexcept
-    : objp_  (static_cast<void *>(&p))
-    , vtable_(detail_log::traits<T>::make_vtable()) {}
-
-  explicit operator bool() const noexcept;
-
-  void info (std::string &&);
-  void error(std::string &&);
-};
-
-class LIBIMP_EXPORT log_std_t {
-public:
-  void info (std::string &&) const;
-  void error(std::string &&) const;
-};
-
-LIBIMP_EXPORT extern log_std_t log_std;
-
 namespace log {
 
 template <typename Fmt, typename... A>
@@ -125,30 +26,137 @@ std::string fmt(Fmt &&ft, A &&... args) {
   return ::fmt::format(std::forward<Fmt>(ft), std::forward<A>(args)...);
 }
 
-class LIBIMP_EXPORT gripper {
-  log_printer printer_;
-  char const *func_;
+enum class level : std::int32_t {
+  trace,
+  debug,
+  info,
+  warning,
+  error,
+  failed,
+};
 
-  gripper &output(void (log_printer::*out_fn)(std::string &&), char type, std::string &&log_str) {
-    auto tm = std::chrono::system_clock::now();
-    auto ms = std::chrono::time_point_cast<std::chrono::milliseconds>(tm).time_since_epoch().count() % 1000;
-    auto px = fmt("[{}][{:%Y-%m-%d %H:%M:%S}.{:03}][{}]\n", type, tm, ms, func_);
-    (printer_.*out_fn)(std::move(px += std::move(log_str)));
+} // namespace log
+
+namespace detail_log {
+
+template <typename T>
+class has_fn_output {
+  static std::false_type check(...);
+  template <typename U>
+  static auto check(U *u) -> decltype(u->output(log::level::trace, std::declval<std::string>()), std::true_type{});
+
+public:
+  using type = decltype(check(static_cast<T *>(nullptr)));
+};
+
+template <typename T>
+constexpr bool has_fn_output_v = has_fn_output<T>::type::value;
+
+struct vtable_t {
+  void (*output)(void *, log::level, std::string &&);
+};
+
+template <typename T>
+class traits {
+  template <typename U>
+  static auto make_fn_output() noexcept
+    -> std::enable_if_t<has_fn_output_v<U>, void (*)(void *, log::level, std::string &&)> {
+    return [](void *p, log::level l, std::string &&s) {
+      static_cast<U *>(p)->output(l, std::move(s));
+    };
+  }
+  template <typename U>
+  static auto make_fn_output() noexcept
+    -> std::enable_if_t<!has_fn_output_v<U>, void (*)(void *, log::level, std::string &&)> {
+    return [](void *, log::level, std::string &&) {};
+  }
+
+public:
+  static auto make_vtable() noexcept {
+    static vtable_t vt {
+      make_fn_output<T>(),
+    };
+    return &vt;
+  }
+};
+
+} // namespace detail_log
+
+namespace log {
+
+class LIBIMP_EXPORT printer {
+  void *objp_ {nullptr};
+  detail_log::vtable_t *vtable_ {nullptr};
+
+public:
+  printer() noexcept = default;
+
+  template <typename T>
+  printer(T &p) noexcept
+    : objp_  (static_cast<void *>(&p))
+    , vtable_(detail_log::traits<T>::make_vtable()) {}
+
+  explicit operator bool() const noexcept;
+
+  void output(log::level, std::string &&);
+};
+
+class LIBIMP_EXPORT std_t {
+public:
+  void output(log::level, std::string &&);
+};
+
+LIBIMP_EXPORT extern std_t std_out;
+
+class gripper {
+  printer printer_;
+  char const *func_;
+  level level_limit_;
+
+  template <typename Fmt, typename... A>
+  gripper &output(log::level l, Fmt &&ft, A &&... args) {
+    if (!printer_ || (enum_cast(l) < enum_cast(level_limit_))) {
+      return *this;
+    }
+    constexpr static char types[] = {
+      'T', 'D', 'I', 'W', 'E', 'F'
+    };
+    auto tp = std::chrono::system_clock::now();
+    auto ms = std::chrono::time_point_cast<std::chrono::milliseconds>(tp).time_since_epoch().count() % 1000;
+    auto px = fmt("[{}][{:%Y-%m-%d %H:%M:%S}.{:03}][{}] ", types[enum_cast(l)], tp, ms, func_);
+    printer_.output(l, std::move(px += fmt(std::forward<Fmt>(ft), std::forward<A>(args)...)));
     return *this;
   }
 
 public:
-  gripper(log_printer printer, char const *func) noexcept 
-    : printer_(printer)
-    , func_   (func) {}
+  gripper(printer printer, char const *func, level level_limit = level::info) noexcept 
+    : printer_    (printer)
+    , func_       (func)
+    , level_limit_(level_limit) {}
 
+  template <typename Fmt, typename... A>
+  gripper &trace(Fmt &&ft, A &&... args) {
+    return output(log::level::trace, std::forward<Fmt>(ft), std::forward<A>(args)...);
+  }
+  template <typename Fmt, typename... A>
+  gripper &debug(Fmt &&ft, A &&... args) {
+    return output(log::level::debug, std::forward<Fmt>(ft), std::forward<A>(args)...);
+  }
   template <typename Fmt, typename... A>
   gripper &info(Fmt &&ft, A &&... args) {
-    return output(&log_printer::info, 'I', fmt(std::forward<Fmt>(ft), std::forward<A>(args)...));
+    return output(log::level::info, std::forward<Fmt>(ft), std::forward<A>(args)...);
+  }
+  template <typename Fmt, typename... A>
+  gripper &warning(Fmt &&ft, A &&... args) {
+    return output(log::level::warning, std::forward<Fmt>(ft), std::forward<A>(args)...);
   }
   template <typename Fmt, typename... A>
   gripper &error(Fmt &&ft, A &&... args) {
-    return output(&log_printer::error, 'E', fmt(std::forward<Fmt>(ft), std::forward<A>(args)...));
+    return output(log::level::error, std::forward<Fmt>(ft), std::forward<A>(args)...);
+  }
+  template <typename Fmt, typename... A>
+  gripper &failed(Fmt &&ft, A &&... args) {
+    return output(log::level::failed, std::forward<Fmt>(ft), std::forward<A>(args)...);
   }
 };
 

src/libimp/log.cpp

@@ -5,29 +5,35 @@
 #include "libimp/log.h"
 
 LIBIMP_NAMESPACE_BEG_
+namespace log {
 
-log_printer::operator bool() const noexcept {
+printer::operator bool() const noexcept {
   return (objp_ != nullptr) && (vtable_ != nullptr);
 }
 
-void log_printer::info(std::string && s) {
+void printer::output(log::level l, std::string &&s) {
   if (!*this) return;
-  vtable_->info(objp_, std::move(s));
+  vtable_->output(objp_, l, std::move(s));
 }
 
-void log_printer::error(std::string && s) {
-  if (!*this) return;
-  vtable_->error(objp_, std::move(s));
-}
-
-log_std_t log_std;
-
-void log_std_t::info(std::string && s) const {
-  std::fprintf(stdin, "%s", s.c_str());
-}
-
-void log_std_t::error(std::string && s) const {
-  std::fprintf(stderr, "%s", s.c_str());
+std_t std_out;
+
+void std_t::output(log::level l, std::string &&s) {
+  switch (l) {
+  case level::trace:
+  case level::debug:
+  case level::info:
+    std::fprintf(stdout, "%s\n", s.c_str());
+    break;
+  case level::warning:
+  case level::error:
+  case level::failed:
+    std::fprintf(stderr, "%s\n", s.c_str());
+    break;
+  default:
+    break;
+  }
 }
 
+} // namespace log
 LIBIMP_NAMESPACE_END_

test/test_imp_log.cpp

@@ -4,49 +4,43 @@
 #include "libimp/log.h"
 
 TEST(log, detail) {
-  EXPECT_FALSE(imp::detail_log::has_fn_info_v<int>);
-  EXPECT_FALSE(imp::detail_log::has_fn_error_v<int>);
+  EXPECT_FALSE(imp::detail_log::has_fn_output_v<int>);
 
   struct foo {
     int info(std::string);
   };
-  EXPECT_TRUE (imp::detail_log::has_fn_info_v<foo>);
-  EXPECT_FALSE(imp::detail_log::has_fn_error_v<foo>);
+  EXPECT_FALSE(imp::detail_log::has_fn_output_v<foo>);
 
   struct bar {
     int info(char const *);
-    void error(std::string &&);
+    void output(imp::log::level, std::string &&);
   };
-  EXPECT_FALSE(imp::detail_log::has_fn_info_v<bar>);
-  EXPECT_TRUE (imp::detail_log::has_fn_error_v<bar>);
+  EXPECT_TRUE(imp::detail_log::has_fn_output_v<bar>);
 
   struct str {
     str(std::string const &);
   };
   struct foo_bar {
-    void info(std::string const &);
-    void error(str);
+    void output(imp::log::level, str);
   };
-  EXPECT_TRUE(imp::detail_log::has_fn_info_v<foo_bar>);
-  EXPECT_TRUE(imp::detail_log::has_fn_error_v<foo_bar>);
+  EXPECT_TRUE(imp::detail_log::has_fn_output_v<foo_bar>);
 
   auto vt_int = imp::detail_log::traits<int>::make_vtable();
   EXPECT_NE(vt_int, nullptr);
-  vt_int->info (nullptr, "123");
-  vt_int->error(nullptr, "321");
+  vt_int->output(nullptr, imp::log::level::debug, "123");
 
   struct log {
     std::string what;
-    void error(std::string &&s) {
-      what += s;
+    void output(imp::log::level l, std::string &&s) {
+      if (l == imp::log::level::error) what += s;
     }
   } ll;
   auto vt_log = imp::detail_log::traits<log>::make_vtable();
   EXPECT_NE(vt_log, nullptr);
-  vt_log->info (&ll, "123");
-  vt_log->error(&ll, "321");
-  vt_log->info (&ll, "654");
-  vt_log->error(&ll, "456");
+  vt_log->output(&ll, imp::log::level::info , "123");
+  vt_log->output(&ll, imp::log::level::error, "321");
+  vt_log->output(&ll, imp::log::level::info , "654");
+  vt_log->output(&ll, imp::log::level::error, "456");
   EXPECT_EQ(ll.what, "321456");
 }
 
@@ -54,27 +48,26 @@ TEST(log, log_printer) {
   struct log {
     std::string i;
     std::string e;
-    void info(std::string &&s) {
-      i += s;
-    }
-    void error(std::string &&s) {
-      e += s;
+
+    void output(imp::log::level l, std::string &&s) {
+      if (l == imp::log::level::error) e += s;
+      else if (l == imp::log::level::info) i += s;
     }
   } ll;
 
-  imp::log_printer pt = ll;
-  pt.info("hello ");
-  pt.error("failed: ");
-  pt.info("log-pt");
-  pt.error("whatever");
+  imp::log::printer pt = ll;
+  pt.output(imp::log::level::info , "hello ");
+  pt.output(imp::log::level::error, "failed: ");
+  pt.output(imp::log::level::info , "log-pt");
+  pt.output(imp::log::level::error, "whatever");
   EXPECT_EQ(ll.i, "hello log-pt");
   EXPECT_EQ(ll.e, "failed: whatever");
 
-  imp::log_printer ps = imp::log_std;
-  ps.info("hello world\n");
+  imp::log::printer ps = imp::log::std_out;
+  ps.output(imp::log::level::info, "hello world\n");
 }
 
 TEST(log, gripper) {
-  imp::log::gripper log {imp::log_std, __func__};
+  imp::log::gripper log {imp::log::std_out, __func__};
   log.info("hello");
 }